[Reland] Make canceling Timers fast.

third_party/WebKit/Source/platform/TimerPerfTest.cpp

+// 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 "base/memory/ptr_util.h"
+#include "platform/testing/UnitTestHelpers.h"
+#include "public/platform/Platform.h"
+#include "testing/gtest/include/gtest/gtest.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;
+    std::vector<std::unique_ptr<Timer<TimerPerfTest>>> timers(numIterations);
+    for (int i = 0; i < numIterations; i++) {
+        timers[i] = base::MakeUnique<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();
+
+    printf("TimerBase::startOneShot cost (us/call) %f (total %ld us)\n", (postEnd - postStart).InMicroseconds() / static_cast<double>(numIterations), (postEnd - postStart).InMicroseconds());
+    printf("Time to run %d trivial tasks (us) %ld\n", numIterations, (m_runEnd - m_runStart).InMicroseconds());
+}
+
+TEST_F(TimerPerfTest, PostThenCancelTenThousandTimers)
+{
+    const int numIterations = 10000;
+    std::vector<std::unique_ptr<Timer<TimerPerfTest>>> timers(numIterations);
+    for (int i = 0; i < numIterations; i++) {
+        timers[i] = base::MakeUnique<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();
+
+    printf("TimerBase::startOneShot cost (us/call) %f (total %ld us)\n", (postEnd - postStart).InMicroseconds() / static_cast<double>(numIterations), (postEnd - postStart).InMicroseconds());
+    printf("TimerBase::stop cost (us/call) %f (total %ld us)\n", (cancelEnd - cancelStart).InMicroseconds() / static_cast<double>(numIterations), (cancelEnd - cancelStart).InMicroseconds());
+    printf("Time to run %d canceled tasks (us) %ld\n", numIterations, (m_runEnd - m_runStart).InMicroseconds());
+}
+
+} // namespace blink