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path: root/webrtc/rtc_base/synchronization/yield_policy.cc
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-rw-r--r--webrtc/rtc_base/synchronization/yield_policy.cc82
1 files changed, 82 insertions, 0 deletions
diff --git a/webrtc/rtc_base/synchronization/yield_policy.cc b/webrtc/rtc_base/synchronization/yield_policy.cc
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+++ b/webrtc/rtc_base/synchronization/yield_policy.cc
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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 rtc {
+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 rtc