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// 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"
#include "./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
struct WebPWorkerImpl {
pthread_mutex_t mutex_;
pthread_cond_t condition_;
pthread_t 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)
#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 void Execute(WebPWorker* const worker); // Forward declaration.
static THREADFN ThreadLoop(void* ptr) {
WebPWorker* const worker = (WebPWorker*)ptr;
int done = 0;
while (!done) {
pthread_mutex_lock(&worker->impl_->mutex_);
while (worker->status_ == OK) { // wait in idling mode
pthread_cond_wait(&worker->impl_->condition_, &worker->impl_->mutex_);
}
if (worker->status_ == WORK) {
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(&worker->impl_->condition_);
pthread_mutex_unlock(&worker->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.
if (worker->impl_ == NULL) return;
pthread_mutex_lock(&worker->impl_->mutex_);
if (worker->status_ >= OK) {
// wait for the worker to finish
while (worker->status_ != OK) {
pthread_cond_wait(&worker->impl_->condition_, &worker->impl_->mutex_);
}
// assign new status and release the working thread if needed
if (new_status != OK) {
worker->status_ = new_status;
pthread_cond_signal(&worker->impl_->condition_);
}
}
pthread_mutex_unlock(&worker->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
worker->impl_ = (WebPWorkerImpl*)WebPSafeCalloc(1, sizeof(*worker->impl_));
if (worker->impl_ == NULL) {
return 0;
}
if (pthread_mutex_init(&worker->impl_->mutex_, NULL)) {
goto Error;
}
if (pthread_cond_init(&worker->impl_->condition_, NULL)) {
pthread_mutex_destroy(&worker->impl_->mutex_);
goto Error;
}
pthread_mutex_lock(&worker->impl_->mutex_);
ok = !pthread_create(&worker->impl_->thread_, NULL, ThreadLoop, worker);
if (ok) worker->status_ = OK;
pthread_mutex_unlock(&worker->impl_->mutex_);
if (!ok) {
pthread_mutex_destroy(&worker->impl_->mutex_);
pthread_cond_destroy(&worker->impl_->condition_);
Error:
WebPSafeFree(worker->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) {
ChangeState(worker, NOT_OK);
pthread_join(worker->impl_->thread_, NULL);
pthread_mutex_destroy(&worker->impl_->mutex_);
pthread_cond_destroy(&worker->impl_->condition_);
WebPSafeFree(worker->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;
}
//------------------------------------------------------------------------------