From a3533d7c93d83c82bf9f94ae47f9da7d9bfe8b91 Mon Sep 17 00:00:00 2001
From: Paul Adenot <paul@paul.cx>
Date: Tue, 26 Aug 2014 17:02:28 +0200
Subject: [PATCH] Bug 848954 - Part 20 - Remove the now useless DriverHolder
 class. r=roc

---
 content/media/GraphDriver.cpp        | 18 -------------
 content/media/GraphDriver.h          | 38 ----------------------------
 content/media/MediaStreamGraph.cpp   |  9 +++----
 content/media/MediaStreamGraphImpl.h | 21 ++++++++++++++-
 4 files changed, 24 insertions(+), 62 deletions(-)

diff --git a/content/media/GraphDriver.cpp b/content/media/GraphDriver.cpp
index 00df8816e765..2e0d4c29fd3e 100644
--- a/content/media/GraphDriver.cpp
+++ b/content/media/GraphDriver.cpp
@@ -41,24 +41,6 @@ GraphDriver::GraphDriver(MediaStreamGraphImpl* aGraphImpl)
     mNextDriver(nullptr)
 { }
 
-DriverHolder::DriverHolder(MediaStreamGraphImpl* aGraphImpl)
-  : mGraphImpl(aGraphImpl)
-{ }
-
-GraphTime
-DriverHolder::GetCurrentTime()
-{
-  MOZ_ASSERT(mDriver, "Can't get current time without a clock.");
-  return mDriver->GetCurrentTime();
-}
-
-void
-DriverHolder::Switch(GraphDriver* aDriver)
-{
-  MOZ_ASSERT(!mDriver, "This is only for initial switch.");
-  mDriver = aDriver;
-}
-
 void GraphDriver::SetGraphTime(GraphDriver* aPreviousDriver,
                                GraphTime aLastSwitchNextIterationStart,
                                GraphTime aLastSwitchNextIterationEnd,
diff --git a/content/media/GraphDriver.h b/content/media/GraphDriver.h
index 2731c98d0a31..e96390313f59 100644
--- a/content/media/GraphDriver.h
+++ b/content/media/GraphDriver.h
@@ -228,44 +228,6 @@ protected:
   { }
 };
 
-/**
- * A driver holder allows a MediaStreamGraph to seamlessly switch between
- * different Drivers, remembering the current time of the graph at time of
- * switch.
- */
-class DriverHolder
-{
-public:
-  DriverHolder(MediaStreamGraphImpl* aGraphImpl);
-  GraphTime GetCurrentTime();
-
-  // Immediately switch to another driver.
-  void Switch(GraphDriver* aDriver);
-  // Create the new driver, but switch to a new one when the new driver is
-  // ready. System drivers don't have much problems here, but audio drivers can
-  // take a little while to start to fire callbacks.
-  void SwitchAtNextIteration(GraphDriver* aDriver);
-
-  GraphDriver* GetDriver() {
-    MOZ_ASSERT(mDriver);
-    return mDriver.get();
-  }
-
-  void SetCurrentDriver(GraphDriver* aDriver) {
-    mDriver = aDriver;
-  }
-
-protected:
-  // The current driver
-  nsRefPtr<GraphDriver> mDriver;
-  // The lifetime of this pointer is equal to the lifetime of the graph, so it
-  // will never be null.
-  MediaStreamGraphImpl* mGraphImpl;
-  // XXX
-  GraphTime mNextIterationStart;
-  GraphTime mNextStateComputedTime;
-};
-
 class MediaStreamGraphInitThreadRunnable;
 
 /**
diff --git a/content/media/MediaStreamGraph.cpp b/content/media/MediaStreamGraph.cpp
index eb48fb03d958..b8b6cb52b66d 100644
--- a/content/media/MediaStreamGraph.cpp
+++ b/content/media/MediaStreamGraph.cpp
@@ -2640,8 +2640,7 @@ MediaStreamGraphImpl::MediaStreamGraphImpl(bool aRealtime,
                                            TrackRate aSampleRate,
                                            DOMMediaStream::TrackTypeHints aHint= DOMMediaStream::HINT_CONTENTS_UNKNOWN,
                                            dom::AudioChannel aChannel)
-  : mDriverHolder(MOZ_THIS_IN_INITIALIZER_LIST())
-  , mProcessingGraphUpdateIndex(0)
+  : mProcessingGraphUpdateIndex(0)
   , mPortCount(0)
   , mMonitor("MediaStreamGraphImpl")
   , mLifecycleState(LIFECYCLE_THREAD_NOT_STARTED)
@@ -2673,13 +2672,13 @@ MediaStreamGraphImpl::MediaStreamGraphImpl(bool aRealtime,
   if (mRealtime) {
     if (aHint & DOMMediaStream::HINT_CONTENTS_AUDIO) {
       AudioCallbackDriver* driver = new AudioCallbackDriver(this, aChannel);
-      mDriverHolder.Switch(driver);
+      mDriver = driver;
       mMixer.AddCallback(driver);
     } else {
-      mDriverHolder.Switch(new SystemClockDriver(this));
+      mDriver = new SystemClockDriver(this);
     }
   } else {
-    mDriverHolder.Switch(new OfflineClockDriver(this, MEDIA_GRAPH_TARGET_PERIOD_MS));
+     mDriver = new OfflineClockDriver(this, MEDIA_GRAPH_TARGET_PERIOD_MS);
   }
 
   mLastMainThreadUpdate = TimeStamp::Now();
diff --git a/content/media/MediaStreamGraphImpl.h b/content/media/MediaStreamGraphImpl.h
index a6297f8c09a1..9749f15be144 100644
--- a/content/media/MediaStreamGraphImpl.h
+++ b/content/media/MediaStreamGraphImpl.h
@@ -398,6 +398,17 @@ public:
     return RateConvertTicksRoundDown(aRate, GraphRate(), aTime);
   }
 
+  /**
+   * Signal to the graph that the thread has paused indefinitly,
+   * or resumed.
+   */
+  void PausedIndefinitly();
+  void ResumedFromPaused();
+
+  GraphDriver* CurrentDriver() {
+    return mDriver;
+  }
+
   /**
    * Effectively set the new driver, while we are switching.
    * It is only safe to call this at the very end of an iteration, when there
@@ -405,7 +416,7 @@ public:
    * should return and pass the control to the new driver shortly after.
    */
   void SetCurrentDriver(GraphDriver* aDriver) {
-    mDriverHolder.SetCurrentDriver(aDriver);
+    mDriver = aDriver;
   }
 
   Monitor& GetMonitor() {
@@ -413,6 +424,14 @@ public:
   }
 
   // Data members
+  //
+  /**
+   * Graphs own owning references to their driver, until shutdown. When a driver
+   * switch occur, previous driver is either deleted, or it's ownership is
+   * passed to a event that will take care of the asynchronous cleanup, as
+   * audio stream can take some time to shut down.
+   */
+  nsRefPtr<GraphDriver> mDriver;
 
   // The following state is managed on the graph thread only, unless
   // mLifecycleState > LIFECYCLE_RUNNING in which case the graph thread