Allow textures to be moved from one GL context group to another.

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"
+
+#ifndef GL_MAILBOX_SIZE_CHROMIUM
+#define GL_MAILBOX_SIZE_CHROMIUM 64

[apatrick_chromium, 2012/04/27 22:31:58]

Including GL header files in a header file causes trouble because there are
several different GL headers and they conflict: mesa's, ANGLE's, our GLES2
headers and gl_utils.h. So there is some redundancy for GL_MAINBOX_SIZE_CHROMIUM
and GLbyte.

[Ken Russell (switch to Gerrit), 2012/04/28 00:27:40]

OK. Consider adding comments to point to the files that need to be kept in sync.

+#endif
+
+typedef signed char GLbyte;
+
+namespace gpu {
+namespace gles2 {
+
+class TextureDefinition;
+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 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);
+
+  // Put the texture definition in the named mailbox.
+  bool ProduceTexture(unsigned target,
+                      const MailboxName& name,
+                      TextureDefinition* definition,
+                      TextureManager* owner);
+
+  // Destroy any texture definitions and mailboxes owned by the given texture
+  // manager.
+  void DestroyOwnedTextures(TextureManager* owner, bool have_context);
+
+ 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(TargetName lhs, TargetName rhs);
+
+  struct OwnedTextureDefinition {
+    OwnedTextureDefinition(TextureDefinition* definition,
+                           TextureManager* owner);
+    ~OwnedTextureDefinition();
+    linked_ptr<TextureDefinition> definition;
+    TextureManager* owner;
+  };
+
+  typedef std::map<
+      TargetName,
+      OwnedTextureDefinition,
+      std::pointer_to_binary_function<TargetName, TargetName, bool> >
+          TextureDefinitionMap;
+
+  crypto::HMAC hmac_;
+  TextureDefinitionMap textures_;
+
+  DISALLOW_COPY_AND_ASSIGN(MailboxManager);
+};
+}  // namespage gles2
+}  // namespace gpu
+
+#endif  // GPU_COMMAND_BUFFER_SERVICE_MAILBOX_MANAGER_H_
+
+