Bug 1441916 - Introduce the notion of the APZ sampler thread. r=botond

The sampler thread is similar to the controller thread in that it doesn't
correspond to a particular actual thread, but instead introduces an
abstraction that allows us to reason about code flow and data ownership
that is logically grouped on a single thread. For now the sampler thread
remains mapped to the compositor thread, but eventually we will allow
it to be render backend thread when webrender is enabled.

MozReview-Commit-ID: D6i2t5lDvkv

--HG--
extra : rebase_source : 06211ad878973c76ca3fd618386bbbd0cfdd4821

gfx/layers/Compositor.cpp

@@ -61,14 +61,6 @@ Compositor::EndFrame()
   mLastCompositionEndTime = TimeStamp::Now();
 }
 
-/* static */ void
-Compositor::AssertOnCompositorThread()
-{
-  MOZ_ASSERT(!CompositorThreadHolder::Loop() ||
-             CompositorThreadHolder::Loop() == MessageLoop::current(),
-             "Can only call this from the compositor thread!");
-}
-
 bool
 Compositor::ShouldDrawDiagnostics(DiagnosticFlags aFlags)
 {

gfx/layers/Compositor.h

@@ -497,12 +497,6 @@ public:
 
   widget::CompositorWidget* GetWidget() const { return mWidget; }
 
-  /**
-   * Debug-build assertion that can be called to ensure code is running on the
-   * compositor thread.
-   */
-  static void AssertOnCompositorThread();
-
   // Return statistics for the most recent frame we computed statistics for.
   virtual void GetFrameStats(GPUStats* aStats);
 

gfx/layers/apz/public/IAPZCTreeManager.cpp

@@ -9,7 +9,7 @@
 #include "gfxPrefs.h"                       // for gfxPrefs
 #include "InputData.h"                      // for InputData, etc
 #include "mozilla/EventStateManager.h"      // for WheelPrefs
-#include "mozilla/layers/APZThreadUtils.h"  // for AssertOnCompositorThread, etc
+#include "mozilla/layers/APZThreadUtils.h"  // for AssertOnControllerThread, etc
 #include "mozilla/MouseEvents.h"            // for WidgetMouseEvent
 #include "mozilla/TextEvents.h"             // for WidgetKeyboardEvent
 #include "mozilla/TouchEvents.h"            // for WidgetTouchEvent

gfx/layers/apz/public/IAPZCTreeManager.h

@@ -113,7 +113,7 @@ public:
 
   /**
    * Kicks an animation to zoom to a rect. This may be either a zoom out or zoom
-   * in. The actual animation is done on the compositor thread after being set
+   * in. The actual animation is done on the sampler thread after being set
    * up. |aRect| must be given in CSS pixels, relative to the document.
    * |aFlags| is a combination of the ZoomToRectBehavior enum values.
    */

gfx/layers/apz/src/APZCTreeManager.cpp

@@ -20,7 +20,7 @@
 #include "mozilla/gfx/GPUParent.h"      // for GPUParent
 #include "mozilla/gfx/Logging.h"        // for gfx::TreeLog
 #include "mozilla/gfx/Point.h"          // for Point
-#include "mozilla/layers/APZThreadUtils.h"  // for AssertOnCompositorThread, etc
+#include "mozilla/layers/APZThreadUtils.h"  // for AssertOnControllerThread, etc
 #include "mozilla/layers/AsyncCompositionManager.h" // for ViewTransform
 #include "mozilla/layers/AsyncDragMetrics.h" // for AsyncDragMetrics
 #include "mozilla/layers/CompositorBridgeParent.h" // for CompositorBridgeParent, etc
@@ -269,7 +269,7 @@ void
 APZCTreeManager::NotifyLayerTreeAdopted(uint64_t aLayersId,
                                         const RefPtr<APZCTreeManager>& aOldApzcTreeManager)
 {
-  APZThreadUtils::AssertOnCompositorThread();
+  APZThreadUtils::AssertOnSamplerThread();
 
