mirror of
https://github.com/mollyim/webrtc.git
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2fc37573b9
Bug: none Change-Id: I94def80a7eb815f74d1be691d21b5f3661771a71 Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/279821 Reviewed-by: Harald Alvestrand <hta@webrtc.org> Reviewed-by: Evan Shrubsole <eshr@webrtc.org> Commit-Queue: Tomas Gunnarsson <tommi@webrtc.org> Cr-Commit-Position: refs/heads/main@{#38457}
137 lines
4.1 KiB
C++
137 lines
4.1 KiB
C++
/*
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* Copyright 2004 The WebRTC Project Authors. 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 LICENSE 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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#ifndef RTC_BASE_EVENT_H_
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#define RTC_BASE_EVENT_H_
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#include "api/units/time_delta.h"
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#if defined(WEBRTC_WIN)
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#include <windows.h>
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#elif defined(WEBRTC_POSIX)
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#include <pthread.h>
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#else
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#error "Must define either WEBRTC_WIN or WEBRTC_POSIX."
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#endif
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#include "rtc_base/synchronization/yield_policy.h"
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namespace rtc {
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// RTC_DISALLOW_WAIT() utility
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//
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// Sets a stack-scoped flag that disallows use of `rtc::Event::Wait` by means
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// of raising a DCHECK when a call to `rtc::Event::Wait()` is made..
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// This is useful to guard synchronization-free scopes against regressions.
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//
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// Example of what this would catch (`ScopeToProtect` calls `Foo`):
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//
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// void Foo(TaskQueue* tq) {
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// Event event;
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// tq->PostTask([&event]() {
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// event.Set();
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// });
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// event.Wait(Event::kForever); // <- Will trigger a DCHECK.
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// }
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//
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// void ScopeToProtect() {
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// TaskQueue* tq = GetSomeTaskQueue();
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// RTC_DISALLOW_WAIT(); // Policy takes effect.
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// Foo(tq);
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// }
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//
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#if RTC_DCHECK_IS_ON
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#define RTC_DISALLOW_WAIT() ScopedDisallowWait disallow_wait_##__LINE__
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#else
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#define RTC_DISALLOW_WAIT()
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#endif
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class Event {
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public:
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// TODO(bugs.webrtc.org/14366): Consider removing this redundant alias.
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static constexpr webrtc::TimeDelta kForever =
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webrtc::TimeDelta::PlusInfinity();
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Event();
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Event(bool manual_reset, bool initially_signaled);
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Event(const Event&) = delete;
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Event& operator=(const Event&) = delete;
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~Event();
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void Set();
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void Reset();
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// Waits for the event to become signaled, but logs a warning if it takes more
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// than `warn_after`, and gives up completely if it takes more than
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// `give_up_after`. (If `warn_after >= give_up_after`, no warning will be
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// logged.) Either or both may be `kForever`, which means wait indefinitely.
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//
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// Care is taken so that the underlying OS wait call isn't requested to sleep
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// shorter than `give_up_after`.
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//
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// Returns true if the event was signaled, false if there was a timeout or
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// some other error.
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bool Wait(webrtc::TimeDelta give_up_after, webrtc::TimeDelta warn_after);
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// Waits with the given timeout and a reasonable default warning timeout.
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bool Wait(webrtc::TimeDelta give_up_after) {
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return Wait(give_up_after, give_up_after.IsPlusInfinity()
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? webrtc::TimeDelta::Seconds(3)
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: kForever);
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}
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private:
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#if defined(WEBRTC_WIN)
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HANDLE event_handle_;
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#elif defined(WEBRTC_POSIX)
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pthread_mutex_t event_mutex_;
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pthread_cond_t event_cond_;
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const bool is_manual_reset_;
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bool event_status_;
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#endif
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};
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// These classes are provided for compatibility with Chromium.
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// The rtc::Event implementation is overriden inside of Chromium for the
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// purposes of detecting when threads are blocked that shouldn't be as well as
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// to use the more accurate event implementation that's there than is provided
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// by default on some platforms (e.g. Windows).
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// When building with standalone WebRTC, this class is a noop.
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// For further information, please see the
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// ScopedAllowBaseSyncPrimitives(ForTesting) classes in Chromium.
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class ScopedAllowBaseSyncPrimitives {
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public:
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ScopedAllowBaseSyncPrimitives() {}
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~ScopedAllowBaseSyncPrimitives() {}
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};
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class ScopedAllowBaseSyncPrimitivesForTesting {
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public:
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ScopedAllowBaseSyncPrimitivesForTesting() {}
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~ScopedAllowBaseSyncPrimitivesForTesting() {}
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};
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#if RTC_DCHECK_IS_ON
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class ScopedDisallowWait {
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public:
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ScopedDisallowWait() = default;
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private:
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class DisallowYieldHandler : public YieldInterface {
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public:
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void YieldExecution() override { RTC_DCHECK_NOTREACHED(); }
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} handler_;
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rtc::ScopedYieldPolicy policy{&handler_};
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};
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#endif
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} // namespace rtc
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#endif // RTC_BASE_EVENT_H_
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