source: trunk/src/concurrent.cpp@ 2426

//
// C++ Interface: concurrent
//
// Description:
//
//
// Author: Kohji Nakamura <k.nakamura@nao.ac.jp>, (C) 2012
//
// Copyright: See COPYING file that comes with this distribution
//
//
#include <stdio.h>
#include <omp.h>
#include <errno.h>
#include <assert.h>
#include <limits.h>
#include "concurrent.h"

//#define LOG(x) do {}while(false)
#define LOG(x) fprintf(stderr, "Error: %d\n", (x))

namespace concurrent {
/* ======================= Mutex ======================= */
Mutex::Mutex() throw(int)
{
        int result = pthread_mutex_init(&mutex, NULL);
        if (result != 0) {
                LOG(result);
                throw result;
        }
}

Mutex::~Mutex()
{
        int result = pthread_mutex_destroy(&mutex);
        if (result != 0) {
                LOG(result);
        }
}

void Mutex::lock() throw(int)
{
        int result = pthread_mutex_lock(&mutex);
        if (result != 0) {
                LOG(result);
                throw result;
        }
}

bool Mutex::try_lock() throw(int)
{
        int result = pthread_mutex_trylock(&mutex);
        if (result == 0) {
                return true;
        }
        if (result == EBUSY) {
                return false;
        }
        LOG(result);
        throw result;
}

void Mutex::unlock() throw(int)
{
        int result = pthread_mutex_unlock(&mutex);
        if (result != 0) {
                LOG(result);
                throw result;
        }
}

/* ======================= Semaphore ======================= */
Semaphore::Semaphore(unsigned initial) throw(int)
{
        //mutex = PTHREAD_MUTEX_INITIALIZER;
        //cond = PTHREAD_COND_INITIALIZER;
        sem = initial;

        int result = pthread_mutex_init(&mutex, NULL);
        if (result != 0) {
                LOG(result);
                throw result;
        }

        result = pthread_cond_init(&cond, NULL);
        if (result != 0) {
                pthread_mutex_destroy(&mutex);
                LOG(result);
                throw result;
        }
}

Semaphore::~Semaphore()
{
        int result = pthread_mutex_destroy(&mutex);
        result = pthread_cond_destroy(&cond);
}

void Semaphore::up(unsigned amount) throw(int)
{
        assert(0 < amount && amount <= UINT_MAX - sem);
        int result = pthread_mutex_lock(&mutex);
        if (result == 0) {
                sem += amount;
                result = pthread_cond_signal(&cond);
                int result2 = pthread_mutex_unlock(&mutex);
                if (result == 0 && result2 == 0) {
                        return;
                }
                if (result != 0 && result2 != 0) {
                        LOG(result);
                        result = 0;
                }
                if (result == 0) {
                        result = result2;
                }
        }
        LOG(result);
        throw result;
}

void Semaphore::down(unsigned amount) throw(int)
{
        assert(0 < amount);
        int result = pthread_mutex_lock(&mutex);
        if (result == 0) {
                while (sem < amount) {
                        result = pthread_cond_wait(&cond, &mutex);
                        if (result != 0) {
                                LOG(result);
                                break;
                        }
                }
                if (sem >= amount) {
                        sem -= amount;
                }
                int result2 = pthread_mutex_unlock(&mutex);
                if (result == 0 && result2 == 0) {
                        return;
                }
                if (result != 0 && result2 != 0) {
                        LOG(result);
                        result = 0;
                }
                if (result == 0) {
                        result = result2;
                }
        }
        LOG(result);
        throw result;
}

/* ======================= Broker ======================= */
Broker::Broker(bool (*producer)(void *context) throw(PCException),
                           void (*consumer)(void *context) throw(PCException))
{
        this->producer = producer;
        this->consumer = consumer;
}

Broker::~Broker()
{
}

void Broker::enableNested()
{
        omp_set_nested(1);
}

void Broker::disableNested()
{
        omp_set_nested(0);
}

void Broker::setNestedState(bool nested)
{
        omp_set_nested(static_cast<int>(nested));
}

bool Broker::getNestedState()
{
        return omp_get_nested() ? true : false;
}

void Broker::runProducerAsMasterThread(void *context, unsigned do_ahead)
        throw(PCException)
{
        _run(context, do_ahead, ProdAsMaster);
}

void Broker::runConsumerAsMasterThread(void *context, unsigned do_ahead)
        throw(PCException)
{
        _run(context, do_ahead, ConsAsMaster);
}

void Broker::run(void *context, unsigned do_ahead) throw(PCException)
{
        _run(context, do_ahead, Unspecified);
}

void Broker::_run(void *context, unsigned do_ahead, ThreadSpec threadSpec)
        throw(PCException)
{
        assert(do_ahead > 0);
#ifdef _OPENMP
        PCException *prodEx = NULL;
        PCException *consEx = NULL;
        unsigned queuedJobs = 0;
        int consumerTerminated = 0;
        Semaphore semaphore_for_consumer;
        Semaphore semaphore_for_producer(do_ahead);

        #pragma omp parallel num_threads(2) \
                shared(semaphore_for_consumer, semaphore_for_producer, \
                           consumerTerminated, queuedJobs)
        {
                //fprintf(stderr, "run: %p %d\n", context, omp_get_thread_num());
                bool runProd = true;
                if (threadSpec == Unspecified) {
                        #pragma omp single
                        {
                                runProd = false;
                        }
                } else {
                        bool isMaster = false;
                        #pragma omp master
                        {
                                isMaster = true;
                        }
                        if (threadSpec == ProdAsMaster) {
                                runProd = isMaster;
                        } else { // ConsAsMaster
                                runProd = ! isMaster;
                        }
                }

                if (runProd) { // producer
                        for (;;) {
                                semaphore_for_producer.down();
                                int consumerDead = 0;
                                #pragma omp atomic
                                consumerDead += consumerTerminated;
                                if (consumerDead) {
                                        break;
                                }
                                try {
                                        bool produced = producer(context);
                                        if (! produced) {
                                                break;
                                        }
                                } catch (PCException &e) {
                                        prodEx = &e;
                                        break;
                                }
                                #pragma omp atomic
                                queuedJobs++;
                                semaphore_for_consumer.up();
                        }
                        // additional 'up' to give consumer a chance to terminate.
                        semaphore_for_consumer.up();
                } else { // consumer
                        for (;;) {
                                semaphore_for_consumer.down();
                                unsigned remainingJobs = 0U;
                                #pragma omp atomic
                                remainingJobs += queuedJobs;
                                if (remainingJobs == 0U) {
                                        break;
                                }
                                #pragma omp atomic
                                queuedJobs--;
                                try {
                                        consumer(context);
                                } catch (PCException &e) {
                                        consEx = &e;
                                        break;
                                }
                                semaphore_for_producer.up();
                        }
                        #pragma omp atomic
                        consumerTerminated++;
                        // additional 'up' to give producer a chance to terminate.
                        semaphore_for_producer.up();
                }
        }
        if (prodEx) {
                prodEx->raise();
        } else if (consEx) {
                consEx->raise();
        }
#else
        runSequential(context);
#endif
}

void Broker::runSequential(void *context) throw(PCException)
{
        for (;;) {
                bool produced = producer(context);
                if (! produced) {
                        break;
                }
                consumer(context);
        }
}

} // namespace