1 /*
2 * Copyright 2020 The Android Open Source Project
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 <deque>
21 #include <iterator>
22 #include <memory>
23 #include <mutex>
24 #include <vector>
25
26 namespace bluetooth {
27 namespace common {
28
29 template <typename T>
30 class CircularBuffer {
31 public:
32 explicit CircularBuffer(size_t size);
33
34 // Push one item to the circular buffer
35 void Push(T item);
36 // Take a snapshot of the circular buffer and return it as a vector
37 std::vector<T> Pull() const;
38 // Drain everything from the circular buffer and return them as a vector
39 std::vector<T> Drain();
40
41 private:
42 const size_t size_;
43 std::deque<T> queue_;
44 mutable std::mutex mutex_;
45 };
46
47 class Timestamper {
48 public:
49 virtual long long GetTimestamp() const = 0;
~Timestamper()50 virtual ~Timestamper() {}
51 };
52
53 class TimestamperInMilliseconds : public Timestamper {
54 public:
GetTimestamp()55 long long GetTimestamp() const override {
56 return std::chrono::duration_cast<std::chrono::milliseconds>(std::chrono::system_clock::now().time_since_epoch())
57 .count();
58 }
~TimestamperInMilliseconds()59 virtual ~TimestamperInMilliseconds() {}
60 };
61
62 template <typename T>
63 struct TimestampedEntry {
64 long long timestamp;
65 T entry;
66 };
67
68 template <typename T>
69 class TimestampedCircularBuffer : public CircularBuffer<TimestampedEntry<T>> {
70 public:
71 explicit TimestampedCircularBuffer(
72 size_t size, std::unique_ptr<Timestamper> timestamper = std::make_unique<TimestamperInMilliseconds>());
73
74 void Push(T item);
75 std::vector<TimestampedEntry<T>> Pull() const;
76 std::vector<TimestampedEntry<T>> Drain();
77
78 private:
79 std::unique_ptr<Timestamper> timestamper_{std::make_unique<TimestamperInMilliseconds>()};
80 };
81
82 } // namespace common
83 } // namespace bluetooth
84
85 template <typename T>
CircularBuffer(size_t size)86 bluetooth::common::CircularBuffer<T>::CircularBuffer(size_t size) : size_(size) {}
87
88 template <typename T>
Push(const T item)89 void bluetooth::common::CircularBuffer<T>::Push(const T item) {
90 std::unique_lock<std::mutex> lock(mutex_);
91 queue_.push_back(item);
92 while (queue_.size() > size_) {
93 queue_.pop_front();
94 }
95 }
96
97 template <typename T>
Pull()98 std::vector<T> bluetooth::common::CircularBuffer<T>::Pull() const {
99 std::unique_lock<std::mutex> lock(mutex_);
100 return std::vector<T>(queue_.cbegin(), queue_.cend());
101 }
102
103 template <typename T>
Drain()104 std::vector<T> bluetooth::common::CircularBuffer<T>::Drain() {
105 std::unique_lock<std::mutex> lock(mutex_);
106 std::vector<T> items(std::make_move_iterator(queue_.begin()), std::make_move_iterator(queue_.end()));
107 queue_.clear();
108 return items;
109 }
110
111 template <typename T>
TimestampedCircularBuffer(size_t size,std::unique_ptr<Timestamper> timestamper)112 bluetooth::common::TimestampedCircularBuffer<T>::TimestampedCircularBuffer(
113 size_t size, std::unique_ptr<Timestamper> timestamper)
114 : CircularBuffer<TimestampedEntry<T>>(size), timestamper_(std::move(timestamper)) {}
115
116 template <typename T>
Push(const T item)117 void bluetooth::common::TimestampedCircularBuffer<T>::Push(const T item) {
118 TimestampedEntry<T> timestamped_entry{timestamper_->GetTimestamp(), item};
119 bluetooth::common::CircularBuffer<TimestampedEntry<T>>::Push(timestamped_entry);
120 }
121
122 template <typename T>
Pull()123 std::vector<struct bluetooth::common::TimestampedEntry<T>> bluetooth::common::TimestampedCircularBuffer<T>::Pull()
124 const {
125 return bluetooth::common::CircularBuffer<TimestampedEntry<T>>::Pull();
126 }
127
128 template <typename T>
Drain()129 std::vector<struct bluetooth::common::TimestampedEntry<T>> bluetooth::common::TimestampedCircularBuffer<T>::Drain() {
130 return bluetooth::common::CircularBuffer<TimestampedEntry<T>>::Drain();
131 }
132