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1 /* | |
2 * Copyright 2017 The WebRTC Project Authors. All rights reserved. | |
3 * | |
4 * Use of this source code is governed by a BSD-style license | |
5 * that can be found in the LICENSE file in the root of the source | |
6 * tree. An additional intellectual property rights grant can be found | |
7 * in the file PATENTS. All contributing project authors may | |
8 * be found in the AUTHORS file in the root of the source tree. | |
9 */ | |
10 | |
11 #ifndef WEBRTC_P2P_BASE_PACKETLOSSESTIMATOR_H_ | |
12 #define WEBRTC_P2P_BASE_PACKETLOSSESTIMATOR_H_ | |
13 | |
14 #include <stdint.h> | |
15 #include <string> | |
16 #include <unordered_map> | |
17 | |
18 namespace cricket { | |
19 | |
20 // Estimates the response rate for a series of messages expecting responses. | |
21 // Messages and their corresponding responses are identified by a string id. | |
22 // | |
23 // Responses are considered lost if they are not received within | |
24 // |consider_lost_after_ms|. If a response is received after | |
25 // |consider_lost_after_ms|, it is still considered as a response. | |
26 // Messages sent more than |forget_after_ms| ago are not considered | |
27 // anymore. The response rate is initially assumed to be 1.0. | |
28 // | |
29 // If the current time is 7, |forget_after_ms| is 6, and | |
30 // |consider_lost_after_ms| is 2, the response rate considers messages sent | |
31 // between times 1 and 5, so only messages in the following window can be | |
32 // considered lost: | |
33 // | |
34 // Time: 0 1 2 3 4 5 6 7 | |
35 // Wind: <-------> | | |
36 // | |
37 // Responses received to the right of the window are still counted. | |
38 class PacketLossEstimator { | |
39 public: | |
40 explicit PacketLossEstimator(int64_t consider_lost_after_ms, | |
41 int64_t forget_after_ms); | |
42 | |
43 // Registers that a message with the given |id| was sent at |sent_time|. | |
44 void ExpectResponse(std::string id, int64_t sent_time); | |
45 | |
46 // Registers a response with the given |id| was received at |received_time|. | |
47 void ReceivedResponse(std::string id, int64_t received_time); | |
48 | |
49 // Calculates the current response rate based on the expected and received | |
50 // messages. Messages sent more than |forget_after| ms ago will be forgotten. | |
51 void UpdateResponseRate(int64_t now); | |
52 | |
53 // Gets the current response rate as updated by UpdateResponseRate. | |
54 double get_response_rate() const { return response_rate_; } | |
55 | |
56 std::size_t tracked_packet_count_for_testing() const; | |
57 | |
58 // Output tracked packet state as a string. | |
59 std::string TrackedPacketsString(std::size_t max) const; | |
Taylor Brandstetter
2017/03/09 00:06:43
Append "ForTesting"?
| |
60 | |
61 private: | |
62 struct PacketInfo { | |
63 int64_t sent_time; | |
64 bool response_received; | |
65 }; | |
66 | |
67 // Called periodically by ExpectResponse and ReceivedResponse to manage memory | |
68 // usage. | |
69 void MaybeForgetOldRequests(int64_t now); | |
70 | |
71 bool ConsiderLost(const PacketInfo&, int64_t now) const; | |
72 bool Forget(const PacketInfo&, int64_t now) const; | |
73 | |
74 int64_t consider_lost_after_ms_; | |
75 int64_t forget_after_ms_; | |
76 | |
77 int64_t last_forgot_at_ = 0; | |
78 | |
79 std::unordered_map<std::string, PacketInfo> tracked_packets_; | |
80 | |
81 double response_rate_ = 1.0; | |
82 }; | |
83 | |
84 } // namespace cricket | |
85 | |
86 #endif // WEBRTC_P2P_BASE_PACKETLOSSESTIMATOR_H_ | |
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