开源的一个线程池

/*
    Thread Pool implementation for unix / linux environments
    Copyright (C) 2008 Shobhit Gupta

    This program is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program.  If not, see <http://www.gnu.org/licenses/>.
*/

#include <iostream>
#include "threadpool.h"

using namespace std;


#define ITERATIONS 200

class SampleWorkerThread : public WorkerThread
{
public:
        int id;

unsigned virtual executeThis()
{
// Instead of sleep() we could do anytime consuming work here.
//Using ThreadPools is advantageous only when the work to be done is really time consuming. (atleast 1 or 2 seconds)
sleep(2);

return(0);
}


        SampleWorkerThread(int id) : WorkerThread(id), id(id)
        {
//           cout << "Creating SampleWorkerThread " << id << "\t address=" << this << endl;
        }

        ~SampleWorkerThread()
        {
//           cout << "Deleting SampleWorkerThread " << id << "\t address=" << this << endl;
        }
};


int main(int argc, char **argv)
{
//ThreadPool(N);
//Create a Threadpool with N number of threads
ThreadPool* myPool = new ThreadPool(25);
myPool->initializeThreads();

//We will count time elapsed after initializeThreads()
    time_t t1=time(NULL);

//Lets start bullying ThreadPool with tonnes of work !!!
for(unsigned int i=0;i<ITERATIONS;i++){
SampleWorkerThread* myThread = new SampleWorkerThread(i);
//cout << "myThread[" << myThread->id << "] = [" << myThread << "]" << endl;
myPool->assignWork(myThread);
}

// destroyPool(int maxPollSecs)
// Before actually destroying the ThreadPool, this function checks if all the pending work is completed.
// If the work is still not done, then it will check again after maxPollSecs
// The default value for maxPollSecs is 2 seconds.
// And ofcourse the user is supposed to adjust it for his needs.

    myPool->destroyPool(2);

    time_t t2=time(NULL);
    cout << t2-t1 << " seconds elapsed\n" << endl;
delete myPool;

    return 0;
}
----------------------
/*
    Thread Pool implementation for unix / linux environments
    Copyright (C) 2008 Shobhit Gupta

    This program is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program.  If not, see <http://www.gnu.org/licenses/>.
*/

#include <stdlib.h>
#include "threadpool.h"

using namespace std;

pthread_mutex_t ThreadPool::mutexSync = PTHREAD_MUTEX_INITIALIZER;
pthread_mutex_t ThreadPool::mutexWorkCompletion = PTHREAD_MUTEX_INITIALIZER;



ThreadPool::ThreadPool()
{
ThreadPool(2);
}

ThreadPool::ThreadPool(int maxThreads)
{
   if (maxThreads < 1)  maxThreads=1;
 
   //mutexSync = PTHREAD_MUTEX_INITIALIZER;
   //mutexWorkCompletion = PTHREAD_MUTEX_INITIALIZER;
  
   pthread_mutex_lock(&mutexSync);
   this->maxThreads = maxThreads;
   this->queueSize = maxThreads;
   //workerQueue = new WorkerThread *[maxThreads];
   workerQueue.resize(maxThreads, NULL);
   topIndex = 0;
   bottomIndex = 0;
   incompleteWork = 0;
   sem_init(&availableWork, 0, 0);
   sem_init(&availableThreads, 0, queueSize);
   pthread_mutex_unlock(&mutexSync);
}

void ThreadPool::initializeThreads()
{
   for(int i = 0; i<maxThreads; ++i)
{
pthread_t tempThread;
pthread_create(&tempThread, NULL, &ThreadPool::threadExecute, (void *) this );
//threadIdVec[i] = tempThread;
   }

