source/common/threadpool.h

   1 /*****************************************************************************
   2  * Copyright (C) 2013 x265 project
   3  *
   4  * Authors: Steve Borho <steve@borho.org>
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License as published by
   8  * the Free Software Foundation; either version 2 of the License, or
   9  * (at your option) any later version.
  10  *
  11  * This program is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  * GNU General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU General Public License
  17  * along with this program; if not, write to the Free Software
  18  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02111, USA.
  19  *
  20  * This program is also available under a commercial proprietary license.
  21  * For more information, contact us at license @ x265.com
  22  *****************************************************************************/
  23
  24 #ifndef X265_THREADPOOL_H
  25 #define X265_THREADPOOL_H
  26
  27 #include "common.h"
  28
  29 namespace x265 {
  30 // x265 private namespace
  31
  32 class ThreadPool;
  33
  34 int getCpuCount();
  35
  36 // Any class that wants to distribute work to the thread pool must
  37 // derive from JobProvider and implement FindJob().
  38 class JobProvider
  39 {
  40 protected:
  41
  42     ThreadPool   *m_pool;
  43
  44     JobProvider  *m_nextProvider;
  45     JobProvider  *m_prevProvider;
  46
  47 public:
  48
  49     JobProvider(ThreadPool *p) : m_pool(p), m_nextProvider(0), m_prevProvider(0) {}
  50
  51     virtual ~JobProvider() {}
  52
  53     void setThreadPool(ThreadPool *p) { m_pool = p; }
  54
  55     // Register this job provider with the thread pool, jobs are available
  56     void enqueue();
  57
  58     // Remove this job provider from the thread pool, all jobs complete
  59     void dequeue();
  60
  61     // Worker threads will call this method to find a job.  Must return true if
  62     // work was completed.  False if no work was available.
  63     virtual bool findJob(int threadId) = 0;
  64
  65     // All derived objects that call Enqueue *MUST* call flush before allowing
  66     // their object to be destroyed, otherwise you will see random crashes involving
  67     // partially freed vtables and you will be unhappy
  68     void flush();
  69
  70     friend class ThreadPoolImpl;
  71     friend class PoolThread;
  72 };
  73
  74 // Abstract interface to ThreadPool.  Each encoder instance should call
  75 // AllocThreadPool() to get a handle to the singleton object and then make
  76 // it available to their job provider structures (wave-front frame encoders,
  77 // etc).
  78 class ThreadPool
  79 {
  80 protected:
  81
  82     // Destructor is inaccessable, force the use of reference counted Release()
  83     ~ThreadPool() {}
  84
  85     virtual void enqueueJobProvider(JobProvider &) = 0;
  86
  87     virtual void dequeueJobProvider(JobProvider &) = 0;
  88
  89 public:
  90
  91     // When numthreads == 0, a default thread count is used. A request may grow
  92     // an existing pool but it will never shrink.
  93     static ThreadPool *allocThreadPool(int numthreads = 0);
  94
  95     static ThreadPool *getThreadPool();
  96
  97     virtual void pokeIdleThread() = 0;
  98
  99     // The pool is reference counted so all calls to AllocThreadPool() should be
 100     // followed by a call to Release()
 101     virtual void release() = 0;
 102
 103     virtual int  getThreadCount() const = 0;
 104
 105     friend class JobProvider;
 106 };
 107 } // end namespace x265
 108
 109 #endif // ifndef X265_THREADPOOL_H