view Mutex.cpp @ 53:7e59caea821b

* Make a better job of preloading Python, especially when it's in a
  framework.  Go for the Python file in the frameworks directory in
  preference to any libpythonX.Y.dylib.  Particularly, don't try to
  preload any library without an absolute path until we've exhausted
  all our framework possibilities (so as to avoid picking up an
  ancient system library).

/* -*- c-basic-offset: 4 indent-tabs-mode: nil -*-  vi:set ts=8 sts=4 sw=4: */

/*
   Basic cross-platform mutex abstraction class.
   This file copyright 2007 Chris Cannam.
*/

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

#ifndef _WIN32
#include <sys/time.h>
#include <time.h>
#endif

using std::cerr;
using std::endl;
using std::string;

#ifdef _WIN32

Mutex::Mutex()
#ifndef NO_THREAD_CHECKS
    :
    m_lockedBy(-1)
#endif
{
    m_mutex = CreateMutex(NULL, FALSE, NULL);
#ifdef DEBUG_MUTEX
    cerr << "MUTEX DEBUG: " << (void *)GetCurrentThreadId() << ": Initialised mutex " << &m_mutex << endl;
#endif
}

Mutex::~Mutex()
{
#ifdef DEBUG_MUTEX
    cerr << "MUTEX DEBUG: " << (void *)GetCurrentThreadId() << ": Destroying mutex " << &m_mutex << endl;
#endif
    CloseHandle(m_mutex);
}

void
Mutex::lock()
{
#ifndef NO_THREAD_CHECKS
    DWORD tid = GetCurrentThreadId();
    if (m_lockedBy == tid) {
        cerr << "ERROR: Deadlock on mutex " << &m_mutex << endl;
    }
#endif
#ifdef DEBUG_MUTEX
    cerr << "MUTEX DEBUG: " << (void *)tid << ": Want to lock mutex " << &m_mutex << endl;
#endif
    WaitForSingleObject(m_mutex, INFINITE);
#ifndef NO_THREAD_CHECKS
    m_lockedBy = tid;
#endif
#ifdef DEBUG_MUTEX
    cerr << "MUTEX DEBUG: " << (void *)tid << ": Locked mutex " << &m_mutex << endl;
#endif
}

void
Mutex::unlock()
{
#ifndef NO_THREAD_CHECKS
    DWORD tid = GetCurrentThreadId();
    if (m_lockedBy != tid) {
        cerr << "ERROR: Mutex " << &m_mutex << " not owned by unlocking thread" << endl;
        return;
    }
#endif
#ifdef DEBUG_MUTEX
    cerr << "MUTEX DEBUG: " << (void *)tid << ": Unlocking mutex " << &m_mutex << endl;
#endif
#ifndef NO_THREAD_CHECKS
    m_lockedBy = -1;
#endif
    ReleaseMutex(m_mutex);
}

bool
Mutex::trylock()
{
#ifndef NO_THREAD_CHECKS
    DWORD tid = GetCurrentThreadId();
#endif
    DWORD result = WaitForSingleObject(m_mutex, 0);
    if (result == WAIT_TIMEOUT || result == WAIT_FAILED) {
#ifdef DEBUG_MUTEX
        cerr << "MUTEX DEBUG: " << (void *)tid << ": Mutex " << &m_mutex << " unavailable" << endl;
#endif
        return false;
    } else {
#ifndef NO_THREAD_CHECKS
        m_lockedBy = tid;
#endif
#ifdef DEBUG_MUTEX
        cerr << "MUTEX DEBUG: " << (void *)tid << ": Locked mutex " << &m_mutex << " (from trylock)" << endl;
#endif
        return true;
    }
}

#else  /* !_WIN32 */

Mutex::Mutex()
#ifndef NO_THREAD_CHECKS
    :
    m_lockedBy(0),
    m_locked(false)
#endif
{
    pthread_mutex_init(&m_mutex, 0);
#ifdef DEBUG_MUTEX
    cerr << "MUTEX DEBUG: " << (void *)pthread_self() << ": Initialised mutex " << &m_mutex << endl;
#endif
}

Mutex::~Mutex()
{
#ifdef DEBUG_MUTEX
    cerr << "MUTEX DEBUG: " << (void *)pthread_self() << ": Destroying mutex " << &m_mutex << endl;
#endif
    pthread_mutex_destroy(&m_mutex);
}

void
Mutex::lock()
{
#ifndef NO_THREAD_CHECKS
    pthread_t tid = pthread_self();
    if (m_locked && m_lockedBy == tid) {
        cerr << "ERROR: Deadlock on mutex " << &m_mutex << endl;
    }
#endif
#ifdef DEBUG_MUTEX
    cerr << "MUTEX DEBUG: " << (void *)tid << ": Want to lock mutex " << &m_mutex << endl;
#endif
    pthread_mutex_lock(&m_mutex);
#ifndef NO_THREAD_CHECKS
    m_lockedBy = tid;
    m_locked = true;
#endif
#ifdef DEBUG_MUTEX
    cerr << "MUTEX DEBUG: " << (void *)tid << ": Locked mutex " << &m_mutex << endl;
#endif
}

void
Mutex::unlock()
{
#ifndef NO_THREAD_CHECKS
    pthread_t tid = pthread_self();
    if (!m_locked) {
        cerr << "ERROR: Mutex " << &m_mutex << " not locked in unlock" << endl;
        return;
    } else if (m_lockedBy != tid) {
        cerr << "ERROR: Mutex " << &m_mutex << " not owned by unlocking thread" << endl;
        return;
    }
#endif
#ifdef DEBUG_MUTEX
    cerr << "MUTEX DEBUG: " << (void *)tid << ": Unlocking mutex " << &m_mutex << endl;
#endif
#ifndef NO_THREAD_CHECKS
    m_locked = false;
#endif
    pthread_mutex_unlock(&m_mutex);
}

bool
Mutex::trylock()
{
#ifndef NO_THREAD_CHECKS
    pthread_t tid = pthread_self();
#endif
    if (pthread_mutex_trylock(&m_mutex)) {
#ifdef DEBUG_MUTEX
        cerr << "MUTEX DEBUG: " << (void *)tid << ": Mutex " << &m_mutex << " unavailable" << endl;
#endif
        return false;
    } else {
#ifndef NO_THREAD_CHECKS
        m_lockedBy = tid;
        m_locked = true;
#endif
#ifdef DEBUG_MUTEX
        cerr << "MUTEX DEBUG: " << (void *)tid << ": Locked mutex " << &m_mutex << " (from trylock)" << endl;
#endif
        return true;
    }
}

#endif

MutexLocker::MutexLocker(Mutex *mutex) :
    m_mutex(mutex)
{
    if (m_mutex) {
        m_mutex->lock();
    }
}

MutexLocker::~MutexLocker()
{
    if (m_mutex) {
        m_mutex->unlock();
    }
}