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1 // Copyright 2014 The Chromium Authors. All rights reserved. | 1 // Copyright 2014 The Chromium Authors. All rights reserved. |
2 // Use of this source code is governed by a BSD-style license that can be | 2 // Use of this source code is governed by a BSD-style license that can be |
3 // found in the LICENSE file. | 3 // found in the LICENSE file. |
4 // | 4 // |
5 // A convenience class to store rtt samples and calculate smoothed rtt. | 5 // A convenience class to store rtt samples and calculate smoothed rtt. |
6 | 6 |
7 #ifndef NET_QUIC_CONGESTION_CONTROL_RTT_STATS_H_ | 7 #ifndef NET_QUIC_CONGESTION_CONTROL_RTT_STATS_H_ |
8 #define NET_QUIC_CONGESTION_CONTROL_RTT_STATS_H_ | 8 #define NET_QUIC_CONGESTION_CONTROL_RTT_STATS_H_ |
9 | 9 |
| 10 #include <stdint.h> |
| 11 |
10 #include <algorithm> | 12 #include <algorithm> |
11 | 13 |
12 #include "base/basictypes.h" | 14 #include "base/macros.h" |
13 #include "net/quic/quic_protocol.h" | 15 #include "net/quic/quic_protocol.h" |
14 #include "net/quic/quic_time.h" | 16 #include "net/quic/quic_time.h" |
15 | 17 |
16 namespace net { | 18 namespace net { |
17 | 19 |
18 namespace test { | 20 namespace test { |
19 class RttStatsPeer; | 21 class RttStatsPeer; |
20 } // namespace test | 22 } // namespace test |
21 | 23 |
22 class NET_EXPORT_PRIVATE RttStats { | 24 class NET_EXPORT_PRIVATE RttStats { |
23 public: | 25 public: |
24 RttStats(); | 26 RttStats(); |
25 | 27 |
26 // Updates the RTT from an incoming ack which is received |send_delta| after | 28 // Updates the RTT from an incoming ack which is received |send_delta| after |
27 // the packet is sent and the peer reports the ack being delayed |ack_delay|. | 29 // the packet is sent and the peer reports the ack being delayed |ack_delay|. |
28 void UpdateRtt(QuicTime::Delta send_delta, | 30 void UpdateRtt(QuicTime::Delta send_delta, |
29 QuicTime::Delta ack_delay, | 31 QuicTime::Delta ack_delay, |
30 QuicTime now); | 32 QuicTime now); |
31 | 33 |
32 // Causes the smoothed_rtt to be increased to the latest_rtt if the latest_rtt | 34 // Causes the smoothed_rtt to be increased to the latest_rtt if the latest_rtt |
33 // is larger. The mean deviation is increased to the most recent deviation if | 35 // is larger. The mean deviation is increased to the most recent deviation if |
34 // it's larger. | 36 // it's larger. |
35 void ExpireSmoothedMetrics(); | 37 void ExpireSmoothedMetrics(); |
36 | 38 |
37 // Forces RttStats to sample a new recent min rtt within the next | 39 // Forces RttStats to sample a new recent min rtt within the next |
38 // |num_samples| UpdateRtt calls. | 40 // |num_samples| UpdateRtt calls. |
39 void SampleNewRecentMinRtt(uint32 num_samples); | 41 void SampleNewRecentMinRtt(uint32_t num_samples); |
40 | 42 |
41 // Called when connection migrates and rtt measurement needs to be reset. | 43 // Called when connection migrates and rtt measurement needs to be reset. |
42 void OnConnectionMigration(); | 44 void OnConnectionMigration(); |
43 | 45 |
44 // Returns the EWMA smoothed RTT for the connection. | 46 // Returns the EWMA smoothed RTT for the connection. |
45 // May return Zero if no valid updates have occurred. | 47 // May return Zero if no valid updates have occurred. |
46 QuicTime::Delta smoothed_rtt() const { return smoothed_rtt_; } | 48 QuicTime::Delta smoothed_rtt() const { return smoothed_rtt_; } |
