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+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*-
+ * vim: sw=2 ts=8 et :
+ */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_layers_ShadowLayers_h
+#define mozilla_layers_ShadowLayers_h 1
+
+#include <stddef.h> // for size_t
+#include <stdint.h> // for uint64_t
+#include "gfxTypes.h"
+#include "mozilla/Attributes.h" // for override
+#include "mozilla/gfx/Rect.h"
+#include "mozilla/WidgetUtils.h" // for ScreenRotation
+#include "mozilla/dom/ScreenOrientation.h" // for ScreenOrientation
+#include "mozilla/ipc/SharedMemory.h" // for SharedMemory, etc
+#include "mozilla/layers/CompositableForwarder.h"
+#include "mozilla/layers/TextureForwarder.h"
+#include "mozilla/layers/CompositorTypes.h" // for OpenMode, etc
+#include "mozilla/layers/CompositorBridgeChild.h"
+#include "nsCOMPtr.h" // for already_AddRefed
+#include "nsRegion.h" // for nsIntRegion
+#include "nsTArrayForwardDeclare.h" // for InfallibleTArray
+#include "nsIWidget.h"
+#include <vector>
+#include "nsExpirationTracker.h"
+
+namespace mozilla {
+namespace layers {
+
+class ClientLayerManager;
+class CompositorBridgeChild;
+class EditReply;
+class FixedSizeSmallShmemSectionAllocator;
+class ImageContainer;
+class Layer;
+class PLayerChild;
+class PLayerTransactionChild;
+class LayerTransactionChild;
+class ShadowableLayer;
+class SurfaceDescriptor;
+class TextureClient;
+class ThebesBuffer;
+class ThebesBufferData;
+class Transaction;
+
+/**
+ * See ActiveResourceTracker below.
+ */
+class ActiveResource
+{
+public:
+ virtual void NotifyInactive() = 0;
+ nsExpirationState* GetExpirationState() { return &mExpirationState; }
+ bool IsActivityTracked() { return mExpirationState.IsTracked(); }
+private:
+ nsExpirationState mExpirationState;
+};
+
+/**
+ * A convenience class on top of nsExpirationTracker
+ */
+class ActiveResourceTracker : public nsExpirationTracker<ActiveResource, 3>
+{
+public:
+ ActiveResourceTracker(uint32_t aExpirationCycle, const char* aName)
+ : nsExpirationTracker(aExpirationCycle, aName)
+ {}
+
+ virtual void NotifyExpired(ActiveResource* aResource) override
+ {
+ RemoveObject(aResource);
+ aResource->NotifyInactive();
+ }
+};
+
+/**
+ * We want to share layer trees across thread contexts and address
+ * spaces for several reasons; chief among them
+ *
+ * - a parent process can paint a child process's layer tree while
+ * the child process is blocked, say on content script. This is
+ * important on mobile devices where UI responsiveness is key.
+ *
+ * - a dedicated "compositor" process can asynchronously (wrt the
+ * browser process) composite and animate layer trees, allowing a
+ * form of pipeline parallelism between compositor/browser/content
+ *
+ * - a dedicated "compositor" process can take all responsibility for
+ * accessing the GPU, which is desirable on systems with
+ * buggy/leaky drivers because the compositor process can die while
+ * browser and content live on (and failover mechanisms can be
+ * installed to quickly bring up a replacement compositor)
+ *
+ * The Layers model has a crisply defined API, which makes it easy to
+ * safely "share" layer trees. The ShadowLayers API extends Layers to
+ * allow a remote, parent process to access a child process's layer
+ * tree.
+ *
+ * ShadowLayerForwarder publishes a child context's layer tree to a
+ * parent context. This comprises recording layer-tree modifications
+ * into atomic transactions and pushing them over IPC.
+ *
+ * LayerManagerComposite grafts layer subtrees published by child-context
+ * ShadowLayerForwarder(s) into a parent-context layer tree.
+ *
+ * (Advanced note: because our process tree may have a height >2, a
+ * non-leaf subprocess may both receive updates from child processes
+ * and publish them to parent processes. Put another way,
+ * LayerManagers may be both LayerManagerComposites and
+ * ShadowLayerForwarders.)
+ *
+ * There are only shadow types for layers that have different shadow
+ * vs. not-shadow behavior. ColorLayers and ContainerLayers behave
+ * the same way in both regimes (so far).
