/*******************************************************************************
* Copyright (c) 2010 Wind River Systems, Inc. and others.
* All rights reserved. This program and the accompanying materials
* are made available under the terms of the Eclipse Public License v1.0
* and Eclipse Distribution License v1.0 which accompany this distribution.
* The Eclipse Public License is available at
* http://www.eclipse.org/legal/epl-v10.html
* and the Eclipse Distribution License is available at
* http://www.eclipse.org/org/documents/edl-v10.php.
* You may elect to redistribute this code under either of these licenses.
*
* Contributors:
* Wind River Systems - initial API and implementation
*******************************************************************************/
#include <config.h>
#if defined(WIN32) && !defined(DISABLE_PTHREADS_WIN32)
#include <assert.h>
#include <framework/myalloc.h>
#include <framework/errors.h>
#include <system/Windows/pthreads-win32.h>
/*********************************************************************
Support of pthreads on Windows is implemented according to
recommendations from the paper:
Strategies for Implementing POSIX Condition Variables on Win32
C++ Report, SIGS, Vol. 10, No. 5, June, 1998
Douglas C. Schmidt and Irfan Pyarali
Department of Computer Science
Washington University, St. Louis, Missouri
**********************************************************************/
/* TODO: POSIX pthread functions don't set errno */
typedef struct {
int waiters_count;
CRITICAL_SECTION waiters_count_lock;
HANDLE sema;
HANDLE waiters_done;
size_t was_broadcast;
} PThreadCond;
int pthread_mutex_init(pthread_mutex_t * mutex, const pthread_mutexattr_t * attr) {
assert(attr == NULL);
*mutex = (pthread_mutex_t)CreateMutex(NULL, FALSE, NULL);
if (*mutex == NULL) return set_win32_errno(GetLastError());
return 0;
}
int pthread_mutex_lock(pthread_mutex_t * mutex) {
assert(mutex != NULL);
assert(*mutex != NULL);
if (WaitForSingleObject(*mutex, INFINITE) == WAIT_FAILED) return set_win32_errno(GetLastError());
return 0;
}
int pthread_mutex_unlock(pthread_mutex_t * mutex) {
assert(mutex != NULL);
assert(*mutex != NULL);
if (!ReleaseMutex(*mutex)) return set_win32_errno(GetLastError());
return 0;
}
int pthread_mutex_destroy(pthread_mutex_t *mutex) {
assert(mutex != NULL);
assert(*mutex != NULL);
if (!CloseHandle(*mutex)) return set_win32_errno(GetLastError());
return 0;
}
int pthread_cond_init(pthread_cond_t * cond, const pthread_condattr_t * attr) {
PThreadCond * p = (PThreadCond *)loc_alloc_zero(sizeof(PThreadCond));
assert(attr == NULL);
p->waiters_count = 0;
p->was_broadcast = 0;
p->sema = CreateSemaphore(NULL, 0, 0x7fffffff, NULL);
if (p->sema == NULL) return set_win32_errno(GetLastError());
InitializeCriticalSection(&p->waiters_count_lock);
p->waiters_done = CreateEvent(NULL, FALSE, FALSE, NULL);
if (p->waiters_done == NULL) return set_win32_errno(GetLastError());
*cond = (pthread_cond_t)p;
return 0;
}
int pthread_cond_wait(pthread_cond_t * cond, pthread_mutex_t * mutex) {
DWORD res = 0;
int last_waiter = 0;
PThreadCond * p = (PThreadCond *)*cond;
EnterCriticalSection(&p->waiters_count_lock);
p->waiters_count++;
LeaveCriticalSection(&p->waiters_count_lock);
/* This call atomically releases the mutex and waits on the */
