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