+ *
+ *
+ * The mecanism to shadow the layer tree on the compositor through IPC works as
+ * follows:
+ * The layer tree is managed on the content thread, and shadowed in the compositor
+ * thread. The shadow layer tree is only kept in sync with whatever happens in
+ * the content thread. To do this we use IPDL protocols. IPDL is a domain
+ * specific language that describes how two processes or thread should
+ * communicate. C++ code is generated from .ipdl files to implement the message
+ * passing, synchronization and serialization logic. To use the generated code
+ * we implement classes that inherit the generated IPDL actor. the ipdl actors
+ * of a protocol PX are PXChild or PXParent (the generated class), and we
+ * conventionally implement XChild and XParent. The Parent side of the protocol
+ * is the one that lives on the compositor thread. Think of IPDL actors as
+ * endpoints of communication. they are useful to send messages and also to
+ * dispatch the message to the right actor on the other side. One nice property
+ * of an IPDL actor is that when an actor, say PXChild is sent in a message, the
+ * PXParent comes out in the other side. we use this property a lot to dispatch
+ * messages to the right layers and compositable, each of which have their own
+ * ipdl actor on both side.
+ *
+ * Most of the synchronization logic happens in layer transactions and
+ * compositable transactions.
+ * A transaction is a set of changes to the layers and/or the compositables
+ * that are sent and applied together to the compositor thread to keep the
+ * LayerComposite in a coherent state.
+ * Layer transactions maintain the shape of the shadow layer tree, and
+ * synchronize the texture data held by compositables. Layer transactions
+ * are always between the content thread and the compositor thread.
+ * Compositable transactions are subset of a layer transaction with which only
+ * compositables and textures can be manipulated, and does not always originate
+ * from the content thread. (See CompositableForwarder.h and ImageBridgeChild.h)
+ */
+
+class ShadowLayerForwarder final : public LayersIPCActor
+ , public CompositableForwarder
+ , public LegacySurfaceDescriptorAllocator
+{
+ friend class ClientLayerManager;
+
+public:
+ NS_INLINE_DECL_THREADSAFE_REFCOUNTING(ShadowLayerForwarder, override);
+
+ /**
+ * Setup the IPDL actor for aCompositable to be part of layers
+ * transactions.
+ */
+ void Connect(CompositableClient* aCompositable,
+ ImageContainer* aImageContainer) override;
+
+ /**
+ * Adds an edit in the layers transaction in order to attach
+ * the corresponding compositable and layer on the compositor side.
+ * Connect must have been called on aCompositable beforehand.
+ */
+ void Attach(CompositableClient* aCompositable,
+ ShadowableLayer* aLayer);
+
+ /**
+ * Adds an edit in the transaction in order to attach a Compositable that
+ * is not managed by this ShadowLayerForwarder (for example, by ImageBridge
+ * in the case of async-video).
+ * Since the compositable is not managed by this forwarder, we can't use
+ * the compositable or it's IPDL actor here, so we use an ID instead, that
+ * is matched on the compositor side.
+ */
+ void AttachAsyncCompositable(uint64_t aCompositableID,
+ ShadowableLayer* aLayer);
+
+ /**
+ * Begin recording a transaction to be forwarded atomically to a
+ * LayerManagerComposite.
+ */
+ void BeginTransaction(const gfx::IntRect& aTargetBounds,
+ ScreenRotation aRotation,
+ mozilla::dom::ScreenOrientationInternal aOrientation);
+
+ /**
+ * The following methods may only be called after BeginTransaction()
+ * but before EndTransaction(). They mirror the LayerManager
+ * interface in Layers.h.
+ */
+
+ /**
+ * Notify the shadow manager that a new, "real" layer has been
+ * created, and a corresponding shadow layer should be created in
+ * the compositing process.
+ */
+ void CreatedPaintedLayer(ShadowableLayer* aThebes);
+ void CreatedContainerLayer(ShadowableLayer* aContainer);
+ void CreatedImageLayer(ShadowableLayer* aImage);
+ void CreatedColorLayer(ShadowableLayer* aColor);
+ void CreatedCanvasLayer(ShadowableLayer* aCanvas);
+ void CreatedRefLayer(ShadowableLayer* aRef);
+
+ /**
+ * At least one attribute of |aMutant| has changed, and |aMutant|
+ * needs to sync to its shadow layer. This initial implementation
+ * forwards all attributes when any is mutated.
+ */
+ void Mutated(ShadowableLayer* aMutant);
+
+ void SetRoot(ShadowableLayer* aRoot);
+ /**
+ * Insert |aChild| after |aAfter| in |aContainer|. |aAfter| can be
+ * nullptr to indicated that |aChild| should be appended to the end of
+ * |aContainer|'s child list.