/* semaphore until <pthread_cond_signal> or <pthread_cond_broadcast> */
/* are called by another thread. */
res = SignalObjectAndWait(*mutex, p->sema, INFINITE, FALSE);
if (res == WAIT_FAILED) return set_win32_errno(GetLastError());
/* Re-acquire lock to avoid race conditions. */
EnterCriticalSection(&p->waiters_count_lock);
/* We're no longer waiting... */
p->waiters_count--;
/* Check to see if we're the last waiter after <pthread_cond_broadcast>. */
last_waiter = p->was_broadcast && p->waiters_count == 0;
LeaveCriticalSection(&p->waiters_count_lock);
/* If we're the last waiter thread during this particular broadcast */
/* then let all the other threads proceed. */
if (last_waiter) {
/* This call atomically signals the <waiters_done_> event and waits until */
/* it can acquire the <mutex>. This is required to ensure fairness. */
DWORD err = SignalObjectAndWait(p->waiters_done, *mutex, INFINITE, FALSE);
if (err == WAIT_FAILED) return set_win32_errno(GetLastError());
}
else {
/* Always regain the external mutex since that's the guarantee we */
/* give to our callers. */
DWORD err = WaitForSingleObject(*mutex, INFINITE);
if (err == WAIT_FAILED) return set_win32_errno(GetLastError());
}
assert(res == WAIT_OBJECT_0);
return 0;
}
int pthread_cond_timedwait(pthread_cond_t * cond, pthread_mutex_t * mutex, const struct timespec * abstime) {
DWORD res = 0;
int last_waiter = 0;
PThreadCond * p = (PThreadCond *)*cond;
DWORD timeout = 0;
struct timespec timenow;
if (clock_gettime(CLOCK_REALTIME, &timenow)) return errno;
if (abstime->tv_sec < timenow.tv_sec) return ETIMEDOUT;
if (abstime->tv_sec == timenow.tv_sec) {
if (abstime->tv_nsec <= timenow.tv_nsec) return ETIMEDOUT;
}
timeout = (DWORD)((abstime->tv_sec - timenow.tv_sec) * 1000 + (abstime->tv_nsec - timenow.tv_nsec) / 1000000 + 5);
EnterCriticalSection(&p->waiters_count_lock);
p->waiters_count++;
LeaveCriticalSection(&p->waiters_count_lock);
/* This call atomically releases the mutex and waits on the */
/* semaphore until <pthread_cond_signal> or <pthread_cond_broadcast> */
/* are called by another thread. */
res = SignalObjectAndWait(*mutex, p->sema, timeout, FALSE);
if (res == WAIT_FAILED) return set_win32_errno(GetLastError());
/* Re-acquire lock to avoid race conditions. */
EnterCriticalSection(&p->waiters_count_lock);
/* We're no longer waiting... */
p->waiters_count--;
/* Check to see if we're the last waiter after <pthread_cond_broadcast>. */
last_waiter = p->was_broadcast && p->waiters_count == 0;
LeaveCriticalSection(&p->waiters_count_lock);
/* If we're the last waiter thread during this particular broadcast */
/* then let all the other threads proceed. */
if (last_waiter) {
/* This call atomically signals the <waiters_done> event and waits until */
/* it can acquire the <mutex>. This is required to ensure fairness. */
DWORD err = SignalObjectAndWait(p->waiters_done, *mutex, INFINITE, FALSE);
if (err == WAIT_FAILED) return set_win32_errno(GetLastError());
}
else {
/* Always regain the external mutex since that's the guarantee we */
/* give to our callers. */
DWORD err = WaitForSingleObject(*mutex, INFINITE);
if (err == WAIT_FAILED) return set_win32_errno(GetLastError());
}
if (res == WAIT_TIMEOUT) return errno = ETIMEDOUT;
assert(res == WAIT_OBJECT_0);
return 0;
}
int pthread_cond_signal(pthread_cond_t * cond) {
int have_waiters = 0;
