<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<meta name="generator" content="rustdoc">
<meta name="description" content="Source to the Rust file `/Users/travis/.cargo/registry/src/github.com-1ecc6299db9ec823/futures-0.1.20/src/sync/mpsc/mod.rs`.">
<meta name="keywords" content="rust, rustlang, rust-lang">
<title>mod.rs.html -- source</title>
<link rel="stylesheet" type="text/css" href="../../../../normalize.css">
<link rel="stylesheet" type="text/css" href="../../../../rustdoc.css" id="mainThemeStyle">
<link rel="stylesheet" type="text/css" href="../../../../dark.css">
<link rel="stylesheet" type="text/css" href="../../../../main.css" id="themeStyle">
<script src="../../../../storage.js"></script>
</head>
<body class="rustdoc source">
<!--[if lte IE 8]>
<div class="warning">
This old browser is unsupported and will most likely display funky
things.
</div>
<![endif]-->
<nav class="sidebar">
<div class="sidebar-menu">☰</div>
</nav>
<div class="theme-picker">
<button id="theme-picker" aria-label="Pick another theme!">
<img src="../../../../brush.svg" width="18" alt="Pick another theme!">
</button>
<div id="theme-choices"></div>
</div>
<script src="../../../../theme.js"></script>
<nav class="sub">
<form class="search-form js-only">
<div class="search-container">
<input class="search-input" name="search"
autocomplete="off"
placeholder="Click or press ‘S’ to search, ‘?’ for more options…"
type="search">
</div>
</form>
</nav>
<section id='main' class="content"><pre class="line-numbers"><span id="1"> 1</span>
<span id="2"> 2</span>
<span id="3"> 3</span>
<span id="4"> 4</span>
<span id="5"> 5</span>
<span id="6"> 6</span>
<span id="7"> 7</span>
<span id="8"> 8</span>
<span id="9"> 9</span>
<span id="10"> 10</span>
<span id="11"> 11</span>
<span id="12"> 12</span>
<span id="13"> 13</span>
<span id="14"> 14</span>
<span id="15"> 15</span>
<span id="16"> 16</span>
<span id="17"> 17</span>
<span id="18"> 18</span>
<span id="19"> 19</span>
<span id="20"> 20</span>
<span id="21"> 21</span>
<span id="22"> 22</span>
<span id="23"> 23</span>
<span id="24"> 24</span>
<span id="25"> 25</span>
<span id="26"> 26</span>
<span id="27"> 27</span>
<span id="28"> 28</span>
<span id="29"> 29</span>
<span id="30"> 30</span>
<span id="31"> 31</span>
<span id="32"> 32</span>
<span id="33"> 33</span>
<span id="34"> 34</span>
<span id="35"> 35</span>
<span id="36"> 36</span>
<span id="37"> 37</span>
<span id="38"> 38</span>
<span id="39"> 39</span>
<span id="40"> 40</span>
<span id="41"> 41</span>
<span id="42"> 42</span>
<span id="43"> 43</span>
<span id="44"> 44</span>
<span id="45"> 45</span>
<span id="46"> 46</span>
<span id="47"> 47</span>
<span id="48"> 48</span>
<span id="49"> 49</span>
<span id="50"> 50</span>
<span id="51"> 51</span>
<span id="52"> 52</span>
<span id="53"> 53</span>
<span id="54"> 54</span>
<span id="55"> 55</span>
<span id="56"> 56</span>
<span id="57"> 57</span>
<span id="58"> 58</span>
<span id="59"> 59</span>
<span id="60"> 60</span>
<span id="61"> 61</span>
<span id="62"> 62</span>
<span id="63"> 63</span>
<span id="64"> 64</span>
<span id="65"> 65</span>
<span id="66"> 66</span>
<span id="67"> 67</span>
<span id="68"> 68</span>
<span id="69"> 69</span>
<span id="70"> 70</span>
<span id="71"> 71</span>
<span id="72"> 72</span>
<span id="73"> 73</span>
<span id="74"> 74</span>
<span id="75"> 75</span>
<span id="76"> 76</span>
<span id="77"> 77</span>
<span id="78"> 78</span>
<span id="79"> 79</span>
<span id="80"> 80</span>
<span id="81"> 81</span>
<span id="82"> 82</span>
<span id="83"> 83</span>
<span id="84"> 84</span>
<span id="85"> 85</span>
<span id="86"> 86</span>
<span id="87"> 87</span>
<span id="88"> 88</span>
<span id="89"> 89</span>
<span id="90"> 90</span>
<span id="91"> 91</span>
<span id="92"> 92</span>
<span id="93"> 93</span>
<span id="94"> 94</span>
<span id="95"> 95</span>
<span id="96"> 96</span>
<span id="97"> 97</span>
<span id="98"> 98</span>
<span id="99"> 99</span>
<span id="100"> 100</span>
<span id="101"> 101</span>
<span id="102"> 102</span>
<span id="103"> 103</span>
<span id="104"> 104</span>
<span id="105"> 105</span>
<span id="106"> 106</span>
<span id="107"> 107</span>
<span id="108"> 108</span>
<span id="109"> 109</span>
<span id="110"> 110</span>
<span id="111"> 111</span>
<span id="112"> 112</span>
<span id="113"> 113</span>
<span id="114"> 114</span>
<span id="115"> 115</span>
<span id="116"> 116</span>
<span id="117"> 117</span>
<span id="118"> 118</span>
<span id="119"> 119</span>
<span id="120"> 120</span>
<span id="121"> 121</span>
<span id="122"> 122</span>
<span id="123"> 123</span>
<span id="124"> 124</span>
<span id="125"> 125</span>
<span id="126"> 126</span>
<span id="127"> 127</span>
<span id="128"> 128</span>
<span id="129"> 129</span>
<span id="130"> 130</span>
<span id="131"> 131</span>
<span id="132"> 132</span>
<span id="133"> 133</span>
<span id="134"> 134</span>
<span id="135"> 135</span>
<span id="136"> 136</span>
<span id="137"> 137</span>
<span id="138"> 138</span>
<span id="139"> 139</span>
<span id="140"> 140</span>
<span id="141"> 141</span>
<span id="142"> 142</span>
<span id="143"> 143</span>
<span id="144"> 144</span>
<span id="145"> 145</span>
<span id="146"> 146</span>
<span id="147"> 147</span>
<span id="148"> 148</span>
<span id="149"> 149</span>
<span id="150"> 150</span>
<span id="151"> 151</span>
<span id="152"> 152</span>
<span id="153"> 153</span>
<span id="154"> 154</span>
<span id="155"> 155</span>
<span id="156"> 156</span>
<span id="157"> 157</span>
<span id="158"> 158</span>
<span id="159"> 159</span>
<span id="160"> 160</span>
<span id="161"> 161</span>
<span id="162"> 162</span>
<span id="163"> 163</span>
<span id="164"> 164</span>
<span id="165"> 165</span>
<span id="166"> 166</span>
<span id="167"> 167</span>
<span id="168"> 168</span>
<span id="169"> 169</span>
<span id="170"> 170</span>
<span id="171"> 171</span>
<span id="172"> 172</span>
<span id="173"> 173</span>
<span id="174"> 174</span>
<span id="175"> 175</span>
<span id="176"> 176</span>
<span id="177"> 177</span>
<span id="178"> 178</span>
<span id="179"> 179</span>
<span id="180"> 180</span>
<span id="181"> 181</span>
<span id="182"> 182</span>
<span id="183"> 183</span>
<span id="184"> 184</span>
<span id="185"> 185</span>
<span id="186"> 186</span>
<span id="187"> 187</span>
<span id="188"> 188</span>
<span id="189"> 189</span>
<span id="190"> 190</span>
<span id="191"> 191</span>
<span id="192"> 192</span>
<span id="193"> 193</span>
<span id="194"> 194</span>
<span id="195"> 195</span>
<span id="196"> 196</span>
<span id="197"> 197</span>
<span id="198"> 198</span>
<span id="199"> 199</span>
<span id="200"> 200</span>
<span id="201"> 201</span>
<span id="202"> 202</span>
<span id="203"> 203</span>
<span id="204"> 204</span>
<span id="205"> 205</span>
<span id="206"> 206</span>
<span id="207"> 207</span>
<span id="208"> 208</span>
<span id="209"> 209</span>
<span id="210"> 210</span>
<span id="211"> 211</span>
<span id="212"> 212</span>
<span id="213"> 213</span>
<span id="214"> 214</span>
<span id="215"> 215</span>
<span id="216"> 216</span>
<span id="217"> 217</span>
<span id="218"> 218</span>
<span id="219"> 219</span>
<span id="220"> 220</span>
<span id="221"> 221</span>
<span id="222"> 222</span>
<span id="223"> 223</span>
<span id="224"> 224</span>
<span id="225"> 225</span>
<span id="226"> 226</span>
<span id="227"> 227</span>
<span id="228"> 228</span>
<span id="229"> 229</span>
<span id="230"> 230</span>
<span id="231"> 231</span>
<span id="232"> 232</span>
<span id="233"> 233</span>
<span id="234"> 234</span>
<span id="235"> 235</span>
<span id="236"> 236</span>
<span id="237"> 237</span>
<span id="238"> 238</span>
<span id="239"> 239</span>
<span id="240"> 240</span>
<span id="241"> 241</span>
<span id="242"> 242</span>
<span id="243"> 243</span>
<span id="244"> 244</span>
<span id="245"> 245</span>
<span id="246"> 246</span>
<span id="247"> 247</span>
<span id="248"> 248</span>
<span id="249"> 249</span>
<span id="250"> 250</span>
<span id="251"> 251</span>
<span id="252"> 252</span>
<span id="253"> 253</span>
<span id="254"> 254</span>
<span id="255"> 255</span>
<span id="256"> 256</span>
<span id="257"> 257</span>
<span id="258"> 258</span>
<span id="259"> 259</span>
<span id="260"> 260</span>
<span id="261"> 261</span>
<span id="262"> 262</span>
<span id="263"> 263</span>
<span id="264"> 264</span>
<span id="265"> 265</span>
<span id="266"> 266</span>
<span id="267"> 267</span>
<span id="268"> 268</span>
<span id="269"> 269</span>
<span id="270"> 270</span>
<span id="271"> 271</span>
<span id="272"> 272</span>
<span id="273"> 273</span>
<span id="274"> 274</span>
<span id="275"> 275</span>
<span id="276"> 276</span>
<span id="277"> 277</span>
<span id="278"> 278</span>
<span id="279"> 279</span>
<span id="280"> 280</span>
<span id="281"> 281</span>
<span id="282"> 282</span>
<span id="283"> 283</span>
<span id="284"> 284</span>
<span id="285"> 285</span>
<span id="286"> 286</span>
<span id="287"> 287</span>
<span id="288"> 288</span>
<span id="289"> 289</span>
<span id="290"> 290</span>
<span id="291"> 291</span>
<span id="292"> 292</span>
<span id="293"> 293</span>
<span id="294"> 294</span>
<span id="295"> 295</span>
<span id="296"> 296</span>
<span id="297"> 297</span>
<span id="298"> 298</span>
<span id="299"> 299</span>
<span id="300"> 300</span>
<span id="301"> 301</span>
<span id="302"> 302</span>
<span id="303"> 303</span>
<span id="304"> 304</span>
<span id="305"> 305</span>
<span id="306"> 306</span>
<span id="307"> 307</span>
<span id="308"> 308</span>
<span id="309"> 309</span>
<span id="310"> 310</span>
<span id="311"> 311</span>
<span id="312"> 312</span>
<span id="313"> 313</span>
<span id="314"> 314</span>
<span id="315"> 315</span>
<span id="316"> 316</span>
<span id="317"> 317</span>
<span id="318"> 318</span>
<span id="319"> 319</span>
<span id="320"> 320</span>
<span id="321"> 321</span>
<span id="322"> 322</span>
<span id="323"> 323</span>
<span id="324"> 324</span>
<span id="325"> 325</span>
<span id="326"> 326</span>
<span id="327"> 327</span>
<span id="328"> 328</span>
<span id="329"> 329</span>
<span id="330"> 330</span>
<span id="331"> 331</span>
<span id="332"> 332</span>
<span id="333"> 333</span>
<span id="334"> 334</span>
<span id="335"> 335</span>
<span id="336"> 336</span>
<span id="337"> 337</span>
<span id="338"> 338</span>
<span id="339"> 339</span>
<span id="340"> 340</span>
<span id="341"> 341</span>
<span id="342"> 342</span>
<span id="343"> 343</span>
<span id="344"> 344</span>
<span id="345"> 345</span>
<span id="346"> 346</span>
<span id="347"> 347</span>
<span id="348"> 348</span>
<span id="349"> 349</span>
<span id="350"> 350</span>
<span id="351"> 351</span>
<span id="352"> 352</span>
<span id="353"> 353</span>
<span id="354"> 354</span>
<span id="355"> 355</span>
<span id="356"> 356</span>
<span id="357"> 357</span>
<span id="358"> 358</span>
<span id="359"> 359</span>
<span id="360"> 360</span>
<span id="361"> 361</span>
<span id="362"> 362</span>
<span id="363"> 363</span>
<span id="364"> 364</span>
<span id="365"> 365</span>
<span id="366"> 366</span>
<span id="367"> 367</span>
<span id="368"> 368</span>
<span id="369"> 369</span>
<span id="370"> 370</span>
<span id="371"> 371</span>
<span id="372"> 372</span>
<span id="373"> 373</span>
<span id="374"> 374</span>
<span id="375"> 375</span>
<span id="376"> 376</span>
<span id="377"> 377</span>
<span id="378"> 378</span>
<span id="379"> 379</span>
<span id="380"> 380</span>
<span id="381"> 381</span>
<span id="382"> 382</span>
<span id="383"> 383</span>
<span id="384"> 384</span>
<span id="385"> 385</span>
<span id="386"> 386</span>
<span id="387"> 387</span>
<span id="388"> 388</span>
<span id="389"> 389</span>
<span id="390"> 390</span>
<span id="391"> 391</span>
<span id="392"> 392</span>
<span id="393"> 393</span>
<span id="394"> 394</span>
<span id="395"> 395</span>
<span id="396"> 396</span>
<span id="397"> 397</span>
<span id="398"> 398</span>
<span id="399"> 399</span>
<span id="400"> 400</span>
<span id="401"> 401</span>
<span id="402"> 402</span>
<span id="403"> 403</span>
<span id="404"> 404</span>
<span id="405"> 405</span>
<span id="406"> 406</span>
<span id="407"> 407</span>
<span id="408"> 408</span>
<span id="409"> 409</span>
<span id="410"> 410</span>
<span id="411"> 411</span>
<span id="412"> 412</span>
<span id="413"> 413</span>
<span id="414"> 414</span>
<span id="415"> 415</span>
<span id="416"> 416</span>
<span id="417"> 417</span>
<span id="418"> 418</span>
<span id="419"> 419</span>
<span id="420"> 420</span>
<span id="421"> 421</span>
<span id="422"> 422</span>
<span id="423"> 423</span>
<span id="424"> 424</span>
<span id="425"> 425</span>
<span id="426"> 426</span>
<span id="427"> 427</span>
<span id="428"> 428</span>
<span id="429"> 429</span>
<span id="430"> 430</span>
<span id="431"> 431</span>
<span id="432"> 432</span>
<span id="433"> 433</span>
<span id="434"> 434</span>
<span id="435"> 435</span>
<span id="436"> 436</span>
<span id="437"> 437</span>
<span id="438"> 438</span>
<span id="439"> 439</span>
<span id="440"> 440</span>
<span id="441"> 441</span>
<span id="442"> 442</span>
<span id="443"> 443</span>
<span id="444"> 444</span>
<span id="445"> 445</span>
<span id="446"> 446</span>
<span id="447"> 447</span>
<span id="448"> 448</span>
<span id="449"> 449</span>
<span id="450"> 450</span>
<span id="451"> 451</span>
<span id="452"> 452</span>
<span id="453"> 453</span>
<span id="454"> 454</span>
<span id="455"> 455</span>
<span id="456"> 456</span>
<span id="457"> 457</span>
<span id="458"> 458</span>
<span id="459"> 459</span>
<span id="460"> 460</span>
<span id="461"> 461</span>
<span id="462"> 462</span>
<span id="463"> 463</span>
<span id="464"> 464</span>
<span id="465"> 465</span>
<span id="466"> 466</span>
<span id="467"> 467</span>
<span id="468"> 468</span>
<span id="469"> 469</span>
<span id="470"> 470</span>
<span id="471"> 471</span>
<span id="472"> 472</span>
<span id="473"> 473</span>
<span id="474"> 474</span>
<span id="475"> 475</span>
<span id="476"> 476</span>
<span id="477"> 477</span>
<span id="478"> 478</span>
<span id="479"> 479</span>
<span id="480"> 480</span>
<span id="481"> 481</span>
<span id="482"> 482</span>
<span id="483"> 483</span>
<span id="484"> 484</span>
<span id="485"> 485</span>
<span id="486"> 486</span>
<span id="487"> 487</span>
<span id="488"> 488</span>
<span id="489"> 489</span>
<span id="490"> 490</span>
<span id="491"> 491</span>
<span id="492"> 492</span>
<span id="493"> 493</span>
<span id="494"> 494</span>
<span id="495"> 495</span>
<span id="496"> 496</span>
<span id="497"> 497</span>
<span id="498"> 498</span>
<span id="499"> 499</span>
<span id="500"> 500</span>
<span id="501"> 501</span>
<span id="502"> 502</span>
<span id="503"> 503</span>
<span id="504"> 504</span>
<span id="505"> 505</span>
<span id="506"> 506</span>
<span id="507"> 507</span>
<span id="508"> 508</span>
<span id="509"> 509</span>
<span id="510"> 510</span>
<span id="511"> 511</span>
<span id="512"> 512</span>
<span id="513"> 513</span>
<span id="514"> 514</span>
<span id="515"> 515</span>
<span id="516"> 516</span>
<span id="517"> 517</span>
<span id="518"> 518</span>
<span id="519"> 519</span>
<span id="520"> 520</span>
<span id="521"> 521</span>
<span id="522"> 522</span>
<span id="523"> 523</span>
<span id="524"> 524</span>
<span id="525"> 525</span>
<span id="526"> 526</span>
<span id="527"> 527</span>
<span id="528"> 528</span>
<span id="529"> 529</span>
<span id="530"> 530</span>
<span id="531"> 531</span>
<span id="532"> 532</span>
<span id="533"> 533</span>
<span id="534"> 534</span>
<span id="535"> 535</span>
<span id="536"> 536</span>
<span id="537"> 537</span>
<span id="538"> 538</span>
<span id="539"> 539</span>
<span id="540"> 540</span>
<span id="541"> 541</span>
<span id="542"> 542</span>
<span id="543"> 543</span>
<span id="544"> 544</span>
<span id="545"> 545</span>
<span id="546"> 546</span>
<span id="547"> 547</span>
<span id="548"> 548</span>
<span id="549"> 549</span>
<span id="550"> 550</span>
<span id="551"> 551</span>
<span id="552"> 552</span>
<span id="553"> 553</span>
<span id="554"> 554</span>
<span id="555"> 555</span>
<span id="556"> 556</span>
<span id="557"> 557</span>
<span id="558"> 558</span>
<span id="559"> 559</span>
<span id="560"> 560</span>
<span id="561"> 561</span>
<span id="562"> 562</span>
<span id="563"> 563</span>
<span id="564"> 564</span>
<span id="565"> 565</span>
<span id="566"> 566</span>
<span id="567"> 567</span>
<span id="568"> 568</span>
<span id="569"> 569</span>
<span id="570"> 570</span>
<span id="571"> 571</span>
<span id="572"> 572</span>
<span id="573"> 573</span>
<span id="574"> 574</span>
<span id="575"> 575</span>
<span id="576"> 576</span>
<span id="577"> 577</span>
<span id="578"> 578</span>
