cc: Enforce correct recycling in resource pool.

cc/resource_provider.h

 // Copyright 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CC_RESOURCE_PROVIDER_H_
 #define CC_RESOURCE_PROVIDER_H_
 
 #include <deque>
 #include <string>
 #include <vector>
@@ skipping 203 matching lines @@
 
     private:
         ResourceProvider* m_resourceProvider;
         ResourceProvider::ResourceId m_resourceId;
         SkBitmap m_skBitmap;
         scoped_ptr<SkCanvas> m_skCanvas;
 
         DISALLOW_COPY_AND_ASSIGN(ScopedWriteLockSoftware);
     };
 
+    class Fence : public base::RefCounted<Fence> {
+    public:
+        virtual bool hasPassed() = 0;
+    protected:
+        friend class base::RefCounted<Fence>;
+        virtual ~Fence() {}
+    };
+
     // Acquire pixel buffer for resource. The pixel buffer can be used to
     // set resource pixels without performing unnecessary copying.
     void acquirePixelBuffer(ResourceId id);
     void releasePixelBuffer(ResourceId id);
 
     // Map/unmap the acquired pixel buffer.
     uint8_t* mapPixelBuffer(ResourceId id);
     void unmapPixelBuffer(ResourceId id);
 
     // Update pixels from acquired pixel buffer.
     void setPixelsFromBuffer(ResourceId id);
 
     // Asynchronously update pixels from acquired pixel buffer.
     void beginSetPixels(ResourceId id);
     bool didSetPixelsComplete(ResourceId id);
 
     // For tests only! This prevents detecting uninitialized reads.
     // Use setPixels or lockForWrite to allocate implicitly.
     void allocateForTesting(ResourceId id);
 
+    // Sets the current read fence. If a resource is locked for read
+    // and has read fences enabled, the resource will not allow writes
+    // until this fence has passed.
+    void setReadLockFence(scoped_refptr<Fence> fence) { m_currentReadLockFence = fence; }
+    Fence* getReadLockFence() { return m_currentReadLockFence; }
+
+    // Enable read lock fences for a specific resource.
+    void enableReadLockFences(ResourceProvider::ResourceId, bool enable);
+
+    // Indicates if we can currently lock this resource for write.
+    bool canLockForWrite(ResourceId);
+
 private:
     struct Resource {
         Resource();
         ~Resource();
         Resource(unsigned textureId, const gfx::Size& size, GLenum format, GLenum filter);
         Resource(uint8_t* pixels, const gfx::Size& size, GLenum format, GLenum filter);
 
         unsigned glId;
         // Pixel buffer used for set pixels without unnecessary copying.
         unsigned glPixelBufferId;
         // Query used to determine when asynchronous set pixels complete.
         unsigned glUploadQueryId;
         TextureMailbox mailbox;
         uint8_t* pixels;
         uint8_t* pixelBuffer;
         int lockForReadCount;
         bool lockedForWrite;
         bool external;
         bool exported;
         bool markedForDeletion;
         bool pendingSetPixels;
         bool allocated;
+        bool enableReadLockFences;
+        scoped_refptr<Fence> readLockFence;
         gfx::Size size;
         GLenum format;
         // TODO(skyostil): Use a separate sampler object for filter state.
         GLenum filter;
         ResourceType type;
     };
     typedef base::hash_map<ResourceId, Resource> ResourceMap;
     struct Child {
         Child();
         ~Child();
 
         ResourceIdMap childToParentMap;
         ResourceIdMap parentToChildMap;
     };
     typedef base::hash_map<int, Child> ChildMap;
 
+    bool readLockFenceHasPassed(Resource* resource) { return !resource->readLockFence ||
+                                                              resource->readLockFence->hasPassed(); }
+
     explicit ResourceProvider(OutputSurface*);
     bool initialize();
 
     const Resource* lockForRead(ResourceId);
     void unlockForRead(ResourceId);
     const Resource* lockForWrite(ResourceId);
     void unlockForWrite(ResourceId);
     static void populateSkBitmapWithResource(SkBitmap*, const Resource*);
 
     bool transferResource(WebKit::WebGraphicsContext3D*, ResourceId, TransferableResource*);
@@ skipping 10 matching lines @@
     bool m_useTextureStorageExt;
     bool m_useTextureUsageHint;
     bool m_useShallowFlush;
     scoped_ptr<TextureUploader> m_textureUploader;
     scoped_ptr<AcceleratedTextureCopier> m_textureCopier;
     int m_maxTextureSize;
     GLenum m_bestTextureFormat;
 
     base::ThreadChecker m_threadChecker;
 
+    scoped_refptr<Fence> m_currentReadLockFence;
+
     DISALLOW_COPY_AND_ASSIGN(ResourceProvider);
 };
 
 }
 
 #endif  // CC_RESOURCE_PROVIDER_H_