[Sync] Store the past 10 traffic records in memory.

sync/engine/traffic_recorder.cc

+// 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.
+
+#include "sync/engine/traffic_recorder.h"
+
+#include "base/json/json_writer.h"
+#include "base/logging.h"
+#include "base/memory/scoped_ptr.h"
+#include "base/values.h"
+#include "sync/protocol/proto_value_conversions.h"
+#include "sync/protocol/sync.pb.h"
+#include "sync/sessions/sync_session.h"
+
+namespace browser_sync {
+
+TrafficRecorder::TrafficRecord::TrafficRecord(const std::string& message,
+                                              TrafficMessageType message_type,
+                                              bool truncated) :
+    message(message),
+    message_type(message_type),
+    truncated(truncated) {
+}
+
+TrafficRecorder::TrafficRecord::TrafficRecord()
+    : message_type(UNKNOWN_MESSAGE_TYPE),
+      truncated(false) {
+}
+
+TrafficRecorder::TrafficRecord::~TrafficRecord() {
+}
+
+const unsigned int kMaxMessages = 10;
+const unsigned int kMaxMessageSize = 5 * 1024;
+
+TrafficRecorder::TrafficRecorder() {
+}
+
+TrafficRecorder::~TrafficRecorder() {
+}
+
+
+void TrafficRecorder::AddTrafficToQueue(const TrafficRecord& record) {
+  records_.push_back(record);
+
+  // We might have more records than our limit.
+  // Maintain the size invariant by deleting items.
+  while (records_.size() > browser_sync::kMaxMessages) {
+    records_.pop_front();
+  }
+}
+
+void TrafficRecorder::StoreProtoInQueue(
+    const ::google::protobuf::MessageLite& msg,
+    TrafficMessageType type) {
+  bool truncated = false;
+  std::string message;
+  if (msg.ByteSize() >= browser_sync::kMaxMessageSize) {
+    // TODO(lipalani): Trim the specifics to fit in size.
+    truncated = true;
+  } else {
+    msg.SerializeToString(&message);
+  }
+
+  TrafficRecord record(message, type, truncated);
+  AddTrafficToQueue(record);
+}
+
+void TrafficRecorder::RecordClientToServerMessage(
+    const sync_pb::ClientToServerMessage& msg) {
+  StoreProtoInQueue(msg, CLIENT_TO_SERVER_MESSAGE);
+}
+
+void TrafficRecorder::RecordClientToServerResponse(
+    const sync_pb::ClientToServerResponse& response) {
+  StoreProtoInQueue(response, CLIENT_TO_SERVER_RESPONSE);
+}
+
+}  // namespace browser_sync
+