<span id="579"> 579</span>
<span id="580"> 580</span>
<span id="581"> 581</span>
<span id="582"> 582</span>
<span id="583"> 583</span>
<span id="584"> 584</span>
<span id="585"> 585</span>
<span id="586"> 586</span>
<span id="587"> 587</span>
<span id="588"> 588</span>
<span id="589"> 589</span>
<span id="590"> 590</span>
<span id="591"> 591</span>
<span id="592"> 592</span>
<span id="593"> 593</span>
<span id="594"> 594</span>
<span id="595"> 595</span>
<span id="596"> 596</span>
<span id="597"> 597</span>
<span id="598"> 598</span>
<span id="599"> 599</span>
<span id="600"> 600</span>
<span id="601"> 601</span>
<span id="602"> 602</span>
<span id="603"> 603</span>
<span id="604"> 604</span>
<span id="605"> 605</span>
<span id="606"> 606</span>
<span id="607"> 607</span>
<span id="608"> 608</span>
<span id="609"> 609</span>
<span id="610"> 610</span>
<span id="611"> 611</span>
<span id="612"> 612</span>
<span id="613"> 613</span>
<span id="614"> 614</span>
<span id="615"> 615</span>
<span id="616"> 616</span>
<span id="617"> 617</span>
<span id="618"> 618</span>
<span id="619"> 619</span>
<span id="620"> 620</span>
<span id="621"> 621</span>
<span id="622"> 622</span>
<span id="623"> 623</span>
<span id="624"> 624</span>
<span id="625"> 625</span>
<span id="626"> 626</span>
<span id="627"> 627</span>
<span id="628"> 628</span>
<span id="629"> 629</span>
<span id="630"> 630</span>
<span id="631"> 631</span>
<span id="632"> 632</span>
<span id="633"> 633</span>
<span id="634"> 634</span>
<span id="635"> 635</span>
<span id="636"> 636</span>
<span id="637"> 637</span>
<span id="638"> 638</span>
<span id="639"> 639</span>
<span id="640"> 640</span>
<span id="641"> 641</span>
<span id="642"> 642</span>
<span id="643"> 643</span>
<span id="644"> 644</span>
<span id="645"> 645</span>
<span id="646"> 646</span>
<span id="647"> 647</span>
<span id="648"> 648</span>
<span id="649"> 649</span>
<span id="650"> 650</span>
<span id="651"> 651</span>
<span id="652"> 652</span>
<span id="653"> 653</span>
<span id="654"> 654</span>
<span id="655"> 655</span>
<span id="656"> 656</span>
<span id="657"> 657</span>
<span id="658"> 658</span>
<span id="659"> 659</span>
<span id="660"> 660</span>
<span id="661"> 661</span>
<span id="662"> 662</span>
<span id="663"> 663</span>
<span id="664"> 664</span>
<span id="665"> 665</span>
<span id="666"> 666</span>
<span id="667"> 667</span>
<span id="668"> 668</span>
<span id="669"> 669</span>
<span id="670"> 670</span>
<span id="671"> 671</span>
<span id="672"> 672</span>
<span id="673"> 673</span>
<span id="674"> 674</span>
<span id="675"> 675</span>
<span id="676"> 676</span>
<span id="677"> 677</span>
<span id="678"> 678</span>
<span id="679"> 679</span>
<span id="680"> 680</span>
<span id="681"> 681</span>
<span id="682"> 682</span>
<span id="683"> 683</span>
<span id="684"> 684</span>
<span id="685"> 685</span>
<span id="686"> 686</span>
<span id="687"> 687</span>
<span id="688"> 688</span>
<span id="689"> 689</span>
<span id="690"> 690</span>
<span id="691"> 691</span>
<span id="692"> 692</span>
<span id="693"> 693</span>
<span id="694"> 694</span>
<span id="695"> 695</span>
<span id="696"> 696</span>
<span id="697"> 697</span>
<span id="698"> 698</span>
<span id="699"> 699</span>
<span id="700"> 700</span>
<span id="701"> 701</span>
<span id="702"> 702</span>
<span id="703"> 703</span>
<span id="704"> 704</span>
<span id="705"> 705</span>
<span id="706"> 706</span>
<span id="707"> 707</span>
<span id="708"> 708</span>
<span id="709"> 709</span>
<span id="710"> 710</span>
<span id="711"> 711</span>
<span id="712"> 712</span>
<span id="713"> 713</span>
<span id="714"> 714</span>
<span id="715"> 715</span>
<span id="716"> 716</span>
<span id="717"> 717</span>
<span id="718"> 718</span>
<span id="719"> 719</span>
<span id="720"> 720</span>
<span id="721"> 721</span>
<span id="722"> 722</span>
<span id="723"> 723</span>
<span id="724"> 724</span>
<span id="725"> 725</span>
<span id="726"> 726</span>
<span id="727"> 727</span>
<span id="728"> 728</span>
<span id="729"> 729</span>
<span id="730"> 730</span>
<span id="731"> 731</span>
<span id="732"> 732</span>
<span id="733"> 733</span>
<span id="734"> 734</span>
<span id="735"> 735</span>
<span id="736"> 736</span>
<span id="737"> 737</span>
<span id="738"> 738</span>
<span id="739"> 739</span>
<span id="740"> 740</span>
<span id="741"> 741</span>
<span id="742"> 742</span>
<span id="743"> 743</span>
<span id="744"> 744</span>
<span id="745"> 745</span>
<span id="746"> 746</span>
<span id="747"> 747</span>
<span id="748"> 748</span>
<span id="749"> 749</span>
<span id="750"> 750</span>
<span id="751"> 751</span>
<span id="752"> 752</span>
<span id="753"> 753</span>
<span id="754"> 754</span>
<span id="755"> 755</span>
<span id="756"> 756</span>
<span id="757"> 757</span>
<span id="758"> 758</span>
<span id="759"> 759</span>
<span id="760"> 760</span>
<span id="761"> 761</span>
<span id="762"> 762</span>
<span id="763"> 763</span>
<span id="764"> 764</span>
<span id="765"> 765</span>
<span id="766"> 766</span>
<span id="767"> 767</span>
<span id="768"> 768</span>
<span id="769"> 769</span>
<span id="770"> 770</span>
<span id="771"> 771</span>
<span id="772"> 772</span>
<span id="773"> 773</span>
<span id="774"> 774</span>
<span id="775"> 775</span>
<span id="776"> 776</span>
<span id="777"> 777</span>
<span id="778"> 778</span>
<span id="779"> 779</span>
<span id="780"> 780</span>
<span id="781"> 781</span>
<span id="782"> 782</span>
<span id="783"> 783</span>
<span id="784"> 784</span>
<span id="785"> 785</span>
<span id="786"> 786</span>
<span id="787"> 787</span>
<span id="788"> 788</span>
<span id="789"> 789</span>
<span id="790"> 790</span>
<span id="791"> 791</span>
<span id="792"> 792</span>
<span id="793"> 793</span>
<span id="794"> 794</span>
<span id="795"> 795</span>
<span id="796"> 796</span>
<span id="797"> 797</span>
<span id="798"> 798</span>
<span id="799"> 799</span>
<span id="800"> 800</span>
<span id="801"> 801</span>
<span id="802"> 802</span>
<span id="803"> 803</span>
<span id="804"> 804</span>
<span id="805"> 805</span>
<span id="806"> 806</span>
<span id="807"> 807</span>
<span id="808"> 808</span>
<span id="809"> 809</span>
<span id="810"> 810</span>
<span id="811"> 811</span>
<span id="812"> 812</span>
<span id="813"> 813</span>
<span id="814"> 814</span>
<span id="815"> 815</span>
<span id="816"> 816</span>
<span id="817"> 817</span>
<span id="818"> 818</span>
<span id="819"> 819</span>
<span id="820"> 820</span>
<span id="821"> 821</span>
<span id="822"> 822</span>
<span id="823"> 823</span>
<span id="824"> 824</span>
<span id="825"> 825</span>
<span id="826"> 826</span>
<span id="827"> 827</span>
<span id="828"> 828</span>
<span id="829"> 829</span>
<span id="830"> 830</span>
<span id="831"> 831</span>
<span id="832"> 832</span>
<span id="833"> 833</span>
<span id="834"> 834</span>
<span id="835"> 835</span>
<span id="836"> 836</span>
<span id="837"> 837</span>
<span id="838"> 838</span>
<span id="839"> 839</span>
<span id="840"> 840</span>
<span id="841"> 841</span>
<span id="842"> 842</span>
<span id="843"> 843</span>
<span id="844"> 844</span>
<span id="845"> 845</span>
<span id="846"> 846</span>
<span id="847"> 847</span>
<span id="848"> 848</span>
<span id="849"> 849</span>
<span id="850"> 850</span>
<span id="851"> 851</span>
<span id="852"> 852</span>
<span id="853"> 853</span>
<span id="854"> 854</span>
<span id="855"> 855</span>
<span id="856"> 856</span>
<span id="857"> 857</span>
<span id="858"> 858</span>
<span id="859"> 859</span>
<span id="860"> 860</span>
<span id="861"> 861</span>
<span id="862"> 862</span>
<span id="863"> 863</span>
<span id="864"> 864</span>
<span id="865"> 865</span>
<span id="866"> 866</span>
<span id="867"> 867</span>
<span id="868"> 868</span>
<span id="869"> 869</span>
<span id="870"> 870</span>
<span id="871"> 871</span>
<span id="872"> 872</span>
<span id="873"> 873</span>
<span id="874"> 874</span>
<span id="875"> 875</span>
<span id="876"> 876</span>
<span id="877"> 877</span>
<span id="878"> 878</span>
<span id="879"> 879</span>
<span id="880"> 880</span>
<span id="881"> 881</span>
<span id="882"> 882</span>
<span id="883"> 883</span>
<span id="884"> 884</span>
<span id="885"> 885</span>
<span id="886"> 886</span>
<span id="887"> 887</span>
<span id="888"> 888</span>
<span id="889"> 889</span>
<span id="890"> 890</span>
<span id="891"> 891</span>
<span id="892"> 892</span>
<span id="893"> 893</span>
<span id="894"> 894</span>
<span id="895"> 895</span>
<span id="896"> 896</span>
<span id="897"> 897</span>
<span id="898"> 898</span>
<span id="899"> 899</span>
<span id="900"> 900</span>
<span id="901"> 901</span>
<span id="902"> 902</span>
<span id="903"> 903</span>
<span id="904"> 904</span>
<span id="905"> 905</span>
<span id="906"> 906</span>
<span id="907"> 907</span>
<span id="908"> 908</span>
<span id="909"> 909</span>
<span id="910"> 910</span>
<span id="911"> 911</span>
<span id="912"> 912</span>
<span id="913"> 913</span>
<span id="914"> 914</span>
<span id="915"> 915</span>
<span id="916"> 916</span>
<span id="917"> 917</span>
<span id="918"> 918</span>
<span id="919"> 919</span>
<span id="920"> 920</span>
<span id="921"> 921</span>
<span id="922"> 922</span>
<span id="923"> 923</span>
<span id="924"> 924</span>
<span id="925"> 925</span>
<span id="926"> 926</span>
<span id="927"> 927</span>
<span id="928"> 928</span>
<span id="929"> 929</span>
<span id="930"> 930</span>
<span id="931"> 931</span>
<span id="932"> 932</span>
<span id="933"> 933</span>
<span id="934"> 934</span>
<span id="935"> 935</span>
<span id="936"> 936</span>
<span id="937"> 937</span>
<span id="938"> 938</span>
<span id="939"> 939</span>
<span id="940"> 940</span>
<span id="941"> 941</span>
<span id="942"> 942</span>
<span id="943"> 943</span>
<span id="944"> 944</span>
<span id="945"> 945</span>
<span id="946"> 946</span>
<span id="947"> 947</span>
<span id="948"> 948</span>
<span id="949"> 949</span>
<span id="950"> 950</span>
<span id="951"> 951</span>
<span id="952"> 952</span>
<span id="953"> 953</span>
<span id="954"> 954</span>
<span id="955"> 955</span>
<span id="956"> 956</span>
<span id="957"> 957</span>
<span id="958"> 958</span>
<span id="959"> 959</span>
<span id="960"> 960</span>
<span id="961"> 961</span>
<span id="962"> 962</span>
<span id="963"> 963</span>
<span id="964"> 964</span>
<span id="965"> 965</span>
<span id="966"> 966</span>
<span id="967"> 967</span>
<span id="968"> 968</span>
<span id="969"> 969</span>
<span id="970"> 970</span>
<span id="971"> 971</span>
<span id="972"> 972</span>
<span id="973"> 973</span>
<span id="974"> 974</span>
<span id="975"> 975</span>
<span id="976"> 976</span>
<span id="977"> 977</span>
<span id="978"> 978</span>
<span id="979"> 979</span>
<span id="980"> 980</span>
<span id="981"> 981</span>
<span id="982"> 982</span>
<span id="983"> 983</span>
<span id="984"> 984</span>
<span id="985"> 985</span>
<span id="986"> 986</span>
<span id="987"> 987</span>
<span id="988"> 988</span>
<span id="989"> 989</span>
<span id="990"> 990</span>
<span id="991"> 991</span>
<span id="992"> 992</span>
<span id="993"> 993</span>
<span id="994"> 994</span>
<span id="995"> 995</span>
<span id="996"> 996</span>
<span id="997"> 997</span>
<span id="998"> 998</span>
<span id="999"> 999</span>
<span id="1000">1000</span>
<span id="1001">1001</span>
<span id="1002">1002</span>
<span id="1003">1003</span>
<span id="1004">1004</span>
<span id="1005">1005</span>
<span id="1006">1006</span>
<span id="1007">1007</span>
<span id="1008">1008</span>
<span id="1009">1009</span>
<span id="1010">1010</span>
<span id="1011">1011</span>
<span id="1012">1012</span>
<span id="1013">1013</span>
<span id="1014">1014</span>
<span id="1015">1015</span>
<span id="1016">1016</span>
<span id="1017">1017</span>
<span id="1018">1018</span>
<span id="1019">1019</span>
<span id="1020">1020</span>
<span id="1021">1021</span>
<span id="1022">1022</span>
<span id="1023">1023</span>
<span id="1024">1024</span>
<span id="1025">1025</span>
<span id="1026">1026</span>
<span id="1027">1027</span>
<span id="1028">1028</span>
<span id="1029">1029</span>
<span id="1030">1030</span>
<span id="1031">1031</span>
<span id="1032">1032</span>
<span id="1033">1033</span>
<span id="1034">1034</span>
<span id="1035">1035</span>
<span id="1036">1036</span>
<span id="1037">1037</span>
<span id="1038">1038</span>
<span id="1039">1039</span>
<span id="1040">1040</span>
<span id="1041">1041</span>
<span id="1042">1042</span>
<span id="1043">1043</span>
<span id="1044">1044</span>
<span id="1045">1045</span>
<span id="1046">1046</span>
<span id="1047">1047</span>
<span id="1048">1048</span>
<span id="1049">1049</span>
<span id="1050">1050</span>
<span id="1051">1051</span>
<span id="1052">1052</span>
<span id="1053">1053</span>
<span id="1054">1054</span>
<span id="1055">1055</span>
<span id="1056">1056</span>
<span id="1057">1057</span>
<span id="1058">1058</span>
<span id="1059">1059</span>
<span id="1060">1060</span>
<span id="1061">1061</span>
<span id="1062">1062</span>
<span id="1063">1063</span>
<span id="1064">1064</span>
<span id="1065">1065</span>
<span id="1066">1066</span>
<span id="1067">1067</span>
<span id="1068">1068</span>
<span id="1069">1069</span>
<span id="1070">1070</span>
<span id="1071">1071</span>
<span id="1072">1072</span>
<span id="1073">1073</span>
<span id="1074">1074</span>
<span id="1075">1075</span>
<span id="1076">1076</span>
<span id="1077">1077</span>
<span id="1078">1078</span>
<span id="1079">1079</span>
<span id="1080">1080</span>
<span id="1081">1081</span>
<span id="1082">1082</span>
<span id="1083">1083</span>
<span id="1084">1084</span>
<span id="1085">1085</span>
<span id="1086">1086</span>
<span id="1087">1087</span>
<span id="1088">1088</span>
<span id="1089">1089</span>
<span id="1090">1090</span>
<span id="1091">1091</span>
<span id="1092">1092</span>
<span id="1093">1093</span>
<span id="1094">1094</span>
<span id="1095">1095</span>
<span id="1096">1096</span>
<span id="1097">1097</span>
<span id="1098">1098</span>
<span id="1099">1099</span>
<span id="1100">1100</span>
<span id="1101">1101</span>
<span id="1102">1102</span>
<span id="1103">1103</span>
<span id="1104">1104</span>
<span id="1105">1105</span>
<span id="1106">1106</span>
<span id="1107">1107</span>
<span id="1108">1108</span>
<span id="1109">1109</span>
<span id="1110">1110</span>
<span id="1111">1111</span>
<span id="1112">1112</span>
<span id="1113">1113</span>
<span id="1114">1114</span>
<span id="1115">1115</span>
<span id="1116">1116</span>
<span id="1117">1117</span>
<span id="1118">1118</span>
<span id="1119">1119</span>
<span id="1120">1120</span>
<span id="1121">1121</span>
<span id="1122">1122</span>
<span id="1123">1123</span>
<span id="1124">1124</span>
<span id="1125">1125</span>
<span id="1126">1126</span>
<span id="1127">1127</span>
<span id="1128">1128</span>
<span id="1129">1129</span>
<span id="1130">1130</span>
<span id="1131">1131</span>
<span id="1132">1132</span>
<span id="1133">1133</span>
<span id="1134">1134</span>
<span id="1135">1135</span>
<span id="1136">1136</span>
<span id="1137">1137</span>
<span id="1138">1138</span>
<span id="1139">1139</span>
<span id="1140">1140</span>
<span id="1141">1141</span>
<span id="1142">1142</span>
<span id="1143">1143</span>
<span id="1144">1144</span>
<span id="1145">1145</span>
<span id="1146">1146</span>
<span id="1147">1147</span>
<span id="1148">1148</span>
<span id="1149">1149</span>
</pre><pre class="rust ">
<span class="doccomment">//! A multi-producer, single-consumer, futures-aware, FIFO queue with back pressure.</span>
<span class="doccomment">//!</span>
<span class="doccomment">//! A channel can be used as a communication primitive between tasks running on</span>
<span class="doccomment">//! `futures-rs` executors. Channel creation provides `Receiver` and `Sender`</span>
<span class="doccomment">//! handles. `Receiver` implements `Stream` and allows a task to read values</span>
<span class="doccomment">//! out of the channel. If there is no message to read from the channel, the</span>
<span class="doccomment">//! current task will be notified when a new value is sent. `Sender` implements</span>
<span class="doccomment">//! the `Sink` trait and allows a task to send messages into the channel. If</span>
<span class="doccomment">//! the channel is at capacity, then send will be rejected and the task will be</span>
<span class="doccomment">//! notified when additional capacity is available.</span>
<span class="doccomment">//!</span>
<span class="doccomment">//! # Disconnection</span>
<span class="doccomment">//!</span>
<span class="doccomment">//! When all `Sender` handles have been dropped, it is no longer possible to</span>