   MOZ_ASSERT(aOldApzcTreeManager);
   aOldApzcTreeManager->mFocusState.RemoveFocusTarget(aLayersId);
@@ -295,7 +295,7 @@ APZCTreeManager::NotifyLayerTreeAdopted(uint64_t aLayersId,
 void
 APZCTreeManager::NotifyLayerTreeRemoved(uint64_t aLayersId)
 {
-  APZThreadUtils::AssertOnCompositorThread();
+  APZThreadUtils::AssertOnSamplerThread();
 
   mFocusState.RemoveFocusTarget(aLayersId);
 
@@ -333,7 +333,7 @@ APZCTreeManager::UpdateHitTestingTreeImpl(uint64_t aRootLayerTreeId,
                                           uint64_t aOriginatingLayersId,
                                           uint32_t aPaintSequenceNumber)
 {
-  APZThreadUtils::AssertOnCompositorThread();
+  APZThreadUtils::AssertOnSamplerThread();
 
   RecursiveMutexAutoLock lock(mTreeLock);
 
@@ -528,7 +528,7 @@ APZCTreeManager::PushStateToWR(wr::TransactionBuilder& aTxn,
                                const TimeStamp& aSampleTime,
                                nsTArray<wr::WrTransformProperty>& aTransformArray)
 {
-  APZThreadUtils::AssertOnCompositorThread();
+  APZThreadUtils::AssertOnSamplerThread();
 
   RecursiveMutexAutoLock lock(mTreeLock);
 
@@ -2982,7 +2982,7 @@ bool
 APZCTreeManager::GetAPZTestData(uint64_t aLayersId,
                                 APZTestData* aOutData)
 {
-  APZThreadUtils::AssertOnCompositorThread();
+  APZThreadUtils::AssertOnSamplerThread();
   MutexAutoLock lock(mTestDataLock);
   auto it = mTestData.find(aLayersId);
   if (it == mTestData.end()) {

gfx/layers/apz/src/APZCTreeManager.h

@@ -77,7 +77,7 @@ struct AncestorTransform;
  * This class manages the tree of AsyncPanZoomController instances. There is one
  * instance of this class owned by each CompositorBridgeParent, and it contains as
  * many AsyncPanZoomController instances as there are scrollable container layers.
- * This class generally lives on the compositor thread, although some functions
+ * This class generally lives on the sampler thread, although some functions
  * may be called from other threads as noted; thread safety is ensured internally.
  *
  * The bulk of the work of this class happens as part of the UpdateHitTestingTree
@@ -126,7 +126,7 @@ public:
    * some other compositor. That other compositor's APZCTreeManager is also
    * provided. This allows APZCTreeManager to transfer any necessary state
    * from the old APZCTreeManager related to that layers id.
-   * This function must be called on the compositor thread.
+   * This function must be called on the sampler thread.
    */
   void NotifyLayerTreeAdopted(uint64_t aLayersId,
                               const RefPtr<APZCTreeManager>& aOldTreeManager);
@@ -136,7 +136,7 @@ public:
    * associated compositor has been removed/destroyed. Note that this does
    * NOT get called during shutdown situations, when the root layer tree is
    * also getting destroyed.
-   * This function must be called on the compositor thread.
+   * This function must be called on the sampler thread.
    */
   void NotifyLayerTreeRemoved(uint64_t aLayersId);
 
@@ -158,7 +158,7 @@ public:
    * Preserve nodes and APZC instances where possible, but retire those whose
    * layers are no longer in the layer tree.
    *
-   * This must be called on the compositor thread as it walks the layer tree.
+   * This must be called on the sampler thread as it walks the layer tree.
    *
    * @param aRootLayerTreeId The layer tree ID of the root layer corresponding
    *                         to this APZCTreeManager
@@ -193,7 +193,7 @@ public:
                             uint32_t aPaintSequenceNumber);
 
