gpu/command_buffer/service/cmd_parser.cc

   1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 // This file contains the implementation of the command parser.
   6
   7 #include "gpu/command_buffer/service/cmd_parser.h"
   8
   9 #include "base/logging.h"
  10 #include "base/debug/trace_event.h"
  11
  12 namespace gpu {
  13
  14 CommandParser::CommandParser(AsyncAPIInterface* handler)
  15     : get_(0),
  16       put_(0),
  17       buffer_(NULL),
  18       entry_count_(0),
  19       handler_(handler) {
  20 }
  21
  22 void CommandParser::SetBuffer(
  23     void* shm_address,
  24     size_t shm_size,
  25     ptrdiff_t offset,
  26     size_t size) {
  27   // check proper alignments.
  28   DCHECK_EQ(0, (reinterpret_cast<intptr_t>(shm_address)) % 4);
  29   DCHECK_EQ(0, offset % 4);
  30   DCHECK_EQ(0u, size % 4);
  31   // check that the command buffer fits into the memory buffer.
  32   DCHECK_GE(shm_size, offset + size);
  33   get_ = 0;
  34   put_ = 0;
  35   char* buffer_begin = static_cast<char*>(shm_address) + offset;
  36   buffer_ = reinterpret_cast<CommandBufferEntry*>(buffer_begin);
  37   entry_count_ = size / 4;
  38 }
  39
  40 // Process one command, reading the header from the command buffer, and
  41 // forwarding the command index and the arguments to the handler.
  42 // Note that:
  43 // - validation needs to happen on a copy of the data (to avoid race
  44 // conditions). This function only validates the header, leaving the arguments
  45 // validation to the handler, so it can pass a reference to them.
  46 // - get_ is modified *after* the command has been executed.
  47 error::Error CommandParser::ProcessCommand() {
  48   CommandBufferOffset get = get_;
  49   if (get == put_)
  50     return error::kNoError;
  51
  52   CommandHeader header = buffer_[get].value_header;
  53   if (header.size == 0) {
  54     DVLOG(1) << "Error: zero sized command in command buffer";
  55     return error::kInvalidSize;
  56   }
  57
  58   if (static_cast<int>(header.size) + get > entry_count_) {
  59     DVLOG(1) << "Error: get offset out of bounds";
  60     return error::kOutOfBounds;
  61   }
  62
  63   TRACE_EVENT0(TRACE_DISABLED_BY_DEFAULT("cb_command"),
  64                handler_->GetCommandName(header.command));
  65
  66   error::Error result = handler_->DoCommand(
  67       header.command, header.size - 1, buffer_ + get);
  68
  69   // TODO(gman): If you want to log errors this is the best place to catch them.
  70   //     It seems like we need an official way to turn on a debug mode and
  71   //     get these errors.
  72   if (error::IsError(result)) {
  73     ReportError(header.command, result);
  74   }
  75
  76   // If get was not set somewhere else advance it.
  77   if (get == get_ && result != error::kDeferCommandUntilLater)
  78     get_ = (get + header.size) % entry_count_;
  79
  80   return result;
  81 }
  82
  83 void CommandParser::ReportError(unsigned int command_id,
  84                                 error::Error result) {
  85   DVLOG(1) << "Error: " << result << " for Command "
  86            << handler_->GetCommandName(command_id);
  87 }
  88
  89 // Processes all the commands, while the buffer is not empty. Stop if an error
  90 // is encountered.
  91 error::Error CommandParser::ProcessAllCommands() {
  92   while (!IsEmpty()) {
  93     error::Error error = ProcessCommand();
  94     if (error)
  95       return error;
  96   }
  97   return error::kNoError;
  98 }
  99
 100 }  // namespace gpu