// 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 "../utils/thread_utils.h" #include "../utils/utils.h" #ifdef WEBP_USE_THREAD #if defined(_WIN32) #include <windows.h> typedef HANDLE pthread_t; typedef CRITICAL_SECTION pthread_mutex_t; #if _WIN32_WINNT >= 0x0600 // Windows Vista / Server 2008 or greater #define USE_WINDOWS_CONDITION_VARIABLE typedef CONDITION_VARIABLE pthread_cond_t; #else typedef struct { HANDLE waiting_sem_; HANDLE received_sem_; HANDLE signal_event_; } pthread_cond_t; #endif // _WIN32_WINNT >= 0x600 #ifndef WINAPI_FAMILY_PARTITION #define WINAPI_PARTITION_DESKTOP 1 #define WINAPI_FAMILY_PARTITION(x) x #endif #if !WINAPI_FAMILY_PARTITION(WINAPI_PARTITION_DESKTOP) #define USE_CREATE_THREAD #endif #else // !_WIN32 #include <pthread.h> #endif // _WIN32 typedef struct { pthread_mutex_t mutex_; pthread_cond_t condition_; pthread_t thread_; } WebPWorkerImpl; #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) #if _WIN32_WINNT >= 0x0501 // Windows XP or greater #define WaitForSingleObject(obj, timeout) \ WaitForSingleObjectEx(obj, timeout, FALSE /*bAlertable*/) #endif static int pthread_create(pthread_t* const thread, const void* attr, unsigned int (__stdcall *start)(void*), void* arg) { (void)attr; #ifdef USE_CREATE_THREAD *thread = CreateThread(NULL, /* lpThreadAttributes */ 0, /* dwStackSize */ start, arg, 0, /* dwStackSize */ NULL); /* lpThreadId */ #else *thread = (pthread_t)_beginthreadex(NULL, /* void *security */ 0, /* unsigned stack_size */ start, arg, 0, /* unsigned initflag */ NULL); /* unsigned *thrdaddr */ #endif 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; #if _WIN32_WINNT >= 0x0600 // Windows Vista / Server 2008 or greater InitializeCriticalSectionEx(mutex, 0 /*dwSpinCount*/, 0 /*Flags*/); #else InitializeCriticalSection(mutex); #endif 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; #ifdef USE_WINDOWS_CONDITION_VARIABLE (void)condition; #else ok &= (CloseHandle(condition->waiting_sem_) != 0); ok &= (CloseHandle(condition->received_sem_) != 0); ok &= (CloseHandle(condition->signal_event_) != 0); #endif return !ok; } static int pthread_cond_init(pthread_cond_t* const condition, void* cond_attr) { (void)cond_attr; #ifdef USE_WINDOWS_CONDITION_VARIABLE InitializeConditionVariable(condition); #else 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; } #endif return 0; } static int pthread_cond_signal(pthread_cond_t* const condition) { int ok = 1; #ifdef USE_WINDOWS_CONDITION_VARIABLE WakeConditionVariable(condition); #else 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); } #endif return !ok; } static int pthread_cond_wait(pthread_cond_t* const condition, pthread_mutex_t* const mutex) { int ok; #ifdef USE_WINDOWS_CONDITION_VARIABLE ok = SleepConditionVariableCS(condition, mutex, INFINITE); #else // 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); #endif return !ok; } #else // !_WIN32 # define THREADFN void* # define THREAD_RETURN(val) val #endif // _WIN32 //------------------------------------------------------------------------------ static THREADFN ThreadLoop(void* ptr) { WebPWorker* const worker = (WebPWorker*)ptr; WebPWorkerImpl* const impl = (WebPWorkerImpl*)worker->impl_; int done = 0; while (!done) { pthread_mutex_lock(&impl->mutex_); while (worker->status_ == OK) { // wait in idling mode pthread_cond_wait(&impl->condition_, &impl->mutex_); } if (worker->status_ == WORK) { WebPGetWorkerInterface()->Execute(worker); 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(&impl->condition_); pthread_mutex_unlock(&impl->mutex_); } return