HPCC-13616 Cache sessions and prepared queries in Cassandra driver

Backport structural changes to code from master. This mostly moves definitions
into the header file, but also moves some code from function context to
cluster class.

This change will make upmerges much easier in the future, as well as being a
step towards caching/sharing cluster and session objects.

Signed-off-by: Richard Chapman <rchapman@hpccsystems.com>

plugins/cassandra/cassandraembed.hpp

@@ -0,0 +1,363 @@
+/*##############################################################################
+
+    HPCC SYSTEMS software Copyright (C) 2015 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 _CASSANDRAEMBED_INCL
+#define _CASSANDRAEMBED_INCL
+
+namespace cassandraembed {
+
+extern void UNSUPPORTED(const char *feature) __attribute__((noreturn));
+extern void failx(const char *msg, ...) __attribute__((noreturn))  __attribute__((format(printf, 1, 2)));
+extern void fail(const char *msg) __attribute__((noreturn));
+extern void check(CassError rc);
+extern bool isInteger(const CassValueType t);
+extern bool isString(CassValueType t);
+
+// Wrappers to Cassandra structures that require corresponding releases
+
+class CassandraCluster : public CInterface
+{
+public:
+    inline CassandraCluster(CassCluster *_cluster)
+    : cluster(_cluster), batchMode((CassBatchType) -1), pageSize(0), maxFutures(0), maxRetries(0)
+    {
+    }
+    void setOptions(const StringArray &options);
+    inline ~CassandraCluster()
+    {
+        if (cluster)
+            cass_cluster_free(cluster);
+    }
+    inline operator CassCluster *() const
+    {
+        return cluster;
+    }
+private:
+    void checkSetOption(CassError rc, const char *name);
+    cass_bool_t getBoolOption(const char *val, const char *option);
+    unsigned getUnsignedOption(const char *val, const char *option);
+    unsigned getDoubleOption(const char *val, const char *option);
+    __uint64 getUnsigned64Option(const char *val, const char *option);
+    CassandraCluster(const CassandraCluster &);
+    CassCluster *cluster;
+public:
+    // These are here as convenient to set from same options string. They are really properties of the session
+    // or query rather than the cluster, but we have one session per cluster so we get away with it at the moment.
+    CassBatchType batchMode;
+    unsigned pageSize;
+	unsigned maxFutures;
+	unsigned maxRetries;
+    StringAttr keyspace;
+};
+
+class CassandraFuture : public CInterface
+{
+public:
+    inline CassandraFuture(CassFuture *_future) : future(_future)
+    {
+    }
+    inline ~CassandraFuture()
+    {
+        if (future)
+            cass_future_free(future);
+    }
+    inline operator CassFuture *() const
+    {
+        return future;
+    }
+    void wait(const char *why) const;
+    inline void set(CassFuture *_future)
+    {
+        if (future)
+            cass_future_free(future);
+        future = _future;
+    }
+protected:
+    CassandraFuture(const CassandraFuture &);
+    CassFuture *future;
+};
+
+class CassandraFutureResult : public CassandraFuture
+{
+public:
+    inline CassandraFutureResult(CassFuture *_future) : CassandraFuture(_future)
+    {
+        result = NULL;
+    }
+    inline ~CassandraFutureResult()
+    {
+        if (result)
+            cass_result_free(result);
+    }
+    inline operator const CassResult *() const
+    {
+        if (!result)
+        {
+            wait("FutureResult");
+            result = cass_future_get_result(future);
+        }
+        return result;
+    }
+private:
+    CassandraFutureResult(const CassandraFutureResult &);
+    mutable const CassResult *result;
+
+};
+
+class CassandraSession : public CInterface
+{
+public:
+    inline CassandraSession() : session(NULL) {}
+    inline CassandraSession(CassSession *_session) : session(_session)
+    {
+    }
+    inline ~CassandraSession()
+    {
+        set(NULL);
+    }
+    void set(CassSession *_session);
+    inline operator CassSession *() const
+    {
+        return session;
+    }
+private:
+    CassandraSession(const CassandraSession &);
+    CassSession *session;
+};
+
+class CassandraBatch : public CInterface
+{
+public:
+    inline CassandraBatch(CassBatch *_batch) : batch(_batch)
+    {
+    }
+    inline ~CassandraBatch()
+    {
+        if (batch)
+            cass_batch_free(batch);
+    }
+    inline operator CassBatch *() const
+    {
+        return batch;
+    }
+private:
+    CassandraBatch(const CassandraBatch &);
+    CassBatch *batch;
+};
+
+class CassandraPrepared : public CInterfaceOf<IInterface>
+{
+public:
+    inline CassandraPrepared(const CassPrepared *_prepared)
+    : prepared(_prepared)
+    {
+    }
+    inline ~CassandraPrepared()
+    {
+        if (prepared)
+            cass_prepared_free(prepared);
+    }
+    inline operator const CassPrepared *() const
+    {
+        return prepared;
+    }
+private:
+    CassandraPrepared(const CassandraPrepared &);
+    const CassPrepared *prepared;
+};
+
+class CassandraStatement : public CInterface
+{
+public:
+    inline CassandraStatement(CassStatement *_statement) : statement(_statement)
+    {
+    }
