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Unified Diff: Source/core/html/StableState.cpp

Issue 153813002: Support "await a stable state" and "provide a stable state" (Closed) Base URL: svn://svn.chromium.org/blink/trunk
Patch Set: assert more Created 6 years, 10 months ago
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Index: Source/core/html/StableState.cpp
diff --git a/Source/core/html/StableState.cpp b/Source/core/html/StableState.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..26b071da48bb11296d43a51b4656dbccc95286ed
--- /dev/null
+++ b/Source/core/html/StableState.cpp
@@ -0,0 +1,54 @@
+// Copyright 2014 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "config.h"
+#include "core/html/StableState.h"
+
+#include "wtf/HashSet.h"
+#include "wtf/MainThread.h"
+
+namespace WebCore {
+
+typedef HashSet<StableState::Awaiter*> StableStateAwaiters;
+
+static StableStateAwaiters& stableStateAwaiters()
+{
+ DEFINE_STATIC_LOCAL(StableStateAwaiters, stableStateAwaiters, ());
+ return stableStateAwaiters;
+}
+
+static bool isInStableState = false;
acolwell GONE FROM CHROMIUM 2014/02/10 22:36:05 nit: Now that we have more than one piece of state
philipj_slow 2014/02/17 11:59:24 Then the call sites would have to say something li
+
+StableState::Awaiter::~Awaiter()
+{
+ ASSERT(isMainThread());
+ stableStateAwaiters().remove(this);
+}
+
+void StableState::await(Awaiter& awaiter)
+{
+ ASSERT(isMainThread());
+ ASSERT(!isInStableState);
+ stableStateAwaiters().add(&awaiter);
+}
+
+void StableState::provide()
+{
+ ASSERT(isMainThread());
+ ASSERT(!isInStableState);
+
+ if (stableStateAwaiters().isEmpty())
+ return;
+
+ isInStableState = true;
+
+ StableStateAwaiters awaiters;
+ awaiters.swap(stableStateAwaiters());
acolwell GONE FROM CHROMIUM 2014/02/10 22:36:05 Can't this cause a use-after-free if executing did
philipj_slow 2014/02/17 11:59:24 Yes, indeed it can. Since the callbacks aren't run
+ for (StableStateAwaiters::iterator it = awaiters.begin(); it != awaiters.end(); ++it)
+ (*it)->didAwaitStableState();
+
+ isInStableState = false;
+}
+
+} // namespace WebCore

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