PThreadCond * p = (PThreadCond *)*cond;
EnterCriticalSection(&p->waiters_count_lock);
have_waiters = p->waiters_count > 0;
LeaveCriticalSection(&p->waiters_count_lock);
/* If there aren't any waiters, then this is a no-op. */
if (have_waiters) {
if (!ReleaseSemaphore(p->sema, 1, 0)) return set_win32_errno(GetLastError());
}
return 0;
}
int pthread_cond_broadcast(pthread_cond_t * cond) {
int have_waiters = 0;
PThreadCond * p = (PThreadCond *)*cond;
/* This is needed to ensure that <waiters_count_> and <was_broadcast_> are */
/* consistent relative to each other. */
EnterCriticalSection(&p->waiters_count_lock);
if (p->waiters_count > 0) {
/* We are broadcasting, even if there is just one waiter... */
/* Record that we are broadcasting, which helps optimize */
/* <pthread_cond_wait> for the non-broadcast case. */
p->was_broadcast = 1;
have_waiters = 1;
}
if (have_waiters) {
/* Wake up all the waiters atomically. */
if (!ReleaseSemaphore(p->sema, p->waiters_count, 0)) return set_win32_errno(GetLastError());
LeaveCriticalSection(&p->waiters_count_lock);
/* Wait for all the awakened threads to acquire the counting */
/* semaphore. */
if (WaitForSingleObject(p->waiters_done, INFINITE) == WAIT_FAILED) return set_win32_errno(GetLastError());
/* This assignment is okay, even without the <waiters_count_lock_> held */
/* because no other waiter threads can wake up to access it. */
p->was_broadcast = 0;
}
else {
LeaveCriticalSection(&p->waiters_count_lock);
}
return 0;
}
int pthread_cond_destroy(pthread_cond_t * cond) {
PThreadCond * p = (PThreadCond *)*cond;
DeleteCriticalSection(&p->waiters_count_lock);
if (!CloseHandle(p->sema)) return set_win32_errno(GetLastError());
if (!CloseHandle(p->waiters_done)) return set_win32_errno(GetLastError());
loc_free(p);
*cond = NULL;
return 0;
}
typedef struct ThreadArgs ThreadArgs;
struct ThreadArgs {
void * (*start)(void *);
void * args;
};
static void start_thread(void * x) {
ThreadArgs a = *(ThreadArgs *)x;
loc_free(x);
ExitThread((DWORD)a.start(a.args));
}
int pthread_create(pthread_t * res, const pthread_attr_t * attr,
void * (*start)(void *), void * args) {
HANDLE thread = NULL;
DWORD thread_id = 0;
ThreadArgs * a = (ThreadArgs *)loc_alloc(sizeof(ThreadArgs));
a->start = start;
a->args = args;
thread = CreateThread(0, 0, (LPTHREAD_START_ROUTINE)start_thread, a, 0, &thread_id);
if (thread == NULL) {
int err = set_win32_errno(GetLastError());
loc_free(a);
return errno = err;
}
if (!CloseHandle(thread)) return set_win32_errno(GetLastError());
*res = (pthread_t)thread_id;
return 0;
}
int pthread_join(pthread_t thread_id, void ** value_ptr) {
int error = 0;
HANDLE thread = OpenThread(SYNCHRONIZE | THREAD_QUERY_INFORMATION, FALSE, (DWORD)thread_id);
if (thread == NULL) return set_win32_errno(GetLastError());
if (WaitForSingleObject(thread, INFINITE) == WAIT_FAILED) error = set_win32_errno(GetLastError());
if (!error && value_ptr != NULL && !GetExitCodeThread(thread, (LPDWORD)value_ptr)) error = set_win32_errno(GetLastError());
if (!CloseHandle(thread) && !error) error = set_win32_errno(GetLastError());
return error;
}
pthread_t pthread_self(void) {
return (pthread_t)GetCurrentThreadId();
}
int pthread_equal(pthread_t thread1, pthread_t thread2) {
return thread1 == thread2;
}
int pthread_attr_init(pthread_attr_t * attr) {
*attr = NULL;
return 0;
}
#endif
