/*##############################################################################

    HPCC SYSTEMS software Copyright (C) 2012 HPCC Systems®.

    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
    You may obtain a copy of the License at

       http://www.apache.org/licenses/LICENSE-2.0

    Unless required by applicable law or agreed to in writing, software
    distributed under the License is distributed on an "AS IS" BASIS,
    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    See the License for the specific language governing permissions and
    limitations under the License.
############################################################################## */



#ifndef JAIO_INCL
#define JAIO_INCL

#include "jlib.hpp"
#include "jmisc.hpp"

#if defined (__linux__)

class AsyncRequest;
class jlib_decl AsyncBlockReader
{
public:

  AsyncBlockReader();
  ~AsyncBlockReader();

  void init(int file, offset_t start,size32_t blocksize,void *buf1,void *buf2);
  void *readnext(size32_t &ret);
  void getinfo(offset_t &of,offset_t &p,offset_t &sz);
private:
  void waitblk();
  void enqueue(AsyncRequest *req);
  void finish();
  
  
  AsyncRequest *cur;
  AsyncRequest *next;
  size32_t blksize;
  offset_t offset;
  offset_t pos;
  offset_t start;
  offset_t insize;
  int infile;
  int eof;
};

#endif  



#ifdef _WIN32

class CW32AsyncRequest;                 // forward reference


class jlib_decl CW32AsyncBlockReader
{

private:
    OVERLAPPED overlapped;              // the file io overlap control structure
    HANDLE hfile;
    CW32AsyncRequest * currentRequest, * nextRequest;
    bool eof, pending;                  // pending is true when an IO operation has been 'requested' but no yet completed
    C64bitComposite offset, insize;
    offset_t start;                     // offset is contained also in overlapped as hi and lo DWORDs
    size32_t blockSize;

    void enqueue();                     // calls for next record
    DWORD waitblk();                    // waits for next record, returns bytes read
    void finish();

public:
    CW32AsyncBlockReader();
    ~CW32AsyncBlockReader();

    void init(HANDLE file, offset_t start, size32_t blockSize, void * buffer1, void * buffer2); 
    void * readnext(size32_t &readLength);
    void reset();
    void getinfo(offset_t &of, offset_t &p, offset_t &sz);
};

#endif  // _WIN32




#endif