comparison Mutex.cpp @ 3:134313c59d82

* Add global mutex to PyPlugin -- all plugin method calls are strictly
  serialised in order to avoid problems with Python interpreter's lack of
  thread safety.

+/* -*- 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