The Tor Browser: gfx/layers/ipc/ShadowLayers.h@97036ab72558 (annotated)

gfx/layers/ipc/ShadowLayers.h@97036ab72558 (annotated)

gfx/layers/ipc/ShadowLayers.h

Tue, 06 Jan 2015 21:39:09 +0100

author: Michael Schloh von Bennewitz <michael@schloh.com>
date: Tue, 06 Jan 2015 21:39:09 +0100
branch: TOR_BUG_9701
changeset 8: 97036ab72558
permissions: -rw-r--r--

Conditionally force memory storage according to privacy.thirdparty.isolate;
This solves Tor bug #9701, complying with disk avoidance documented in
https://www.torproject.org/projects/torbrowser/design/#disk-avoidance.

 /* -*- 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 MOZ_OVERRIDE
 #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/CompositorTypes.h"  // for OpenMode, etc
 #include "nsCOMPtr.h"                   // for already_AddRefed
 #include "nsRegion.h"                   // for nsIntRegion
 #include "nsTArrayForwardDeclare.h"     // for InfallibleTArray
 struct nsIntPoint;
 struct nsIntRect;
 namespace mozilla {
 namespace layers {
 class ClientTiledLayerBuffer;
 class CanvasClient;
 class CanvasLayerComposite;
 class CanvasSurface;
 class ColorLayerComposite;
 class CompositableChild;
 class ContainerLayerComposite;
 class ContentClient;
 class ContentClientRemote;
 class EditReply;
 class ImageClient;
 class ImageLayerComposite;
 class Layer;
 class OptionalThebesBuffer;
 class PLayerChild;
 class PLayerTransactionChild;
 class PLayerTransactionParent;
 class LayerTransactionChild;
 class RefLayerComposite;
 class ShadowableLayer;
 class ShmemTextureClient;
 class SurfaceDescriptor;
 class TextureClient;
 class ThebesLayerComposite;
 class ThebesBuffer;
 class ThebesBufferData;
 class TiledLayerComposer;
 class Transaction;
 /**
  * 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 : public CompositableForwarder
 {
   friend class ContentClientIncremental;
   friend class ClientLayerManager;
 public:
   virtual ~ShadowLayerForwarder();
   /**
    * Setup the IPDL actor for aCompositable to be part of layers
    * transactions.
    */
   void Connect(CompositableClient* aCompositable);
   virtual PTextureChild* CreateTexture(const SurfaceDescriptor& aSharedData,
                                        TextureFlags aFlags) MOZ_OVERRIDE;
   virtual void CreatedIncrementalBuffer(CompositableClient* aCompositable,
                                         const TextureInfo& aTextureInfo,
                                         const nsIntRect& aBufferRect) MOZ_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 nsIntRect& aTargetBounds,
                         ScreenRotation aRotation,
                         const nsIntRect& aClientBounds,
                         mozilla::dom::ScreenOrientation 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 CreatedThebesLayer(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
    */
   virtual void UseTiledLayerBuffer(CompositableClient* aCompositable,
                                    const SurfaceDescriptorTiles& aTileLayerDescriptor) MOZ_OVERRIDE;
   /**
    * Notify the compositor that a compositable will be updated asynchronously
    * through ImageBridge, using an ID to connect the protocols on the
    * compositor side.
    */
   void AttachAsyncCompositable(PLayerTransactionChild* aLayer, uint64_t aID);
   virtual void RemoveTextureFromCompositable(CompositableClient* aCompositable,
                                              TextureClient* aTexture) MOZ_OVERRIDE;
   virtual void RemoveTexture(TextureClient* aTexture) MOZ_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) MOZ_OVERRIDE;
   virtual void UpdateTextureIncremental(CompositableClient* aCompositable,
                                         TextureIdentifier aTextureId,
                                         SurfaceDescriptor& aDescriptor,
                                         const nsIntRegion& aUpdatedRegion,
                                         const nsIntRect& aBufferRect,
                                         const nsIntPoint& aBufferRotation) MOZ_OVERRIDE;
   /**
    * Communicate the picture rect of an image to the compositor
    */
   void UpdatePictureRect(CompositableClient* aCompositable,
                          const nsIntRect& aRect);
   /**
    * See CompositableForwarder::UpdatedTexture
    */
   virtual void UpdatedTexture(CompositableClient* aCompositable,
                               TextureClient* aTexture,
                               nsIntRegion* aRegion) MOZ_OVERRIDE;
   /**
    * See CompositableForwarder::UseTexture
    */
   virtual void UseTexture(CompositableClient* aCompositable,
                           TextureClient* aClient) MOZ_OVERRIDE;
   virtual void UseComponentAlphaTextures(CompositableClient* aCompositable,
                                          TextureClient* aClientOnBlack,
                                          TextureClient* aClientOnWhite) MOZ_OVERRIDE;
   /**
    * 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,
                       bool aScheduleComposite,
                       bool* aSent);
   /**
    * Set an actor through which layer updates will be pushed.
    */
   void SetShadowManager(PLayerTransactionChild* aShadowManager);
   /**
    * 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.
    */
   // ISurfaceAllocator
   virtual bool AllocUnsafeShmem(size_t aSize,
                                 mozilla::ipc::SharedMemory::SharedMemoryType aType,
                                 mozilla::ipc::Shmem* aShmem) MOZ_OVERRIDE;
   virtual bool AllocShmem(size_t aSize,
                           mozilla::ipc::SharedMemory::SharedMemoryType aType,
                           mozilla::ipc::Shmem* aShmem) MOZ_OVERRIDE;
   virtual void DeallocShmem(mozilla::ipc::Shmem& aShmem) MOZ_OVERRIDE;
   virtual bool IPCOpen() const MOZ_OVERRIDE;
   virtual bool IsSameProcess() const MOZ_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; }
   static void PlatformSyncBeforeUpdate();
 protected:
   ShadowLayerForwarder();
 #ifdef DEBUG
   void CheckSurfaceDescriptor(const SurfaceDescriptor* aDescriptor) const;
 #else
   void CheckSurfaceDescriptor(const SurfaceDescriptor* aDescriptor) const {}
 #endif
   RefPtr<LayerTransactionChild> mShadowManager;
 #ifdef MOZ_HAVE_SURFACEDESCRIPTORGRALLOC
   // from ISurfaceAllocator
   virtual PGrallocBufferChild* AllocGrallocBuffer(const gfx::IntSize& aSize,
                                                   uint32_t aFormat,
                                                   uint32_t aUsage,
                                                   MaybeMagicGrallocBufferHandle* aHandle) MOZ_OVERRIDE;
   virtual void DeallocGrallocBuffer(PGrallocBufferChild* aChild) MOZ_OVERRIDE;
 #endif
 private:
   Transaction* mTxn;
   DiagnosticTypes mDiagnosticTypes;
   bool mIsFirstPaint;
   bool mWindowOverlayChanged;
 };
 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

The Tor Browser / annotate

gfx/layers/ipc/ShadowLayers.h@97036ab72558 (annotated)

gfx/layers/ipc/ShadowLayers.h