[Reland] Make canceling Timers fast.

third_party/WebKit/Source/web/tests/TimerPerfTest.cpp

Index: third_party/WebKit/Source/web/tests/TimerPerfTest.cpp
diff --git a/third_party/WebKit/Source/web/tests/TimerPerfTest.cpp b/third_party/WebKit/Source/web/tests/TimerPerfTest.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..6babcbf2d41737ef0fe5f508d2d960b60ff9c1f5
--- /dev/null
+++ b/third_party/WebKit/Source/web/tests/TimerPerfTest.cpp
@@ -0,0 +1,101 @@
+
+// Copyright 2016 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 "platform/Timer.h"
+
+#include "platform/testing/UnitTestHelpers.h"
+#include "public/platform/Platform.h"
+#include "testing/gtest/include/gtest/gtest.h"
+#include "wtf/PtrUtil.h"
+#include "wtf/Vector.h"
+
+namespace blink {
+
+class TimerPerfTest : public ::testing::Test {
+public:
+    void nopTask(TimerBase*)
+    {
+    }
+
+    void recordStartRunTime(TimerBase*)
+    {
+        m_runStart = base::ThreadTicks::Now();
+    }
+
+    void recordEndRunTime(TimerBase*)
+    {
+        m_runEnd = base::ThreadTicks::Now();
+        base::MessageLoop::current()->QuitNow();
+    }
+
+    base::ThreadTicks m_runStart;
+    base::ThreadTicks m_runEnd;
+};
+
+TEST_F(TimerPerfTest, PostAndRunTimers)
+{
+    const int numIterations = 10000;
+    Vector<std::unique_ptr<Timer<TimerPerfTest>>> timers(numIterations);
+    for (int i = 0; i < numIterations; i++) {
+        timers[i].reset(new Timer<TimerPerfTest>(this, &TimerPerfTest::nopTask));
+    }
+
+    Timer<TimerPerfTest> measureRunStart(this, &TimerPerfTest::recordStartRunTime);
+    Timer<TimerPerfTest> measureRunEnd(this, &TimerPerfTest::recordEndRunTime);
+
+    measureRunStart.startOneShot(0.0, BLINK_FROM_HERE);
+    base::ThreadTicks postStart = base::ThreadTicks::Now();
+    for (int i = 0; i < numIterations; i++) {
+        timers[i]->startOneShot(0.0, BLINK_FROM_HERE);
+    }
+    base::ThreadTicks postEnd = base::ThreadTicks::Now();
+    measureRunEnd.startOneShot(0.0, BLINK_FROM_HERE);
+
+    testing::enterRunLoop();
+
+    double postingTime = (postEnd - postStart).InMicroseconds();
+    double postingTimeUsPerCall = postingTime / static_cast<double>(numIterations);
+    LOG(INFO) << "TimerBase::startOneShot cost (us/call) " << postingTimeUsPerCall << " (total " << postingTime << " us)";
+    LOG(INFO) << "Time to run " << numIterations << " trivial tasks (us) " << (m_runEnd - m_runStart).InMicroseconds();
+}
+
+TEST_F(TimerPerfTest, PostThenCancelTenThousandTimers)
+{
+    const int numIterations = 10000;
+    Vector<std::unique_ptr<Timer<TimerPerfTest>>> timers(numIterations);
+    for (int i = 0; i < numIterations; i++) {
+        timers[i].reset(new Timer<TimerPerfTest>(this, &TimerPerfTest::nopTask));
+    }
+
+    Timer<TimerPerfTest> measureRunStart(this, &TimerPerfTest::recordStartRunTime);
+    Timer<TimerPerfTest> measureRunEnd(this, &TimerPerfTest::recordEndRunTime);
+
+    measureRunStart.startOneShot(0.0, BLINK_FROM_HERE);
+    base::ThreadTicks postStart = base::ThreadTicks::Now();
+    for (int i = 0; i < numIterations; i++) {
+        timers[i]->startOneShot(0.0, BLINK_FROM_HERE);
+    }
+    base::ThreadTicks postEnd = base::ThreadTicks::Now();
+    measureRunEnd.startOneShot(0.0, BLINK_FROM_HERE);
+
+    base::ThreadTicks cancelStart = base::ThreadTicks::Now();
+    for (int i = 0; i < numIterations; i++) {
+        timers[i]->stop();
+    }
+    base::ThreadTicks cancelEnd = base::ThreadTicks::Now();
+
+    testing::enterRunLoop();
+
+    double postingTime = (postEnd - postStart).InMicroseconds();
+    double postingTimeUsPerCall = postingTime / static_cast<double>(numIterations);
+    LOG(INFO) << "TimerBase::startOneShot cost (us/call) " << postingTimeUsPerCall << " (total " << postingTime << " us)";
+
+    double cancelTime = (cancelEnd - cancelStart).InMicroseconds();
+    double cancelTimeUsPerCall = cancelTime / static_cast<double>(numIterations);
+    LOG(INFO) << "TimerBase::stop cost (us/call) " << cancelTimeUsPerCall << " (total " << cancelTime << " us)";
+    LOG(INFO) << "Time to run " << numIterations << " canceled tasks (us) " << (m_runEnd - m_runStart).InMicroseconds();
+}
+
+} // namespace blink