Bug 1230295 - Add telemetry to report when Ogg chaining is used. r=rillian,r=vladan

dom/media/ogg/OggReader.cpp

@@ -22,6 +22,8 @@ extern "C" {
 #include "MediaMetadataManager.h"
 #include "nsISeekableStream.h"
 #include "gfx2DGlue.h"
+#include "mozilla/Telemetry.h"
+#include "nsPrintfCString.h"
 
 using namespace mozilla::gfx;
 using namespace mozilla::media;
@@ -148,6 +150,17 @@ OggReader::~OggReader()
 {
   ogg_sync_clear(&mOggState);
   MOZ_COUNT_DTOR(OggReader);
+  if (HasAudio() || HasVideo()) {
+    // If we were able to initialize our decoders, report whether we encountered
+    // a chained stream or not.
+    ReentrantMonitorAutoEnter mon(mMonitor);
+    bool isChained = mIsChained;
+    nsCOMPtr<nsIRunnable> task = NS_NewRunnableFunction([=]() -> void {
+      LOG(LogLevel::Debug, (nsPrintfCString("Reporting telemetry MEDIA_OGG_LOADED_IS_CHAINED=%d", isChained).get()));
+      Telemetry::Accumulate(Telemetry::ID::MEDIA_OGG_LOADED_IS_CHAINED, isChained);
+    });
+    AbstractThread::MainThread()->Dispatch(task.forget());
+  }
 }
 
 nsresult OggReader::Init() {
@@ -704,10 +717,13 @@ bool OggReader::DecodeAudioData()
   return true;
 }
 
-void OggReader::SetChained(bool aIsChained) {
+void OggReader::SetChained() {
   {
     ReentrantMonitorAutoEnter mon(mMonitor);
-    mIsChained = aIsChained;
+    if (mIsChained) {
+      return;
+    }
+    mIsChained = true;
   }
   mOnMediaNotSeekable.Notify();
 }
@@ -800,7 +816,7 @@ bool OggReader::ReadOggChain()
   }
 
   if (chained) {
-    SetChained(true);
+    SetChained();
     {
       auto t = mDecodedAudioFrames * USECS_PER_S / mInfo.mAudio.mRate;
       mTimedMetadataEvent.Notify(
@@ -1139,7 +1155,7 @@ int64_t OggReader::RangeEndTime(int64_t aStartOffset,
       // This page is from a bitstream which we haven't encountered yet.
       // It's probably from a new "link" in a "chained" ogg. Don't
       // bother even trying to find a duration...
-      SetChained(true);
+      SetChained();
       endTime = -1;
       break;
     }
@@ -1913,7 +1929,7 @@ media::TimeIntervals OggReader::GetBuffered()
         // ogg), return OK to abort the finding any further ranges. This
         // prevents us searching through the rest of the media when we
         // may not be able to extract timestamps from it.
-        SetChained(true);
+        SetChained();
         return buffered;
       }
     }

dom/media/ogg/OggReader.h

@@ -252,7 +252,7 @@ private:
 
   // Set this media as being a chain and notifies the state machine that the
   // media is no longer seekable.
-  void SetChained(bool aIsChained);
+  void SetChained();
 
   // Returns the next Ogg packet for an bitstream/codec state. Returns a
   // pointer to an ogg_packet on success, or nullptr if the read failed.

toolkit/components/telemetry/Histograms.json

@@ -6285,6 +6285,13 @@
     "n_values": 256,
     "description": "WMF media decoder error or success (0) codes."
   },
+  "MEDIA_OGG_LOADED_IS_CHAINED": {
+    "alert_emails": ["cpearce@mozilla.com"],
+    "expires_in_version": "53",
+    "kind": "boolean",
+    "description": "Whether Ogg audio/video encountered are chained or not.",
+    "bug_numbers": [1230295]
+  },
   "VIDEO_CAN_CREATE_AAC_DECODER": {
     "alert_emails": ["cpearce@mozilla.com"],
     "expires_in_version": "50",