Fix flakiness in PushPullFIFOSmokeTest.SmokeTests/7

third_party/WebKit/Source/platform/audio/PushPullFIFOMultithreadTest.cpp

Index: third_party/WebKit/Source/platform/audio/PushPullFIFOMultithreadTest.cpp
diff --git a/third_party/WebKit/Source/platform/audio/PushPullFIFOMultithreadTest.cpp b/third_party/WebKit/Source/platform/audio/PushPullFIFOMultithreadTest.cpp
index 6034d496a9031b61643d0a1fa0e0acdc539ba9c5..358452b79fa5bee2adb0b6b652dfa3c096a373d2 100644
--- a/third_party/WebKit/Source/platform/audio/PushPullFIFOMultithreadTest.cpp
+++ b/third_party/WebKit/Source/platform/audio/PushPullFIFOMultithreadTest.cpp
@@ -47,15 +47,21 @@ class FIFOClient {
       : fifo_(fifo),
         bus_(AudioBus::Create(fifo->NumberOfChannels(), bus_length)),
         client_thread_(Platform::Current()->CreateThread("client thread")),
+        done_event_(WTF::MakeUnique<WaitableEvent>()),
         jitter_range_ms_(jitter_range_ms) {}
 
-  void Start(double duration_ms, double interval_ms) {
+  ~FIFOClient() {
+    client_thread_.reset();

[o1ka, 2017/05/08 12:11:56]

Why is it needed?

[hongchan, 2017/05/08 18:19:33]

Removed.

+  }
+
+  WaitableEvent* Start(double duration_ms, double interval_ms) {
     duration_ms_ = duration_ms;
     interval_ms_ = interval_ms;
     client_thread_->GetWebTaskRunner()->PostTask(
         BLINK_FROM_HERE,
         CrossThreadBind(&FIFOClient::RunTaskOnOwnThread,
                         CrossThreadUnretained(this)));
+    return done_event_.get();
   }
 
   virtual void Stop(int callback_counter) = 0;
@@ -84,12 +90,14 @@ class FIFOClient {
               interval_with_jitter);
     } else {
       Stop(counter_);
+      done_event_->Signal();
     }
   }
 
   PushPullFIFO* fifo_;
   RefPtr<AudioBus> bus_;
   std::unique_ptr<WebThread> client_thread_;
+  std::unique_ptr<WaitableEvent> done_event_;
 
   // Test duration.
   double duration_ms_;
@@ -179,14 +187,22 @@ TEST_P(PushPullFIFOSmokeTest, SmokeTests) {
   std::unique_ptr<PushClient> push_client = WTF::WrapUnique(new PushClient(
       test_fifo.get(), param.push_buffer_size, param.push_jitter_range_ms));
 
-  LOG(INFO) << "PushPullFIFOSmokeTest - Start";
+  Vector<WaitableEvent*> done_events;
+  done_events.push_back(
+      pull_client->Start(param.test_duration_ms, pull_interval_ms));
+  done_events.push_back(
+      push_client->Start(param.test_duration_ms, push_interval_ms));
+
+  LOG(INFO) << "PushPullFIFOSmokeTest - Started";
 
-  pull_client->Start(param.test_duration_ms, pull_interval_ms);
-  push_client->Start(param.test_duration_ms, push_interval_ms);
+  // We have to wait both of events to be signaled.
+  WaitableEvent::WaitMultiple(done_events);
+  WaitableEvent::WaitMultiple(done_events);
 
   // If the operation does not cause a crash for the test period, it's passed.
-  // Also give a bit more time to finish the tear-down process.
-  HoldTestForDuration(param.test_duration_ms + 150);
+  // Also give a bit more time (10ms per iteration) to finish the tear-down

[o1ka, 2017/05/08 12:11:56]

Not sure what tear down process do you mean?
Nothing will run  after both |done_event_|s are signaled, right?

[hongchan, 2017/05/08 18:19:33]

Done.

+  // process.
+  HoldTestForDuration(10);
 }
 
 FIFOSmokeTestParam smoke_test_params[] = {