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/*
* Copyright 2019 The WebRTC project authors. All Rights Reserved.
*
* Use of this source code is governed by a BSD-style license
* that can be found in the LICENSE 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.
*/
#include "rtc_base/synchronization/yield_policy.h"
#include "absl/base/attributes.h"
#include "absl/base/config.h"
#include "rtc_base/checks.h"
#if !defined(ABSL_HAVE_THREAD_LOCAL) && defined(WEBRTC_POSIX)
#include <pthread.h>
#endif
namespace webrtc {
namespace {
#if defined(ABSL_HAVE_THREAD_LOCAL)
ABSL_CONST_INIT thread_local YieldInterface* current_yield_policy = nullptr;
YieldInterface* GetCurrentYieldPolicy() {
return current_yield_policy;
}
void SetCurrentYieldPolicy(YieldInterface* ptr) {
current_yield_policy = ptr;
}
#elif defined(WEBRTC_POSIX)
// Emscripten does not support the C++11 thread_local keyword but does support
// the pthread thread-local storage API.
// https://github.com/emscripten-core/emscripten/issues/3502
ABSL_CONST_INIT pthread_key_t g_current_yield_policy_tls = 0;
void InitializeTls() {
RTC_CHECK_EQ(pthread_key_create(&g_current_yield_policy_tls, nullptr), 0);
}
pthread_key_t GetCurrentYieldPolicyTls() {
static pthread_once_t init_once = PTHREAD_ONCE_INIT;
RTC_CHECK_EQ(pthread_once(&init_once, &InitializeTls), 0);
return g_current_yield_policy_tls;
}
YieldInterface* GetCurrentYieldPolicy() {
return static_cast<YieldInterface*>(
pthread_getspecific(GetCurrentYieldPolicyTls()));
}
void SetCurrentYieldPolicy(YieldInterface* ptr) {
pthread_setspecific(GetCurrentYieldPolicyTls(), ptr);
}
#else
#error Unsupported platform
#endif
} // namespace
ScopedYieldPolicy::ScopedYieldPolicy(YieldInterface* policy)
: previous_(GetCurrentYieldPolicy()) {
SetCurrentYieldPolicy(policy);
}
ScopedYieldPolicy::~ScopedYieldPolicy() {
SetCurrentYieldPolicy(previous_);
}
void ScopedYieldPolicy::YieldExecution() {
YieldInterface* current = GetCurrentYieldPolicy();
if (current)
current->YieldExecution();
}
} // namespace webrtc
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