Bug 1542321 - Re-init a failed audio driver at increasing intervals. r=padenot

Differential Revision: https://phabricator.services.mozilla.com/D56086

--HG--
extra : moz-landing-system : lando

dom/media/GraphDriver.cpp

@@ -1183,6 +1183,9 @@ void AudioCallbackDriver::FallbackToSystemClockDriver() {
       ("%p: AudioCallbackDriver %p Falling back to SystemClockDriver.", Graph(),
        this));
   mFallbackDriverState = FallbackDriverState::Running;
+  mNextReInitBackoffStep =
+      TimeDuration::FromMilliseconds(AUDIO_INITIAL_FALLBACK_BACKOFF_STEP_MS);
+  mNextReInitAttempt = TimeStamp::Now() + mNextReInitBackoffStep;
   auto fallback =
       MakeRefPtr<FallbackWrapper>(Graph(), this, mSampleRate, mIterationStart,
                                   mIterationEnd, mStateComputedTime);
@@ -1200,6 +1203,8 @@ void AudioCallbackDriver::FallbackDriverStopped(GraphTime aIterationStart,
   mIterationStart = aIterationStart;
   mIterationEnd = aIterationEnd;
   mStateComputedTime = aStateComputedTime;
+  mNextReInitAttempt = TimeStamp();
+  mNextReInitBackoffStep = TimeDuration();
   {
     auto fallback = mFallback.Lock();
     MOZ_ASSERT(fallback.ref()->OnThread());
@@ -1216,12 +1221,26 @@ void AudioCallbackDriver::FallbackDriverStopped(GraphTime aIterationStart,
 void AudioCallbackDriver::MaybeStartAudioStream() {
   AudioStreamState streamState = mAudioStreamState;
   if (streamState != AudioStreamState::None) {
+    LOG(LogLevel::Verbose,
+        ("%p: AudioCallbackDriver %p Cannot re-init.", Graph(), this));
+    return;
+  }
+
+  TimeStamp now = TimeStamp::Now();
+  if (now < mNextReInitAttempt) {
+    LOG(LogLevel::Verbose,
+        ("%p: AudioCallbackDriver %p Not time to re-init yet. %.3fs left.",
+         Graph(), this, (mNextReInitAttempt - now).ToSeconds()));
     return;
   }
 
   LOG(LogLevel::Debug, ("%p: AudioCallbackDriver %p Attempting to re-init "
                         "audio stream from fallback driver.",
                         Graph(), this));
+  mNextReInitBackoffStep = std::min(
+      mNextReInitBackoffStep * 2,
+      TimeDuration::FromMilliseconds(AUDIO_MAX_FALLBACK_BACKOFF_STEP_MS));
+  mNextReInitAttempt = now + mNextReInitBackoffStep;
   Start();
 }
 

dom/media/GraphDriver.h

@@ -57,6 +57,18 @@ static const int SCHEDULE_SAFETY_MARGIN_MS = 10;
 static const int AUDIO_TARGET_MS =
     2 * MEDIA_GRAPH_TARGET_PERIOD_MS + SCHEDULE_SAFETY_MARGIN_MS;
 
+/**
+ * After starting a fallback driver, wait this long before attempting to re-init
+ * the audio stream the first time.
+ */
+static const int AUDIO_INITIAL_FALLBACK_BACKOFF_STEP_MS = 10;
+
+/**
+ * The backoff step duration for when to next attempt to re-init the audio
+ * stream is capped at this value.
+ */
+static const int AUDIO_MAX_FALLBACK_BACKOFF_STEP_MS = 1000;
+
 class AudioCallbackDriver;
 class GraphDriver;
 class MediaTrack;
@@ -758,6 +770,12 @@ class AudioCallbackDriver : public GraphDriver,
   /* Set to true in the first iteration after starting. Accessed in data
    * callback while running, or in Start(). */
   bool mRanFirstIteration = false;
+  /* If using a fallback driver, this is the duration to wait after failing to
+   * start it before attempting to start it again. */
+  TimeDuration mNextReInitBackoffStep;
+  /* If using a fallback driver, this is the next time we'll try to start the
+   * audio stream. */
+  TimeStamp mNextReInitAttempt;
 #ifdef XP_MACOSX
   /* When using the built-in speakers on macbook pro (13 and 15, all models),
    * it's best to hard pan the audio on the right, to avoid feedback into the