Plumbing explicit share groups through context creation

content/common/gpu/client/webgraphicscontext3d_command_buffer_impl.h

 // Copyright (c) 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 CONTENT_COMMON_GPU_CLIENT_WEBGRAPHICSCONTEXT3D_COMMAND_BUFFER_IMPL_H_
 #define CONTENT_COMMON_GPU_CLIENT_WEBGRAPHICSCONTEXT3D_COMMAND_BUFFER_IMPL_H_
 
 #include <string>
 #include <vector>
 
 #include "base/callback.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/memory/weak_ptr.h"
+#include "base/synchronization/lock.h"
 #include "content/common/content_export.h"
 #include "content/common/gpu/client/command_buffer_proxy_impl.h"
 #include "third_party/WebKit/public/platform/WebGraphicsContext3D.h"
 #include "third_party/WebKit/public/platform/WebString.h"
 #include "ui/gfx/native_widget_types.h"
 #include "ui/gl/gpu_preference.h"
 #include "url/gurl.h"
 
 namespace gpu {
 
@@ skipping 48 matching lines @@
     size_t max_transfer_buffer_size;
     size_t mapped_memory_reclaim_limit;
   };
 
   WebGraphicsContext3DCommandBufferImpl(
       int surface_id,
       const GURL& active_url,
       GpuChannelHost* host,
       const Attributes& attributes,
       bool bind_generates_resources,
-      const SharedMemoryLimits& limits);
+      const SharedMemoryLimits& limits,
+      WebGraphicsContext3DCommandBufferImpl* share_context);
 
   virtual ~WebGraphicsContext3DCommandBufferImpl();
 
   // The following 3 IDs let one uniquely identify this context.
   // Gets the GPU process ID for this context.
   int GetGPUProcessID();
 
   CommandBufferProxyImpl* GetCommandBufferProxy() {
     return command_buffer_.get();
   }
 
   CONTENT_EXPORT gpu::ContextSupport* GetContextSupport();
 
   gpu::gles2::GLES2Implementation* GetImplementation() {
     return real_gl_.get();
   }
 
   // Return true if GPU process reported context lost or there was a
   // problem communicating with the GPU process.
   bool IsCommandBufferContextLost();
 
   // Create & initialize a WebGraphicsContext3DCommandBufferImpl.  Return NULL
   // on any failure.
   static CONTENT_EXPORT WebGraphicsContext3DCommandBufferImpl*
       CreateOffscreenContext(
           GpuChannelHost* host,
           const WebGraphicsContext3D::Attributes& attributes,
           const GURL& active_url,
-          const SharedMemoryLimits& limits);
+          const SharedMemoryLimits& limits,
+          WebGraphicsContext3D* share_context);
 
   size_t GetMappedMemoryLimit() {
     return mem_limits_.mapped_memory_reclaim_limit;
   }
 
   //----------------------------------------------------------------------
   // WebGraphicsContext3D methods
 
   // Must be called after initialize() and before any of the following methods.
   // Permanently binds to the first calling thread. Returns false if the
@@ skipping 529 matching lines @@
     SAMPLE_BUFFERS            = 0x3032,
     HEIGHT                    = 0x3056,
     WIDTH                     = 0x3057,
     NONE                      = 0x3038,  // Attrib list = terminator
     SHARE_RESOURCES           = 0x10000,
     BIND_GENERATES_RESOURCES  = 0x10001,
     FAIL_IF_MAJOR_PERF_CAVEAT = 0x10002
   };
   friend class WebGraphicsContext3DErrorMessageCallback;
 
+  class ShareGroup : public base::RefCountedThreadSafe<ShareGroup> {
+   public:
+    ShareGroup();
+
+    WebGraphicsContext3DCommandBufferImpl* GetAnyContext() {

[piman, 2013/12/12 23:56:39]

nit: maybe append "Locked" to these functions to make it explicit that the lock
is expected to be held. It's not obvious at the call site that AddContext and
RemoveContext are different in that respect.

+      // In order to ensure that the context returned is not removed while
+      // in use the share group's lock should be aquired before calling this
+      // function.
+      lock_.AssertAcquired();
+      if (contexts_.empty())
+        return NULL;
+      return contexts_.front();
+    }
+
+    void AddContext(WebGraphicsContext3DCommandBufferImpl* context) {
+      lock_.AssertAcquired();
+      contexts_.push_back(context);
+    }
+
+    void RemoveContext(WebGraphicsContext3DCommandBufferImpl* context) {
+      base::AutoLock auto_lock(lock_);
+      contexts_.erase(std::remove(contexts_.begin(), contexts_.end(), context),
+          contexts_.end());
+    }
+
+    void RemoveAllContexts() {
+      base::AutoLock auto_lock(lock_);
+      contexts_.clear();
+    }
+
+    base::Lock& lock() {
+      return lock_;
+    }
+
+   private:
+    friend class base::RefCountedThreadSafe<ShareGroup>;
+    ~ShareGroup();
+
+    std::vector<WebGraphicsContext3DCommandBufferImpl*> contexts_;
+    base::Lock lock_;
+
+    DISALLOW_COPY_AND_ASSIGN(ShareGroup);
+  };
+
   // Initialize the underlying GL context. May be called multiple times; second
   // and subsequent calls are ignored. Must be called from the thread that is
   // going to use this object to issue GL commands (which might not be the main
   // thread).
   bool MaybeInitializeGL();
 
-  bool InitializeCommandBuffer(bool onscreen);
+  bool InitializeCommandBuffer(bool onscreen,
+      WebGraphicsContext3DCommandBufferImpl* share_context);
 
   void Destroy();
 
   // Create a CommandBufferProxy that renders directly to a view. The view and
   // the associated window must not be destroyed until the returned
   // CommandBufferProxy has been destroyed, otherwise the GPU process might
   // attempt to render to an invalid window handle.
   //
   // NOTE: on Mac OS X, this entry point is only used to set up the
   // accelerated compositor's output. On this platform, we actually pass
@@ skipping 38 matching lines @@
   scoped_ptr<gpu::gles2::GLES2CmdHelper> gles2_helper_;
   scoped_ptr<gpu::TransferBuffer> transfer_buffer_;
   gpu::gles2::GLES2Interface* gl_;
   scoped_ptr<gpu::gles2::GLES2Implementation> real_gl_;
   scoped_ptr<gpu::gles2::GLES2Interface> trace_gl_;
   Error last_error_;
   bool bind_generates_resources_;
   SharedMemoryLimits mem_limits_;
 
   uint32_t flush_id_;
+  scoped_refptr<ShareGroup> share_group_;
 };
 
 }  // namespace content
 
 #endif  // CONTENT_COMMON_GPU_CLIENT_WEBGRAPHICSCONTEXT3D_COMMAND_BUFFER_IMPL_H_