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Unified Diff: base/synchronization/waitable_event_win.cc

Issue 2433773005: Move OS_WIN specific logic in MessagePumpDefault::Run into waitable_event_win.cc (Closed)
Patch Set: Fixed test issue Created 4 years, 2 months ago
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Index: base/synchronization/waitable_event_win.cc
diff --git a/base/synchronization/waitable_event_win.cc b/base/synchronization/waitable_event_win.cc
index d80cabb3ff3ae864fb25f54448885d2c252c5f2b..d0b13ee3d2a6a4cc327e3edc7c32a3e4d0e34db7 100644
--- a/base/synchronization/waitable_event_win.cc
+++ b/base/synchronization/waitable_event_win.cc
@@ -7,6 +7,7 @@
#include <windows.h>
#include <stddef.h>
+#include <algorithm>
#include <utility>
#include "base/debug/activity_tracker.h"
@@ -44,7 +45,18 @@ void WaitableEvent::Signal() {
}
bool WaitableEvent::IsSignaled() {
- return TimedWait(TimeDelta());
+ DWORD result = WaitForSingleObject(handle_.Get(), 0);
+ switch (result) {
+ case WAIT_OBJECT_0:
+ return true;
+ case WAIT_TIMEOUT:
+ return false;
+ }
+
+ // It is most unexpected that this should ever fail. Help consumers learn
+ // about it if it should ever fail.
+ NOTREACHED() << "WaitForSingleObject failed";
+ return false;
}
void WaitableEvent::Wait() {
@@ -59,28 +71,44 @@ void WaitableEvent::Wait() {
}
bool WaitableEvent::TimedWait(const TimeDelta& max_time) {
danakj 2016/10/21 22:01:22 nit: can you name timedeltas with _delta suffix an
stanisc 2016/11/11 03:50:48 Done.
- // Record the event that this thread is blocking upon (for hang diagnosis).
- base::debug::ScopedEventWaitActivity event_activity(this);
-
DCHECK_GE(max_time, TimeDelta());
- if (!max_time.is_zero())
- base::ThreadRestrictions::AssertWaitAllowed();
+ if (max_time.is_zero())
+ return IsSignaled();
- // Truncate the timeout to milliseconds. The API specifies that this method
- // can return in less than |max_time| (when returning false), as the argument
- // is the maximum time that a caller is willing to wait.
- DWORD timeout = saturated_cast<DWORD>(max_time.InMilliseconds());
+ // Record the event that this thread is blocking upon (for hang diagnosis).
+ base::debug::ScopedEventWaitActivity event_activity(this);
+ base::ThreadRestrictions::AssertWaitAllowed();
danakj 2016/10/21 22:01:22 can you put assertions first? (just above event_ac
stanisc 2016/11/11 03:50:48 Done.
- DWORD result = WaitForSingleObject(handle_.Get(), timeout);
- switch (result) {
- case WAIT_OBJECT_0:
- return true;
- case WAIT_TIMEOUT:
- return false;
- }
- // It is most unexpected that this should ever fail. Help consumers learn
- // about it if it should ever fail.
- NOTREACHED() << "WaitForSingleObject failed";
+ constexpr TimeDelta min_delay = TimeDelta::FromMilliseconds(1);
+ TimeTicks target_time = TimeTicks::Now() + max_time;
danakj 2016/10/21 22:01:22 It's possible this was a bad suggestion because it
stanisc 2016/10/21 23:05:25 Yeah, that is unfortunate and redundant that the c
danakj 2016/10/21 23:15:26 I was wondering about an overload also, this seems
+ TimeDelta delay = max_time;
+
+ do {
+ // On Windows, waiting for less than 1 ms results in WaitForSingleObject
+ // returning promptly which may result in the caller code spinning.
+ // We need to ensure that we specify at least the minimally possible 1 ms
+ // delay unless the initial timeout was exactly zero.
+ delay = std::max(delay, min_delay);
danakj 2016/10/21 22:01:22 I think you can just write TimeDelta::FromMillisec
stanisc 2016/11/11 03:50:48 Done.
+ // Truncate the timeout to milliseconds.
+ DWORD timeout = saturated_cast<DWORD>(delay.InMilliseconds());
+ DWORD result = WaitForSingleObject(handle_.Get(), timeout);
+ switch (result) {
+ case WAIT_OBJECT_0:
+ return true;
+ case WAIT_TIMEOUT:
+ // TimedWait can time out earlier than the specified |timeout| on
+ // Windows. To make this consistent with the posix implementation we
+ // should guarantee that TimedWait doesn't return earlier than the
+ // specified |max_time| and wait again for the remaining time.
+ delay = target_time - TimeTicks::Now();
+ break;
+ default:
+ // It is most unexpected that this should ever fail. Help consumers
+ // learn about it if it should ever fail.
+ NOTREACHED() << "WaitForSingleObject failed";
danakj 2016/10/21 22:01:22 This falls into the NOTREACHED+return antipattern.
stanisc 2016/11/11 03:50:48 Good suggestion. Fixed.
+ return false;
+ }
+ } while (delay > TimeDelta());
return false;
}
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