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 <cstddef> |
20 | #include <vector> |
21 | |
22 | #include <folly/Function.h> |
23 | |
24 | namespace folly { |
25 | namespace detail { |
26 | |
27 | /* |
28 | * This class represents a sliding window that can be used to track stats over |
29 | * time. Buckets are dropped and new ones are added with the slide() method. |
30 | * New buckets are created with the constructor function given at construction. |
31 | */ |
32 | template <typename BucketT> |
33 | class SlidingWindow { |
34 | public: |
35 | SlidingWindow(Function<BucketT(void)> fn, size_t numBuckets); |
36 | |
37 | SlidingWindow(SlidingWindow&& rhs); |
38 | |
39 | std::vector<BucketT> get() const; |
40 | |
41 | void set(size_t idx, BucketT bucket); |
42 | |
43 | BucketT front() const; |
44 | |
45 | /* |
46 | * Slides the SlidingWindow by nBuckets, inserting new buckets using the |
47 | * Function given during construction. |
48 | */ |
49 | void slide(size_t nBuckets); |
50 | |
51 | private: |
52 | Function<BucketT(void)> fn_; |
53 | std::vector<BucketT> buckets_; |
54 | size_t curHead_; |
55 | }; |
56 | |
57 | } // namespace detail |
58 | } // namespace folly |
59 | |