Reland Use CopyOnWriteBuffer instead of Buffer to avoid unnecessary copies.

webrtc/api/sctputils.cc

 /*
  *  Copyright 2013 The WebRTC project authors. All Rights Reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
 #include "webrtc/api/sctputils.h"
 
-#include "webrtc/base/buffer.h"
 #include "webrtc/base/bytebuffer.h"
+#include "webrtc/base/copyonwritebuffer.h"
 #include "webrtc/base/logging.h"
 
 namespace webrtc {
 
 // Format defined at
 // http://tools.ietf.org/html/draft-ietf-rtcweb-data-protocol-01#section
 
 static const uint8_t DATA_CHANNEL_OPEN_MESSAGE_TYPE = 0x03;
 static const uint8_t DATA_CHANNEL_OPEN_ACK_MESSAGE_TYPE = 0x02;
 
 enum DataChannelOpenMessageChannelType {
   DCOMCT_ORDERED_RELIABLE = 0x00,
   DCOMCT_ORDERED_PARTIAL_RTXS = 0x01,
   DCOMCT_ORDERED_PARTIAL_TIME = 0x02,
   DCOMCT_UNORDERED_RELIABLE = 0x80,
   DCOMCT_UNORDERED_PARTIAL_RTXS = 0x81,
   DCOMCT_UNORDERED_PARTIAL_TIME = 0x82,
 };
 
-bool IsOpenMessage(const rtc::Buffer& payload) {
+bool IsOpenMessage(const rtc::CopyOnWriteBuffer& payload) {
   // Format defined at
   // http://tools.ietf.org/html/draft-jesup-rtcweb-data-protocol-04
-
-  rtc::ByteBuffer buffer(payload);
-  uint8_t message_type;
-  if (!buffer.ReadUInt8(&message_type)) {
+  if (payload.size() < 1) {
     LOG(LS_WARNING) << "Could not read OPEN message type.";
     return false;
   }
+
+  uint8_t message_type = payload[0];
   return message_type == DATA_CHANNEL_OPEN_MESSAGE_TYPE;
 }
 
-bool ParseDataChannelOpenMessage(const rtc::Buffer& payload,
+bool ParseDataChannelOpenMessage(const rtc::CopyOnWriteBuffer& payload,
                                  std::string* label,
                                  DataChannelInit* config) {
   // Format defined at
   // http://tools.ietf.org/html/draft-jesup-rtcweb-data-protocol-04
 
-  rtc::ByteBuffer buffer(payload);
+  // TODO(jbauch): avoid copying the payload data into the ByteBuffer, see
+  // https://bugs.chromium.org/p/webrtc/issues/detail?id=5670
+  rtc::ByteBuffer buffer(payload.data<char>(), payload.size());
   uint8_t message_type;
   if (!buffer.ReadUInt8(&message_type)) {
     LOG(LS_WARNING) << "Could not read OPEN message type.";
     return false;
   }
   if (message_type != DATA_CHANNEL_OPEN_MESSAGE_TYPE) {
     LOG(LS_WARNING) << "Data Channel OPEN message of unexpected type: "
                     << message_type;
     return false;
   }
@@ skipping 49 matching lines @@
       config->maxRetransmits = reliability_param;
       break;
     case DCOMCT_ORDERED_PARTIAL_TIME:
     case DCOMCT_UNORDERED_PARTIAL_TIME:
       config->maxRetransmitTime = reliability_param;
       break;
   }
   return true;
 }
 
-bool ParseDataChannelOpenAckMessage(const rtc::Buffer& payload) {
-  rtc::ByteBuffer buffer(payload);
-  uint8_t message_type;
-  if (!buffer.ReadUInt8(&message_type)) {
+bool ParseDataChannelOpenAckMessage(const rtc::CopyOnWriteBuffer& payload) {
+  if (payload.size() < 1) {
     LOG(LS_WARNING) << "Could not read OPEN_ACK message type.";
     return false;
   }
+
+  uint8_t message_type = payload[0];
   if (message_type != DATA_CHANNEL_OPEN_ACK_MESSAGE_TYPE) {
     LOG(LS_WARNING) << "Data Channel OPEN_ACK message of unexpected type: "
                     << message_type;
     return false;
   }
   return true;
 }
 
 bool WriteDataChannelOpenMessage(const std::string& label,
                                  const DataChannelInit& config,
-                                 rtc::Buffer* payload) {
+                                 rtc::CopyOnWriteBuffer* payload) {
   // Format defined at
   // http://tools.ietf.org/html/draft-ietf-rtcweb-data-protocol-00#section-6.1
   uint8_t channel_type = 0;
   uint32_t reliability_param = 0;
   uint16_t priority = 0;
   if (config.ordered) {
     if (config.maxRetransmits > -1) {
       channel_type = DCOMCT_ORDERED_PARTIAL_RTXS;
       reliability_param = config.maxRetransmits;
     } else if (config.maxRetransmitTime > -1) {
@@ skipping 10 matching lines @@
       channel_type = DCOMCT_UNORDERED_PARTIAL_TIME;
       reliability_param = config.maxRetransmitTime;
     } else {
       channel_type = DCOMCT_UNORDERED_RELIABLE;
     }
   }
 
   rtc::ByteBuffer buffer(
       NULL, 20 + label.length() + config.protocol.length(),
       rtc::ByteBuffer::ORDER_NETWORK);
+  // TODO(tommi): Add error handling and check resulting length.
   buffer.WriteUInt8(DATA_CHANNEL_OPEN_MESSAGE_TYPE);
   buffer.WriteUInt8(channel_type);
   buffer.WriteUInt16(priority);
   buffer.WriteUInt32(reliability_param);
   buffer.WriteUInt16(static_cast<uint16_t>(label.length()));
   buffer.WriteUInt16(static_cast<uint16_t>(config.protocol.length()));
   buffer.WriteString(label);
   buffer.WriteString(config.protocol);
   payload->SetData(buffer.Data(), buffer.Length());
   return true;
 }
 
-void WriteDataChannelOpenAckMessage(rtc::Buffer* payload) {
-  rtc::ByteBuffer buffer(rtc::ByteBuffer::ORDER_NETWORK);
-  buffer.WriteUInt8(DATA_CHANNEL_OPEN_ACK_MESSAGE_TYPE);
-  payload->SetData(buffer.Data(), buffer.Length());
+void WriteDataChannelOpenAckMessage(rtc::CopyOnWriteBuffer* payload) {
+  uint8_t data = DATA_CHANNEL_OPEN_ACK_MESSAGE_TYPE;
+  payload->SetData(&data, sizeof(data));
 }
+
 }  // namespace webrtc