Always wait for DataReady() on Windows WaveOut.

media/audio/audio_output_controller.cc

 // Copyright (c) 2012 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 "media/audio/audio_output_controller.h"
 
 #include "base/bind.h"
 #include "base/debug/trace_event.h"
 #include "base/message_loop.h"
 #include "base/synchronization/waitable_event.h"
 #include "base/threading/platform_thread.h"
 #include "base/threading/thread_restrictions.h"
 #include "base/time.h"
+#include "build/build_config.h"
 #include "media/audio/shared_memory_util.h"
 
 using base::Time;
 using base::TimeDelta;
 using base::WaitableEvent;
 
 namespace media {
 
 // Polling-related constants.
 const int AudioOutputController::kPollNumAttempts = 3;
@@ skipping 288 matching lines @@
     }
   }
 
   int frames = sync_reader_->Read(source, dest);
   sync_reader_->UpdatePendingBytes(
       buffers_state.total_bytes() + frames * params_.GetBytesPerFrame());
   return frames;
 }
 
 void AudioOutputController::WaitTillDataReady() {
-  if (!sync_reader_->DataReady()) {
-    // In the different place we use different mechanism to poll, get max
-    // polling delay from constants used there.
-    const base::TimeDelta kMaxPollingDelay = TimeDelta::FromMilliseconds(
-        kPollNumAttempts * kPollPauseInMilliseconds);
-    Time start_time = Time::Now();
-    do {
-      base::PlatformThread::Sleep(TimeDelta::FromMilliseconds(1));
-    } while (!sync_reader_->DataReady() &&
-             Time::Now() - start_time < kMaxPollingDelay);
+#if defined(OS_WIN) || defined(OS_MAC)
+  base::Time start = base::Time::Now();
+  // Wait for up to 1.5 seconds for DataReady().  1.5 seconds was chosen because
+  // it's larger than the playback time of the WaveOut buffer size using the
+  // minimum supported sample rate: 4096 / 3000 = ~1.4 seconds.  Even a client
+  // expecting real time playout should be able to fill in this time.
+  const base::TimeDelta max_wait = base::TimeDelta::FromMilliseconds(1500);

[scherkus (not reviewing), 2012/11/21 22:46:55]

s/max_wait/kMaxWait/

[DaleCurtis, 2012/11/21 22:50:15]

Done.

+  while (!sync_reader_->DataReady() &&
+         ((base::Time::Now() - start) < max_wait)) {
+    base::PlatformThread::YieldCurrentThread();
   }
+#else
+  // WaitTillDataReady() is deprecated and should not be used.

[scherkus (not reviewing), 2012/11/21 22:46:55]

make this a string?

[DaleCurtis, 2012/11/21 22:50:15]

I think it's unncessary and just adds string bloat.  Every CHECK() comes with a
line number and this one is pretty clear.

+  CHECK(false);
+#endif
 }
 
 void AudioOutputController::OnError(AudioOutputStream* stream, int code) {
   // Handle error on the audio controller thread.
   message_loop_->PostTask(FROM_HERE, base::Bind(
       &AudioOutputController::DoReportError, this, code));
 }
 
 void AudioOutputController::DoStopCloseAndClearStream(WaitableEvent* done) {
   DCHECK(message_loop_->BelongsToCurrentThread());
@@ skipping 43 matching lines @@
     case kPausedWhenStarting:
     case kPaused:
       // From the outside these three states are equivalent.
       return;
     default:
       NOTREACHED() << "Invalid original state.";
   }
 }
 
 }  // namespace media