src/ThreadPool.h

/*
 * Copyright (C) 2010 The Android Open Source Project
 *
 * 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.
 */

/** \file ThreadPool.h ThreadPool interface */

/** Kind of closure */

typedef enum {
    CLOSURE_KIND_PPI,   // void *, void *, int
    CLOSURE_KIND_PPII,  // void *, void *, int, int
    CLOSURE_KIND_PIIPP  // void *, int, int, void *, void *
} ClosureKind;

/** Closure handlers */

typedef void (*ClosureHandler_generic)(void *p1, void *p2, void *p3, int i1, int i2);
typedef void (*ClosureHandler_ppi)    (void *p1, void *p2, int i1);
typedef void (*ClosureHandler_ppii)   (void *p1, void *p2, int i1, int i2);
typedef void (*ClosureHandler_piipp)  (void *p1, int i1, int i2, void *p2, void *p3);

/** \brief Closure represents a deferred computation */

typedef struct {
    union {
        ClosureHandler_ppi mHandler_ppi;
        ClosureHandler_ppii mHandler_ppii;
        ClosureHandler_piipp mHandler_piipp;
    } mHandler;
    ClosureKind mKind;
    void *mContext1;
    void *mContext2;
    void *mContext3;
    int mParameter1;
    int mParameter2;
} Closure;

/** \brief ThreadPool manages a pool of worker threads that execute Closures */

typedef struct {
    unsigned mInitialized; ///< Indicates which of the following 3 fields are initialized
    pthread_mutex_t mMutex;
    pthread_cond_t mCondNotFull;    ///< Signalled when a client thread could be unblocked
    pthread_cond_t mCondNotEmpty;   ///< Signalled when a worker thread could be unblocked
    SLboolean mShutdown;   ///< Whether shutdown of thread pool has been requested
    unsigned mWaitingNotFull;   ///< Number of client threads waiting to enqueue
    unsigned mWaitingNotEmpty;  ///< Number of worker threads waiting to dequeue
    unsigned mMaxClosures;  ///< Number of slots in circular buffer for closures, not counting spare
    unsigned mMaxThreads;   ///< Number of worker threads
    Closure **mClosureArray;    ///< The circular buffer of closures
    Closure **mClosureFront, **mClosureRear;
    /// Saves a malloc in the typical case
#define CLOSURE_TYPICAL 15
    Closure *mClosureTypical[CLOSURE_TYPICAL+1];
    pthread_t *mThreadArray;    ///< The worker threads
#ifdef ANDROID
// Note: if you set THREAD_TYPICAL to a non-zero value because you
// want to use asynchronous callbacks, be aware that any value greater
// than 1 can result in out-of-order callbacks on a given player, in the
// current implementation.  Thus you should probably configure 1 total or
// change the implementation so that it uses at most 1 thread per player.
#if defined(USE_ASYNCHRONOUS_PLAY_CALLBACK) || \
        defined(USE_ASYNCHRONOUS_STREAMCBEVENT_PROPERTYCHANGE_CALLBACK)
#define THREAD_TYPICAL 1
#else
#define THREAD_TYPICAL 0
#endif
#else // !ANDROID
#define THREAD_TYPICAL 4
#endif
    pthread_t mThreadTypical[THREAD_TYPICAL];
} ThreadPool;

extern SLresult ThreadPool_init(ThreadPool *tp, unsigned maxClosures, unsigned maxThreads);
extern void ThreadPool_deinit(ThreadPool *tp);
extern SLresult ThreadPool_add(ThreadPool *tp, ClosureKind kind,
        ClosureHandler_generic,
        void *cntxt1, void *cntxt2, void *cntxt3, int param1, int param2);
extern Closure *ThreadPool_remove(ThreadPool *tp);
extern SLresult ThreadPool_add_ppi(ThreadPool *tp, ClosureHandler_ppi handler,
        void *cntxt1, void *cntxt2, int param1);
extern SLresult ThreadPool_add_ppii(ThreadPool *tp, ClosureHandler_ppii handler,
        void *cntxt1, void *cntxt2, int param1, int param2);
extern SLresult ThreadPool_add_piipp(ThreadPool *tp, ClosureHandler_piipp handler,
        void *cntxt1, int param1, int param2, void *cntxt2, void *cntxt3);