+ */
+ void InsertAfter(ShadowableLayer* aContainer,
+ ShadowableLayer* aChild,
+ ShadowableLayer* aAfter = nullptr);
+ void RemoveChild(ShadowableLayer* aContainer,
+ ShadowableLayer* aChild);
+ void RepositionChild(ShadowableLayer* aContainer,
+ ShadowableLayer* aChild,
+ ShadowableLayer* aAfter = nullptr);
+
+ /**
+ * Set aMaskLayer as the mask on aLayer.
+ * Note that only image layers are properly supported
+ * LayerTransactionParent::UpdateMask and accompanying ipdl
+ * will need changing to update properties for other kinds
+ * of mask layer.
+ */
+ void SetMask(ShadowableLayer* aLayer,
+ ShadowableLayer* aMaskLayer);
+
+ /**
+ * See CompositableForwarder::UseTiledLayerBuffer
+ */
+ void UseTiledLayerBuffer(CompositableClient* aCompositable,
+ const SurfaceDescriptorTiles& aTileLayerDescriptor) override;
+
+ bool DestroyInTransaction(PTextureChild* aTexture, bool synchronously) override;
+ bool DestroyInTransaction(PCompositableChild* aCompositable, bool synchronously) override;
+
+ virtual void RemoveTextureFromCompositable(CompositableClient* aCompositable,
+ TextureClient* aTexture) override;
+
+ /**
+ * Communicate to the compositor that aRegion in the texture identified by aLayer
+ * and aIdentifier has been updated to aThebesBuffer.
+ */
+ virtual void UpdateTextureRegion(CompositableClient* aCompositable,
+ const ThebesBufferData& aThebesBufferData,
+ const nsIntRegion& aUpdatedRegion) override;
+
+ /**
+ * See CompositableForwarder::UseTextures
+ */
+ virtual void UseTextures(CompositableClient* aCompositable,
+ const nsTArray<TimedTextureClient>& aTextures) override;
+ virtual void UseComponentAlphaTextures(CompositableClient* aCompositable,
+ TextureClient* aClientOnBlack,
+ TextureClient* aClientOnWhite) override;
+
+ /**
+ * Used for debugging to tell the compositor how long this frame took to paint.
+ */
+ void SendPaintTime(uint64_t aId, TimeDuration aPaintTime);
+
+ /**
+ * End the current transaction and forward it to LayerManagerComposite.
+ * |aReplies| are directions from the LayerManagerComposite to the
+ * caller of EndTransaction().
+ */
+ bool EndTransaction(InfallibleTArray<EditReply>* aReplies,
+ const nsIntRegion& aRegionToClear,
+ uint64_t aId,
+ bool aScheduleComposite,
+ uint32_t aPaintSequenceNumber,
+ bool aIsRepeatTransaction,
+ const mozilla::TimeStamp& aTransactionStart,
+ bool* aSent);
+
+ /**
+ * Set an actor through which layer updates will be pushed.
+ */
+ void SetShadowManager(PLayerTransactionChild* aShadowManager);
+
+ /**
+ * Layout calls here to cache current plugin widget configuration
+ * data. We ship this across with the rest of the layer updates when
+ * we update. Chrome handles applying these changes.
+ */
+ void StorePluginWidgetConfigurations(const nsTArray<nsIWidget::Configuration>&
+ aConfigurations);
+
+ void StopReceiveAsyncParentMessge();
+
+ void ClearCachedResources();
+
+ void Composite();
+
+ /**
+ * True if this is forwarding to a LayerManagerComposite.
+ */
+ bool HasShadowManager() const { return !!mShadowManager; }
+ LayerTransactionChild* GetShadowManager() const { return mShadowManager.get(); }
+
+ virtual void WindowOverlayChanged() { mWindowOverlayChanged = true; }
+
+ /**
+ * The following Alloc/Open/Destroy interfaces abstract over the
+ * details of working with surfaces that are shared across
+ * processes. They provide the glue between C++ Layers and the
+ * LayerComposite IPC system.
+ *
+ * The basic lifecycle is
+ *
+ * - a Layer needs a buffer. Its ShadowableLayer subclass calls
+ * AllocBuffer(), then calls one of the Created*Buffer() methods
+ * above to transfer the (temporary) front buffer to its
+ * LayerComposite in the other process. The Layer needs a
+ * gfxASurface to paint, so the ShadowableLayer uses
+ * OpenDescriptor(backBuffer) to get that surface, and hands it
+ * out to the Layer.
+ *
+ * - a Layer has painted new pixels. Its ShadowableLayer calls one
+ * of the Painted*Buffer() methods above with the back buffer
+ * descriptor. This notification is forwarded to the LayerComposite,
+ * which uses OpenDescriptor() to access the newly-painted pixels.
+ * The LayerComposite then updates its front buffer in a Layer- and
+ * platform-dependent way, and sends a surface descriptor back to
+ * the ShadowableLayer that becomes its new back back buffer.
