Line data    Source code

       1             : /**********************************************************************
       2             :  *
       3             :  * Project:  CPL - Common Portability Library
       4             :  * Purpose:  CPL worker thread pool
       5             :  * Author:   Even Rouault, <even dot rouault at spatialys dot com>
       6             :  *
       7             :  **********************************************************************
       8             :  * Copyright (c) 2015, Even Rouault, <even dot rouault at spatialys dot com>
       9             :  *
      10             :  * SPDX-License-Identifier: MIT
      11             :  ****************************************************************************/
      12             : 
      13             : #ifndef CPL_WORKER_THREAD_POOL_H_INCLUDED_
      14             : #define CPL_WORKER_THREAD_POOL_H_INCLUDED_
      15             : 
      16             : #include "cpl_multiproc.h"
      17             : #include "cpl_list.h"
      18             : 
      19             : #include <condition_variable>
      20             : #include <functional>
      21             : #include <memory>
      22             : #include <mutex>
      23             : #include <queue>
      24             : #include <vector>
      25             : 
      26             : /**
      27             :  * \file cpl_worker_thread_pool.h
      28             :  *
      29             :  * Class to manage a pool of worker threads.
      30             :  * @since GDAL 2.1
      31             :  */
      32             : 
      33             : #ifndef DOXYGEN_SKIP
      34             : class CPLWorkerThreadPool;
      35             : 
      36             : struct CPLWorkerThread
      37             : {
      38             :     CPL_DISALLOW_COPY_ASSIGN(CPLWorkerThread)
      39        4700 :     CPLWorkerThread() = default;
      40             : 
      41             :     CPLThreadFunc pfnInitFunc = nullptr;
      42             :     void *pInitData = nullptr;
      43             :     CPLWorkerThreadPool *poTP = nullptr;
      44             :     CPLJoinableThread *hThread = nullptr;
      45             :     bool bMarkedAsWaiting = false;
      46             : 
      47             :     std::mutex m_mutex{};
      48             :     std::condition_variable m_cv{};
      49             : };
      50             : 
      51             : typedef enum
      52             : {
      53             :     CPLWTS_OK,
      54             :     CPLWTS_STOP,
      55             :     CPLWTS_ERROR
      56             : } CPLWorkerThreadState;
      57             : #endif  // ndef DOXYGEN_SKIP
      58             : 
      59             : class CPLJobQueue;
      60             : /// Unique pointer to a job queue.
      61             : using CPLJobQueuePtr = std::unique_ptr<CPLJobQueue>;
      62             : 
      63             : /** Pool of worker threads */
      64             : class CPL_DLL CPLWorkerThreadPool
      65             : {
      66             :     CPL_DISALLOW_COPY_ASSIGN(CPLWorkerThreadPool)
      67             : 
      68             :     std::vector<std::unique_ptr<CPLWorkerThread>> aWT{};
      69             :     mutable std::mutex m_mutex{};
      70             :     std::condition_variable m_cv{};
      71             :     volatile CPLWorkerThreadState eState = CPLWTS_OK;
      72             :     std::queue<std::function<void()>> jobQueue;
      73             :     int nPendingJobs = 0;
      74             : 
      75             :     CPLList *psWaitingWorkerThreadsList = nullptr;
      76             :     int nWaitingWorkerThreads = 0;
      77             : 
      78             :     int m_nMaxThreads = 0;
      79             : 
      80             :     static void WorkerThreadFunction(void *user_data);
      81             : 
      82             :     void DeclareJobFinished();
      83             :     std::function<void()> GetNextJob(CPLWorkerThread *psWorkerThread);
      84             : 
      85             :   public:
      86             :     CPLWorkerThreadPool();
      87             :     explicit CPLWorkerThreadPool(int nThreads);
      88             :     ~CPLWorkerThreadPool();
      89             : 
      90             :     bool Setup(int nThreads, CPLThreadFunc pfnInitFunc, void **pasInitData);
      91             :     bool Setup(int nThreads, CPLThreadFunc pfnInitFunc, void **pasInitData,
      92             :                bool bWaitallStarted);
      93             : 
      94             :     CPLJobQueuePtr CreateJobQueue();
      95             : 
      96             :     bool SubmitJob(std::function<void()> task);
      97             :     bool SubmitJob(CPLThreadFunc pfnFunc, void *pData);
      98             :     bool SubmitJobs(CPLThreadFunc pfnFunc, const std::vector<void *> &apData);
      99             :     void WaitCompletion(int nMaxRemainingJobs = 0);
     100             :     void WaitEvent();
     101             : 
     102             :     /** Return the number of threads setup */
     103             :     int GetThreadCount() const;
     104             : };
     105             : 
     106             : /** Job queue */
     107             : class CPL_DLL CPLJobQueue
     108             : {
     109             :     CPL_DISALLOW_COPY_ASSIGN(CPLJobQueue)
     110             :     CPLWorkerThreadPool *m_poPool = nullptr;
     111             :     std::mutex m_mutex{};
     112             :     std::condition_variable m_cv{};
     113             :     int m_nPendingJobs = 0;
     114             : 
     115             :     void DeclareJobFinished();
     116             : 
     117             :     //! @cond Doxygen_Suppress
     118             :   protected:
     119             :     friend class CPLWorkerThreadPool;
     120             :     explicit CPLJobQueue(CPLWorkerThreadPool *poPool);
     121             :     //! @endcond
     122             : 
     123             :   public:
     124             :     ~CPLJobQueue();
     125             : 
     126             :     /** Return the owning worker thread pool */
     127         696 :     CPLWorkerThreadPool *GetPool()
     128             :     {
     129         696 :         return m_poPool;
     130             :     }
     131             : 
     132             :     bool SubmitJob(CPLThreadFunc pfnFunc, void *pData);
     133             :     bool SubmitJob(std::function<void()> task);
     134             :     void WaitCompletion(int nMaxRemainingJobs = 0);
     135             :     bool WaitEvent();
     136             : };
     137             : 
     138             : #endif  // CPL_WORKER_THREAD_POOL_H_INCLUDED_