Rework FlushSync to return early if commands have been processed since the last update

ppapi/c/dev/ppb_context_3d_trusted_dev.h

 // Copyright (c) 2011 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 PPAPI_C_DEV_PPB_CONTEXT_3D_TRUSTED_DEV_H_
 #define PPAPI_C_DEV_PPB_CONTEXT_3D_TRUSTED_DEV_H_
 
 #include "ppapi/c/dev/ppb_context_3d_dev.h"
 #include "ppapi/c/pp_bool.h"
 #include "ppapi/c/pp_instance.h"
 #include "ppapi/c/pp_resource.h"
 #include "ppapi/c/pp_stdint.h"
 
-#define PPB_CONTEXT_3D_TRUSTED_DEV_INTERFACE_0_3 "PPB_Context3DTrusted(Dev);0.3"
+#define PPB_CONTEXT_3D_TRUSTED_DEV_INTERFACE_0_4 "PPB_Context3DTrusted(Dev);0.4"
 #define PPB_CONTEXT_3D_TRUSTED_DEV_INTERFACE \
-    PPB_CONTEXT_3D_TRUSTED_DEV_INTERFACE_0_3
+    PPB_CONTEXT_3D_TRUSTED_DEV_INTERFACE_0_4
 
 typedef enum {
   kNoError,
   kInvalidSize,
   kOutOfBounds,
   kUnknownCommand,
   kInvalidArguments,
   kLostContext,
   kGenericError
 } PPB_Context3DTrustedError;
@@ skipping 10 matching lines @@
 
   // The current token value. This is used by the writer to defer
   // changes to shared memory objects until the reader has reached a certain
   // point in the command buffer. The reader is responsible for updating the
   // token value, for example in response to an asynchronous set token command
   // embedded in the command buffer. The default token value is zero.
   int32_t token;
 
   // Error status.
   PPB_Context3DTrustedError error;
+
+  // Generation index of this state. The generation index is incremented every
+  // time a new state is retrieved from the command processor, so that
+  // consistency can be kept even if IPC messages are processed out-of-order.
+  uint32_t generation;
 };
 
 struct PPB_Context3DTrusted_Dev {
   // Creates a raw Context3D resource. A raw Context3D is intended to be used
   // with the trusted interface, through the command buffer (for proxying). In
   // particular, when a Surface3D is bound to a raw context, SwapBuffers has no
   // effect.
   PP_Resource (*CreateRaw)(PP_Instance instance_id,
                            PP_Config3D_Dev config,
                            PP_Resource share_context,
@@ skipping 25 matching lines @@
   int32_t (*CreateTransferBuffer)(PP_Resource context, uint32_t size);
 
   // Destroy a transfer buffer and recycle the handle.
   PP_Bool (*DestroyTransferBuffer)(PP_Resource context, int32_t id);
 
   // Get the transfer buffer associated with a handle.
   PP_Bool (*GetTransferBuffer)(PP_Resource context,
                                int32_t id,
                                int* shm_handle,
                                uint32_t* shm_size);
+
+  // Like FlushSync, but returns before processing commands if the get offset is
+  // different than last_known_get. Allows synchronization with the command
+  // processor without forcing immediate command execution.
+  struct PP_Context3DTrustedState (*FlushSyncFast)(PP_Resource context,
+                                                   int32_t put_offset,
+                                                   int32_t last_known_get);
 };
 
 #endif  // PPAPI_C_DEV_PPB_CONTEXT_3D_TRUSTED_DEV_H_