   /**
-   * Called when webrender is enabled, from the compositor thread. This function
+   * Called when webrender is enabled, from the sampler thread. This function
    * walks through the tree of APZC instances and tells webrender about the
    * async scroll position. It also advances APZ animations to the specified
    * sample time. In effect it is the webrender equivalent of (part of) the
@@ -260,7 +260,7 @@ public:
 
   /**
    * Kicks an animation to zoom to a rect. This may be either a zoom out or zoom
-   * in. The actual animation is done on the compositor thread after being set
+   * in. The actual animation is done on the sampler thread after being set
    * up. |aRect| must be given in CSS pixels, relative to the document.
    * |aFlags| is a combination of the ZoomToRectBehavior enum values.
    */

gfx/layers/apz/src/AsyncPanZoomController.cpp

@@ -834,7 +834,7 @@ AsyncPanZoomController::GetInputQueue() const {
 void
 AsyncPanZoomController::Destroy()
 {
-  APZThreadUtils::AssertOnCompositorThread();
+  APZThreadUtils::AssertOnSamplerThread();
 
   CancelAnimation(CancelAnimationFlags::ScrollSnap);
 
@@ -3431,7 +3431,7 @@ AsyncPanZoomController::RequestContentRepaint(const FrameMetrics& aFrameMetrics,
 bool AsyncPanZoomController::UpdateAnimation(const TimeStamp& aSampleTime,
                                              nsTArray<RefPtr<Runnable>>* aOutDeferredTasks)
 {
-  APZThreadUtils::AssertOnCompositorThread();
+  APZThreadUtils::AssertOnSamplerThread();
 
   // This function may get called multiple with the same sample time, because
   // there may be multiple layers with this APZC, and each layer invokes this
@@ -3490,7 +3490,7 @@ AsyncPanZoomController::GetOverscrollTransform(AsyncTransformConsumer aMode) con
 
 bool AsyncPanZoomController::AdvanceAnimations(const TimeStamp& aSampleTime)
 {
-  APZThreadUtils::AssertOnCompositorThread();
+  APZThreadUtils::AssertOnSamplerThread();
 
   // Don't send any state-change notifications until the end of the function,
   // because we may go through some intermediate states while we finish
@@ -3769,7 +3769,7 @@ void AsyncPanZoomController::NotifyLayersUpdated(const ScrollMetadata& aScrollMe
                                                  bool aIsFirstPaint,
                                                  bool aThisLayerTreeUpdated)
 {
-  APZThreadUtils::AssertOnCompositorThread();
+  APZThreadUtils::AssertOnSamplerThread();
 
   RecursiveMutexAutoLock lock(mRecursiveMutex);
   bool isDefault = mScrollMetadata.IsDefault();
@@ -4387,7 +4387,7 @@ void AsyncPanZoomController::UpdateSharedCompositorFrameMetrics()
 
 void AsyncPanZoomController::ShareCompositorFrameMetrics()
 {
-  APZThreadUtils::AssertOnCompositorThread();
+  APZThreadUtils::AssertOnSamplerThread();
 
   // Only create the shared memory buffer if it hasn't already been created,
   // we are using progressive tile painting, and we have a

gfx/layers/apz/src/AsyncPanZoomController.h

@@ -190,7 +190,7 @@ public:
 
   /**
    * Kicks an animation to zoom to a rect. This may be either a zoom out or zoom
-   * in. The actual animation is done on the compositor thread after being set
+   * in. The actual animation is done on the sampler thread after being set
    * up.
    */
   void ZoomToRect(CSSRect aRect, const uint32_t aFlags);
@@ -213,7 +213,7 @@ public:
   void PostDelayedTask(already_AddRefed<Runnable> aTask, int aDelayMs);
 
   // --------------------------------------------------------------------------
-  // These methods must only be called on the compositor thread.
+  // These methods must only be called on the sampler thread.
   //
 
   /**
@@ -776,7 +776,7 @@ protected:
 
