Track UMA stats for when the renderer side audio device wasn't ready.

content/browser/renderer_host/media/audio_sync_reader.cc

Index: content/browser/renderer_host/media/audio_sync_reader.cc
diff --git a/content/browser/renderer_host/media/audio_sync_reader.cc b/content/browser/renderer_host/media/audio_sync_reader.cc
index 0730ec20f4022b40c9fa7df46f4d28e18324df5c..5ea6d6c3e662ca78c022e77b2506ee3d8fe52721 100644
--- a/content/browser/renderer_host/media/audio_sync_reader.cc
+++ b/content/browser/renderer_host/media/audio_sync_reader.cc
@@ -6,12 +6,17 @@
 
 #include <algorithm>
 
+#include "base/metrics/histogram.h"
 #include "base/process_util.h"
 #include "base/shared_memory.h"
 #include "media/audio/audio_buffers_state.h"
 #include "media/audio/audio_parameters.h"
 #include "media/audio/shared_memory_util.h"
 
+#if defined(OS_WIN)
+#include "media/audio/win/core_audio_util_win.h"
+#endif
+
 using media::AudioBus;
 
 namespace content {
@@ -20,7 +25,9 @@ AudioSyncReader::AudioSyncReader(base::SharedMemory* shared_memory,
                                  const media::AudioParameters& params,
                                  int input_channels)
     : shared_memory_(shared_memory),
-      input_channels_(input_channels) {
+      input_channels_(input_channels),
+      renderer_callback_count_(0),
+      renderer_missed_callback_count_(0) {
   packet_size_ = media::PacketSizeInBytes(shared_memory_->created_size());
   int input_memory_size = 0;
   int output_memory_size = AudioBus::CalculateMemorySize(params);
@@ -37,6 +44,39 @@ AudioSyncReader::AudioSyncReader(base::SharedMemory* shared_memory,
 }
 
 AudioSyncReader::~AudioSyncReader() {
+  if (!renderer_callback_count_)
+    return;
+
+  // Reduce renderer callback percentage to 10% intervals.  |percentage_missed|
+  // is a number from 0-10 representing the 10% interval index.  I.e., 0 = 0%,
+  // 1 = 10%, 2 = 20%, ..., 10 = 100%.

[scherkus (not reviewing), 2013/01/24 23:34:39]

OOC why not UMA_HISTOGRAM_PERCENTAGE()?

If there's a reason perhaps the comment be better served by explaining why we're
not using it

+  const int kMissedMax = 11;
+  int percentage_missed = 0.5 + 10 * (static_cast<double>(
+      renderer_missed_callback_count_) / renderer_callback_count_);
+
+  // Recording the percentage of deadline misses gives us a rough overview of
+  // how many users might be running into audio glitches.
+#if defined(OS_LINUX)
+  UMA_HISTOGRAM_ENUMERATION(
+      "Media.AudioRendererMissedDeadlineLinux", percentage_missed, kMissedMax);
+#elif defined(OS_MACOSX)
+  UMA_HISTOGRAM_ENUMERATION(
+      "Media.AudioRendererMissedDeadlineOSX", percentage_missed, kMissedMax);

[scherkus (not reviewing), 2013/01/24 23:34:39]

do we need to have 5 different buckets? UMA already has the capability to
display different histograms based on the OS at a finer grained level than what
you have here

the only tricky one is WASAPI vs WaveOut, but CoreAudioUtil::IsSupported() is
essentially an OS check for Vista+ and I'd be willing to wager that based on
crash reports the # of people that fail the DLL load check is small enough to
not make a difference

[DaleCurtis, 2013/01/26 01:02:55]

Great point. I totally forgot about the OS based filtering.  A single
UMA_HISTOGRAM_PERCENTAGE() is sufficient then. I was just trying to avoid 5x 100
line UMA stat entries.

+#elif defined(OS_WIN)
+  if (CoreAudioUtil::IsSupported()) {
+    UMA_HISTOGRAM_ENUMERATION(
+        "Media.AudioRendererMissedDeadlineWASAPI", percentage_missed,
+        kMissedMax);
+  } else {
+    UMA_HISTOGRAM_ENUMERATION(
+        "Media.AudioRendererMissedDeadlineWaveOut", percentage_missed,
+        kMissedMax);
+  }
+#elif defined(OS_CHROMEOS)
+  UMA_HISTOGRAM_ENUMERATION(
+      "Media.AudioRendererMissedDeadlineChromeOS", percentage_missed,
+      kMissedMax);
+#endif
 }
 
 bool AudioSyncReader::DataReady() {
@@ -57,6 +97,10 @@ void AudioSyncReader::UpdatePendingBytes(uint32 bytes) {
 }
 
 int AudioSyncReader::Read(AudioBus* source, AudioBus* dest) {
+  ++renderer_callback_count_;
+  if (!DataReady())
+    ++renderer_missed_callback_count_;
+
   // Copy optional synchronized live audio input for consumption by renderer
   // process.
   if (source && input_bus_.get()) {