<span class="doccomment">//! send values into the channel. This is considered the termination event of</span>
<span class="doccomment">//! the stream. As such, `Sender::poll` will return `Ok(Ready(None))`.</span>
<span class="doccomment">//!</span>
<span class="doccomment">//! If the receiver handle is dropped, then messages can no longer be read out</span>
<span class="doccomment">//! of the channel. In this case, a `send` will result in an error.</span>
<span class="doccomment">//!</span>
<span class="doccomment">//! # Clean Shutdown</span>
<span class="doccomment">//!</span>
<span class="doccomment">//! If the `Receiver` is simply dropped, then it is possible for there to be</span>
<span class="doccomment">//! messages still in the channel that will not be processed. As such, it is</span>
<span class="doccomment">//! usually desirable to perform a "clean" shutdown. To do this, the receiver</span>
<span class="doccomment">//! will first call `close`, which will prevent any further messages to be sent</span>
<span class="doccomment">//! into the channel. Then, the receiver consumes the channel to completion, at</span>
<span class="doccomment">//! which point the receiver can be dropped.</span>
<span class="comment">// At the core, the channel uses an atomic FIFO queue for message passing. This</span>
<span class="comment">// queue is used as the primary coordination primitive. In order to enforce</span>
<span class="comment">// capacity limits and handle back pressure, a secondary FIFO queue is used to</span>
<span class="comment">// send parked task handles.</span>
<span class="comment">//</span>
<span class="comment">// The general idea is that the channel is created with a `buffer` size of `n`.</span>
<span class="comment">// The channel capacity is `n + num-senders`. Each sender gets one "guaranteed"</span>
<span class="comment">// slot to hold a message. This allows `Sender` to know for a fact that a send</span>
<span class="comment">// will succeed *before* starting to do the actual work of sending the value.</span>
<span class="comment">// Since most of this work is lock-free, once the work starts, it is impossible</span>
<span class="comment">// to safely revert.</span>
<span class="comment">//</span>
<span class="comment">// If the sender is unable to process a send operation, then the current</span>
<span class="comment">// task is parked and the handle is sent on the parked task queue.</span>
<span class="comment">//</span>
<span class="comment">// Note that the implementation guarantees that the channel capacity will never</span>
<span class="comment">// exceed the configured limit, however there is no *strict* guarantee that the</span>
<span class="comment">// receiver will wake up a parked task *immediately* when a slot becomes</span>
<span class="comment">// available. However, it will almost always unpark a task when a slot becomes</span>
<span class="comment">// available and it is *guaranteed* that a sender will be unparked when the</span>
<span class="comment">// message that caused the sender to become parked is read out of the channel.</span>
<span class="comment">//</span>
<span class="comment">// The steps for sending a message are roughly:</span>
<span class="comment">//</span>
<span class="comment">// 1) Increment the channel message count</span>
<span class="comment">// 2) If the channel is at capacity, push the task handle onto the wait queue</span>
<span class="comment">// 3) Push the message onto the message queue.</span>
<span class="comment">//</span>
<span class="comment">// The steps for receiving a message are roughly:</span>
<span class="comment">//</span>
<span class="comment">// 1) Pop a message from the message queue</span>
<span class="comment">// 2) Pop a task handle from the wait queue</span>
<span class="comment">// 3) Decrement the channel message count.</span>
<span class="comment">//</span>
<span class="comment">// It's important for the order of operations on lock-free structures to happen</span>
<span class="comment">// in reverse order between the sender and receiver. This makes the message</span>
<span class="comment">// queue the primary coordination structure and establishes the necessary</span>
<span class="comment">// happens-before semantics required for the acquire / release semantics used</span>
<span class="comment">// by the queue structure.</span>
<span class="kw">use</span> <span class="ident">std</span>::<span class="ident">fmt</span>;
<span class="kw">use</span> <span class="ident">std</span>::<span class="ident">error</span>::<span class="ident">Error</span>;
<span class="kw">use</span> <span class="ident">std</span>::<span class="ident">any</span>::<span class="ident">Any</span>;
<span class="kw">use</span> <span class="ident">std</span>::<span class="ident">sync</span>::<span class="ident">atomic</span>::<span class="ident">AtomicUsize</span>;
<span class="kw">use</span> <span class="ident">std</span>::<span class="ident">sync</span>::<span class="ident">atomic</span>::<span class="ident">Ordering</span>::<span class="ident">SeqCst</span>;
<span class="kw">use</span> <span class="ident">std</span>::<span class="ident">sync</span>::{<span class="ident">Arc</span>, <span class="ident">Mutex</span>};
<span class="kw">use</span> <span class="ident">std</span>::<span class="ident">thread</span>;
<span class="kw">use</span> <span class="ident">std</span>::<span class="ident">usize</span>;
<span class="kw">use</span> <span class="ident">sync</span>::<span class="ident">mpsc</span>::<span class="ident">queue</span>::{<span class="ident">Queue</span>, <span class="ident">PopResult</span>};
<span class="kw">use</span> <span class="ident">sync</span>::<span class="ident">oneshot</span>;
<span class="kw">use</span> <span class="ident">task</span>::{<span class="self">self</span>, <span class="ident">Task</span>};
<span class="kw">use</span> <span class="ident">future</span>::<span class="ident">Executor</span>;
<span class="kw">use</span> <span class="ident">sink</span>::<span class="ident">SendAll</span>;
<span class="kw">use</span> <span class="ident">resultstream</span>::{<span class="self">self</span>, <span class="ident">Results</span>};
<span class="kw">use</span> {<span class="ident">Async</span>, <span class="ident">AsyncSink</span>, <span class="ident">Future</span>, <span class="ident">Poll</span>, <span class="ident">StartSend</span>, <span class="ident">Sink</span>, <span class="ident">Stream</span>};
<span class="kw">mod</span> <span class="ident">queue</span>;
<span class="doccomment">/// The transmission end of a channel which is used to send values.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// This is created by the `channel` method.</span>
<span class="attribute">#[<span class="ident">derive</span>(<span class="ident">Debug</span>)]</span>
<span class="kw">pub</span> <span class="kw">struct</span> <span class="ident">Sender</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> {
<span class="comment">// Channel state shared between the sender and receiver.</span>
<span class="ident">inner</span>: <span class="ident">Arc</span><span class="op"><</span><span class="ident">Inner</span><span class="op"><</span><span class="ident">T</span><span class="op">>></span>,
<span class="comment">// Handle to the task that is blocked on this sender. This handle is sent</span>
<span class="comment">// to the receiver half in order to be notified when the sender becomes</span>
<span class="comment">// unblocked.</span>
<span class="ident">sender_task</span>: <span class="ident">Arc</span><span class="op"><</span><span class="ident">Mutex</span><span class="op"><</span><span class="ident">SenderTask</span><span class="op">>></span>,
<span class="comment">// True if the sender might be blocked. This is an optimization to avoid</span>
<span class="comment">// having to lock the mutex most of the time.</span>
<span class="ident">maybe_parked</span>: <span class="ident">bool</span>,
}
<span class="doccomment">/// The transmission end of a channel which is used to send values.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// This is created by the `unbounded` method.</span>
<span class="attribute">#[<span class="ident">derive</span>(<span class="ident">Debug</span>)]</span>
<span class="kw">pub</span> <span class="kw">struct</span> <span class="ident">UnboundedSender</span><span class="op"><</span><span class="ident">T</span><span class="op">></span>(<span class="ident">Sender</span><span class="op"><</span><span class="ident">T</span><span class="op">></span>);
<span class="kw">trait</span> <span class="ident">AssertKinds</span>: <span class="ident">Send</span> <span class="op">+</span> <span class="ident">Sync</span> <span class="op">+</span> <span class="ident">Clone</span> {}
<span class="kw">impl</span> <span class="ident">AssertKinds</span> <span class="kw">for</span> <span class="ident">UnboundedSender</span><span class="op"><</span><span class="ident">u32</span><span class="op">></span> {}
<span class="doccomment">/// The receiving end of a channel which implements the `Stream` trait.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// This is a concrete implementation of a stream which can be used to represent</span>
<span class="doccomment">/// a stream of values being computed elsewhere. This is created by the</span>
<span class="doccomment">/// `channel` method.</span>
<span class="attribute">#[<span class="ident">derive</span>(<span class="ident">Debug</span>)]</span>
<span class="kw">pub</span> <span class="kw">struct</span> <span class="ident">Receiver</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> {
<span class="ident">inner</span>: <span class="ident">Arc</span><span class="op"><</span><span class="ident">Inner</span><span class="op"><</span><span class="ident">T</span><span class="op">>></span>,
}
<span class="doccomment">/// The receiving end of a channel which implements the `Stream` trait.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// This is a concrete implementation of a stream which can be used to represent</span>
<span class="doccomment">/// a stream of values being computed elsewhere. This is created by the</span>
<span class="doccomment">/// `unbounded` method.</span>
<span class="attribute">#[<span class="ident">derive</span>(<span class="ident">Debug</span>)]</span>
<span class="kw">pub</span> <span class="kw">struct</span> <span class="ident">UnboundedReceiver</span><span class="op"><</span><span class="ident">T</span><span class="op">></span>(<span class="ident">Receiver</span><span class="op"><</span><span class="ident">T</span><span class="op">></span>);
<span class="doccomment">/// Error type for sending, used when the receiving end of a channel is</span>
<span class="doccomment">/// dropped</span>
<span class="attribute">#[<span class="ident">derive</span>(<span class="ident">Clone</span>, <span class="ident">PartialEq</span>, <span class="ident">Eq</span>)]</span>
<span class="kw">pub</span> <span class="kw">struct</span> <span class="ident">SendError</span><span class="op"><</span><span class="ident">T</span><span class="op">></span>(<span class="ident">T</span>);
<span class="doccomment">/// Error type returned from `try_send`</span>
<span class="attribute">#[<span class="ident">derive</span>(<span class="ident">Clone</span>, <span class="ident">PartialEq</span>, <span class="ident">Eq</span>)]</span>
<span class="kw">pub</span> <span class="kw">struct</span> <span class="ident">TrySendError</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> {
<span class="ident">kind</span>: <span class="ident">TrySendErrorKind</span><span class="op"><</span><span class="ident">T</span><span class="op">></span>,
}
<span class="attribute">#[<span class="ident">derive</span>(<span class="ident">Clone</span>, <span class="ident">PartialEq</span>, <span class="ident">Eq</span>)]</span>
<span class="kw">enum</span> <span class="ident">TrySendErrorKind</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> {
<span class="ident">Full</span>(<span class="ident">T</span>),
<span class="ident">Disconnected</span>(<span class="ident">T</span>),
}
<span class="kw">impl</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> <span class="ident">fmt</span>::<span class="ident">Debug</span> <span class="kw">for</span> <span class="ident">SendError</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> {
<span class="kw">fn</span> <span class="ident">fmt</span>(<span class="kw-2">&</span><span class="self">self</span>, <span class="ident">fmt</span>: <span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">fmt</span>::<span class="ident">Formatter</span>) <span class="op">-></span> <span class="ident">fmt</span>::<span class="prelude-ty">Result</span> {
<span class="ident">fmt</span>.<span class="ident">debug_tuple</span>(<span class="string">"SendError"</span>)
.<span class="ident">field</span>(<span class="kw-2">&</span><span class="string">"..."</span>)
.<span class="ident">finish</span>()
}
}
<span class="kw">impl</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> <span class="ident">fmt</span>::<span class="ident">Display</span> <span class="kw">for</span> <span class="ident">SendError</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> {
<span class="kw">fn</span> <span class="ident">fmt</span>(<span class="kw-2">&</span><span class="self">self</span>, <span class="ident">fmt</span>: <span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">fmt</span>::<span class="ident">Formatter</span>) <span class="op">-></span> <span class="ident">fmt</span>::<span class="prelude-ty">Result</span> {
<span class="macro">write</span><span class="macro">!</span>(<span class="ident">fmt</span>, <span class="string">"send failed because receiver is gone"</span>)
}
}
<span class="kw">impl</span><span class="op"><</span><span class="ident">T</span>: <span class="ident">Any</span><span class="op">></span> <span class="ident">Error</span> <span class="kw">for</span> <span class="ident">SendError</span><span class="op"><</span><span class="ident">T</span><span class="op">></span>
{
<span class="kw">fn</span> <span class="ident">description</span>(<span class="kw-2">&</span><span class="self">self</span>) <span class="op">-></span> <span class="kw-2">&</span><span class="ident">str</span> {
<span class="string">"send failed because receiver is gone"</span>
}
}
<span class="kw">impl</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> <span class="ident">SendError</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> {
<span class="doccomment">/// Returns the message that was attempted to be sent but failed.</span>
<span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">into_inner</span>(<span class="self">self</span>) <span class="op">-></span> <span class="ident">T</span> {
<span class="self">self</span>.<span class="number">0</span>
}
}
<span class="kw">impl</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> <span class="ident">fmt</span>::<span class="ident">Debug</span> <span class="kw">for</span> <span class="ident">TrySendError</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> {
<span class="kw">fn</span> <span class="ident">fmt</span>(<span class="kw-2">&</span><span class="self">self</span>, <span class="ident">fmt</span>: <span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">fmt</span>::<span class="ident">Formatter</span>) <span class="op">-></span> <span class="ident">fmt</span>::<span class="prelude-ty">Result</span> {
<span class="ident">fmt</span>.<span class="ident">debug_tuple</span>(<span class="string">"TrySendError"</span>)
.<span class="ident">field</span>(<span class="kw-2">&</span><span class="string">"..."</span>)
.<span class="ident">finish</span>()
}
}
<span class="kw">impl</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> <span class="ident">fmt</span>::<span class="ident">Display</span> <span class="kw">for</span> <span class="ident">TrySendError</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> {
<span class="kw">fn</span> <span class="ident">fmt</span>(<span class="kw-2">&</span><span class="self">self</span>, <span class="ident">fmt</span>: <span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">fmt</span>::<span class="ident">Formatter</span>) <span class="op">-></span> <span class="ident">fmt</span>::<span class="prelude-ty">Result</span> {
<span class="kw">if</span> <span class="self">self</span>.<span class="ident">is_full</span>() {
<span class="macro">write</span><span class="macro">!</span>(<span class="ident">fmt</span>, <span class="string">"send failed because channel is full"</span>)
} <span class="kw">else</span> {
<span class="macro">write</span><span class="macro">!</span>(<span class="ident">fmt</span>, <span class="string">"send failed because receiver is gone"</span>)
}
}
}
