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

sync/engine/traffic_recorder.h

Index: sync/engine/traffic_recorder.h
diff --git a/sync/engine/traffic_recorder.h b/sync/engine/traffic_recorder.h
new file mode 100644
index 0000000000000000000000000000000000000000..9c315bd58e68c04c397fd334b73987f2ab7dea51
--- /dev/null
+++ b/sync/engine/traffic_recorder.h
@@ -0,0 +1,68 @@
+// 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.
+
+#ifndef CHROME_BROWSER_SYNC_ENGINE_TRAFFIC_RECORDER_H_
+#define CHROME_BROWSER_SYNC_ENGINE_TRAFFIC_RECORDER_H_
+#pragma once
+
+#include <deque>
+#include <string>
+
+#include "base/gtest_prod_util.h"
+#include "sync/protocol/sync.pb.h"
+
+namespace sync_pb {
+class ClientToServerResponse;
+class ClientToServerMessage;
+}
+
+namespace browser_sync {
+
+extern const unsigned int kMaxMessages;
+extern const unsigned int kMaxMessageSize;
+
+class TrafficRecorder {
+  enum TrafficMessageType {
+    CLIENT_TO_SERVER_MESSAGE,
+    CLIENT_TO_SERVER_RESPONSE,
+    UNKNOWN_MESSAGE_TYPE
+  };
+
+  struct TrafficRecord {
+    // The serialized message.
+    std::string message;
+    TrafficMessageType message_type;
+    // If the message is too big to be kept in memory then it should be
+    // truncated. For now the entire message is omitted if it is too big.
+    // TODO(lipalani): Truncate the specifics to fit with in size.
+    bool truncated;
+
+    TrafficRecord(const std::string& message,
+                  TrafficMessageType message_type,
+                  bool truncated);
+    TrafficRecord();
+    ~TrafficRecord();
+  };
+
+ public:
+  TrafficRecorder();
+  ~TrafficRecorder();
+
+  void RecordClientToServerMessage(const sync_pb::ClientToServerMessage& msg);
+  void RecordClientToServerResponse(
+      const sync_pb::ClientToServerResponse& response);
+
+ private:
+  FRIEND_TEST_ALL_PREFIXES(TrafficRecorderTest, MaxRecordsTest);

[akalin, 2012/03/27 23:53:44]

I prefer doing read accessors over giving tests access to innards.  You're going
to have to add accessors later anyway, since you have to get the data out
somehow, right?

[lipalani1, 2012/03/29 00:23:13]

Done.

+  FRIEND_TEST_ALL_PREFIXES(TrafficRecorderTest, MaxMessageSizeTest);
+  void AddTrafficToQueue(const TrafficRecord& record);
+  void StoreProtoInQueue(const ::google::protobuf::MessageLite& msg,
+                         TrafficMessageType type);
+
+  std::deque<TrafficRecord> records_;

[akalin, 2012/03/27 23:53:44]

DISALLOW_COPY_AND_ASSIGN()

(don't forget to include base/basictypes.h)

[lipalani1, 2012/03/29 00:23:13]

Done.

+};
+
+}  // namespace browser_sync
+
+#endif  // CHROME_BROWSER_SYNC_ENGINE_TRAFFIC_RECORDER_H_