Add first part of the network_tester functionality.

webrtc/tools/network_tester/config_reader.cc

+/*
+ *  Copyright 2017 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/tools/network_tester/config_reader.h"
+
+#include <string>
+#include <vector>
+
+#include "webrtc/base/ignore_wundef.h"
+#include "webrtc/base/logging.h"
+
+#ifdef WEBRTC_NETWORK_TESTER_PROTO
+RTC_PUSH_IGNORING_WUNDEF()
+#include "webrtc/tools/network_tester/network_tester_config.pb.h"
+RTC_POP_IGNORING_WUNDEF()
+#endif  // WEBRTC_NETWORK_TESTER_PROTO
+
+namespace webrtc {
+
+namespace {
+rtc::Optional<int> ParseMessageSize(std::istream& config_stream) {
+  int byte = config_stream.get();
+  if (config_stream.eof()) {
+    return rtc::Optional<int>();
+  }
+  RTC_DCHECK(0 <= byte && byte <= 255);

[minyue-webrtc, 2017/04/03 08:05:19]

nit
RTC_DCHECK_LE
RTC_DCHECK_GE
for better error message

[michaelt, 2017/04/03 13:05:39]

Done.

+  return rtc::Optional<int>(byte);
+}
+}
+
+ConfigReader::ConfigReader(const std::string& config_file_path)
+    : config_stream_(config_file_path,
+                     std::ios_base::in | std::ios_base::binary) {
+  RTC_DCHECK(config_stream_.is_open());
+  RTC_DCHECK(config_stream_.good());
+}
+
+ConfigReader::~ConfigReader() = default;
+
+rtc::Optional<ConfigReader::Config> ConfigReader::GetNextConfig() {
+#ifdef WEBRTC_NETWORK_TESTER_PROTO
+  auto message_size = ParseMessageSize(config_stream_);
+  if (!message_size)
+    return rtc::Optional<Config>();
+  constexpr size_t kMaxEventSize = (1u << 16) - 1;
+  std::vector<char> message_buffer(kMaxEventSize);
+  config_stream_.read(message_buffer.data(), *message_size);
+  RTC_DCHECK_EQ(config_stream_.gcount(), *message_size);
+  webrtc::network_tester::config::NetworkTesterConfig proto_config;
+  if (!proto_config.ParseFromArray(message_buffer.data(), *message_size))
+    return rtc::Optional<Config>();
+  RTC_DCHECK(proto_config.has_packet_send_interval_ms());
+  RTC_DCHECK(proto_config.has_packet_size());
+  RTC_DCHECK(proto_config.has_execution_time_ms());
+  Config config;
+  config.packet_send_interval_ms = proto_config.packet_send_interval_ms();
+  config.packet_size = proto_config.packet_size();
+  config.execution_time_ms = proto_config.execution_time_ms();
+  return rtc::Optional<Config>(config);
+#else
+  return rtc::Optional<Config>();
+#endif  //  WEBRTC_NETWORK_TESTER_PROTO
+}
+
+}  // namespace webrtc