<span class="kw">impl</span><span class="op"><</span><span class="ident">T</span>: <span class="ident">Any</span><span class="op">></span> <span class="ident">Error</span> <span class="kw">for</span> <span class="ident">TrySendError</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> {
<span class="kw">fn</span> <span class="ident">description</span>(<span class="kw-2">&</span><span class="self">self</span>) <span class="op">-></span> <span class="kw-2">&</span><span class="ident">str</span> {
<span class="kw">if</span> <span class="self">self</span>.<span class="ident">is_full</span>() {
<span class="string">"send failed because channel is full"</span>
} <span class="kw">else</span> {
<span class="string">"send failed because receiver is gone"</span>
}
}
}
<span class="kw">impl</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> <span class="ident">TrySendError</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> {
<span class="doccomment">/// Returns true if this error is a result of the channel being full</span>
<span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">is_full</span>(<span class="kw-2">&</span><span class="self">self</span>) <span class="op">-></span> <span class="ident">bool</span> {
<span class="kw">use</span> <span class="self">self</span>::<span class="ident">TrySendErrorKind</span>::<span class="kw-2">*</span>;
<span class="kw">match</span> <span class="self">self</span>.<span class="ident">kind</span> {
<span class="ident">Full</span>(_) <span class="op">=></span> <span class="bool-val">true</span>,
_ <span class="op">=></span> <span class="bool-val">false</span>,
}
}
<span class="doccomment">/// Returns true if this error is a result of the receiver being dropped</span>
<span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">is_disconnected</span>(<span class="kw-2">&</span><span class="self">self</span>) <span class="op">-></span> <span class="ident">bool</span> {
<span class="kw">use</span> <span class="self">self</span>::<span class="ident">TrySendErrorKind</span>::<span class="kw-2">*</span>;
<span class="kw">match</span> <span class="self">self</span>.<span class="ident">kind</span> {
<span class="ident">Disconnected</span>(_) <span class="op">=></span> <span class="bool-val">true</span>,
_ <span class="op">=></span> <span class="bool-val">false</span>,
}
}
<span class="doccomment">/// Returns the message that was attempted to be sent but failed.</span>
<span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">into_inner</span>(<span class="self">self</span>) <span class="op">-></span> <span class="ident">T</span> {
<span class="kw">use</span> <span class="self">self</span>::<span class="ident">TrySendErrorKind</span>::<span class="kw-2">*</span>;
<span class="kw">match</span> <span class="self">self</span>.<span class="ident">kind</span> {
<span class="ident">Full</span>(<span class="ident">v</span>) <span class="op">|</span> <span class="ident">Disconnected</span>(<span class="ident">v</span>) <span class="op">=></span> <span class="ident">v</span>,
}
}
}
<span class="attribute">#[<span class="ident">derive</span>(<span class="ident">Debug</span>)]</span>
<span class="kw">struct</span> <span class="ident">Inner</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> {
<span class="comment">// Max buffer size of the channel. If `None` then the channel is unbounded.</span>
<span class="ident">buffer</span>: <span class="prelude-ty">Option</span><span class="op"><</span><span class="ident">usize</span><span class="op">></span>,
<span class="comment">// Internal channel state. Consists of the number of messages stored in the</span>
<span class="comment">// channel as well as a flag signalling that the channel is closed.</span>
<span class="ident">state</span>: <span class="ident">AtomicUsize</span>,
<span class="comment">// Atomic, FIFO queue used to send messages to the receiver</span>
<span class="ident">message_queue</span>: <span class="ident">Queue</span><span class="op"><</span><span class="prelude-ty">Option</span><span class="op"><</span><span class="ident">T</span><span class="op">>></span>,
<span class="comment">// Atomic, FIFO queue used to send parked task handles to the receiver.</span>
<span class="ident">parked_queue</span>: <span class="ident">Queue</span><span class="op"><</span><span class="ident">Arc</span><span class="op"><</span><span class="ident">Mutex</span><span class="op"><</span><span class="ident">SenderTask</span><span class="op">>></span><span class="op">></span>,
<span class="comment">// Number of senders in existence</span>
<span class="ident">num_senders</span>: <span class="ident">AtomicUsize</span>,
<span class="comment">// Handle to the receiver's task.</span>
<span class="ident">recv_task</span>: <span class="ident">Mutex</span><span class="op"><</span><span class="ident">ReceiverTask</span><span class="op">></span>,
}
<span class="comment">// Struct representation of `Inner::state`.</span>
<span class="attribute">#[<span class="ident">derive</span>(<span class="ident">Debug</span>, <span class="ident">Clone</span>, <span class="ident">Copy</span>)]</span>
<span class="kw">struct</span> <span class="ident">State</span> {
<span class="comment">// `true` when the channel is open</span>
<span class="ident">is_open</span>: <span class="ident">bool</span>,
<span class="comment">// Number of messages in the channel</span>
<span class="ident">num_messages</span>: <span class="ident">usize</span>,
}
<span class="attribute">#[<span class="ident">derive</span>(<span class="ident">Debug</span>)]</span>
<span class="kw">struct</span> <span class="ident">ReceiverTask</span> {
<span class="ident">unparked</span>: <span class="ident">bool</span>,
<span class="ident">task</span>: <span class="prelude-ty">Option</span><span class="op"><</span><span class="ident">Task</span><span class="op">></span>,
}
<span class="comment">// Returned from Receiver::try_park()</span>
<span class="kw">enum</span> <span class="ident">TryPark</span> {
<span class="ident">Parked</span>,
<span class="ident">Closed</span>,
<span class="ident">NotEmpty</span>,
}
<span class="comment">// The `is_open` flag is stored in the left-most bit of `Inner::state`</span>
<span class="kw">const</span> <span class="ident">OPEN_MASK</span>: <span class="ident">usize</span> <span class="op">=</span> <span class="ident">usize</span>::<span class="ident">MAX</span> <span class="op">-</span> (<span class="ident">usize</span>::<span class="ident">MAX</span> <span class="op">>></span> <span class="number">1</span>);
<span class="comment">// When a new channel is created, it is created in the open state with no</span>
<span class="comment">// pending messages.</span>
<span class="kw">const</span> <span class="ident">INIT_STATE</span>: <span class="ident">usize</span> <span class="op">=</span> <span class="ident">OPEN_MASK</span>;
<span class="comment">// The maximum number of messages that a channel can track is `usize::MAX >> 1`</span>
<span class="kw">const</span> <span class="ident">MAX_CAPACITY</span>: <span class="ident">usize</span> <span class="op">=</span> <span class="op">!</span>(<span class="ident">OPEN_MASK</span>);
<span class="comment">// The maximum requested buffer size must be less than the maximum capacity of</span>
<span class="comment">// a channel. This is because each sender gets a guaranteed slot.</span>
<span class="kw">const</span> <span class="ident">MAX_BUFFER</span>: <span class="ident">usize</span> <span class="op">=</span> <span class="ident">MAX_CAPACITY</span> <span class="op">>></span> <span class="number">1</span>;
<span class="comment">// Sent to the consumer to wake up blocked producers</span>
<span class="attribute">#[<span class="ident">derive</span>(<span class="ident">Debug</span>)]</span>
<span class="kw">struct</span> <span class="ident">SenderTask</span> {
<span class="ident">task</span>: <span class="prelude-ty">Option</span><span class="op"><</span><span class="ident">Task</span><span class="op">></span>,
<span class="ident">is_parked</span>: <span class="ident">bool</span>,
}
<span class="kw">impl</span> <span class="ident">SenderTask</span> {
<span class="kw">fn</span> <span class="ident">new</span>() <span class="op">-></span> <span class="self">Self</span> {
<span class="ident">SenderTask</span> {
<span class="ident">task</span>: <span class="prelude-val">None</span>,
<span class="ident">is_parked</span>: <span class="bool-val">false</span>,
}
}
<span class="kw">fn</span> <span class="ident">notify</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>) {
<span class="self">self</span>.<span class="ident">is_parked</span> <span class="op">=</span> <span class="bool-val">false</span>;
<span class="kw">if</span> <span class="kw">let</span> <span class="prelude-val">Some</span>(<span class="ident">task</span>) <span class="op">=</span> <span class="self">self</span>.<span class="ident">task</span>.<span class="ident">take</span>() {
<span class="ident">task</span>.<span class="ident">notify</span>();
}
}
}
<span class="doccomment">/// Creates an in-memory channel implementation of the `Stream` trait with</span>
<span class="doccomment">/// bounded capacity.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// This method creates a concrete implementation of the `Stream` trait which</span>
<span class="doccomment">/// can be used to send values across threads in a streaming fashion. This</span>
<span class="doccomment">/// channel is unique in that it implements back pressure to ensure that the</span>
<span class="doccomment">/// sender never outpaces the receiver. The channel capacity is equal to</span>
<span class="doccomment">/// `buffer + num-senders`. In other words, each sender gets a guaranteed slot</span>
<span class="doccomment">/// in the channel capacity, and on top of that there are `buffer` "first come,</span>
<span class="doccomment">/// first serve" slots available to all senders.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// The `Receiver` returned implements the `Stream` trait and has access to any</span>
<span class="doccomment">/// number of the associated combinators for transforming the result.</span>
<span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">channel</span><span class="op"><</span><span class="ident">T</span><span class="op">></span>(<span class="ident">buffer</span>: <span class="ident">usize</span>) <span class="op">-></span> (<span class="ident">Sender</span><span class="op"><</span><span class="ident">T</span><span class="op">></span>, <span class="ident">Receiver</span><span class="op"><</span><span class="ident">T</span><span class="op">></span>) {
<span class="comment">// Check that the requested buffer size does not exceed the maximum buffer</span>
<span class="comment">// size permitted by the system.</span>
<span class="macro">assert</span><span class="macro">!</span>(<span class="ident">buffer</span> <span class="op"><</span> <span class="ident">MAX_BUFFER</span>, <span class="string">"requested buffer size too large"</span>);
<span class="ident">channel2</span>(<span class="prelude-val">Some</span>(<span class="ident">buffer</span>))
}
<span class="doccomment">/// Creates an in-memory channel implementation of the `Stream` trait with</span>
<span class="doccomment">/// unbounded capacity.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// This method creates a concrete implementation of the `Stream` trait which</span>
<span class="doccomment">/// can be used to send values across threads in a streaming fashion. A `send`</span>
<span class="doccomment">/// on this channel will always succeed as long as the receive half has not</span>
<span class="doccomment">/// been closed. If the receiver falls behind, messages will be buffered</span>
<span class="doccomment">/// internally.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// **Note** that the amount of available system memory is an implicit bound to</span>
<span class="doccomment">/// the channel. Using an `unbounded` channel has the ability of causing the</span>
<span class="doccomment">/// process to run out of memory. In this case, the process will be aborted.</span>
<span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">unbounded</span><span class="op"><</span><span class="ident">T</span><span class="op">></span>() <span class="op">-></span> (<span class="ident">UnboundedSender</span><span class="op"><</span><span class="ident">T</span><span class="op">></span>, <span class="ident">UnboundedReceiver</span><span class="op"><</span><span class="ident">T</span><span class="op">></span>) {
<span class="kw">let</span> (<span class="ident">tx</span>, <span class="ident">rx</span>) <span class="op">=</span> <span class="ident">channel2</span>(<span class="prelude-val">None</span>);
(<span class="ident">UnboundedSender</span>(<span class="ident">tx</span>), <span class="ident">UnboundedReceiver</span>(<span class="ident">rx</span>))
}
<span class="kw">fn</span> <span class="ident">channel2</span><span class="op"><</span><span class="ident">T</span><span class="op">></span>(<span class="ident">buffer</span>: <span class="prelude-ty">Option</span><span class="op"><</span><span class="ident">usize</span><span class="op">></span>) <span class="op">-></span> (<span class="ident">Sender</span><span class="op"><</span><span class="ident">T</span><span class="op">></span>, <span class="ident">Receiver</span><span class="op"><</span><span class="ident">T</span><span class="op">></span>) {
<span class="kw">let</span> <span class="ident">inner</span> <span class="op">=</span> <span class="ident">Arc</span>::<span class="ident">new</span>(<span class="ident">Inner</span> {
<span class="ident">buffer</span>: <span class="ident">buffer</span>,
<span class="ident">state</span>: <span class="ident">AtomicUsize</span>::<span class="ident">new</span>(<span class="ident">INIT_STATE</span>),
<span class="ident">message_queue</span>: <span class="ident">Queue</span>::<span class="ident">new</span>(),
<span class="ident">parked_queue</span>: <span class="ident">Queue</span>::<span class="ident">new</span>(),
<span class="ident">num_senders</span>: <span class="ident">AtomicUsize</span>::<span class="ident">new</span>(<span class="number">1</span>),
<span class="ident">recv_task</span>: <span class="ident">Mutex</span>::<span class="ident">new</span>(<span class="ident">ReceiverTask</span> {
<span class="ident">unparked</span>: <span class="bool-val">false</span>,
<span class="ident">task</span>: <span class="prelude-val">None</span>,
}),
});
<span class="kw">let</span> <span class="ident">tx</span> <span class="op">=</span> <span class="ident">Sender</span> {
<span class="ident">inner</span>: <span class="ident">inner</span>.<span class="ident">clone</span>(),
<span class="ident">sender_task</span>: <span class="ident">Arc</span>::<span class="ident">new</span>(<span class="ident">Mutex</span>::<span class="ident">new</span>(<span class="ident">SenderTask</span>::<span class="ident">new</span>())),
<span class="ident">maybe_parked</span>: <span class="bool-val">false</span>,
};
<span class="kw">let</span> <span class="ident">rx</span> <span class="op">=</span> <span class="ident">Receiver</span> {
<span class="ident">inner</span>: <span class="ident">inner</span>,
};
(<span class="ident">tx</span>, <span class="ident">rx</span>)
}
<span class="comment">/*
*
* ===== impl Sender =====
*
*/</span>
<span class="kw">impl</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> <span class="ident">Sender</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> {
<span class="doccomment">/// Attempts to send a message on this `Sender<T>` without blocking.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// This function, unlike `start_send`, is safe to call whether it's being</span>
<span class="doccomment">/// called on a task or not. Note that this function, however, will *not*</span>
<span class="doccomment">/// attempt to block the current task if the message cannot be sent.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// It is not recommended to call this function from inside of a future,</span>
<span class="doccomment">/// only from an external thread where you've otherwise arranged to be</span>
<span class="doccomment">/// notified when the channel is no longer full.</span>
<span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">try_send</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>, <span class="ident">msg</span>: <span class="ident">T</span>) <span class="op">-></span> <span class="prelude-ty">Result</span><span class="op"><</span>(), <span class="ident">TrySendError</span><span class="op"><</span><span class="ident">T</span><span class="op">>></span> {
<span class="comment">// If the sender is currently blocked, reject the message</span>
