Title: [274458] trunk/Source/WTF
- Revision
- 274458
- Author
- cdu...@apple.com
- Date
- 2021-03-15 18:57:01 -0700 (Mon, 15 Mar 2021)
Log Message
RunLoop::isMain() should not need to do any heap allocations
https://bugs.webkit.org/show_bug.cgi?id=223227
Reviewed by Darin Adler.
RunLoop::isMain() should not need to do any heap allocations. Before this change,
calling RunLoop::isMain() on a non-main thread would call RunLoop::current() which
would allocate the RunLoop for the current thread. This is inefficient and an issue
for WebAudio since we're not allowed to do heap allocation on the audio rendering
thread.
* wtf/RunLoop.cpp:
(WTF::RunLoop::runLoopHolder):
(WTF::RunLoop::current):
(WTF::RunLoop::isMain):
* wtf/RunLoop.h:
Modified Paths
Diff
Modified: trunk/Source/WTF/ChangeLog (274457 => 274458)
--- trunk/Source/WTF/ChangeLog 2021-03-16 01:25:41 UTC (rev 274457)
+++ trunk/Source/WTF/ChangeLog 2021-03-16 01:57:01 UTC (rev 274458)
@@ -1,3 +1,22 @@
+2021-03-15 Chris Dumez <cdu...@apple.com>
+
+ RunLoop::isMain() should not need to do any heap allocations
+ https://bugs.webkit.org/show_bug.cgi?id=223227
+
+ Reviewed by Darin Adler.
+
+ RunLoop::isMain() should not need to do any heap allocations. Before this change,
+ calling RunLoop::isMain() on a non-main thread would call RunLoop::current() which
+ would allocate the RunLoop for the current thread. This is inefficient and an issue
+ for WebAudio since we're not allowed to do heap allocation on the audio rendering
+ thread.
+
+ * wtf/RunLoop.cpp:
+ (WTF::RunLoop::runLoopHolder):
+ (WTF::RunLoop::current):
+ (WTF::RunLoop::isMain):
+ * wtf/RunLoop.h:
+
2021-03-15 Alex Christensen <achristen...@webkit.org>
REGRESSION(r271642) Another app was relying on DOMWindow reuse
Modified: trunk/Source/WTF/wtf/RunLoop.cpp (274457 => 274458)
--- trunk/Source/WTF/wtf/RunLoop.cpp 2021-03-16 01:25:41 UTC (rev 274457)
+++ trunk/Source/WTF/wtf/RunLoop.cpp 2021-03-16 01:57:01 UTC (rev 274458)
@@ -28,7 +28,6 @@
#include <wtf/NeverDestroyed.h>
#include <wtf/StdLibExtras.h>
-#include <wtf/ThreadSpecific.h>
namespace WTF {
@@ -63,7 +62,7 @@
s_mainRunLoop = &RunLoop::current();
}
-RunLoop& RunLoop::current()
+auto RunLoop::runLoopHolder() -> ThreadSpecific<Holder>&
{
static LazyNeverDestroyed<ThreadSpecific<Holder>> runLoopHolder;
static std::once_flag onceKey;
@@ -70,9 +69,14 @@
std::call_once(onceKey, [&] {
runLoopHolder.construct();
});
- return runLoopHolder.get()->runLoop();
+ return runLoopHolder;
}
+RunLoop& RunLoop::current()
+{
+ return runLoopHolder()->runLoop();
+}
+
RunLoop& RunLoop::main()
{
ASSERT(s_mainRunLoop);
@@ -101,7 +105,8 @@
bool RunLoop::isMain()
{
ASSERT(s_mainRunLoop);
- return s_mainRunLoop == &RunLoop::current();
+ // Avoid constructing the RunLoop for the current thread if it has not been created yet.
+ return runLoopHolder().isSet() && s_mainRunLoop == &RunLoop::current();
}
void RunLoop::performWork()
Modified: trunk/Source/WTF/wtf/RunLoop.h (274457 => 274458)
--- trunk/Source/WTF/wtf/RunLoop.h 2021-03-16 01:25:41 UTC (rev 274457)
+++ trunk/Source/WTF/wtf/RunLoop.h 2021-03-16 01:57:01 UTC (rev 274458)
@@ -36,6 +36,7 @@
#include <wtf/Observer.h>
#include <wtf/RetainPtr.h>
#include <wtf/Seconds.h>
+#include <wtf/ThreadSpecific.h>
#include <wtf/ThreadingPrimitives.h>
#include <wtf/WeakHashSet.h>
#include <wtf/text/WTFString.h>
@@ -190,6 +191,7 @@
private:
class Holder;
+ static ThreadSpecific<Holder>& runLoopHolder();
class DispatchTimer final : public TimerBase {
public:
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