Add a new TickTimer class to NetEq

webrtc/modules/audio_coding/neteq/tick_timer_unittest.cc

+/*
+ *  Copyright (c) 2016 The WebRTC project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+#include "webrtc/modules/audio_coding/neteq/tick_timer.h"
+
+#include "testing/gmock/include/gmock/gmock.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace webrtc {
+
+TEST(TickTimer, Increment) {
+  TickTimer tt;
+  EXPECT_EQ(0u, tt.ticks());
+  tt.Increment();
+  EXPECT_EQ(1u, tt.ticks());
+
+  for (int i = 0; i < 17; ++i) {
+    tt.Increment();
+  }
+  EXPECT_EQ(18u, tt.ticks());
+
+  tt.Increment(17);
+  EXPECT_EQ(35u, tt.ticks());
+}
+
+TEST(TickTimer, WrapAround) {
+  TickTimer tt;
+  tt.Increment(UINT64_MAX);
+  EXPECT_EQ(UINT64_MAX, tt.ticks());
+  tt.Increment();
+  EXPECT_EQ(0u, tt.ticks());
+}
+
+TEST(TickTimer, Stopwatch) {
+  TickTimer tt;
+  // Increment it a "random" number of steps.
+  tt.Increment(17);
+
+  std::unique_ptr<TickTimer::Stopwatch> sw = tt.GetNewStopwatch();
+  ASSERT_TRUE(sw);
+
+  EXPECT_EQ(0u, sw->ElapsedTicks());  // Starts at zero.
+  EXPECT_EQ(0u, sw->ElapsedMs());
+  tt.Increment();
+  EXPECT_EQ(1u, sw->ElapsedTicks());  // Increases with the TickTimer.
+  EXPECT_EQ(10u, sw->ElapsedMs());
+}
+
+TEST(TickTimer, StopwatchWrapAround) {
+  TickTimer tt;
+  tt.Increment(UINT64_MAX);
+
+  std::unique_ptr<TickTimer::Stopwatch> sw = tt.GetNewStopwatch();
+  ASSERT_TRUE(sw);
+
+  tt.Increment();
+  EXPECT_EQ(0u, tt.ticks());
+  EXPECT_EQ(1u, sw->ElapsedTicks());
+  EXPECT_EQ(10u, sw->ElapsedMs());
+
+  tt.Increment();
+  EXPECT_EQ(1u, tt.ticks());
+  EXPECT_EQ(2u, sw->ElapsedTicks());
+  EXPECT_EQ(20u, sw->ElapsedMs());
+}
+
+TEST(TickTimer, StopwatchMsOverflow) {
+  TickTimer tt;
+  std::unique_ptr<TickTimer::Stopwatch> sw = tt.GetNewStopwatch();
+  ASSERT_TRUE(sw);
+
+  tt.Increment(UINT64_MAX / 10);
+  EXPECT_EQ(UINT64_MAX, sw->ElapsedMs());
+
+  tt.Increment();
+  EXPECT_EQ(UINT64_MAX, sw->ElapsedMs());
+
+  tt.Increment(UINT64_MAX - tt.ticks());
+  EXPECT_EQ(UINT64_MAX, tt.ticks());
+  EXPECT_EQ(UINT64_MAX, sw->ElapsedMs());

[tlegrand-webrtc, 2016/04/21 10:37:44]

Is the expected behavior that we cap at UINT64_MAX if running for too long? Is
that what we test here?

[hlundin-webrtc, 2016/04/21 13:50:58]

ElapsedMs will cap, which is what we test. Since the underlying tick counter is
an uint64_t, any multiple (larger than 1) of the elapsed number of ticks will
reach its maximum before the tick counter does. So, if we want to have
conversion to ms inside the Stopwatch, I think it is nice to have this capping
to avoid the weird situation where ElapsedMs() wraps before ElapsedTicks().

In the end, 2^64 ms is a very long time; 584 million years to be precise.

[tlegrand-webrtc, 2016/04/22 11:43:21]

Acknowledged.

+}
+
+TEST(TickTimer, Countdown) {
+  TickTimer tt;
+  // Increment it a "random" number of steps.
+  tt.Increment(4711);
+
+  std::unique_ptr<TickTimer::Countdown> cd = tt.GetNewCountdown(17);
+  ASSERT_TRUE(cd);
+
+  EXPECT_FALSE(cd->Finished());
+  tt.Increment();
+  EXPECT_FALSE(cd->Finished());
+
+  tt.Increment(16);  // Total increment is now 17.
+  EXPECT_TRUE(cd->Finished());
+
+  // Further increments do not change the state.
+  tt.Increment();
+  EXPECT_TRUE(cd->Finished());
+  tt.Increment(1234);
+  EXPECT_TRUE(cd->Finished());
+}
+}  // namespace webrtc