<span class="kw">if</span> <span class="op">!</span><span class="self">self</span>.<span class="ident">poll_unparked</span>(<span class="bool-val">false</span>).<span class="ident">is_ready</span>() {
<span class="kw">return</span> <span class="prelude-val">Err</span>(<span class="ident">TrySendError</span> {
<span class="ident">kind</span>: <span class="ident">TrySendErrorKind</span>::<span class="ident">Full</span>(<span class="ident">msg</span>),
});
}
<span class="comment">// The channel has capacity to accept the message, so send it</span>
<span class="self">self</span>.<span class="ident">do_send</span>(<span class="prelude-val">Some</span>(<span class="ident">msg</span>), <span class="bool-val">false</span>)
.<span class="ident">map_err</span>(<span class="op">|</span><span class="ident">SendError</span>(<span class="ident">v</span>)<span class="op">|</span> {
<span class="ident">TrySendError</span> {
<span class="ident">kind</span>: <span class="ident">TrySendErrorKind</span>::<span class="ident">Disconnected</span>(<span class="ident">v</span>),
}
})
}
<span class="comment">// Do the send without failing</span>
<span class="comment">// None means close</span>
<span class="kw">fn</span> <span class="ident">do_send</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>, <span class="ident">msg</span>: <span class="prelude-ty">Option</span><span class="op"><</span><span class="ident">T</span><span class="op">></span>, <span class="ident">do_park</span>: <span class="ident">bool</span>) <span class="op">-></span> <span class="prelude-ty">Result</span><span class="op"><</span>(), <span class="ident">SendError</span><span class="op"><</span><span class="ident">T</span><span class="op">>></span> {
<span class="comment">// First, increment the number of messages contained by the channel.</span>
<span class="comment">// This operation will also atomically determine if the sender task</span>
<span class="comment">// should be parked.</span>
<span class="comment">//</span>
<span class="comment">// None is returned in the case that the channel has been closed by the</span>
<span class="comment">// receiver. This happens when `Receiver::close` is called or the</span>
<span class="comment">// receiver is dropped.</span>
<span class="kw">let</span> <span class="ident">park_self</span> <span class="op">=</span> <span class="kw">match</span> <span class="self">self</span>.<span class="ident">inc_num_messages</span>(<span class="ident">msg</span>.<span class="ident">is_none</span>()) {
<span class="prelude-val">Some</span>(<span class="ident">park_self</span>) <span class="op">=></span> <span class="ident">park_self</span>,
<span class="prelude-val">None</span> <span class="op">=></span> {
<span class="comment">// The receiver has closed the channel. Only abort if actually</span>
<span class="comment">// sending a message. It is important that the stream</span>
<span class="comment">// termination (None) is always sent. This technically means</span>
<span class="comment">// that it is possible for the queue to contain the following</span>
<span class="comment">// number of messages:</span>
<span class="comment">//</span>
<span class="comment">// num-senders + buffer + 1</span>
<span class="comment">//</span>
<span class="kw">if</span> <span class="kw">let</span> <span class="prelude-val">Some</span>(<span class="ident">msg</span>) <span class="op">=</span> <span class="ident">msg</span> {
<span class="kw">return</span> <span class="prelude-val">Err</span>(<span class="ident">SendError</span>(<span class="ident">msg</span>));
} <span class="kw">else</span> {
<span class="kw">return</span> <span class="prelude-val">Ok</span>(());
}
}
};
<span class="comment">// If the channel has reached capacity, then the sender task needs to</span>
<span class="comment">// be parked. This will send the task handle on the parked task queue.</span>
<span class="comment">//</span>
<span class="comment">// However, when `do_send` is called while dropping the `Sender`,</span>
<span class="comment">// `task::current()` can't be called safely. In this case, in order to</span>
<span class="comment">// maintain internal consistency, a blank message is pushed onto the</span>
<span class="comment">// parked task queue.</span>
<span class="kw">if</span> <span class="ident">park_self</span> {
<span class="self">self</span>.<span class="ident">park</span>(<span class="ident">do_park</span>);
}
<span class="self">self</span>.<span class="ident">queue_push_and_signal</span>(<span class="ident">msg</span>);
<span class="prelude-val">Ok</span>(())
}
<span class="comment">// Do the send without parking current task.</span>
<span class="comment">//</span>
<span class="comment">// To be called from unbounded sender.</span>
<span class="kw">fn</span> <span class="ident">do_send_nb</span>(<span class="kw-2">&</span><span class="self">self</span>, <span class="ident">msg</span>: <span class="ident">T</span>) <span class="op">-></span> <span class="prelude-ty">Result</span><span class="op"><</span>(), <span class="ident">SendError</span><span class="op"><</span><span class="ident">T</span><span class="op">>></span> {
<span class="kw">match</span> <span class="self">self</span>.<span class="ident">inc_num_messages</span>(<span class="bool-val">false</span>) {
<span class="prelude-val">Some</span>(<span class="ident">park_self</span>) <span class="op">=></span> <span class="macro">assert</span><span class="macro">!</span>(<span class="op">!</span><span class="ident">park_self</span>),
<span class="prelude-val">None</span> <span class="op">=></span> <span class="kw">return</span> <span class="prelude-val">Err</span>(<span class="ident">SendError</span>(<span class="ident">msg</span>)),
};
<span class="self">self</span>.<span class="ident">queue_push_and_signal</span>(<span class="prelude-val">Some</span>(<span class="ident">msg</span>));
<span class="prelude-val">Ok</span>(())
}
<span class="comment">// Push message to the queue and signal to the receiver</span>
<span class="kw">fn</span> <span class="ident">queue_push_and_signal</span>(<span class="kw-2">&</span><span class="self">self</span>, <span class="ident">msg</span>: <span class="prelude-ty">Option</span><span class="op"><</span><span class="ident">T</span><span class="op">></span>) {
<span class="comment">// Push the message onto the message queue</span>
<span class="self">self</span>.<span class="ident">inner</span>.<span class="ident">message_queue</span>.<span class="ident">push</span>(<span class="ident">msg</span>);
<span class="comment">// Signal to the receiver that a message has been enqueued. If the</span>
<span class="comment">// receiver is parked, this will unpark the task.</span>
<span class="self">self</span>.<span class="ident">signal</span>();
}
<span class="comment">// Increment the number of queued messages. Returns if the sender should</span>
<span class="comment">// block.</span>
<span class="kw">fn</span> <span class="ident">inc_num_messages</span>(<span class="kw-2">&</span><span class="self">self</span>, <span class="ident">close</span>: <span class="ident">bool</span>) <span class="op">-></span> <span class="prelude-ty">Option</span><span class="op"><</span><span class="ident">bool</span><span class="op">></span> {
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">curr</span> <span class="op">=</span> <span class="self">self</span>.<span class="ident">inner</span>.<span class="ident">state</span>.<span class="ident">load</span>(<span class="ident">SeqCst</span>);
<span class="kw">loop</span> {
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">state</span> <span class="op">=</span> <span class="ident">decode_state</span>(<span class="ident">curr</span>);
<span class="comment">// The receiver end closed the channel.</span>
<span class="kw">if</span> <span class="op">!</span><span class="ident">state</span>.<span class="ident">is_open</span> {
<span class="kw">return</span> <span class="prelude-val">None</span>;
}
<span class="comment">// This probably is never hit? Odds are the process will run out of</span>
<span class="comment">// memory first. It may be worth to return something else in this</span>
<span class="comment">// case?</span>
<span class="macro">assert</span><span class="macro">!</span>(<span class="ident">state</span>.<span class="ident">num_messages</span> <span class="op"><</span> <span class="ident">MAX_CAPACITY</span>, <span class="string">"buffer space exhausted; \
sending this messages would overflow the state"</span>);
<span class="ident">state</span>.<span class="ident">num_messages</span> <span class="op">+=</span> <span class="number">1</span>;
<span class="comment">// The channel is closed by all sender handles being dropped.</span>
<span class="kw">if</span> <span class="ident">close</span> {
<span class="ident">state</span>.<span class="ident">is_open</span> <span class="op">=</span> <span class="bool-val">false</span>;
}
<span class="kw">let</span> <span class="ident">next</span> <span class="op">=</span> <span class="ident">encode_state</span>(<span class="kw-2">&</span><span class="ident">state</span>);
<span class="kw">match</span> <span class="self">self</span>.<span class="ident">inner</span>.<span class="ident">state</span>.<span class="ident">compare_exchange</span>(<span class="ident">curr</span>, <span class="ident">next</span>, <span class="ident">SeqCst</span>, <span class="ident">SeqCst</span>) {
<span class="prelude-val">Ok</span>(_) <span class="op">=></span> {
<span class="comment">// Block if the current number of pending messages has exceeded</span>
<span class="comment">// the configured buffer size</span>
<span class="kw">let</span> <span class="ident">park_self</span> <span class="op">=</span> <span class="kw">match</span> <span class="self">self</span>.<span class="ident">inner</span>.<span class="ident">buffer</span> {
<span class="prelude-val">Some</span>(<span class="ident">buffer</span>) <span class="op">=></span> <span class="ident">state</span>.<span class="ident">num_messages</span> <span class="op">></span> <span class="ident">buffer</span>,
<span class="prelude-val">None</span> <span class="op">=></span> <span class="bool-val">false</span>,
};
<span class="kw">return</span> <span class="prelude-val">Some</span>(<span class="ident">park_self</span>)
}
<span class="prelude-val">Err</span>(<span class="ident">actual</span>) <span class="op">=></span> <span class="ident">curr</span> <span class="op">=</span> <span class="ident">actual</span>,
}
}
}
<span class="comment">// Signal to the receiver task that a message has been enqueued</span>
<span class="kw">fn</span> <span class="ident">signal</span>(<span class="kw-2">&</span><span class="self">self</span>) {
<span class="comment">// TODO</span>
<span class="comment">// This logic can probably be improved by guarding the lock with an</span>
<span class="comment">// atomic.</span>
<span class="comment">//</span>
<span class="comment">// Do this step first so that the lock is dropped when</span>
<span class="comment">// `unpark` is called</span>
<span class="kw">let</span> <span class="ident">task</span> <span class="op">=</span> {
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">recv_task</span> <span class="op">=</span> <span class="self">self</span>.<span class="ident">inner</span>.<span class="ident">recv_task</span>.<span class="ident">lock</span>().<span class="ident">unwrap</span>();
<span class="comment">// If the receiver has already been unparked, then there is nothing</span>
<span class="comment">// more to do</span>
<span class="kw">if</span> <span class="ident">recv_task</span>.<span class="ident">unparked</span> {
<span class="kw">return</span>;
}
<span class="comment">// Setting this flag enables the receiving end to detect that</span>
<span class="comment">// an unpark event happened in order to avoid unnecessarily</span>
<span class="comment">// parking.</span>
<span class="ident">recv_task</span>.<span class="ident">unparked</span> <span class="op">=</span> <span class="bool-val">true</span>;
<span class="ident">recv_task</span>.<span class="ident">task</span>.<span class="ident">take</span>()
};
<span class="kw">if</span> <span class="kw">let</span> <span class="prelude-val">Some</span>(<span class="ident">task</span>) <span class="op">=</span> <span class="ident">task</span> {
<span class="ident">task</span>.<span class="ident">notify</span>();
}
}
<span class="kw">fn</span> <span class="ident">park</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>, <span class="ident">can_park</span>: <span class="ident">bool</span>) {
<span class="comment">// TODO: clean up internal state if the task::current will fail</span>
<span class="kw">let</span> <span class="ident">task</span> <span class="op">=</span> <span class="kw">if</span> <span class="ident">can_park</span> {
<span class="prelude-val">Some</span>(<span class="ident">task</span>::<span class="ident">current</span>())
} <span class="kw">else</span> {
<span class="prelude-val">None</span>
};
{
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">sender</span> <span class="op">=</span> <span class="self">self</span>.<span class="ident">sender_task</span>.<span class="ident">lock</span>().<span class="ident">unwrap</span>();
<span class="ident">sender</span>.<span class="ident">task</span> <span class="op">=</span> <span class="ident">task</span>;
<span class="ident">sender</span>.<span class="ident">is_parked</span> <span class="op">=</span> <span class="bool-val">true</span>;
}
<span class="comment">// Send handle over queue</span>
<span class="kw">let</span> <span class="ident">t</span> <span class="op">=</span> <span class="self">self</span>.<span class="ident">sender_task</span>.<span class="ident">clone</span>();
<span class="self">self</span>.<span class="ident">inner</span>.<span class="ident">parked_queue</span>.<span class="ident">push</span>(<span class="ident">t</span>);
<span class="comment">// Check to make sure we weren't closed after we sent our task on the</span>
<span class="comment">// queue</span>
<span class="kw">let</span> <span class="ident">state</span> <span class="op">=</span> <span class="ident">decode_state</span>(<span class="self">self</span>.<span class="ident">inner</span>.<span class="ident">state</span>.<span class="ident">load</span>(<span class="ident">SeqCst</span>));
<span class="self">self</span>.<span class="ident">maybe_parked</span> <span class="op">=</span> <span class="ident">state</span>.<span class="ident">is_open</span>;
}
<span class="doccomment">/// Polls the channel to determine if there is guaranteed to be capacity to send at least one</span>
<span class="doccomment">/// item without waiting.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// Returns `Ok(Async::Ready(_))` if there is sufficient capacity, or returns</span>
<span class="doccomment">/// `Ok(Async::NotReady)` if the channel is not guaranteed to have capacity. Returns</span>
<span class="doccomment">/// `Err(SendError(_))` if the receiver has been dropped.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// # Panics</span>
<span class="doccomment">///</span>
<span class="doccomment">/// This method will panic if called from outside the context of a task or future.</span>
<span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">poll_ready</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>) <span class="op">-></span> <span class="ident">Poll</span><span class="op"><</span>(), <span class="ident">SendError</span><span class="op"><</span>()<span class="op">>></span> {
<span class="kw">let</span> <span class="ident">state</span> <span class="op">=</span> <span class="ident">decode_state</span>(<span class="self">self</span>.<span class="ident">inner</span>.<span class="ident">state</span>.<span class="ident">load</span>(<span class="ident">SeqCst</span>));
<span class="kw">if</span> <span class="op">!</span><span class="ident">state</span>.<span class="ident">is_open</span> {
<span class="kw">return</span> <span class="prelude-val">Err</span>(<span class="ident">SendError</span>(()));
}
<span class="prelude-val">Ok</span>(<span class="self">self</span>.<span class="ident">poll_unparked</span>(<span class="bool-val">true</span>))
}
<span class="kw">fn</span> <span class="ident">poll_unparked</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>, <span class="ident">do_park</span>: <span class="ident">bool</span>) <span class="op">-></span> <span class="ident">Async</span><span class="op"><</span>()<span class="op">></span> {
<span class="comment">// First check the `maybe_parked` variable. This avoids acquiring the</span>
<span class="comment">// lock in most cases</span>
<span class="kw">if</span> <span class="self">self</span>.<span class="ident">maybe_parked</span> {
<span class="comment">// Get a lock on the task handle</span>
