forked from vit-vit/CTPL
-
Notifications
You must be signed in to change notification settings - Fork 0
/
ctpl.h
247 lines (201 loc) · 9.42 KB
/
ctpl.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
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
/*********************************************************
*
* Copyright (C) 2014 by Vitaliy Vitsentiy
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
*********************************************************/
#ifndef __ctpl_thread_pool_H__
#define __ctpl_thread_pool_H__
#include <functional>
#include <thread>
#include <atomic>
#include <vector>
#include <memory>
#include <exception>
#include <future>
#include <mutex>
#include <boost/lockfree/queue.hpp>
#ifndef _ctplThreadPoolLength_
#define _ctplThreadPoolLength_ 100
#endif
// thread pool to run user's functors with signature
// ret func(int id, other_params)
// where id is the index of the thread that runs the functor
// ret is some return type
namespace ctpl {
class thread_pool {
public:
thread_pool() : q(_ctplThreadPoolLength_) { this->init(); }
thread_pool(int nThreads, int queueSize = _ctplThreadPoolLength_) : q(queueSize) { this->init(); this->resize(nThreads); }
// the destructor waits for all the functions in the queue to be finished
~thread_pool() {
this->stop(true);
}
// get the number of running threads in the pool
int size() { return static_cast<int>(this->threads.size()); }
// number of idle threads
int n_idle() { return this->nWaiting; }
int n_pending() { return this->nPending; }
std::thread & get_thread(int i) { return *this->threads[i]; }
// change the number of threads in the pool
// should be called from one thread, otherwise be careful to not interleave, also with this->stop()
// nThreads must be >= 0
void resize(int nThreads) {
if (!this->isStop && !this->isDone) {
int oldNThreads = static_cast<int>(this->threads.size());
if (oldNThreads <= nThreads) { // if the number of threads is increased
this->threads.resize(nThreads);
this->flags.resize(nThreads);
for (int i = oldNThreads; i < nThreads; ++i) {
this->flags[i] = std::make_shared<std::atomic<bool>>(false);
this->set_thread(i);
}
}
else { // the number of threads is decreased
for (int i = oldNThreads - 1; i >= nThreads; --i) {
*this->flags[i] = true; // this thread will finish
this->threads[i]->detach();
}
{
// stop the detached threads that were waiting
std::unique_lock<std::mutex> lock(this->mutex);
this->cv.notify_all();
}
this->threads.resize(nThreads); // safe to delete because the threads are detached
this->flags.resize(nThreads); // safe to delete because the threads have copies of shared_ptr of the flags, not originals
}
}
}
// empty the queue
void clear_queue() {
std::function<void(int id)> * _f;
while (this->q.pop(_f))
delete _f; // empty the queue
}
// pops a functional wraper to the original function
std::function<void(int)> pop() {
std::function<void(int id)> * _f = nullptr;
this->q.pop(_f);
std::unique_ptr<std::function<void(int id)>> func(_f); // at return, delete the function even if an exception occurred
std::function<void(int)> f;
if (_f)
f = *_f;
return f;
}
// wait for all computing threads to finish and stop all threads
// may be called asyncronously to not pause the calling thread while waiting
// if isWait == true, all the functions in the queue are run, otherwise the queue is cleared without running the functions
void stop(bool isWait = false) {
if (!isWait) {
if (this->isStop)
return;
this->isStop = true;
for (int i = 0, n = this->size(); i < n; ++i) {
*this->flags[i] = true; // command the threads to stop
}
this->clear_queue(); // empty the queue
}
else {
if (this->isDone || this->isStop)
return;
this->isDone = true; // give the waiting threads a command to finish
}
{
std::unique_lock<std::mutex> lock(this->mutex);
this->cv.notify_all(); // stop all waiting threads
}
for (int i = 0; i < static_cast<int>(this->threads.size()); ++i) { // wait for the computing threads to finish
if (this->threads[i]->joinable())
this->threads[i]->join();
}
// if there were no threads in the pool but some functors in the queue, the functors are not deleted by the threads
// therefore delete them here
this->clear_queue();
this->threads.clear();
this->flags.clear();
}
template<typename F, typename... Rest>
auto push(F && f, Rest&&... rest) ->std::future<decltype(f(0, rest...))> {
auto pck = std::make_shared<std::packaged_task<decltype(f(0, rest...))(int)>>(
std::bind(std::forward<F>(f), std::placeholders::_1, std::forward<Rest>(rest)...)
);
auto _f = new std::function<void(int id)>([pck](int id) {
(*pck)(id);
});
++this->nPending;
this->q.push(_f);
std::unique_lock<std::mutex> lock(this->mutex);
this->cv.notify_one();
return pck->get_future();
}
// run the user's function that excepts argument int - id of the running thread. returned value is templatized
// operator returns std::future, where the user can get the result and rethrow the catched exceptins
template<typename F>
auto push(F && f) ->std::future<decltype(f(0))> {
auto pck = std::make_shared<std::packaged_task<decltype(f(0))(int)>>(std::forward<F>(f));
auto _f = new std::function<void(int id)>([pck](int id) {
(*pck)(id);
});
++this->nPending;
this->q.push(_f);
std::unique_lock<std::mutex> lock(this->mutex);
this->cv.notify_one();
return pck->get_future();
}
private:
// deleted
thread_pool(const thread_pool &);// = delete;
thread_pool(thread_pool &&);// = delete;
thread_pool & operator=(const thread_pool &);// = delete;
thread_pool & operator=(thread_pool &&);// = delete;
void set_thread(int i) {
std::shared_ptr<std::atomic<bool>> flag(this->flags[i]); // a copy of the shared ptr to the flag
auto f = [this, i, flag/* a copy of the shared ptr to the flag */]() {
std::atomic<bool> & _flag = *flag;
std::function<void(int id)> * _f;
bool isPop = this->q.pop(_f);
while (true) {
while (isPop) { // if there is anything in the queue
--this->nPending;
std::unique_ptr<std::function<void(int id)>> func(_f); // at return, delete the function even if an exception occurred
(*_f)(i);
if (_flag)
return; // the thread is wanted to stop, return even if the queue is not empty yet
else
isPop = this->q.pop(_f);
}
// the queue is empty here, wait for the next command
std::unique_lock<std::mutex> lock(this->mutex);
++this->nWaiting;
this->cv.wait(lock, [this, &_f, &isPop, &_flag](){ isPop = this->q.pop(_f); return isPop || this->isDone || _flag; });
--this->nWaiting;
if (!isPop)
return; // if the queue is empty and this->isDone == true or *flag then return
}
};
this->threads[i].reset(new std::thread(f)); // compiler may not support std::make_unique()
}
void init() { this->nWaiting = 0; this->nPending = 0; this->isStop = false; this->isDone = false; }
std::vector<std::unique_ptr<std::thread>> threads;
std::vector<std::shared_ptr<std::atomic<bool>>> flags;
mutable boost::lockfree::queue<std::function<void(int id)> *> q;
std::atomic<bool> isDone;
std::atomic<bool> isStop;
std::atomic<int> nWaiting; // how many threads are waiting
std::atomic<int> nPending; // how many tasks are waiting
std::mutex mutex;
std::condition_variable cv;
};
}
#endif // __ctpl_thread_pool_H__