Upstream version 7.36.149.0

[platform/framework/web/crosswalk.git] / src / net / quic / congestion_control / hybrid_slow_start.h

diff --git a/src/net/quic/congestion_control/hybrid_slow_start.h b/src/net/quic/congestion_control/hybrid_slow_start.h
index cee9c73..5d36c53 100644 (file)
--- a/src/net/quic/congestion_control/hybrid_slow_start.h
+++ b/src/net/quic/congestion_control/hybrid_slow_start.h
@@ -26,36 +26,61 @@ class NET_EXPORT_PRIVATE HybridSlowStart {
  public:
   explicit HybridSlowStart(const QuicClock* clock);
 
+  void OnPacketAcked(QuicPacketSequenceNumber acked_sequence_number,
+                     bool in_slow_start);
+
+  void OnPacketSent(QuicPacketSequenceNumber sequence_number);
+
+  // ShouldExitSlowStart should be called on every new ack frame, since a new
+  // RTT measurement can be made then.
+  // rtt: the RTT for this ack packet.
+  // min_rtt: is the lowest delay (RTT) we have seen during the session.
+  // congestion_window: the congestion window in packets.
+  bool ShouldExitSlowStart(QuicTime::Delta rtt,
+                           QuicTime::Delta min_rtt,
+                           int64 congestion_window);
+
   // Start a new slow start phase.
   void Restart();
 
+  // TODO(ianswett): The following methods should be private, but that requires
+  // a follow up CL to update the unit test.
   // Returns true if this ack the last sequence number of our current slow start
   // round.
   // Call Reset if this returns true.
-  bool EndOfRound(QuicPacketSequenceNumber ack);
-
-  // Call for each round (burst) in the slow start phase.
-  void Reset(QuicPacketSequenceNumber end_sequence_number);
+  bool IsEndOfRound(QuicPacketSequenceNumber ack) const;
 
-  // rtt: it the RTT for this ack packet.
-  // delay_min: is the lowest delay (RTT) we have seen during the session.
-  void Update(QuicTime::Delta rtt, QuicTime::Delta delay_min);
+  // Call for the start of each receive round (burst) in the slow start phase.
+  void StartReceiveRound(QuicPacketSequenceNumber last_sent);
 
-  // Returns true when we should exit slow start.
-  bool Exit();
-
-  bool started() { return started_; }
+  // Whether slow start has started.
+  bool started() const {
+    return started_;
+  }
 
  private:
+  // Whether a condition for exiting slow start has been found.
+  enum HystartState {
+    NOT_FOUND,
+    ACK_TRAIN,  // A closely spaced ack train is too long.
+    DELAY,  // Too much increase in the round's min_rtt was observed.
+  };
+
   const QuicClock* clock_;
+  // Whether the hybrid slow start has been started.
   bool started_;
-  bool found_ack_train_;
-  bool found_delay_;
-  QuicTime round_start_;  // Beginning of each slow start round.
-  QuicPacketSequenceNumber end_sequence_number_;  // End of slow start round.
-  QuicTime last_time_;  // Last time when the ACK spacing was close.
-  uint8 sample_count_;  // Number of samples to decide current RTT.
-  QuicTime::Delta current_rtt_;  // The minimum rtt of current round.
+  HystartState hystart_found_;
+  // Last sequence number sent which was CWND limited.
+  QuicPacketSequenceNumber last_sent_sequence_number_;
+
+  // Variables for tracking acks received during a slow start round.
+  QuicTime round_start_;  // Beginning of each slow start receive round.
+  QuicPacketSequenceNumber end_sequence_number_;  // End of the receive round.
+  // Last time when the spacing between ack arrivals was less than 2 ms.
+  // Defaults to the beginning of the round.
+  QuicTime last_close_ack_pair_time_;
+  uint32 rtt_sample_count_;  // Number of rtt samples in the current round.
+  QuicTime::Delta current_min_rtt_;  // The minimum rtt of current round.
 
   DISALLOW_COPY_AND_ASSIGN(HybridSlowStart);
 };