gpu: Reuse transfer buffers more aggresively

gpu/command_buffer/common/gles2_cmd_format.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.
 
 // This file defines the GLES2 command buffer commands.
 
 #ifndef GPU_COMMAND_BUFFER_COMMON_GLES2_CMD_FORMAT_H_
 #define GPU_COMMAND_BUFFER_COMMON_GLES2_CMD_FORMAT_H_
 
 
@@ skipping 134 matching lines @@
 struct QuerySync {
   void Reset() {
     process_count = 0;
     result = 0;
   }
 
   base::subtle::Atomic32 process_count;
   uint64 result;
 };
 
+struct AsyncUploadSync {
+  void Reset() {
+    base::subtle::Release_Store(&async_upload_token, 0);
+  }
+
+  void SetAsyncUploadToken(uint32 token) {
+    DCHECK_NE(token, 0u);
+    base::subtle::Release_Store(&async_upload_token, token);
+  }
+
+  bool HasAsyncUploadTokenPassed(uint32 token) {
+    DCHECK_NE(token, 0u);
+    uint32_t current_token = base::subtle::Acquire_Load(&async_upload_token);
+    return (current_token - token < 0x80000000);
+  }
+
+  base::subtle::Atomic32 async_upload_token;
+};
+
 COMPILE_ASSERT(sizeof(ProgramInput) == 20, ProgramInput_size_not_20);
 COMPILE_ASSERT(offsetof(ProgramInput, type) == 0,
                OffsetOf_ProgramInput_type_not_0);
 COMPILE_ASSERT(offsetof(ProgramInput, size) == 4,
                OffsetOf_ProgramInput_size_not_4);
 COMPILE_ASSERT(offsetof(ProgramInput, location_offset) == 8,
                OffsetOf_ProgramInput_location_offset_not_8);
 COMPILE_ASSERT(offsetof(ProgramInput, name_offset) == 12,
                OffsetOf_ProgramInput_name_offset_not_12);
 COMPILE_ASSERT(offsetof(ProgramInput, name_length) == 16,
@@ skipping 275 matching lines @@
   CommandHeader header;
 };
 
 #pragma pack(pop)
 
 }  // namespace cmd
 }  // namespace gles2
 }  // namespace gpu
 
 #endif  // GPU_COMMAND_BUFFER_COMMON_GLES2_CMD_FORMAT_H_