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">task</span> <span class="op">=</span> <span class="self">self</span>.<span class="ident">sender_task</span>.<span class="ident">lock</span>().<span class="ident">unwrap</span>();
<span class="kw">if</span> <span class="op">!</span><span class="ident">task</span>.<span class="ident">is_parked</span> {
<span class="self">self</span>.<span class="ident">maybe_parked</span> <span class="op">=</span> <span class="bool-val">false</span>;
<span class="kw">return</span> <span class="ident">Async</span>::<span class="ident">Ready</span>(())
}
<span class="comment">// At this point, an unpark request is pending, so there will be an</span>
<span class="comment">// unpark sometime in the future. We just need to make sure that</span>
<span class="comment">// the correct task will be notified.</span>
<span class="comment">//</span>
<span class="comment">// Update the task in case the `Sender` has been moved to another</span>
<span class="comment">// task</span>
<span class="ident">task</span>.<span class="ident">task</span> <span class="op">=</span> <span class="kw">if</span> <span class="ident">do_park</span> {
<span class="prelude-val">Some</span>(<span class="ident">task</span>::<span class="ident">current</span>())
} <span class="kw">else</span> {
<span class="prelude-val">None</span>
};
<span class="ident">Async</span>::<span class="ident">NotReady</span>
} <span class="kw">else</span> {
<span class="ident">Async</span>::<span class="ident">Ready</span>(())
}
}
}
<span class="kw">impl</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> <span class="ident">Sink</span> <span class="kw">for</span> <span class="ident">Sender</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> {
<span class="kw">type</span> <span class="ident">SinkItem</span> <span class="op">=</span> <span class="ident">T</span>;
<span class="kw">type</span> <span class="ident">SinkError</span> <span class="op">=</span> <span class="ident">SendError</span><span class="op"><</span><span class="ident">T</span><span class="op">></span>;
<span class="kw">fn</span> <span class="ident">start_send</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>, <span class="ident">msg</span>: <span class="ident">T</span>) <span class="op">-></span> <span class="ident">StartSend</span><span class="op"><</span><span class="ident">T</span>, <span class="ident">SendError</span><span class="op"><</span><span class="ident">T</span><span class="op">>></span> {
<span class="comment">// If the sender is currently blocked, reject the message before doing</span>
<span class="comment">// any work.</span>
<span class="kw">if</span> <span class="op">!</span><span class="self">self</span>.<span class="ident">poll_unparked</span>(<span class="bool-val">true</span>).<span class="ident">is_ready</span>() {
<span class="kw">return</span> <span class="prelude-val">Ok</span>(<span class="ident">AsyncSink</span>::<span class="ident">NotReady</span>(<span class="ident">msg</span>));
}
<span class="comment">// The channel has capacity to accept the message, so send it.</span>
<span class="self">self</span>.<span class="ident">do_send</span>(<span class="prelude-val">Some</span>(<span class="ident">msg</span>), <span class="bool-val">true</span>)<span class="question-mark">?</span>;
<span class="prelude-val">Ok</span>(<span class="ident">AsyncSink</span>::<span class="ident">Ready</span>)
}
<span class="kw">fn</span> <span class="ident">poll_complete</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>) <span class="op">-></span> <span class="ident">Poll</span><span class="op"><</span>(), <span class="ident">SendError</span><span class="op"><</span><span class="ident">T</span><span class="op">>></span> {
<span class="prelude-val">Ok</span>(<span class="ident">Async</span>::<span class="ident">Ready</span>(()))
}
<span class="kw">fn</span> <span class="ident">close</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>) <span class="op">-></span> <span class="ident">Poll</span><span class="op"><</span>(), <span class="ident">SendError</span><span class="op"><</span><span class="ident">T</span><span class="op">>></span> {
<span class="prelude-val">Ok</span>(<span class="ident">Async</span>::<span class="ident">Ready</span>(()))
}
}
<span class="kw">impl</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> <span class="ident">UnboundedSender</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> {
<span class="doccomment">/// Sends the provided message along this channel.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// This is an unbounded sender, so this function differs from `Sink::send`</span>
<span class="doccomment">/// by ensuring the return type reflects that the channel is always ready to</span>
<span class="doccomment">/// receive messages.</span>
<span class="attribute">#[<span class="ident">deprecated</span>(<span class="ident">note</span> <span class="op">=</span> <span class="string">"renamed to `unbounded_send`"</span>)]</span>
<span class="attribute">#[<span class="ident">doc</span>(<span class="ident">hidden</span>)]</span>
<span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">send</span>(<span class="kw-2">&</span><span class="self">self</span>, <span class="ident">msg</span>: <span class="ident">T</span>) <span class="op">-></span> <span class="prelude-ty">Result</span><span class="op"><</span>(), <span class="ident">SendError</span><span class="op"><</span><span class="ident">T</span><span class="op">>></span> {
<span class="self">self</span>.<span class="ident">unbounded_send</span>(<span class="ident">msg</span>)
}
<span class="doccomment">/// Sends the provided message along this channel.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// This is an unbounded sender, so this function differs from `Sink::send`</span>
<span class="doccomment">/// by ensuring the return type reflects that the channel is always ready to</span>
<span class="doccomment">/// receive messages.</span>
<span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">unbounded_send</span>(<span class="kw-2">&</span><span class="self">self</span>, <span class="ident">msg</span>: <span class="ident">T</span>) <span class="op">-></span> <span class="prelude-ty">Result</span><span class="op"><</span>(), <span class="ident">SendError</span><span class="op"><</span><span class="ident">T</span><span class="op">>></span> {
<span class="self">self</span>.<span class="number">0</span>.<span class="ident">do_send_nb</span>(<span class="ident">msg</span>)
}
}
<span class="kw">impl</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> <span class="ident">Sink</span> <span class="kw">for</span> <span class="ident">UnboundedSender</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> {
<span class="kw">type</span> <span class="ident">SinkItem</span> <span class="op">=</span> <span class="ident">T</span>;
<span class="kw">type</span> <span class="ident">SinkError</span> <span class="op">=</span> <span class="ident">SendError</span><span class="op"><</span><span class="ident">T</span><span class="op">></span>;
<span class="kw">fn</span> <span class="ident">start_send</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>, <span class="ident">msg</span>: <span class="ident">T</span>) <span class="op">-></span> <span class="ident">StartSend</span><span class="op"><</span><span class="ident">T</span>, <span class="ident">SendError</span><span class="op"><</span><span class="ident">T</span><span class="op">>></span> {
<span class="self">self</span>.<span class="number">0</span>.<span class="ident">start_send</span>(<span class="ident">msg</span>)
}
<span class="kw">fn</span> <span class="ident">poll_complete</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>) <span class="op">-></span> <span class="ident">Poll</span><span class="op"><</span>(), <span class="ident">SendError</span><span class="op"><</span><span class="ident">T</span><span class="op">>></span> {
<span class="self">self</span>.<span class="number">0</span>.<span class="ident">poll_complete</span>()
}
<span class="kw">fn</span> <span class="ident">close</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>) <span class="op">-></span> <span class="ident">Poll</span><span class="op"><</span>(), <span class="ident">SendError</span><span class="op"><</span><span class="ident">T</span><span class="op">>></span> {
<span class="prelude-val">Ok</span>(<span class="ident">Async</span>::<span class="ident">Ready</span>(()))
}
}
<span class="kw">impl</span><span class="op"><</span><span class="lifetime">'a</span>, <span class="ident">T</span><span class="op">></span> <span class="ident">Sink</span> <span class="kw">for</span> <span class="kw-2">&</span><span class="lifetime">'a</span> <span class="ident">UnboundedSender</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> {
<span class="kw">type</span> <span class="ident">SinkItem</span> <span class="op">=</span> <span class="ident">T</span>;
<span class="kw">type</span> <span class="ident">SinkError</span> <span class="op">=</span> <span class="ident">SendError</span><span class="op"><</span><span class="ident">T</span><span class="op">></span>;
<span class="kw">fn</span> <span class="ident">start_send</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>, <span class="ident">msg</span>: <span class="ident">T</span>) <span class="op">-></span> <span class="ident">StartSend</span><span class="op"><</span><span class="ident">T</span>, <span class="ident">SendError</span><span class="op"><</span><span class="ident">T</span><span class="op">>></span> {
<span class="self">self</span>.<span class="number">0</span>.<span class="ident">do_send_nb</span>(<span class="ident">msg</span>)<span class="question-mark">?</span>;
<span class="prelude-val">Ok</span>(<span class="ident">AsyncSink</span>::<span class="ident">Ready</span>)
}
<span class="kw">fn</span> <span class="ident">poll_complete</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>) <span class="op">-></span> <span class="ident">Poll</span><span class="op"><</span>(), <span class="ident">SendError</span><span class="op"><</span><span class="ident">T</span><span class="op">>></span> {
<span class="prelude-val">Ok</span>(<span class="ident">Async</span>::<span class="ident">Ready</span>(()))
}
<span class="kw">fn</span> <span class="ident">close</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>) <span class="op">-></span> <span class="ident">Poll</span><span class="op"><</span>(), <span class="ident">SendError</span><span class="op"><</span><span class="ident">T</span><span class="op">>></span> {
<span class="prelude-val">Ok</span>(<span class="ident">Async</span>::<span class="ident">Ready</span>(()))
}
}
<span class="kw">impl</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> <span class="ident">Clone</span> <span class="kw">for</span> <span class="ident">UnboundedSender</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> {
<span class="kw">fn</span> <span class="ident">clone</span>(<span class="kw-2">&</span><span class="self">self</span>) <span class="op">-></span> <span class="ident">UnboundedSender</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> {
<span class="ident">UnboundedSender</span>(<span class="self">self</span>.<span class="number">0</span>.<span class="ident">clone</span>())
}
}
<span class="kw">impl</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> <span class="ident">Clone</span> <span class="kw">for</span> <span class="ident">Sender</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> {
<span class="kw">fn</span> <span class="ident">clone</span>(<span class="kw-2">&</span><span class="self">self</span>) <span class="op">-></span> <span class="ident">Sender</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> {
<span class="comment">// Since this atomic op isn't actually guarding any memory and we don't</span>
<span class="comment">// care about any orderings besides the ordering on the single atomic</span>
<span class="comment">// variable, a relaxed ordering is acceptable.</span>
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">curr</span> <span class="op">=</span> <span class="self">self</span>.<span class="ident">inner</span>.<span class="ident">num_senders</span>.<span class="ident">load</span>(<span class="ident">SeqCst</span>);
<span class="kw">loop</span> {
<span class="comment">// If the maximum number of senders has been reached, then fail</span>
<span class="kw">if</span> <span class="ident">curr</span> <span class="op">==</span> <span class="self">self</span>.<span class="ident">inner</span>.<span class="ident">max_senders</span>() {
<span class="macro">panic</span><span class="macro">!</span>(<span class="string">"cannot clone `Sender` -- too many outstanding senders"</span>);
}
<span class="macro">debug_assert</span><span class="macro">!</span>(<span class="ident">curr</span> <span class="op"><</span> <span class="self">self</span>.<span class="ident">inner</span>.<span class="ident">max_senders</span>());
<span class="kw">let</span> <span class="ident">next</span> <span class="op">=</span> <span class="ident">curr</span> <span class="op">+</span> <span class="number">1</span>;
<span class="kw">let</span> <span class="ident">actual</span> <span class="op">=</span> <span class="self">self</span>.<span class="ident">inner</span>.<span class="ident">num_senders</span>.<span class="ident">compare_and_swap</span>(<span class="ident">curr</span>, <span class="ident">next</span>, <span class="ident">SeqCst</span>);
<span class="comment">// The ABA problem doesn't matter here. We only care that the</span>
<span class="comment">// number of senders never exceeds the maximum.</span>
<span class="kw">if</span> <span class="ident">actual</span> <span class="op">==</span> <span class="ident">curr</span> {
<span class="kw">return</span> <span class="ident">Sender</span> {
<span class="ident">inner</span>: <span class="self">self</span>.<span class="ident">inner</span>.<span class="ident">clone</span>(),
<span class="ident">sender_task</span>: <span class="ident">Arc</span>::<span class="ident">new</span>(<span class="ident">Mutex</span>::<span class="ident">new</span>(<span class="ident">SenderTask</span>::<span class="ident">new</span>())),
<span class="ident">maybe_parked</span>: <span class="bool-val">false</span>,
};
}
<span class="ident">curr</span> <span class="op">=</span> <span class="ident">actual</span>;
}
}
}
<span class="kw">impl</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> <span class="ident">Drop</span> <span class="kw">for</span> <span class="ident">Sender</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> {
<span class="kw">fn</span> <span class="ident">drop</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>) {
<span class="comment">// Ordering between variables don't matter here</span>
<span class="kw">let</span> <span class="ident">prev</span> <span class="op">=</span> <span class="self">self</span>.<span class="ident">inner</span>.<span class="ident">num_senders</span>.<span class="ident">fetch_sub</span>(<span class="number">1</span>, <span class="ident">SeqCst</span>);
<span class="kw">if</span> <span class="ident">prev</span> <span class="op">==</span> <span class="number">1</span> {
<span class="kw">let</span> _ <span class="op">=</span> <span class="self">self</span>.<span class="ident">do_send</span>(<span class="prelude-val">None</span>, <span class="bool-val">false</span>);
}
}
}
<span class="comment">/*
*
* ===== impl Receiver =====
*
*/</span>
<span class="kw">impl</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> <span class="ident">Receiver</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> {
<span class="doccomment">/// Closes the receiving half</span>
<span class="doccomment">///</span>
<span class="doccomment">/// This prevents any further messages from being sent on the channel while</span>
<span class="doccomment">/// still enabling the receiver to drain messages that are buffered.</span>
<span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">close</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>) {
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">curr</span> <span class="op">=</span> <span class="self">self</span>.<span class="ident">inner</span>.<span class="ident">state</span>.<span class="ident">load</span>(<span class="ident">SeqCst</span>);
<span class="kw">loop</span> {
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">state</span> <span class="op">=</span> <span class="ident">decode_state</span>(<span class="ident">curr</span>);
<span class="kw">if</span> <span class="op">!</span><span class="ident">state</span>.<span class="ident">is_open</span> {
<span class="kw">break</span>
}
<span class="ident">state</span>.<span class="ident">is_open</span> <span class="op">=</span> <span class="bool-val">false</span>;
