source/common/threadpool.h

   1 /*****************************************************************************
   2  * x265: singleton thread pool and interface classes
   3  *****************************************************************************
   4  * Copyright (C) 2013 x265 project
   5  *
   6  * Authors: Steve Borho <steve@borho.org>
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License as published by
  10  * the Free Software Foundation; either version 2 of the License, or
  11  * (at your option) any later version.
  12  *
  13  * This program is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16  * GNU General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU General Public License
  19  * along with this program; if not, write to the Free Software
  20  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02111, USA.
  21  *
  22  * This program is also available under a commercial proprietary license.
  23  * For more information, contact us at license @ x265.com
  24  *****************************************************************************/
  25
  26 #ifndef X265_THREADPOOL_H
  27 #define X265_THREADPOOL_H
  28
  29 #include "common.h"
  30
  31 namespace x265 {
  32 // x265 private namespace
  33
  34 class ThreadPool;
  35
  36 int getCpuCount();
  37
  38 // Any class that wants to distribute work to the thread pool must
  39 // derive from JobProvider and implement FindJob().
  40 class JobProvider
  41 {
  42 protected:
  43
  44     ThreadPool   *m_pool;
  45
  46     JobProvider  *m_nextProvider;
  47     JobProvider  *m_prevProvider;
  48
  49 public:
  50
  51     JobProvider(ThreadPool *p) : m_pool(p), m_nextProvider(0), m_prevProvider(0) {}
  52
  53     virtual ~JobProvider() {}
  54
  55     void setThreadPool(ThreadPool *p) { m_pool = p; }
  56
  57     // Register this job provider with the thread pool, jobs are available
  58     void enqueue();
  59
  60     // Remove this job provider from the thread pool, all jobs complete
  61     void dequeue();
  62
  63     // Worker threads will call this method to find a job.  Must return true if
  64     // work was completed.  False if no work was available.
  65     virtual bool findJob(int threadId) = 0;
  66
  67     // All derived objects that call Enqueue *MUST* call flush before allowing
  68     // their object to be destroyed, otherwise you will see random crashes involving
  69     // partially freed vtables and you will be unhappy
  70     void flush();
  71
  72     friend class ThreadPoolImpl;
  73     friend class PoolThread;
  74 };
  75
  76 // Abstract interface to ThreadPool.  Each encoder instance should call
  77 // AllocThreadPool() to get a handle to the singleton object and then make
  78 // it available to their job provider structures (wave-front frame encoders,
  79 // etc).
  80 class ThreadPool
  81 {
  82 protected:
  83
  84     // Destructor is inaccessable, force the use of reference counted Release()
  85     ~ThreadPool() {}
  86
  87     virtual void enqueueJobProvider(JobProvider &) = 0;
  88
  89     virtual void dequeueJobProvider(JobProvider &) = 0;
  90
  91 public:
  92
  93     // When numthreads == 0, a default thread count is used. A request may grow
  94     // an existing pool but it will never shrink.
  95     static ThreadPool *allocThreadPool(int numthreads = 0);
  96
  97     static ThreadPool *getThreadPool();
  98
  99     virtual void pokeIdleThread() = 0;
 100
 101     // The pool is reference counted so all calls to AllocThreadPool() should be
 102     // followed by a call to Release()
 103     virtual void release() = 0;
 104
 105     virtual int  getThreadCount() const = 0;
 106
 107     friend class JobProvider;
 108 };
 109 } // end namespace x265
 110
 111 #endif // ifndef X265_THREADPOOL_H