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// Copyright 2013 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
//
// Original source:
// https://chromium.googlesource.com/webm/libwebp
// Enable GNU extensions in glibc so that we can call pthread_setname_np().
// This must be before any #include statements.
#ifndef _GNU_SOURCE
#define _GNU_SOURCE
#endif
#include <assert.h>
#include <string.h> // for memset()
#include "./vpx_config.h"
#include "./vpx_thread.h"
#include "vpx_mem/vpx_mem.h"
#include "vpx_util/vpx_pthread.h"
#if CONFIG_MULTITHREAD
struct VPxWorkerImpl {
pthread_mutex_t mutex_;
pthread_cond_t condition_;
pthread_t thread_;
};
//------------------------------------------------------------------------------
static void execute(VPxWorker *const worker); // Forward declaration.
static THREADFN thread_loop(void *ptr) {
VPxWorker *const worker = (VPxWorker *)ptr;
#ifdef __APPLE__
if (worker->thread_name != NULL) {
// Apple's version of pthread_setname_np takes one argument and operates on
// the current thread only. The maximum size of the thread_name buffer was
// noted in the Chromium source code and was confirmed by experiments. If
// thread_name is too long, pthread_setname_np returns -1 with errno
// ENAMETOOLONG (63).
char thread_name[64];
strncpy(thread_name, worker->thread_name, sizeof(thread_name) - 1);
thread_name[sizeof(thread_name) - 1] = '\0';
pthread_setname_np(thread_name);
}
#elif (defined(__GLIBC__) && !defined(__GNU__)) || defined(__BIONIC__)
if (worker->thread_name != NULL) {
// Linux and Android require names (with nul) fit in 16 chars, otherwise
// pthread_setname_np() returns ERANGE (34).
char thread_name[16];
strncpy(thread_name, worker->thread_name, sizeof(thread_name) - 1);
thread_name[sizeof(thread_name) - 1] = '\0';
pthread_setname_np(pthread_self(), thread_name);
}
#endif
pthread_mutex_lock(&worker->impl_->mutex_);
for (;;) {
while (worker->status_ == VPX_WORKER_STATUS_OK) { // wait in idling mode
pthread_cond_wait(&worker->impl_->condition_, &worker->impl_->mutex_);
}
if (worker->status_ == VPX_WORKER_STATUS_WORKING) {
// When worker->status_ is VPX_WORKER_STATUS_WORKING, the main thread
// doesn't change worker->status_ and will wait until the worker changes
// worker->status_ to VPX_WORKER_STATUS_OK. See change_state(). So the
// worker can safely call execute() without holding worker->impl_->mutex_.
// When the worker reacquires worker->impl_->mutex_, worker->status_ must
// still be VPX_WORKER_STATUS_WORKING.
pthread_mutex_unlock(&worker->impl_->mutex_);
execute(worker);
pthread_mutex_lock(&worker->impl_->mutex_);
assert(worker->status_ == VPX_WORKER_STATUS_WORKING);
worker->status_ = VPX_WORKER_STATUS_OK;
// signal to the main thread that we're done (for sync())
pthread_cond_signal(&worker->impl_->condition_);
} else {
assert(worker->status_ == VPX_WORKER_STATUS_NOT_OK); // finish the worker
break;
}
}
pthread_mutex_unlock(&worker->impl_->mutex_);
return THREAD_EXIT_SUCCESS; // Thread is finished
}
// main thread state control
static void change_state(VPxWorker *const worker, VPxWorkerStatus 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_ >= VPX_WORKER_STATUS_OK) {
// wait for the worker to finish
while (worker->status_ != VPX_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 != VPX_WORKER_STATUS_OK) {
worker->status_ = new_status;
pthread_cond_signal(&worker->impl_->condition_);
}
}
pthread_mutex_unlock(&worker->impl_->mutex_);
}
#endif // CONFIG_MULTITHREAD
//------------------------------------------------------------------------------
static void init(VPxWorker *const worker) {
memset(worker, 0, sizeof(*worker));
worker->status_ = VPX_WORKER_STATUS_NOT_OK;
}
static int sync(VPxWorker *const worker) {
#if CONFIG_MULTITHREAD
change_state(worker, VPX_WORKER_STATUS_OK);
#endif
assert(worker->status_ <= VPX_WORKER_STATUS_OK);
return !worker->had_error;
}
static int reset(VPxWorker *const worker) {
int ok = 1;
worker->had_error = 0;
if (worker->status_ < VPX_WORKER_STATUS_OK) {
#if CONFIG_MULTITHREAD
worker->impl_ = (VPxWorkerImpl *)vpx_calloc(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, thread_loop, worker);
if (ok) worker->status_ = VPX_WORKER_STATUS_OK;
pthread_mutex_unlock(&worker->impl_->mutex_);
if (!ok) {
pthread_mutex_destroy(&worker->impl_->mutex_);
pthread_cond_destroy(&worker->impl_->condition_);
Error:
vpx_free(worker->impl_);
worker->impl_ = NULL;
return 0;
}
#else
worker->status_ = VPX_WORKER_STATUS_OK;
#endif
} else if (worker->status_ > VPX_WORKER_STATUS_OK) {
ok = sync(worker);
}
assert(!ok || (worker->status_ == VPX_WORKER_STATUS_OK));
return ok;
}
static void execute(VPxWorker *const worker) {
if (worker->hook != NULL) {
worker->had_error |= !worker->hook(worker->data1, worker->data2);
}
}
static void launch(VPxWorker *const worker) {
#if CONFIG_MULTITHREAD
change_state(worker, VPX_WORKER_STATUS_WORKING);
#else
execute(worker);
#endif
}
static void end(VPxWorker *const worker) {
#if CONFIG_MULTITHREAD
if (worker->impl_ != NULL) {
change_state(worker, VPX_WORKER_STATUS_NOT_OK);
pthread_join(worker->impl_->thread_, NULL);
pthread_mutex_destroy(&worker->impl_->mutex_);
pthread_cond_destroy(&worker->impl_->condition_);
vpx_free(worker->impl_);
worker->impl_ = NULL;
}
#else
worker->status_ = VPX_WORKER_STATUS_NOT_OK;
assert(worker->impl_ == NULL);
#endif
assert(worker->status_ == VPX_WORKER_STATUS_NOT_OK);
}
//------------------------------------------------------------------------------
static VPxWorkerInterface g_worker_interface = { init, reset, sync,
launch, execute, end };
int vpx_set_worker_interface(const VPxWorkerInterface *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 VPxWorkerInterface *vpx_get_worker_interface(void) {
return &g_worker_interface;
}
//------------------------------------------------------------------------------
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