<span class="kw">let</span> <span class="ident">next</span> <span class="op">=</span> <span class="ident">encode_state</span>(<span class="kw-2">&</span><span class="ident">state</span>);
<span class="kw">match</span> <span class="self">self</span>.<span class="ident">inner</span>.<span class="ident">state</span>.<span class="ident">compare_exchange</span>(<span class="ident">curr</span>, <span class="ident">next</span>, <span class="ident">SeqCst</span>, <span class="ident">SeqCst</span>) {
<span class="prelude-val">Ok</span>(_) <span class="op">=></span> <span class="kw">break</span>,
<span class="prelude-val">Err</span>(<span class="ident">actual</span>) <span class="op">=></span> <span class="ident">curr</span> <span class="op">=</span> <span class="ident">actual</span>,
}
}
<span class="comment">// Wake up any threads waiting as they'll see that we've closed the</span>
<span class="comment">// channel and will continue on their merry way.</span>
<span class="kw">loop</span> {
<span class="kw">match</span> <span class="kw">unsafe</span> { <span class="self">self</span>.<span class="ident">inner</span>.<span class="ident">parked_queue</span>.<span class="ident">pop</span>() } {
<span class="ident">PopResult</span>::<span class="ident">Data</span>(<span class="ident">task</span>) <span class="op">=></span> {
<span class="ident">task</span>.<span class="ident">lock</span>().<span class="ident">unwrap</span>().<span class="ident">notify</span>();
}
<span class="ident">PopResult</span>::<span class="ident">Empty</span> <span class="op">=></span> <span class="kw">break</span>,
<span class="ident">PopResult</span>::<span class="ident">Inconsistent</span> <span class="op">=></span> <span class="ident">thread</span>::<span class="ident">yield_now</span>(),
}
}
}
<span class="kw">fn</span> <span class="ident">next_message</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>) <span class="op">-></span> <span class="ident">Async</span><span class="op"><</span><span class="prelude-ty">Option</span><span class="op"><</span><span class="ident">T</span><span class="op">>></span> {
<span class="comment">// Pop off a message</span>
<span class="kw">loop</span> {
<span class="kw">match</span> <span class="kw">unsafe</span> { <span class="self">self</span>.<span class="ident">inner</span>.<span class="ident">message_queue</span>.<span class="ident">pop</span>() } {
<span class="ident">PopResult</span>::<span class="ident">Data</span>(<span class="ident">msg</span>) <span class="op">=></span> {
<span class="kw">return</span> <span class="ident">Async</span>::<span class="ident">Ready</span>(<span class="ident">msg</span>);
}
<span class="ident">PopResult</span>::<span class="ident">Empty</span> <span class="op">=></span> {
<span class="comment">// The queue is empty, return NotReady</span>
<span class="kw">return</span> <span class="ident">Async</span>::<span class="ident">NotReady</span>;
}
<span class="ident">PopResult</span>::<span class="ident">Inconsistent</span> <span class="op">=></span> {
<span class="comment">// Inconsistent means that there will be a message to pop</span>
<span class="comment">// in a short time. This branch can only be reached if</span>
<span class="comment">// values are being produced from another thread, so there</span>
<span class="comment">// are a few ways that we can deal with this:</span>
<span class="comment">//</span>
<span class="comment">// 1) Spin</span>
<span class="comment">// 2) thread::yield_now()</span>
<span class="comment">// 3) task::current().unwrap() & return NotReady</span>
<span class="comment">//</span>
<span class="comment">// For now, thread::yield_now() is used, but it would</span>
<span class="comment">// probably be better to spin a few times then yield.</span>
<span class="ident">thread</span>::<span class="ident">yield_now</span>();
}
}
}
}
<span class="comment">// Unpark a single task handle if there is one pending in the parked queue</span>
<span class="kw">fn</span> <span class="ident">unpark_one</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>) {
<span class="kw">loop</span> {
<span class="kw">match</span> <span class="kw">unsafe</span> { <span class="self">self</span>.<span class="ident">inner</span>.<span class="ident">parked_queue</span>.<span class="ident">pop</span>() } {
<span class="ident">PopResult</span>::<span class="ident">Data</span>(<span class="ident">task</span>) <span class="op">=></span> {
<span class="ident">task</span>.<span class="ident">lock</span>().<span class="ident">unwrap</span>().<span class="ident">notify</span>();
<span class="kw">return</span>;
}
<span class="ident">PopResult</span>::<span class="ident">Empty</span> <span class="op">=></span> {
<span class="comment">// Queue empty, no task to wake up.</span>
<span class="kw">return</span>;
}
<span class="ident">PopResult</span>::<span class="ident">Inconsistent</span> <span class="op">=></span> {
<span class="comment">// Same as above</span>
<span class="ident">thread</span>::<span class="ident">yield_now</span>();
}
}
}
}
<span class="comment">// Try to park the receiver task</span>
<span class="kw">fn</span> <span class="ident">try_park</span>(<span class="kw-2">&</span><span class="self">self</span>) <span class="op">-></span> <span class="ident">TryPark</span> {
<span class="kw">let</span> <span class="ident">curr</span> <span class="op">=</span> <span class="self">self</span>.<span class="ident">inner</span>.<span class="ident">state</span>.<span class="ident">load</span>(<span class="ident">SeqCst</span>);
<span class="kw">let</span> <span class="ident">state</span> <span class="op">=</span> <span class="ident">decode_state</span>(<span class="ident">curr</span>);
<span class="comment">// If the channel is closed, then there is no need to park.</span>
<span class="kw">if</span> <span class="op">!</span><span class="ident">state</span>.<span class="ident">is_open</span> <span class="op">&&</span> <span class="ident">state</span>.<span class="ident">num_messages</span> <span class="op">==</span> <span class="number">0</span> {
<span class="kw">return</span> <span class="ident">TryPark</span>::<span class="ident">Closed</span>;
}
<span class="comment">// First, track the task in the `recv_task` slot</span>
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">recv_task</span> <span class="op">=</span> <span class="self">self</span>.<span class="ident">inner</span>.<span class="ident">recv_task</span>.<span class="ident">lock</span>().<span class="ident">unwrap</span>();
<span class="kw">if</span> <span class="ident">recv_task</span>.<span class="ident">unparked</span> {
<span class="comment">// Consume the `unpark` signal without actually parking</span>
<span class="ident">recv_task</span>.<span class="ident">unparked</span> <span class="op">=</span> <span class="bool-val">false</span>;
<span class="kw">return</span> <span class="ident">TryPark</span>::<span class="ident">NotEmpty</span>;
}
<span class="ident">recv_task</span>.<span class="ident">task</span> <span class="op">=</span> <span class="prelude-val">Some</span>(<span class="ident">task</span>::<span class="ident">current</span>());
<span class="ident">TryPark</span>::<span class="ident">Parked</span>
}
<span class="kw">fn</span> <span class="ident">dec_num_messages</span>(<span class="kw-2">&</span><span class="self">self</span>) {
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">curr</span> <span class="op">=</span> <span class="self">self</span>.<span class="ident">inner</span>.<span class="ident">state</span>.<span class="ident">load</span>(<span class="ident">SeqCst</span>);
<span class="kw">loop</span> {
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">state</span> <span class="op">=</span> <span class="ident">decode_state</span>(<span class="ident">curr</span>);
<span class="ident">state</span>.<span class="ident">num_messages</span> <span class="op">-=</span> <span class="number">1</span>;
<span class="kw">let</span> <span class="ident">next</span> <span class="op">=</span> <span class="ident">encode_state</span>(<span class="kw-2">&</span><span class="ident">state</span>);
<span class="kw">match</span> <span class="self">self</span>.<span class="ident">inner</span>.<span class="ident">state</span>.<span class="ident">compare_exchange</span>(<span class="ident">curr</span>, <span class="ident">next</span>, <span class="ident">SeqCst</span>, <span class="ident">SeqCst</span>) {
<span class="prelude-val">Ok</span>(_) <span class="op">=></span> <span class="kw">break</span>,
<span class="prelude-val">Err</span>(<span class="ident">actual</span>) <span class="op">=></span> <span class="ident">curr</span> <span class="op">=</span> <span class="ident">actual</span>,
}
}
}
}
<span class="kw">impl</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> <span class="ident">Stream</span> <span class="kw">for</span> <span class="ident">Receiver</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> {
<span class="kw">type</span> <span class="ident">Item</span> <span class="op">=</span> <span class="ident">T</span>;
<span class="kw">type</span> <span class="ident">Error</span> <span class="op">=</span> ();
<span class="kw">fn</span> <span class="ident">poll</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>) <span class="op">-></span> <span class="ident">Poll</span><span class="op"><</span><span class="prelude-ty">Option</span><span class="op"><</span><span class="ident">T</span><span class="op">></span>, ()<span class="op">></span> {
<span class="kw">loop</span> {
<span class="comment">// Try to read a message off of the message queue.</span>
<span class="kw">let</span> <span class="ident">msg</span> <span class="op">=</span> <span class="kw">match</span> <span class="self">self</span>.<span class="ident">next_message</span>() {
<span class="ident">Async</span>::<span class="ident">Ready</span>(<span class="ident">msg</span>) <span class="op">=></span> <span class="ident">msg</span>,
<span class="ident">Async</span>::<span class="ident">NotReady</span> <span class="op">=></span> {
<span class="comment">// There are no messages to read, in this case, attempt to</span>
<span class="comment">// park. The act of parking will verify that the channel is</span>
<span class="comment">// still empty after the park operation has completed.</span>
<span class="kw">match</span> <span class="self">self</span>.<span class="ident">try_park</span>() {
<span class="ident">TryPark</span>::<span class="ident">Parked</span> <span class="op">=></span> {
<span class="comment">// The task was parked, and the channel is still</span>
<span class="comment">// empty, return NotReady.</span>
<span class="kw">return</span> <span class="prelude-val">Ok</span>(<span class="ident">Async</span>::<span class="ident">NotReady</span>);
}
<span class="ident">TryPark</span>::<span class="ident">Closed</span> <span class="op">=></span> {
<span class="comment">// The channel is closed, there will be no further</span>
<span class="comment">// messages.</span>
<span class="kw">return</span> <span class="prelude-val">Ok</span>(<span class="ident">Async</span>::<span class="ident">Ready</span>(<span class="prelude-val">None</span>));
}
<span class="ident">TryPark</span>::<span class="ident">NotEmpty</span> <span class="op">=></span> {
<span class="comment">// A message has been sent while attempting to</span>
<span class="comment">// park. Loop again, the next iteration is</span>
<span class="comment">// guaranteed to get the message.</span>
<span class="kw">continue</span>;
}
}
}
};
<span class="comment">// If there are any parked task handles in the parked queue, pop</span>
<span class="comment">// one and unpark it.</span>
<span class="self">self</span>.<span class="ident">unpark_one</span>();
<span class="comment">// Decrement number of messages</span>
<span class="self">self</span>.<span class="ident">dec_num_messages</span>();
<span class="comment">// Return the message</span>
<span class="kw">return</span> <span class="prelude-val">Ok</span>(<span class="ident">Async</span>::<span class="ident">Ready</span>(<span class="ident">msg</span>));
}
}
}
<span class="kw">impl</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> <span class="ident">Drop</span> <span class="kw">for</span> <span class="ident">Receiver</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> {
<span class="kw">fn</span> <span class="ident">drop</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>) {
<span class="comment">// Drain the channel of all pending messages</span>
<span class="self">self</span>.<span class="ident">close</span>();
<span class="kw">while</span> <span class="self">self</span>.<span class="ident">next_message</span>().<span class="ident">is_ready</span>() {
<span class="comment">// ...</span>
}
}
}
<span class="kw">impl</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> <span class="ident">UnboundedReceiver</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> {
<span class="doccomment">/// Closes the receiving half</span>
<span class="doccomment">///</span>
<span class="doccomment">/// This prevents any further messages from being sent on the channel while</span>
<span class="doccomment">/// still enabling the receiver to drain messages that are buffered.</span>
<span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">close</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>) {
<span class="self">self</span>.<span class="number">0</span>.<span class="ident">close</span>();
}
}
<span class="kw">impl</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> <span class="ident">Stream</span> <span class="kw">for</span> <span class="ident">UnboundedReceiver</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> {
<span class="kw">type</span> <span class="ident">Item</span> <span class="op">=</span> <span class="ident">T</span>;
<span class="kw">type</span> <span class="ident">Error</span> <span class="op">=</span> ();
<span class="kw">fn</span> <span class="ident">poll</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>) <span class="op">-></span> <span class="ident">Poll</span><span class="op"><</span><span class="prelude-ty">Option</span><span class="op"><</span><span class="ident">T</span><span class="op">></span>, ()<span class="op">></span> {
<span class="self">self</span>.<span class="number">0</span>.<span class="ident">poll</span>()
}
}
<span class="doccomment">/// Handle returned from the `spawn` function.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// This handle is a stream that proxies a stream on a separate `Executor`.</span>
<span class="doccomment">/// Created through the `mpsc::spawn` function, this handle will produce</span>
<span class="doccomment">/// the same values as the proxied stream, as they are produced in the executor,</span>
<span class="doccomment">/// and uses a limited buffer to exert back-pressure on the remote stream.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// If this handle is dropped, then the stream will no longer be polled and is</span>
<span class="doccomment">/// scheduled to be dropped.</span>
<span class="kw">pub</span> <span class="kw">struct</span> <span class="ident">SpawnHandle</span><span class="op"><</span><span class="ident">Item</span>, <span class="ident">Error</span><span class="op">></span> {
<span class="ident">rx</span>: <span class="ident">Receiver</span><span class="op"><</span><span class="prelude-ty">Result</span><span class="op"><</span><span class="ident">Item</span>, <span class="ident">Error</span><span class="op">>></span>,
<span class="ident">_cancel_tx</span>: <span class="ident">oneshot</span>::<span class="ident">Sender</span><span class="op"><</span>()<span class="op">></span>,
}
<span class="doccomment">/// Type of future which `Executor` instances must be able to execute for `spawn`.</span>
<span class="kw">pub</span> <span class="kw">struct</span> <span class="ident">Execute</span><span class="op"><</span><span class="ident">S</span>: <span class="ident">Stream</span><span class="op">></span> {
<span class="ident">inner</span>: <span class="ident">SendAll</span><span class="op"><</span><span class="ident">Sender</span><span class="op"><</span><span class="prelude-ty">Result</span><span class="op"><</span><span class="ident">S</span>::<span class="ident">Item</span>, <span class="ident">S</span>::<span class="ident">Error</span><span class="op">>></span>, <span class="ident">Results</span><span class="op"><</span><span class="ident">S</span>, <span class="ident">SendError</span><span class="op"><</span><span class="prelude-ty">Result</span><span class="op"><</span><span class="ident">S</span>::<span class="ident">Item</span>, <span class="ident">S</span>::<span class="ident">Error</span><span class="op">>></span><span class="op">>></span>,
<span class="ident">cancel_rx</span>: <span class="ident">oneshot</span>::<span class="ident">Receiver</span><span class="op"><</span>()<span class="op">></span>,
