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        3532 :     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             :     bool m_bNotifyEvent = false;
      75             : 
      76             :     CPLList *psWaitingWorkerThreadsList = nullptr;
      77             :     int nWaitingWorkerThreads = 0;
      78             : 
      79             :     int m_nMaxThreads = 0;
      80             : 
      81             :     static void WorkerThreadFunction(void *user_data);
      82             : 
      83             :     void DeclareJobFinished();
      84             :     std::function<void()> GetNextJob(CPLWorkerThread *psWorkerThread);
      85             : 
      86             :   public:
      87             :     CPLWorkerThreadPool();
      88             :     explicit CPLWorkerThreadPool(int nThreads);
      89             :     ~CPLWorkerThreadPool();
      90             : 
      91             :     bool Setup(int nThreads, CPLThreadFunc pfnInitFunc, void **pasInitData);
      92             :     bool Setup(int nThreads, CPLThreadFunc pfnInitFunc, void **pasInitData,
      93             :                bool bWaitallStarted);
      94             : 
      95             :     CPLJobQueuePtr CreateJobQueue();
      96             : 
      97             :     bool SubmitJob(std::function<void()> task);
      98             :     bool SubmitJob(CPLThreadFunc pfnFunc, void *pData);
      99             :     bool SubmitJobs(CPLThreadFunc pfnFunc, const std::vector<void *> &apData);
     100             :     void WaitCompletion(int nMaxRemainingJobs = 0);
     101             :     void WaitEvent();
     102             :     void WakeUpWaitEvent();
     103             : 
     104             :     /** Return the number of threads setup */
     105             :     int GetThreadCount() const;
     106             : };
     107             : 
     108             : /** Job queue */
     109             : class CPL_DLL CPLJobQueue
     110             : {
     111             :     CPL_DISALLOW_COPY_ASSIGN(CPLJobQueue)
     112             :     CPLWorkerThreadPool *m_poPool = nullptr;
     113             :     std::mutex m_mutex{};
     114             :     std::condition_variable m_cv{};
     115             :     int m_nPendingJobs = 0;
     116             : 
     117             :     void DeclareJobFinished();
     118             : 
     119             :     //! @cond Doxygen_Suppress
     120             :   protected:
     121             :     friend class CPLWorkerThreadPool;
     122             :     explicit CPLJobQueue(CPLWorkerThreadPool *poPool);
     123             :     //! @endcond
     124             : 
     125             :   public:
     126             :     ~CPLJobQueue();
     127             : 
     128             :     /** Return the owning worker thread pool */
     129         727 :     CPLWorkerThreadPool *GetPool()
     130             :     {
     131         727 :         return m_poPool;
     132             :     }
     133             : 
     134             :     bool SubmitJob(CPLThreadFunc pfnFunc, void *pData);
     135             :     bool SubmitJob(std::function<void()> task);
     136             :     void WaitCompletion(int nMaxRemainingJobs = 0);
     137             :     bool WaitEvent();
     138             : };
     139             : 
     140             : #endif  // CPL_WORKER_THREAD_POOL_H_INCLUDED_