   /* Access to the following two fields is protected by the mRefPtrMonitor,
      since they are accessed on the UI thread but can be cleared on the
-     compositor thread. */
+     sampler thread. */
   RefPtr<GeckoContentController> mGeckoContentController;
   RefPtr<GestureEventListener> mGestureEventListener;
   mutable Monitor mRefPtrMonitor;

gfx/layers/apz/src/HitTestingTreeNode.cpp

@@ -10,7 +10,7 @@
 #include "gfxPrefs.h"
 #include "LayersLogging.h"                              // for Stringify
 #include "mozilla/gfx/Point.h"                          // for Point4D
-#include "mozilla/layers/APZThreadUtils.h"              // for AssertOnCompositorThread
+#include "mozilla/layers/APZThreadUtils.h"              // for AssertOnSamplerThread
 #include "mozilla/layers/APZUtils.h"                    // for CompleteAsyncTransform
 #include "mozilla/layers/AsyncCompositionManager.h"     // for ViewTransform::operator Matrix4x4()
 #include "mozilla/layers/AsyncDragMetrics.h"            // for AsyncDragMetrics
@@ -59,7 +59,7 @@ HitTestingTreeNode::~HitTestingTreeNode()
 void
 HitTestingTreeNode::Destroy()
 {
-  APZThreadUtils::AssertOnCompositorThread();
+  APZThreadUtils::AssertOnSamplerThread();
 
   mPrevSibling = nullptr;
   mLastChild = nullptr;

gfx/layers/apz/src/OverscrollHandoffState.h

@@ -35,7 +35,7 @@ protected:
   // Reference-counted classes cannot have public destructors.
   ~OverscrollHandoffChain();
 public:
-  // Threadsafe so that the controller and compositor threads can both maintain
+  // Threadsafe so that the controller and sampler threads can both maintain
   // nsRefPtrs to the same handoff chain.
   // Mutable so that we can pass around the class by
   // RefPtr<const OverscrollHandoffChain> and thus enforce that, once built,

gfx/layers/apz/util/APZThreadUtils.cpp

@@ -6,7 +6,7 @@
 
 #include "mozilla/layers/APZThreadUtils.h"
 
-#include "mozilla/layers/Compositor.h"
+#include "mozilla/layers/CompositorThread.h"
 
 namespace mozilla {
 namespace layers {
@@ -43,10 +43,10 @@ APZThreadUtils::AssertOnControllerThread() {
 }
 
 /*static*/ void
-APZThreadUtils::AssertOnCompositorThread()
+APZThreadUtils::AssertOnSamplerThread()
 {
   if (GetThreadAssertionsEnabled()) {
-    Compositor::AssertOnCompositorThread();
+    MOZ_ASSERT(CompositorThreadHolder::IsInCompositorThread());
   }
 }
 

gfx/layers/apz/util/APZThreadUtils.h

@@ -42,10 +42,10 @@ public:
 
   /**
    * This can be used to assert that the current thread is the
-   * compositor thread (which applies the async transform).
+   * sampler thread (which samples the async transform).
    * This does nothing if thread assertions are disabled.
    */
-  static void AssertOnCompositorThread();
+  static void AssertOnSamplerThread();
 
   /**
    * Run the given task on the APZ "controller thread" for this platform. If

gfx/layers/ipc/CompositorBridgeParent.cpp

@@ -2096,9 +2096,8 @@ UpdateIndirectTree(uint64_t aId, Layer* aRoot, const TargetConfig& aTargetConfig
 /* static */ CompositorBridgeParent::LayerTreeState*
 CompositorBridgeParent::GetIndirectShadowTree(uint64_t aId)
 {
-  // Only the compositor thread should use this method variant, however it is
-  // safe to be called on the main thread during APZ gtests.
-  APZThreadUtils::AssertOnCompositorThread();
+  // Only the compositor thread should use this method variant
+  MOZ_ASSERT(CompositorThreadHolder::IsInCompositorThread());
 
   MonitorAutoLock lock(*sIndirectLayerTreesLock);
   LayerTreeMap::iterator cit = sIndirectLayerTrees.find(aId);