1 | /* |
2 | * Copyright 2018-present Facebook, Inc. |
3 | * |
4 | * Licensed under the Apache License, Version 2.0 (the "License"); |
5 | * you may not use this file except in compliance with the License. |
6 | * You may obtain a copy of the License at |
7 | * |
8 | * http://www.apache.org/licenses/LICENSE-2.0 |
9 | * |
10 | * Unless required by applicable law or agreed to in writing, software |
11 | * distributed under the License is distributed on an "AS IS" BASIS, |
12 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
13 | * See the License for the specific language governing permissions and |
14 | * limitations under the License. |
15 | */ |
16 | |
17 | #pragma once |
18 | |
19 | #include <folly/stats/detail/BufferedStatTDigest.h> |
20 | |
21 | namespace folly { |
22 | |
23 | struct QuantileEstimates { |
24 | public: |
25 | double sum; |
26 | double count; |
27 | |
28 | // vector of {quantile, value} |
29 | std::vector<std::pair<double, double>> quantiles; |
30 | }; |
31 | |
32 | /* |
33 | * A QuantileEstimator that buffers writes for 1 second. |
34 | */ |
35 | template <typename ClockT = std::chrono::steady_clock> |
36 | class SimpleQuantileEstimator { |
37 | public: |
38 | using TimePoint = typename ClockT::time_point; |
39 | |
40 | SimpleQuantileEstimator(); |
41 | |
42 | QuantileEstimates estimateQuantiles( |
43 | Range<const double*> quantiles, |
44 | TimePoint now = ClockT::now()); |
45 | |
46 | void addValue(double value, TimePoint now = ClockT::now()); |
47 | |
48 | /// Flush buffered values |
49 | void flush() { |
50 | bufferedDigest_.flush(); |
51 | } |
52 | |
53 | private: |
54 | detail::BufferedDigest<TDigest, ClockT> bufferedDigest_; |
55 | }; |
56 | |
57 | /* |
58 | * A QuantileEstimator that keeps values for nWindows * windowDuration (see |
59 | * constructor). Values are buffered for windowDuration. |
60 | */ |
61 | template <typename ClockT = std::chrono::steady_clock> |
62 | class SlidingWindowQuantileEstimator { |
63 | public: |
64 | using TimePoint = typename ClockT::time_point; |
65 | |
66 | SlidingWindowQuantileEstimator( |
67 | std::chrono::seconds windowDuration, |
68 | size_t nWindows = 60); |
69 | |
70 | QuantileEstimates estimateQuantiles( |
71 | Range<const double*> quantiles, |
72 | TimePoint now = ClockT::now()); |
73 | |
74 | void addValue(double value, TimePoint now = ClockT::now()); |
75 | |
76 | /// Flush buffered values |
77 | void flush() { |
78 | bufferedSlidingWindow_.flush(); |
79 | } |
80 | |
81 | private: |
82 | detail::BufferedSlidingWindow<TDigest, ClockT> bufferedSlidingWindow_; |
83 | }; |
84 | |
85 | extern template class SimpleQuantileEstimator<std::chrono::steady_clock>; |
86 | extern template class SlidingWindowQuantileEstimator<std::chrono::steady_clock>; |
87 | |
88 | } // namespace folly |
89 | |