// Copyright 2011 Google Inc. All Rights Reserved. // // Use of this source code is governed by a BSD-style license // that can be found in the COPYING file in the root of the source // tree. An additional intellectual property rights grant can be found // in the file PATENTS. All contributing project authors may // be found in the AUTHORS file in the root of the source tree. // ----------------------------------------------------------------------------- // // Multi-threaded worker // // Author: Skal (pascal.massimino@gmail.com) #include <assert.h> #include <string.h> // for memset() #include "./thread.h" #if defined(__cplusplus) || defined(c_plusplus) extern "C" { #endif #ifdef WEBP_USE_THREAD #if defined(_WIN32) //------------------------------------------------------------------------------ // simplistic pthread emulation layer #include <process.h> // _beginthreadex requires __stdcall #define THREADFN unsigned int __stdcall #define THREAD_RETURN(val) (unsigned int)((DWORD_PTR)val) static int pthread_create(pthread_t* const thread, const void* attr, unsigned int (__stdcall *start)(void*), void* arg) { (void)attr; *thread = (pthread_t)_beginthreadex(NULL, /* void *security */ 0, /* unsigned stack_size */ start, arg, 0, /* unsigned initflag */ NULL); /* unsigned *thrdaddr */ if (*thread == NULL) return 1; SetThreadPriority(*thread, THREAD_PRIORITY_ABOVE_NORMAL); return 0; } static int pthread_join(pthread_t thread, void** value_ptr) { (void)value_ptr; return (WaitForSingleObject(thread, INFINITE) != WAIT_OBJECT_0 || CloseHandle(thread) == 0); } // Mutex static int pthread_mutex_init(pthread_mutex_t* const mutex, void* mutexattr) { (void)mutexattr; InitializeCriticalSection(mutex); return 0; } static int pthread_mutex_lock(pthread_mutex_t* const mutex) { EnterCriticalSection(mutex); return 0; } static int pthread_mutex_unlock(pthread_mutex_t* const mutex) { LeaveCriticalSection(mutex); return 0; } static int pthread_mutex_destroy(pthread_mutex_t* const mutex) { DeleteCriticalSection(mutex); return 0; } // Condition static int pthread_cond_destroy(pthread_cond_t* const condition) { int ok = 1; ok &= (CloseHandle(condition->waiting_sem_) != 0); ok &= (CloseHandle(condition->received_sem_) != 0); ok &= (CloseHandle(condition->signal_event_) != 0); return !ok; } static int pthread_cond_init(pthread_cond_t* const condition, void* cond_attr) { (void)cond_attr; condition->waiting_sem_ = CreateSemaphore(NULL, 0, 1, NULL); condition->received_sem_ = CreateSemaphore(NULL, 0, 1, NULL); condition->signal_event_ = CreateEvent(NULL, FALSE, FALSE, NULL); if (condition->waiting_sem_ == NULL || condition->received_sem_ == NULL || condition->signal_event_ == NULL) { pthread_cond_destroy(condition); return 1; } return 0; } static int pthread_cond_signal(pthread_cond_t* const condition) { int ok = 1; if (WaitForSingleObject(condition->waiting_sem_, 0) == WAIT_OBJECT_0) { // a thread is waiting in pthread_cond_wait: allow it to be notified ok = SetEvent(condition->signal_event_); // wait until the event is consumed so the signaler cannot consume // the event via its own pthread_cond_wait. ok &= (WaitForSingleObject(condition->received_sem_, INFINITE) != WAIT_OBJECT_0); } return !ok; } static int pthread_cond_wait(pthread_cond_t* const condition, pthread_mutex_t* const mutex) { int ok; // note that there is a consumer available so the signal isn't dropped in // pthread_cond_signal if (!ReleaseSemaphore(condition->waiting_sem_, 1, NULL)) return 1; // now unlock the mutex so pthread_cond_signal may be issued pthread_mutex_unlock(mutex); ok = (WaitForSingleObject(condition->signal_event_, INFINITE) == WAIT_OBJECT_0); ok &= ReleaseSemaphore(condition->received_sem_, 1, NULL); pthread_mutex_lock(mutex); return !ok; } #else // _WIN32 # define THREADFN void* # define THREAD_RETURN(val) val #endif //------------------------------------------------------------------------------ static THREADFN WebPWorkerThreadLoop(void *ptr) { // thread loop WebPWorker* const worker = (WebPWorker*)ptr; int done = 0; while (!done) { pthread_mutex_lock(&worker->mutex_); while (worker->status_ == OK) { // wait in idling mode pthread_cond_wait(&worker->condition_, &worker->mutex_); } if (worker->status_ == WORK) { if (worker->hook) { worker->had_error |= !worker->hook(worker->data1, worker->data2); } worker->status_ = OK; } else if (worker->status_ == NOT_OK) { // finish the worker done = 1; } // signal to the main thread that we're done (for Sync()) pthread_cond_signal(&worker->condition_); pthread_mutex_unlock(&worker->mutex_); } return THREAD_RETURN(NULL); // Thread is finished } // main thread state control static void WebPWorkerChangeState(WebPWorker* const worker, WebPWorkerStatus new_status) { // no-op when attempting to change state on a thread that didn't come up if (worker->status_ < OK) return; pthread_mutex_lock(&worker->mutex_); // wait for the worker to finish while (worker->status_ != OK) { pthread_cond_wait(&worker->condition_, &worker->mutex_); } // assign new status and release the working thread if needed if (new_status != OK) { worker->status_ = new_status; pthread_cond_signal(&worker->condition_); } pthread_mutex_unlock(&worker->mutex_); } #endif //------------------------------------------------------------------------------ void WebPWorkerInit(WebPWorker* const worker) { memset(worker, 0, sizeof(*worker)); worker->status_ = NOT_OK; } int WebPWorkerSync(WebPWorker* const worker) { #ifdef WEBP_USE_THREAD WebPWorkerChangeState(worker, OK); #endif assert(worker->status_ <= OK); return !worker->had_error; } int WebPWorkerReset(WebPWorker* const worker) { int ok = 1; worker->had_error = 0; if (worker->status_ < OK) { #ifdef WEBP_USE_THREAD if (pthread_mutex_init(&worker->mutex_, NULL) || pthread_cond_init(&worker->condition_, NULL)) { return 0; } pthread_mutex_lock(&worker->mutex_); ok = !pthread_create(&worker->thread_, NULL, WebPWorkerThreadLoop, worker); if (ok) worker->status_ = OK; pthread_mutex_unlock(&worker->mutex_); #else worker->status_ = OK; #endif } else if (worker->status_ > OK) { ok = WebPWorkerSync(worker); } assert(!ok || (worker->status_ == OK)); return ok; } void WebPWorkerLaunch(WebPWorker* const worker) { #ifdef WEBP_USE_THREAD WebPWorkerChangeState(worker, WORK); #else if (worker->hook) worker->had_error |= !worker->hook(worker->data1, worker->data2); #endif } void WebPWorkerEnd(WebPWorker* const worker) { if (worker->status_ >= OK) { #ifdef WEBP_USE_THREAD WebPWorkerChangeState(worker, NOT_OK); pthread_join(worker->thread_, NULL); pthread_mutex_destroy(&worker->mutex_); pthread_cond_destroy(&worker->condition_); #else worker->status_ = NOT_OK; #endif } assert(worker->status_ == NOT_OK); } //------------------------------------------------------------------------------ #if defined(__cplusplus) || defined(c_plusplus) } // extern "C" #endif