}

ThreadPool::~ThreadPool()
{
   workerQueue.clear();
}



void ThreadPool::destroyPool(int maxPollSecs = 2)
{
while( incompleteWork>0 )
{
        //cout << "Work is still incomplete=" << incompleteWork << endl;
sleep(maxPollSecs);
}
cout << "All Done!! Wow! That was a lot of work!" << endl;
sem_destroy(&availableWork);
sem_destroy(&availableThreads);
        pthread_mutex_destroy(&mutexSync);
        pthread_mutex_destroy(&mutexWorkCompletion);

}


bool ThreadPool::assignWork(WorkerThread *workerThread)
{
        pthread_mutex_lock(&mutexWorkCompletion);
incompleteWork++;
//cout << "assignWork...incomapleteWork=" << incompleteWork << endl;
pthread_mutex_unlock(&mutexWorkCompletion);
   
sem_wait(&availableThreads);

pthread_mutex_lock(&mutexSync);
//workerVec[topIndex] = workerThread;
workerQueue[topIndex] = workerThread;
                //cout << "Assigning Worker[" << workerThread->id << "] Address:[" << workerThread << "] to Queue index [" << topIndex << "]" << endl;
if(queueSize !=1 )
topIndex = (topIndex+1) % (queueSize-1);
sem_post(&availableWork);
pthread_mutex_unlock(&mutexSync);
return true;
}

bool ThreadPool::fetchWork(WorkerThread **workerArg)
{
sem_wait(&availableWork);

pthread_mutex_lock(&mutexSync);
WorkerThread * workerThread = workerQueue[bottomIndex];
                workerQueue[bottomIndex] = NULL;
*workerArg = workerThread;
if(queueSize !=1 )
bottomIndex = (bottomIndex+1) % (queueSize-1);
sem_post(&availableThreads);
pthread_mutex_unlock(&mutexSync);
    return true;
}

void *ThreadPool::threadExecute(void *param)
{
WorkerThread *worker = NULL;

while(((ThreadPool *)param)->fetchWork(&worker))
{
if(worker)
                {
worker->executeThis();
                        //cout << "worker[" << worker->id << "]\tdelete address: [" << worker << "]" << endl;
                        delete worker;
                        worker = NULL;
                }

pthread_mutex_lock( &(((ThreadPool *)param)->mutexWorkCompletion) );
                //cout << "Thread " << pthread_self() << " has completed a Job !" << endl;
((ThreadPool *)param)->incompleteWork--;
pthread_mutex_unlock( &(((ThreadPool *)param)->mutexWorkCompletion) );
}
return 0;
}
-------------------------------------
/*
    Thread Pool implementation for unix / linux environments
    Copyright (C) 2008 Shobhit Gupta

    This program is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program.  If not, see <http://www.gnu.org/licenses/>.
*/

#include <pthread.h>
#include <semaphore.h>
#include <iostream>
#include <vector>

using namespace std;
/*
WorkerThread class
This class needs to be sobclassed by the user.
*/
class WorkerThread{
public:
    int id;

    unsigned virtual executeThis()
{
return 0;
}

    WorkerThread(int id) : id(id) {}
    virtual ~WorkerThread(){}
};

/*
ThreadPool class manages all the ThreadPool related activities. This includes keeping track of idle threads and ynchronizations between all threads.
*/
class ThreadPool{
public:
    ThreadPool();
    ThreadPool(int maxThreadsTemp);
    virtual ~ThreadPool();

void destroyPool(int maxPollSecs);

    bool assignWork(WorkerThread *worker);
    bool fetchWork(WorkerThread **worker);

void initializeThreads();

    static void *threadExecute(void *param);
   
    static pthread_mutex_t mutexSync;
    static pthread_mutex_t mutexWorkCompletion;
   
   
private:
    int maxThreads;
   
    pthread_cond_t  condCrit;
    sem_t availableWork;
    sem_t availableThreads;

    //WorkerThread ** workerQueue;
    vector<WorkerThread *> workerQueue;

    int topIndex;
    int bottomIndex;

int incompleteWork;

   
    int queueSize;

};