gpu: Change Produce/ConsumeTexture to allow texture sharing

gpu/command_buffer/service/mailbox_manager.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 GPU_COMMAND_BUFFER_SERVICE_MAILBOX_MANAGER_H_
 #define GPU_COMMAND_BUFFER_SERVICE_MAILBOX_MANAGER_H_
 
 #include <functional>
 #include <map>
 
 #include "base/memory/linked_ptr.h"
 #include "base/memory/ref_counted.h"
 #include "crypto/hmac.h"
 #include "gpu/command_buffer/common/constants.h"
 #include "gpu/gpu_export.h"
 
 // From gl2/gl2ext.h.
 #ifndef GL_MAILBOX_SIZE_CHROMIUM
 #define GL_MAILBOX_SIZE_CHROMIUM 64
 #endif
 
 typedef signed char GLbyte;
 
 namespace gpu {
 namespace gles2 {
 
-class TextureDefinition;
+class Texture;
 class TextureManager;
 
 // Identifies a mailbox where a texture definition can be stored for
 // transferring textures between contexts that are not in the same context
 // group. It is a random key signed with a hash of a private key.
 struct GPU_EXPORT MailboxName {
   MailboxName();
   GLbyte key[GL_MAILBOX_SIZE_CHROMIUM / 2];
   GLbyte signature[GL_MAILBOX_SIZE_CHROMIUM / 2];
 };
 
 // Manages resources scoped beyond the context or context group level.
 class GPU_EXPORT MailboxManager : public base::RefCounted<MailboxManager> {
  public:
   MailboxManager();
 
   // Generate a unique mailbox name signed with the manager's private key.
   void GenerateMailboxName(MailboxName* name);
 
-  // Remove the texture definition from the named mailbox and empty the mailbox.
-  TextureDefinition* ConsumeTexture(unsigned target, const MailboxName& name);
+  // Look up the texture definition from the named mailbox.
+  Texture* ConsumeTexture(unsigned target, const MailboxName& name);
 
-  // Put the texture definition in the named mailbox.
+  // Put the texture into the named mailbox.
   bool ProduceTexture(unsigned target,
                       const MailboxName& name,
-                      TextureDefinition* definition,
-                      TextureManager* owner);
+                      Texture* texture);
 
-  // Destroy any texture definitions and mailboxes owned by the given texture
-  // manager.
-  void DestroyOwnedTextures(TextureManager* owner, bool have_context);
+  // Destroy any mailbox that reference the given texture.
+  void TextureDeleted(Texture* texture);
 
   std::string private_key() {
     return std::string(private_key_, sizeof(private_key_));
   }
 
  private:
   friend class base::RefCounted<MailboxManager>;
 
   ~MailboxManager();
 
   void SignMailboxName(MailboxName* name);
   bool IsMailboxNameValid(const MailboxName& name);
 
   struct TargetName {
     TargetName(unsigned target, const MailboxName& name);
     unsigned target;
     MailboxName name;
   };
 
   static bool TargetNameLess(const TargetName& lhs, const TargetName& rhs);
 
-  struct OwnedTextureDefinition {
-    OwnedTextureDefinition(TextureDefinition* definition,
-                           TextureManager* owner);
-    ~OwnedTextureDefinition();
-    linked_ptr<TextureDefinition> definition;
-    TextureManager* owner;
-  };
-
+  // This is a bidirectional map between mailbox and textures. We can have
+  // multiple mailboxes per texture, but one texture per mailbox. We keep an
+  // iterator in the MailboxToTextureMap to be able to manage changes to
+  // the TextureToMailboxMap efficiently.
+  typedef std::multimap<Texture*, TargetName> TextureToMailboxMap;
   typedef std::map<
       TargetName,
-      OwnedTextureDefinition,
+      TextureToMailboxMap::iterator,
       std::pointer_to_binary_function<
-          const TargetName&, const TargetName&, bool> > TextureDefinitionMap;
+          const TargetName&, const TargetName&, bool> > MailboxToTextureMap;
 
   char private_key_[GL_MAILBOX_SIZE_CHROMIUM / 2];
   crypto::HMAC hmac_;
-  TextureDefinitionMap textures_;
+  MailboxToTextureMap mailbox_to_textures_;
+  TextureToMailboxMap textures_to_mailboxes_;
 
   DISALLOW_COPY_AND_ASSIGN(MailboxManager);
 };
 }  // namespage gles2
 }  // namespace gpu
 
 #endif  // GPU_COMMAND_BUFFER_SERVICE_MAILBOX_MANAGER_H_