THREAD_RETURN(NULL); // Thread is finished } // main thread state control static void ChangeState(WebPWorker* const worker, WebPWorkerStatus new_status) { // No-op when attempting to change state on a thread that didn't come up. // Checking status_ without acquiring the lock first would result in a data // race. WebPWorkerImpl* const impl = (WebPWorkerImpl*)worker->impl_; if (impl == NULL) return; pthread_mutex_lock(&impl->mutex_); if (worker->status_ >= OK) { // wait for the worker to finish while (worker->status_ != OK) { pthread_cond_wait(&impl->condition_, &impl->mutex_); } // assign new status and release the working thread if needed if (new_status != OK) { worker->status_ = new_status; pthread_cond_signal(&impl->condition_); } } pthread_mutex_unlock(&impl->mutex_); } #endif // WEBP_USE_THREAD //------------------------------------------------------------------------------ static void Init(WebPWorker* const worker) { memset(worker, 0, sizeof(*worker)); worker->status_ = NOT_OK; } static int Sync(WebPWorker* const worker) { #ifdef WEBP_USE_THREAD ChangeState(worker, OK); #endif assert(worker->status_ <= OK); return !worker->had_error; } static int Reset(WebPWorker* const worker) { int ok = 1; worker->had_error = 0; if (worker->status_ < OK) { #ifdef WEBP_USE_THREAD WebPWorkerImpl* const impl = (WebPWorkerImpl*)WebPSafeCalloc(1, sizeof(WebPWorkerImpl)); worker->impl_ = (void*)impl; if (worker->impl_ == NULL) { return 0; } if (pthread_mutex_init(&impl->mutex_, NULL)) { goto Error; } if (pthread_cond_init(&impl->condition_, NULL)) { pthread_mutex_destroy(&impl->mutex_); goto Error; } pthread_mutex_lock(&impl->mutex_); ok = !pthread_create(&impl->thread_, NULL, ThreadLoop, worker); if (ok) worker->status_ = OK; pthread_mutex_unlock(&impl->mutex_); if (!ok) { pthread_mutex_destroy(&impl->mutex_); pthread_cond_destroy(&impl->condition_); Error: WebPSafeFree(impl); worker->impl_ = NULL; return 0; } #else worker->status_ = OK; #endif } else if (worker->status_ > OK) { ok = Sync(worker); } assert(!ok || (worker->status_ == OK)); return ok; } static void Execute(WebPWorker* const worker) { if (worker->hook != NULL) { worker->had_error |= !worker->hook(worker->data1, worker->data2); } } static void Launch(WebPWorker* const worker) { #ifdef WEBP_USE_THREAD ChangeState(worker, WORK); #else Execute(worker); #endif } static void End(WebPWorker* const worker) { #ifdef WEBP_USE_THREAD if (worker->impl_ != NULL) { WebPWorkerImpl* const impl = (WebPWorkerImpl*)worker->impl_; ChangeState(worker, NOT_OK); pthread_join(impl->thread_, NULL); pthread_mutex_destroy(&impl->mutex_); pthread_cond_destroy(&impl->condition_); WebPSafeFree(impl); worker->impl_ = NULL; } #else worker->status_ = NOT_OK; assert(worker->impl_ == NULL); #endif assert(worker->status_ == NOT_OK); } //------------------------------------------------------------------------------ static WebPWorkerInterface g_worker_interface = { Init, Reset, Sync, Launch, Execute, End }; int WebPSetWorkerInterface(const WebPWorkerInterface* const winterface) { if (winterface == NULL || winterface->Init == NULL || winterface->Reset == NULL || winterface->Sync == NULL || winterface->Launch == NULL || winterface->Execute == NULL || winterface->End == NULL) { return 0; } g_worker_interface = *winterface; return 1; } const WebPWorkerInterface* WebPGetWorkerInterface(void) { return &g_worker_interface; } //------------------------------------------------------------------------------