47 | 49 |
48 int64 initial_rtt_us() const { return initial_rtt_us_; } | 50 int64_t initial_rtt_us() const { return initial_rtt_us_; } |
49 | 51 |
50 // Sets an initial RTT to be used for SmoothedRtt before any RTT updates. | 52 // Sets an initial RTT to be used for SmoothedRtt before any RTT updates. |
51 void set_initial_rtt_us(int64 initial_rtt_us) { | 53 void set_initial_rtt_us(int64_t initial_rtt_us) { |
52 if (initial_rtt_us <= 0) { | 54 if (initial_rtt_us <= 0) { |
53 LOG(DFATAL) << "Attempt to set initial rtt to <= 0."; | 55 LOG(DFATAL) << "Attempt to set initial rtt to <= 0."; |
54 return; | 56 return; |
55 } | 57 } |
56 initial_rtt_us_ = initial_rtt_us; | 58 initial_rtt_us_ = initial_rtt_us; |
57 } | 59 } |
58 | 60 |
59 // The most recent rtt measurement. | 61 // The most recent rtt measurement. |
60 // May return Zero if no valid updates have occurred. | 62 // May return Zero if no valid updates have occurred. |
61 QuicTime::Delta latest_rtt() const { return latest_rtt_; } | 63 QuicTime::Delta latest_rtt() const { return latest_rtt_; } |
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90 // Implements the resampling algorithm and the windowed min rtt algorithm. | 92 // Implements the resampling algorithm and the windowed min rtt algorithm. |
91 void UpdateRecentMinRtt(QuicTime::Delta rtt_sample, QuicTime now); | 93 void UpdateRecentMinRtt(QuicTime::Delta rtt_sample, QuicTime now); |
92 | 94 |
93 QuicTime::Delta latest_rtt_; | 95 QuicTime::Delta latest_rtt_; |
94 QuicTime::Delta min_rtt_; | 96 QuicTime::Delta min_rtt_; |
95 QuicTime::Delta smoothed_rtt_; | 97 QuicTime::Delta smoothed_rtt_; |
96 // Mean RTT deviation during this session. | 98 // Mean RTT deviation during this session. |
97 // Approximation of standard deviation, the error is roughly 1.25 times | 99 // Approximation of standard deviation, the error is roughly 1.25 times |
98 // larger than the standard deviation, for a normally distributed signal. | 100 // larger than the standard deviation, for a normally distributed signal. |
99 QuicTime::Delta mean_deviation_; | 101 QuicTime::Delta mean_deviation_; |
100 int64 initial_rtt_us_; | 102 int64_t initial_rtt_us_; |
101 | 103 |
102 RttSample new_min_rtt_; | 104 RttSample new_min_rtt_; |
103 uint32 num_min_rtt_samples_remaining_; | 105 uint32_t num_min_rtt_samples_remaining_; |
104 | 106 |
105 // State variables for Kathleen Nichols MinRTT algorithm. | 107 // State variables for Kathleen Nichols MinRTT algorithm. |
106 QuicTime::Delta recent_min_rtt_window_; | 108 QuicTime::Delta recent_min_rtt_window_; |
107 RttSample recent_min_rtt_; // a in the windowed algorithm. | 109 RttSample recent_min_rtt_; // a in the windowed algorithm. |
108 RttSample half_window_rtt_; // b in the sampled algorithm. | 110 RttSample half_window_rtt_; // b in the sampled algorithm. |
109 RttSample quarter_window_rtt_; // c in the sampled algorithm. | 111 RttSample quarter_window_rtt_; // c in the sampled algorithm. |
110 | 112 |
111 DISALLOW_COPY_AND_ASSIGN(RttStats); | 113 DISALLOW_COPY_AND_ASSIGN(RttStats); |
112 }; | 114 }; |
113 | 115 |
114 } // namespace net | 116 } // namespace net |
115 | 117 |
116 #endif // NET_QUIC_CONGESTION_CONTROL_RTT_STATS_H_ | 118 #endif // NET_QUIC_CONGESTION_CONTROL_RTT_STATS_H_ |
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