}
<span class="doccomment">/// Spawns a `stream` onto the instance of `Executor` provided, `executor`,</span>
<span class="doccomment">/// returning a handle representing the remote stream.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// The `stream` will be canceled if the `SpawnHandle` is dropped.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// The `SpawnHandle` returned is a stream that is a proxy for `stream` itself.</span>
<span class="doccomment">/// When `stream` has additional items available, then the `SpawnHandle`</span>
<span class="doccomment">/// will have those same items available.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// At most `buffer + 1` elements will be buffered at a time. If the buffer</span>
<span class="doccomment">/// is full, then `stream` will stop progressing until more space is available.</span>
<span class="doccomment">/// This allows the `SpawnHandle` to exert backpressure on the `stream`.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// # Panics</span>
<span class="doccomment">///</span>
<span class="doccomment">/// This function will panic if `executor` is unable spawn a `Future` containing</span>
<span class="doccomment">/// the entirety of the `stream`.</span>
<span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">spawn</span><span class="op"><</span><span class="ident">S</span>, <span class="ident">E</span><span class="op">></span>(<span class="ident">stream</span>: <span class="ident">S</span>, <span class="ident">executor</span>: <span class="kw-2">&</span><span class="ident">E</span>, <span class="ident">buffer</span>: <span class="ident">usize</span>) <span class="op">-></span> <span class="ident">SpawnHandle</span><span class="op"><</span><span class="ident">S</span>::<span class="ident">Item</span>, <span class="ident">S</span>::<span class="ident">Error</span><span class="op">></span>
<span class="kw">where</span> <span class="ident">S</span>: <span class="ident">Stream</span>,
<span class="ident">E</span>: <span class="ident">Executor</span><span class="op"><</span><span class="ident">Execute</span><span class="op"><</span><span class="ident">S</span><span class="op">>></span>
{
<span class="kw">let</span> (<span class="ident">cancel_tx</span>, <span class="ident">cancel_rx</span>) <span class="op">=</span> <span class="ident">oneshot</span>::<span class="ident">channel</span>();
<span class="kw">let</span> (<span class="ident">tx</span>, <span class="ident">rx</span>) <span class="op">=</span> <span class="ident">channel</span>(<span class="ident">buffer</span>);
<span class="ident">executor</span>.<span class="ident">execute</span>(<span class="ident">Execute</span> {
<span class="ident">inner</span>: <span class="ident">tx</span>.<span class="ident">send_all</span>(<span class="ident">resultstream</span>::<span class="ident">new</span>(<span class="ident">stream</span>)),
<span class="ident">cancel_rx</span>: <span class="ident">cancel_rx</span>,
}).<span class="ident">expect</span>(<span class="string">"failed to spawn stream"</span>);
<span class="ident">SpawnHandle</span> {
<span class="ident">rx</span>: <span class="ident">rx</span>,
<span class="ident">_cancel_tx</span>: <span class="ident">cancel_tx</span>,
}
}
<span class="doccomment">/// Spawns a `stream` onto the instance of `Executor` provided, `executor`,</span>
<span class="doccomment">/// returning a handle representing the remote stream, with unbounded buffering.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// The `stream` will be canceled if the `SpawnHandle` is dropped.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// The `SpawnHandle` returned is a stream that is a proxy for `stream` itself.</span>
<span class="doccomment">/// When `stream` has additional items available, then the `SpawnHandle`</span>
<span class="doccomment">/// will have those same items available.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// An unbounded buffer is used, which means that values will be buffered as</span>
<span class="doccomment">/// fast as `stream` can produce them, without any backpressure. Therefore, if</span>
<span class="doccomment">/// `stream` is an infinite stream, it can use an unbounded amount of memory, and</span>
<span class="doccomment">/// potentially hog CPU resources.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// # Panics</span>
<span class="doccomment">///</span>
<span class="doccomment">/// This function will panic if `executor` is unable spawn a `Future` containing</span>
<span class="doccomment">/// the entirety of the `stream`.</span>
<span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">spawn_unbounded</span><span class="op"><</span><span class="ident">S</span>, <span class="ident">E</span><span class="op">></span>(<span class="ident">stream</span>: <span class="ident">S</span>, <span class="ident">executor</span>: <span class="kw-2">&</span><span class="ident">E</span>) <span class="op">-></span> <span class="ident">SpawnHandle</span><span class="op"><</span><span class="ident">S</span>::<span class="ident">Item</span>, <span class="ident">S</span>::<span class="ident">Error</span><span class="op">></span>
<span class="kw">where</span> <span class="ident">S</span>: <span class="ident">Stream</span>,
<span class="ident">E</span>: <span class="ident">Executor</span><span class="op"><</span><span class="ident">Execute</span><span class="op"><</span><span class="ident">S</span><span class="op">>></span>
{
<span class="kw">let</span> (<span class="ident">cancel_tx</span>, <span class="ident">cancel_rx</span>) <span class="op">=</span> <span class="ident">oneshot</span>::<span class="ident">channel</span>();
<span class="kw">let</span> (<span class="ident">tx</span>, <span class="ident">rx</span>) <span class="op">=</span> <span class="ident">channel2</span>(<span class="prelude-val">None</span>);
<span class="ident">executor</span>.<span class="ident">execute</span>(<span class="ident">Execute</span> {
<span class="ident">inner</span>: <span class="ident">tx</span>.<span class="ident">send_all</span>(<span class="ident">resultstream</span>::<span class="ident">new</span>(<span class="ident">stream</span>)),
<span class="ident">cancel_rx</span>: <span class="ident">cancel_rx</span>,
}).<span class="ident">expect</span>(<span class="string">"failed to spawn stream"</span>);
<span class="ident">SpawnHandle</span> {
<span class="ident">rx</span>: <span class="ident">rx</span>,
<span class="ident">_cancel_tx</span>: <span class="ident">cancel_tx</span>,
}
}
<span class="kw">impl</span><span class="op"><</span><span class="ident">I</span>, <span class="ident">E</span><span class="op">></span> <span class="ident">Stream</span> <span class="kw">for</span> <span class="ident">SpawnHandle</span><span class="op"><</span><span class="ident">I</span>, <span class="ident">E</span><span class="op">></span> {
<span class="kw">type</span> <span class="ident">Item</span> <span class="op">=</span> <span class="ident">I</span>;
<span class="kw">type</span> <span class="ident">Error</span> <span class="op">=</span> <span class="ident">E</span>;
<span class="kw">fn</span> <span class="ident">poll</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>) <span class="op">-></span> <span class="ident">Poll</span><span class="op"><</span><span class="prelude-ty">Option</span><span class="op"><</span><span class="ident">I</span><span class="op">></span>, <span class="ident">E</span><span class="op">></span> {
<span class="kw">match</span> <span class="self">self</span>.<span class="ident">rx</span>.<span class="ident">poll</span>() {
<span class="prelude-val">Ok</span>(<span class="ident">Async</span>::<span class="ident">Ready</span>(<span class="prelude-val">Some</span>(<span class="prelude-val">Ok</span>(<span class="ident">t</span>)))) <span class="op">=></span> <span class="prelude-val">Ok</span>(<span class="ident">Async</span>::<span class="ident">Ready</span>(<span class="prelude-val">Some</span>(<span class="ident">t</span>.<span class="ident">into</span>()))),
<span class="prelude-val">Ok</span>(<span class="ident">Async</span>::<span class="ident">Ready</span>(<span class="prelude-val">Some</span>(<span class="prelude-val">Err</span>(<span class="ident">e</span>)))) <span class="op">=></span> <span class="prelude-val">Err</span>(<span class="ident">e</span>),
<span class="prelude-val">Ok</span>(<span class="ident">Async</span>::<span class="ident">Ready</span>(<span class="prelude-val">None</span>)) <span class="op">=></span> <span class="prelude-val">Ok</span>(<span class="ident">Async</span>::<span class="ident">Ready</span>(<span class="prelude-val">None</span>)),
<span class="prelude-val">Ok</span>(<span class="ident">Async</span>::<span class="ident">NotReady</span>) <span class="op">=></span> <span class="prelude-val">Ok</span>(<span class="ident">Async</span>::<span class="ident">NotReady</span>),
<span class="prelude-val">Err</span>(_) <span class="op">=></span> <span class="macro">unreachable</span><span class="macro">!</span>(<span class="string">"mpsc::Receiver should never return Err"</span>),
}
}
}
<span class="kw">impl</span><span class="op"><</span><span class="ident">I</span>, <span class="ident">E</span><span class="op">></span> <span class="ident">fmt</span>::<span class="ident">Debug</span> <span class="kw">for</span> <span class="ident">SpawnHandle</span><span class="op"><</span><span class="ident">I</span>, <span class="ident">E</span><span class="op">></span> {
<span class="kw">fn</span> <span class="ident">fmt</span>(<span class="kw-2">&</span><span class="self">self</span>, <span class="ident">f</span>: <span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">fmt</span>::<span class="ident">Formatter</span>) <span class="op">-></span> <span class="ident">fmt</span>::<span class="prelude-ty">Result</span> {
<span class="ident">f</span>.<span class="ident">debug_struct</span>(<span class="string">"SpawnHandle"</span>)
.<span class="ident">finish</span>()
}
}
<span class="kw">impl</span><span class="op"><</span><span class="ident">S</span>: <span class="ident">Stream</span><span class="op">></span> <span class="ident">Future</span> <span class="kw">for</span> <span class="ident">Execute</span><span class="op"><</span><span class="ident">S</span><span class="op">></span> {
<span class="kw">type</span> <span class="ident">Item</span> <span class="op">=</span> ();
<span class="kw">type</span> <span class="ident">Error</span> <span class="op">=</span> ();
<span class="kw">fn</span> <span class="ident">poll</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>) <span class="op">-></span> <span class="ident">Poll</span><span class="op"><</span>(), ()<span class="op">></span> {
<span class="kw">match</span> <span class="self">self</span>.<span class="ident">cancel_rx</span>.<span class="ident">poll</span>() {
<span class="prelude-val">Ok</span>(<span class="ident">Async</span>::<span class="ident">NotReady</span>) <span class="op">=></span> (),
_ <span class="op">=></span> <span class="kw">return</span> <span class="prelude-val">Ok</span>(<span class="ident">Async</span>::<span class="ident">Ready</span>(())),
}
<span class="kw">match</span> <span class="self">self</span>.<span class="ident">inner</span>.<span class="ident">poll</span>() {
<span class="prelude-val">Ok</span>(<span class="ident">Async</span>::<span class="ident">NotReady</span>) <span class="op">=></span> <span class="prelude-val">Ok</span>(<span class="ident">Async</span>::<span class="ident">NotReady</span>),
_ <span class="op">=></span> <span class="prelude-val">Ok</span>(<span class="ident">Async</span>::<span class="ident">Ready</span>(()))
}
}
}
<span class="kw">impl</span><span class="op"><</span><span class="ident">S</span>: <span class="ident">Stream</span><span class="op">></span> <span class="ident">fmt</span>::<span class="ident">Debug</span> <span class="kw">for</span> <span class="ident">Execute</span><span class="op"><</span><span class="ident">S</span><span class="op">></span> {
<span class="kw">fn</span> <span class="ident">fmt</span>(<span class="kw-2">&</span><span class="self">self</span>, <span class="ident">f</span>: <span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">fmt</span>::<span class="ident">Formatter</span>) <span class="op">-></span> <span class="ident">fmt</span>::<span class="prelude-ty">Result</span> {
<span class="ident">f</span>.<span class="ident">debug_struct</span>(<span class="string">"Execute"</span>)
.<span class="ident">finish</span>()
}
}
<span class="comment">/*
*
* ===== impl Inner =====
*
*/</span>
<span class="kw">impl</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> <span class="ident">Inner</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> {
<span class="comment">// The return value is such that the total number of messages that can be</span>
<span class="comment">// enqueued into the channel will never exceed MAX_CAPACITY</span>
<span class="kw">fn</span> <span class="ident">max_senders</span>(<span class="kw-2">&</span><span class="self">self</span>) <span class="op">-></span> <span class="ident">usize</span> {
<span class="kw">match</span> <span class="self">self</span>.<span class="ident">buffer</span> {
<span class="prelude-val">Some</span>(<span class="ident">buffer</span>) <span class="op">=></span> <span class="ident">MAX_CAPACITY</span> <span class="op">-</span> <span class="ident">buffer</span>,
<span class="prelude-val">None</span> <span class="op">=></span> <span class="ident">MAX_BUFFER</span>,
}
}
}
<span class="kw">unsafe</span> <span class="kw">impl</span><span class="op"><</span><span class="ident">T</span>: <span class="ident">Send</span><span class="op">></span> <span class="ident">Send</span> <span class="kw">for</span> <span class="ident">Inner</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> {}
<span class="kw">unsafe</span> <span class="kw">impl</span><span class="op"><</span><span class="ident">T</span>: <span class="ident">Send</span><span class="op">></span> <span class="ident">Sync</span> <span class="kw">for</span> <span class="ident">Inner</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> {}
<span class="comment">/*
*
* ===== Helpers =====
*
*/</span>
<span class="kw">fn</span> <span class="ident">decode_state</span>(<span class="ident">num</span>: <span class="ident">usize</span>) <span class="op">-></span> <span class="ident">State</span> {
<span class="ident">State</span> {
<span class="ident">is_open</span>: <span class="ident">num</span> <span class="op">&</span> <span class="ident">OPEN_MASK</span> <span class="op">==</span> <span class="ident">OPEN_MASK</span>,
<span class="ident">num_messages</span>: <span class="ident">num</span> <span class="op">&</span> <span class="ident">MAX_CAPACITY</span>,
}
}
<span class="kw">fn</span> <span class="ident">encode_state</span>(<span class="ident">state</span>: <span class="kw-2">&</span><span class="ident">State</span>) <span class="op">-></span> <span class="ident">usize</span> {
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">num</span> <span class="op">=</span> <span class="ident">state</span>.<span class="ident">num_messages</span>;
<span class="kw">if</span> <span class="ident">state</span>.<span class="ident">is_open</span> {
<span class="ident">num</span> <span class="op">|=</span> <span class="ident">OPEN_MASK</span>;
}
<span class="ident">num</span>
}
</pre>
</section>
<section id='search' class="content hidden"></section>
<section class="footer"></section>
<aside id="help" class="hidden">
<div>
<h1 class="hidden">Help</h1>
<div class="shortcuts">
<h2>Keyboard Shortcuts</h2>
<dl>
<dt><kbd>?</kbd></dt>
<dd>Show this help dialog</dd>
<dt><kbd>S</kbd></dt>
<dd>Focus the search field</dd>
<dt><kbd>↑</kbd></dt>
<dd>Move up in search results</dd>
<dt><kbd>↓</kbd></dt>
<dd>Move down in search results</dd>
<dt><kbd>↹</kbd></dt>
<dd>Switch tab</dd>
<dt><kbd>⏎</kbd></dt>
<dd>Go to active search result</dd>
<dt><kbd>+</kbd></dt>
<dd>Expand all sections</dd>
<dt><kbd>-</kbd></dt>
<dd>Collapse all sections</dd>
</dl>
</div>
<div class="infos">
<h2>Search Tricks</h2>
<p>
Prefix searches with a type followed by a colon (e.g.
<code>fn:</code>) to restrict the search to a given type.
</p>
<p>
Accepted types are: <code>fn</code>, <code>mod</code>,
<code>struct</code>, <code>enum</code>,
<code>trait</code>, <code>type</code>, <code>macro</code>,
and <code>const</code>.
</p>
<p>
Search functions by type signature (e.g.
<code>vec -> usize</code> or <code>* -> vec</code>)
</p>
</div>
</div>
</aside>
<script>
window.rootPath = "../../../../";
window.currentCrate = "futures";
</script>
<script src="../../../../main.js"></script>
<script defer src="../../../../search-index.js"></script>
</body>
</html>