drwnThreadPool.h

/*****************************************************************************
** DARWIN: A FRAMEWORK FOR MACHINE LEARNING RESEARCH AND DEVELOPMENT
** Distributed under the terms of the BSD license (see the LICENSE file)
** Copyright (c) 2007-2015, Stephen Gould
** All rights reserved.
**
******************************************************************************
** FILENAME:    drwnThreadPool.h
** AUTHOR(S):   Stephen Gould <stephen.gould@anu.edu.au>
**              (based on code by David Breeden <breeden@cs.stanford.edu>
**              and Ian Goodfellow <ia3n@cs.stanford.edu>)
**
*****************************************************************************/

#pragma once
#include <queue>

#if defined(_WIN32)||defined(WIN32)||defined(__WIN32__)
#define DRWN_USE_WIN32THREADS
#else
#define DRWN_USE_PTHREADS
#endif

#ifdef DRWN_USE_PTHREADS
#include <pthread.h>
#endif

#ifdef DRWN_USE_WIN32THREADS
#include <windows.h>
#include <process.h>
#undef min
#undef max
#endif

using namespace std;

// drwnThreadJob --------------------------------------------------------------

class drwnThreadPool;


class drwnThreadJob {
    friend class drwnThreadPool;

 private:
    drwnThreadPool *_owner;
    unsigned _threadId;
    bool _bAquiredLock;

 public:
    drwnThreadJob();
    virtual ~drwnThreadJob();

    virtual void operator()() = 0;

 protected:
    inline unsigned threadId() { return _threadId; }
    
    void lock();    
    void unlock();  
};

// drwnThreadPool -------------------------------------------------------------


class drwnThreadPool {
    friend class drwnThreadJob;

 public:
    static unsigned MAX_THREADS; 

 public:
    drwnThreadPool(const unsigned size = MAX_THREADS);
    ~drwnThreadPool();

    void start();

    void addJob(drwnThreadJob* job);

    void finish(bool bShowStatus = false);

    unsigned numThreads() const { return _nThreads; }
    unsigned numJobsRemaining();

private:
    // main thread function
#ifdef DRWN_USE_PTHREADS
    static void *runJobs(void *argPtr);
#endif
#ifdef DRWN_USE_WIN32THREADS
    static unsigned __stdcall runJobs(void *argPtr);
#endif

#if defined(DRWN_USE_PTHREADS)||defined(DRWN_USE_WIN32THREADS)
    struct drwnThreadArgs {
        drwnThreadPool *owner;
        unsigned threadId;
        int jobsProcessed;
    };

    queue<drwnThreadJob *> _jobQ;  

    unsigned _nThreads;            

#ifdef DRWN_USE_PTHREADS
    pthread_t *_threads;          
    drwnThreadArgs *_args;        

    pthread_mutex_t _mutex;       
    pthread_cond_t _cond;         
#endif
#ifdef DRWN_USE_WIN32THREADS
    HANDLE *_threads;             
    drwnThreadArgs *_args;        

    CRITICAL_SECTION _mutex;      
    CONDITION_VARIABLE _cond;     
#endif

    bool _bQuit;                  

    bool _bProfilerEnabled;       
#else
    unsigned _nThreads;
    void *_threads;
    void *_args;
#endif
};