mutex.cpp

FreeAMP(MP3播放)程序源代码-用来研究MP3解码

/*____________________________________________________________________________
        
        FreeAmp - The Free MP3 Player

        Portions Copyright (C) 1998-2000 EMusic.com

        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 2 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, write to the Free Software
        Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
        
        $Id: mutex.cpp,v 1.2 2000/05/06 12:05:49 ijr Exp $
____________________________________________________________________________*/
#include "config.h"

#include <string.h>
#include <pthread.h>
#include <iostream.h>
#include <sys/time.h>
#include <unistd.h>
#include <assert.h>
#include <errno.h>

#include "mutex.h"

#ifdef DEBUG_MUTEXES
vector<MutexInfo *> mutexList;
#endif

Mutex::Mutex(bool createOwned)
{
    pthread_mutexattr_t attr;

    m_iBusy = 0;
    m_tOwner = 0;
    pthread_cond_init(&m_tCond, NULL);

    pthread_mutexattr_init(&attr);
    memset(&m_mutex, '\0', sizeof(m_mutex));
    if (!pthread_mutex_init(&m_mutex, &attr))
        if (createOwned)
            pthread_mutex_lock(&m_mutex);
    pthread_mutexattr_destroy(&attr);

#ifdef DEBUG_MUTEXES
    m_info = new MutexInfo;
    m_info->address = this;
    m_info->owner = NULL;
    m_info->waits = new vector<TraceRef *>;

    if (createOwned) {
        TraceRef *tr = new TraceRef;
        tr->file = "[creator]";
        tr->line = 0;
        m_info->owner = tr;
    }

    mutexList.push_back(m_info);
#endif
}

Mutex::~Mutex()
{
    pthread_mutex_destroy(&m_mutex);
    pthread_cond_destroy(&m_tCond);
#ifdef DEBUG_MUTEXES
    if (m_info) {
        if (m_info->owner)
            delete m_info->owner;
        if (m_info->waits) {
            vector<TraceRef *>::iterator a = m_info->waits->begin();
            for (; a != m_info->waits->end(); a++) 
                 delete (*a);
            delete m_info->waits;
        }
        vector<MutexInfo *>::iterator i = mutexList.begin();
        for (; i != mutexList.end(); i++) {
            if (*i == m_info) {
                mutexList.erase(i);
                break;
            }
        }
        delete m_info;
    }
#endif
}

#ifdef DEBUG_MUTEXES
bool Mutex::__Acquire(char *name, int line, long timeout)
#else
bool Mutex::Acquire(long timeout)
#endif
{
#ifdef DEBUG_MUTEXES
    TraceRef *wait = new TraceRef;
    wait->file = name;
    wait->line = line;
    
    m_info->waits->push_back(wait);
#endif
    pthread_mutex_lock(&m_mutex);
    if (m_iBusy != 0) {
        if (m_tOwner != pthread_self()) {
            do {
                if (timeout == WAIT_FOREVER)
                    pthread_cond_wait(&m_tCond, &m_mutex);
                else {
                    struct timespec sTime;
                    struct timeval  sNow;

                    gettimeofday(&sNow, NULL);
                    sTime.tv_sec = sNow.tv_sec;
                    sTime.tv_nsec = sNow.tv_usec + timeout;
                    if (sTime.tv_nsec >= 1000000) {
                        sTime.tv_nsec -= 1000000;
                        sTime.tv_sec++;
                    }
                    sTime.tv_nsec *= 1000;

                    if (pthread_cond_timedwait(&m_tCond, &m_mutex, &sTime) == 
                        ETIMEDOUT) {
                        pthread_mutex_unlock(&m_mutex);
#ifdef DEBUG_MUTEXES
                        vector<TraceRef *>::iterator i = m_info->waits->begin();
                        for (; i != m_info->waits->end(); i++) {
                            if (*i == wait) {
                                m_info->waits->erase(i);
                                break;
                            }
                        }
                        delete wait;
#endif
                        return false;
                    }
                }
            } while(m_iBusy != 0);
        }
    }
    m_tOwner = pthread_self();
    m_iBusy++;
    pthread_mutex_unlock(&m_mutex);

#ifdef DEBUG_MUTEXES
    vector<TraceRef *>::iterator i = m_info->waits->begin();
    for (; i != m_info->waits->end(); i++) {
        if (*i == wait) {
            m_info->waits->erase(i);
            break;
        }
    }
    m_info->owner = wait;
#endif

    return true;
}

void Mutex::Release()
{
    int iOwnerShip;

    pthread_mutex_lock(&m_mutex);
    iOwnerShip = --m_iBusy;
    pthread_mutex_unlock(&m_mutex);

    if (iOwnerShip == 0) {
        pthread_cond_signal(&m_tCond);
#ifdef DEBUG_MUTEXES
        delete m_info->owner;
        m_info->owner = NULL;
#endif
    }
}

void Mutex::DumpMutex(void)
{
#if HAVE_LINUXTHREADS
    cerr << "pMutex = " << this << "\n";
    cerr << "Spinlock = " << m_mutex.m_spinlock << "\n";
    cerr << "Count = " << m_mutex.m_count << "\n";
    cerr << "Kind = " << m_mutex.m_owner << "\n";
    cerr << "Waiting = " << m_mutex.m_waiting.head << "\n";
#endif
}

#ifdef DEBUG_MUTEXES
void Mutex::DumpAllMutexes(void)
{
    cerr << "-------------- Mutex Dump Start ------------\n";
    vector<MutexInfo *>::iterator i = mutexList.begin();
    for (; i != mutexList.end(); i++) {
        MutexInfo *ml = *i;
        cerr << "Mutex " << ml->address << endl;
        cerr << "Owned: ";
        if (ml->owner)
            cerr << ml->owner->file << ":" << ml->owner->line;
        cerr << endl;
        cerr << "Waits: ";
        if (ml->waits->size() > 0) {
            vector<TraceRef *>::iterator j = ml->waits->begin();
            for (; j != ml->waits->end(); j++) {
                if (j != ml->waits->begin()) 
                    cerr << "       ";
                cerr << (*j)->file << ":" << (*j)->line << endl;
            }
        }
        else
            cerr << endl;
        cerr << "-------------------\n";
    }
    cerr << "-------------- Mutex Dump Done -------------\n";
}
#endif