gpu: Reuse transfer buffers more aggresively

gpu/command_buffer/build_gles2_cmd_buffer.py

 #!/usr/bin/env python
 # 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.
 
 """code generator for GLES2 command buffers."""
 
 import itertools
 import os
 import os.path
@@ skipping 810 matching lines @@
     ],
   },
   'QueryTarget': {
     'type': 'GLenum',
     'valid': [
       'GL_ANY_SAMPLES_PASSED_EXT',
       'GL_ANY_SAMPLES_PASSED_CONSERVATIVE_EXT',
       'GL_COMMANDS_ISSUED_CHROMIUM',
       'GL_LATENCY_QUERY_CHROMIUM',
       'GL_ASYNC_PIXEL_UNPACK_COMPLETED_CHROMIUM',
+      'GL_ASYNC_PIXEL_UNPACK_COMPLETED_PRIVATE_CHROMIUM',

[reveman, 2014/01/02 01:31:29]

Are clients prevented from using this somehow?

Did you consider adding a new pair of Begin/EndQuery commands instead? ie.
BeginInternalQueryEXT and EndInternalQueryEXT. Or a "bool private" parameter to
the existing Begin/EndQuery commands.

[jadahl, 2014/01/02 10:59:54]

The idea is that this target should be private, and not allowed to be used by
some client. Not sure how to enforce that rule except with error reporting. Any
ideas here?

What we'd gain from having a "bool private"? Would it be applicable to all types
of queries? Also the assumption that one type of target only has one running
query would longer hold, and any such assumptions throughout the code would no
longer be true.

[reveman, 2014/01/02 11:56:44]

The idea is that this would make it easy to keep it internal as we'd simply not
expose it in the client API. It could be limited to ASYNC_PIXEL_UNPACK_COMPLETED
for now but it would be trivial to add support for other targets if necessary.

The key type for the QueryMap you introduced in this patch would instead be a
std::pair<bool, GLuint>. Where "bool" is whether the query is private. Are we
making more assumptions than this related to running queries?

       'GL_ASYNC_PIXEL_PACK_COMPLETED_CHROMIUM',
     ],
   },
   'RenderBufferParameter': {
     'type': 'GLenum',
     'valid': [
       'GL_RENDERBUFFER_RED_SIZE',
       'GL_RENDERBUFFER_GREEN_SIZE',
       'GL_RENDERBUFFER_BLUE_SIZE',
       'GL_RENDERBUFFER_ALPHA_SIZE',
@@ skipping 6997 matching lines @@
     gen.WriteGLES2Header("../GLES2/gl2chromium_autogen.h")
 
   if gen.errors > 0:
     print "%d errors" % gen.errors
     return 1
   return 0
 
 
 if __name__ == '__main__':
   sys.exit(main(sys.argv[1:]))