+    inline CassandraStatement(const char *simple) : statement(cass_statement_new(simple, 0))
+    {
+    }
+    inline ~CassandraStatement()
+    {
+        if (statement)
+            cass_statement_free(statement);
+    }
+    operator CassStatement *() const
+    {
+        return statement;
+    }
+    inline CassStatement *getClear()
+    {
+        CassStatement *ret = statement;
+        statement = NULL;
+        return ret;
+    }
+private:
+    CassandraStatement(const CassandraStatement &);
+    CassStatement *statement;
+};
+
+class LinkedSemaphore : public CInterfaceOf<IInterface>, public Semaphore
+{
+public:
+    LinkedSemaphore(unsigned initialCount) : Semaphore(initialCount) {}
+};
+
+class CassandraRetryingFuture : public CInterface
+{
+public:
+    CassandraRetryingFuture(CassSession *_session, CassStatement *_statement, LinkedSemaphore *_limiter = NULL, unsigned _retries = 10);
+    ~CassandraRetryingFuture();
+    inline operator CassFuture *() const
+    {
+        return future;
+    }
+    void wait(const char *why);
+private:
+    bool retry(const char *why);
+    void execute();
+    static void signaller(CassFuture *future, void *data);
+
+    CassandraRetryingFuture(const CassandraFuture &);
+    CassFuture *future;
+    CassSession *session;
+    CassandraStatement statement;
+    unsigned retries;
+    LinkedSemaphore *limiter;
+};
+
+class CassandraResult : public CInterfaceOf<IInterface>
+{
+public:
+    inline CassandraResult(const CassResult *_result) : result(_result)
+    {
+    }
+    inline ~CassandraResult()
+    {
+        if (result)
+            cass_result_free(result);
+    }
+    inline operator const CassResult *() const
+    {
+        return result;
+    }
+private:
+    CassandraResult(const CassandraResult &);
+    const CassResult *result;
+};
+
+class CassandraIterator : public CInterfaceOf<IInterface>
+{
+public:
+    inline CassandraIterator(CassIterator *_iterator) : iterator(_iterator)
+    {
+    }
+    inline ~CassandraIterator()
+    {
+        if (iterator)
+            cass_iterator_free(iterator);
+    }
+    inline void set(CassIterator *_iterator)
+    {
+        if (iterator)
+            cass_iterator_free(iterator);
+        iterator = _iterator;
+    }
+    inline operator CassIterator *() const
+    {
+        return iterator;
+    }
+protected:
+    CassandraIterator(const CassandraIterator &);
+    CassIterator *iterator;
+};
+
+class CassandraCollection : public CInterface
+{
+public:
+    inline CassandraCollection(CassCollection *_collection) : collection(_collection)
+    {
+    }
+    inline ~CassandraCollection()
+    {
+        if (collection)
+            cass_collection_free(collection);
+    }
+    inline operator CassCollection *() const
+    {
+        return collection;
+    }
+private:
+    CassandraCollection(const CassandraCollection &);
+    CassCollection *collection;
+};
+
+class CassandraStatementInfo : public CInterface
+{
+public:
+    IMPLEMENT_IINTERFACE;
+    CassandraStatementInfo(CassandraSession *_session, CassandraPrepared *_prepared, unsigned _numBindings, CassBatchType _batchMode, unsigned pageSize, unsigned _maxFutures, unsigned _maxRetries);
+    ~CassandraStatementInfo();
+    void stop();
+    bool next();
+    void startStream();
+    void endStream();
+    void execute();
+    inline size_t rowCount() const
+    {
+        return cass_result_row_count(*result);
+    }
+    inline bool hasResult() const
+    {
+        return result != NULL;
+    }
+    inline const CassRow *queryRow() const
+    {
+        assertex(iterator && *iterator);
+        return cass_iterator_get_row(*iterator);
+    }
+    inline CassStatement *queryStatement() const
+    {
+        assertex(statement && *statement);
+        return *statement;
+    }
+protected:
+    Linked<CassandraSession> session;
+    Linked<CassandraPrepared> prepared;
+    Owned<CassandraBatch> batch;
+    Owned<CassandraStatement> statement;
+    Owned<CassandraFutureResult> result;
+    Owned<CassandraIterator> iterator;
+    unsigned numBindings;
+    CIArrayOf<CassandraRetryingFuture> futures;
+    Owned<LinkedSemaphore> semaphore;
+    unsigned maxFutures;
+    unsigned maxRetries;
+    bool inBatch;
+    CassBatchType batchMode;
+};
+
+extern bool getBooleanResult(const RtlFieldInfo *field, const CassValue *value);
+extern void getDataResult(const RtlFieldInfo *field, const CassValue *value, size32_t &chars, void * &result);
+extern __int64 getSignedResult(const RtlFieldInfo *field, const CassValue *value);
+extern unsigned __int64 getUnsignedResult(const RtlFieldInfo *field, const CassValue *value);
+extern double getRealResult(const RtlFieldInfo *field, const CassValue *value);
+extern void getStringResult(const RtlFieldInfo *field, const CassValue *value, size32_t &chars, char * &result);
+extern void getUTF8Result(const RtlFieldInfo *field, const CassValue *value, size32_t &chars, char * &result);
+extern void getUnicodeResult(const RtlFieldInfo *field, const CassValue *value, size32_t &chars, UChar * &result);
+extern void getDecimalResult(const RtlFieldInfo *field, const CassValue *value, Decimal &result);
+
+} // namespace
+#endif