annotate Mutex.cpp @ 24:7d28bed0864e

* Rearrange Python plugin construction.

  Formerly, the PyPluginAdapter has retained a single plugin instance pointer
  for each plugin found, and its createPlugin method has simply returned a new
  PyPlugin object wrapping the same instance pointer.  This has a couple of
  negative consequences:
   - Because construction of the actual Python instance occurred before the
     wrapper was constructed, it was not possible to pass arguments (i.e.
     the sample rate) from the wrapper constructor to the Python plugin
     instance constructor -- they had to be passed later, to initialise,
     disadvantaging those plugins that would like to use the sample rate
     for parameter & step/block size calculations etc
   - Because there was only a single Python plugin instance, it was not
     possible to run more than one instance at once with any isolation

  This rework instead stores the Python class pointer (rather than instance
  pointer) in the PyPluginAdapter, and each PyPlugin wrapper instance creates
  its own Python plugin instance.  What could possibly go wrong?

/* -*- 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();
    }
}