+ *
+ * - a Layer wants to destroy its buffers. Its ShadowableLayer
+ * calls Destroyed*Buffer(), which gives up control of the back
+ * buffer descriptor. The actual back buffer surface is then
+ * destroyed using DestroySharedSurface() just before notifying
+ * the parent process. When the parent process is notified, the
+ * LayerComposite also calls DestroySharedSurface() on its front
+ * buffer, and the double-buffer pair is gone.
+ */
+
+ virtual bool IPCOpen() const override;
+
+ /**
+ * Construct a shadow of |aLayer| on the "other side", at the
+ * LayerManagerComposite.
+ */
+ PLayerChild* ConstructShadowFor(ShadowableLayer* aLayer);
+
+ /**
+ * Flag the next paint as the first for a document.
+ */
+ void SetIsFirstPaint() { mIsFirstPaint = true; }
+
+ void SetPaintSyncId(int32_t aSyncId) { mPaintSyncId = aSyncId; }
+
+ void SetLayerObserverEpoch(uint64_t aLayerObserverEpoch);
+
+ static void PlatformSyncBeforeUpdate();
+
+ virtual bool AllocSurfaceDescriptor(const gfx::IntSize& aSize,
+ gfxContentType aContent,
+ SurfaceDescriptor* aBuffer) override;
+
+ virtual bool AllocSurfaceDescriptorWithCaps(const gfx::IntSize& aSize,
+ gfxContentType aContent,
+ uint32_t aCaps,
+ SurfaceDescriptor* aBuffer) override;
+
+ virtual void DestroySurfaceDescriptor(SurfaceDescriptor* aSurface) override;
+
+ virtual void UpdateFwdTransactionId() override;
+ virtual uint64_t GetFwdTransactionId() override;
+
+ bool InForwarderThread() override {
+ return NS_IsMainThread();
+ }
+
+ // Returns true if aSurface wraps a Shmem.
+ static bool IsShmem(SurfaceDescriptor* aSurface);
+
+ TextureForwarder* GetTextureForwarder() override { return GetCompositorBridgeChild(); }
+ LayersIPCActor* GetLayersIPCActor() override { return this; }
+
+ ActiveResourceTracker& GetActiveResourceTracker() { return *mActiveResourceTracker.get(); }
+protected:
+ virtual ~ShadowLayerForwarder();
+
+ explicit ShadowLayerForwarder(ClientLayerManager* aClientLayerManager);
+
+#ifdef DEBUG
+ void CheckSurfaceDescriptor(const SurfaceDescriptor* aDescriptor) const;
+#else
+ void CheckSurfaceDescriptor(const SurfaceDescriptor* aDescriptor) const {}
+#endif
+
+ bool InWorkerThread();
+
+ CompositorBridgeChild* GetCompositorBridgeChild();
+
+ RefPtr<LayerTransactionChild> mShadowManager;
+ RefPtr<CompositorBridgeChild> mCompositorBridgeChild;
+
+private:
+
+ ClientLayerManager* mClientLayerManager;
+ Transaction* mTxn;
+ MessageLoop* mMessageLoop;
+ DiagnosticTypes mDiagnosticTypes;
+ bool mIsFirstPaint;
+ bool mWindowOverlayChanged;
+ int32_t mPaintSyncId;
+ InfallibleTArray<PluginWindowData> mPluginWindowData;
+ UniquePtr<ActiveResourceTracker> mActiveResourceTracker;
+};
+
+class CompositableClient;
+
+/**
+ * A ShadowableLayer is a Layer can be shared with a parent context
+ * through a ShadowLayerForwarder. A ShadowableLayer maps to a
+ * Shadow*Layer in a parent context.
+ *
+ * Note that ShadowLayers can themselves be ShadowableLayers.
+ */
+class ShadowableLayer
+{
+public:
+ virtual ~ShadowableLayer() {}
+
+ virtual Layer* AsLayer() = 0;
+
+ /**
+ * True if this layer has a shadow in a parent process.
+ */
+ bool HasShadow() { return !!mShadow; }
+
+ /**
+ * Return the IPC handle to a Shadow*Layer referring to this if one
+ * exists, nullptr if not.
+ */
+ PLayerChild* GetShadow() { return mShadow; }
+
+ virtual CompositableClient* GetCompositableClient() { return nullptr; }
+protected:
+ ShadowableLayer() : mShadow(nullptr) {}
+
+ PLayerChild* mShadow;
+};
+
+} // namespace layers
+} // namespace mozilla
+
+#endif // ifndef mozilla_layers_ShadowLayers_h