1 // Copyright 2024 The Chromium Authors
2 // Use of this source code is governed by a BSD-style license that can be
3 // found in the LICENSE file.
4 #include "base/synchronization/cancelable_event.h"
5
6 #include "base/notreached.h"
7 #include "base/synchronization/waitable_event.h"
8 #include "base/threading/scoped_blocking_call.h"
9 #include "base/trace_event/base_tracing.h"
10 #include "build/build_config.h"
11
12 namespace base {
13
Signal()14 void CancelableEvent::Signal() {
15 #if BUILDFLAG(ENABLE_BASE_TRACING)
16 // Must be ordered before SignalImpl() to match the `TerminatingFlow` in
17 // TimedWait() and Cancel().
18 if (!only_used_while_idle_) {
19 TRACE_EVENT_INSTANT("wakeup.flow,toplevel.flow", "CancelableEvent::Signal",
20 perfetto::Flow::FromPointer(this));
21 }
22 #endif
23 SignalImpl();
24 }
25
Cancel()26 bool CancelableEvent::Cancel() {
27 #if BUILDFLAG(ENABLE_BASE_TRACING)
28 if (!only_used_while_idle_) {
29 TRACE_EVENT_INSTANT("wakeup.flow,toplevel.flow", "CancelableEvent::Cancel",
30 perfetto::TerminatingFlow::FromPointer(this));
31 }
32 #endif
33 return CancelImpl();
34 }
35
TimedWait(TimeDelta timeout)36 bool CancelableEvent::TimedWait(TimeDelta timeout) {
37 // Consider this thread blocked for scheduling purposes. Ignore this for
38 // non-blocking CancelableEvents.
39 std::optional<internal::ScopedBlockingCallWithBaseSyncPrimitives>
40 scoped_blocking_call;
41 if (!only_used_while_idle_) {
42 scoped_blocking_call.emplace(FROM_HERE, BlockingType::MAY_BLOCK);
43 }
44
45 const bool result = TimedWaitImpl(timeout);
46
47 #if BUILDFLAG(ENABLE_BASE_TRACING)
48 if (result && !only_used_while_idle_) {
49 TRACE_EVENT_INSTANT("wakeup.flow,toplevel.flow",
50 "CancelableEvent::Wait Complete",
51 perfetto::TerminatingFlow::FromPointer(this));
52 }
53 #endif
54
55 return result;
56 }
57
58 } // namespace base
59