-
Notifications
You must be signed in to change notification settings - Fork 30
/
Channel.h
175 lines (137 loc) · 3.82 KB
/
Channel.h
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
//
// Created by benny on 2022/3/21.
//
#ifndef CPPCOROUTINES_TASKS_07_CHANNEL_CHANNEL_H_
#define CPPCOROUTINES_TASKS_07_CHANNEL_CHANNEL_H_
#include "coroutine_common.h"
#include "ChannelAwaiter.h"
#include <exception>
template<typename ValueType>
struct Channel {
struct ChannelClosedException : std::exception {
const char *what() const noexcept override {
return "Channel is closed.";
}
};
void check_closed() {
if (!_is_active.load(std::memory_order_relaxed)) {
throw ChannelClosedException();
}
}
void try_push_reader(ReaderAwaiter<ValueType> *reader_awaiter) {
std::unique_lock lock(channel_lock);
check_closed();
if (!buffer.empty()) {
auto value = buffer.front();
buffer.pop();
if (!writer_list.empty()) {
auto writer = writer_list.front();
writer_list.pop_front();
buffer.push(writer->_value);
lock.unlock();
writer->resume();
} else {
lock.unlock();
}
reader_awaiter->resume(value);
return;
}
if (!writer_list.empty()) {
auto writer = writer_list.front();
writer_list.pop_front();
lock.unlock();
reader_awaiter->resume(writer->_value);
writer->resume();
return;
}
reader_list.push_back(reader_awaiter);
}
void try_push_writer(WriterAwaiter<ValueType> *writer_awaiter) {
std::unique_lock lock(channel_lock);
check_closed();
// suspended readers
if (!reader_list.empty()) {
auto reader = reader_list.front();
reader_list.pop_front();
lock.unlock();
reader->resume(writer_awaiter->_value);
writer_awaiter->resume();
return;
}
// write to buffer
if (buffer.size() < buffer_capacity) {
buffer.push(writer_awaiter->_value);
lock.unlock();
writer_awaiter->resume();
return;
}
// suspend writer
writer_list.push_back(writer_awaiter);
}
void remove_writer(WriterAwaiter<ValueType> *writer_awaiter) {
std::lock_guard lock(channel_lock);
auto size = writer_list.remove(writer_awaiter);
debug("remove writer ", size);
}
void remove_reader(ReaderAwaiter<ValueType> *reader_awaiter) {
std::lock_guard lock(channel_lock);
auto size = reader_list.remove(reader_awaiter);
debug("remove reader ", size);
}
auto write(ValueType value) {
check_closed();
return WriterAwaiter<ValueType>{this, value};
}
auto operator<<(ValueType value) {
return write(value);
}
auto read() {
check_closed();
return ReaderAwaiter<ValueType>{this};
}
auto operator>>(ValueType &value_ref) {
auto awaiter = read();
awaiter.p_value = &value_ref;
return awaiter;
}
void close() {
bool expect = true;
if (_is_active.compare_exchange_strong(expect, false, std::memory_order_relaxed)) {
clean_up();
}
}
explicit Channel(int capacity = 0) : buffer_capacity(capacity) {
_is_active.store(true, std::memory_order_relaxed);
}
bool is_active() {
return _is_active.load(std::memory_order_relaxed);
}
Channel(Channel &&channel) = delete;
Channel(Channel &) = delete;
Channel &operator=(Channel &) = delete;
~Channel() {
close();
}
private:
int buffer_capacity;
std::queue<ValueType> buffer;
std::list<WriterAwaiter<ValueType> *> writer_list;
std::list<ReaderAwaiter<ValueType> *> reader_list;
std::atomic<bool> _is_active;
std::mutex channel_lock;
std::condition_variable channel_condition;
void clean_up() {
std::lock_guard lock(channel_lock);
for (auto writer : writer_list) {
writer->resume();
}
writer_list.clear();
for (auto reader : reader_list) {
reader->resume_unsafe();
}
reader_list.clear();
decltype(buffer) empty_buffer;
std::swap(buffer, empty_buffer);
}
};
#endif //CPPCOROUTINES_TASKS_07_CHANNEL_CHANNEL_H_