conc_queue.hpp
3.62 KB
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
// This file is part of OpenCV project.
// It is subject to the license terms in the LICENSE file found in the top-level directory
// of this distribution and at http://opencv.org/license.html.
//
// Copyright (C) 2019 Intel Corporation
#ifndef OPENCV_GAPI_EXECUTOR_CONC_QUEUE_HPP
#define OPENCV_GAPI_EXECUTOR_CONC_QUEUE_HPP
#include <queue>
#include <mutex>
#include <condition_variable>
#include <opencv2/gapi/own/assert.hpp>
namespace cv {
namespace gapi {
namespace own {
// This class implements a bare minimum interface of TBB's
// concurrent_bounded_queue with only std:: stuff to make streaming
// API work without TBB.
//
// Highly inefficient, please use it as a last resort if TBB is not
// available in the build.
template<class T>
class concurrent_bounded_queue {
std::queue<T> m_data;
std::size_t m_capacity;
std::mutex m_mutex;
std::condition_variable m_cond_empty;
std::condition_variable m_cond_full;
void unsafe_pop(T &t);
public:
concurrent_bounded_queue() : m_capacity(0) {}
concurrent_bounded_queue(const concurrent_bounded_queue<T> &cc)
: m_data(cc.m_data), m_capacity(cc.m_capacity) {
// FIXME: what to do with all that locks, etc?
}
concurrent_bounded_queue(concurrent_bounded_queue<T> &&cc)
: m_data(std::move(cc.m_data)), m_capacity(cc.m_capacity) {
// FIXME: what to do with all that locks, etc?
}
// FIXME: && versions
void push(const T &t);
void pop(T &t);
bool try_pop(T &t);
void set_capacity(std::size_t capacity);
// Not thread-safe - as in TBB
void clear();
};
// Internal: do shared pop things assuming the lock is already there
template<typename T>
void concurrent_bounded_queue<T>::unsafe_pop(T &t) {
GAPI_Assert(!m_data.empty());
t = m_data.front();
m_data.pop();
}
// Push an element to the queue. Blocking if there's no space left
template<typename T>
void concurrent_bounded_queue<T>::push(const T& t) {
std::unique_lock<std::mutex> lock(m_mutex);
if (m_capacity && m_capacity == m_data.size()) {
// if there is a limit and it is reached, wait
m_cond_full.wait(lock, [&](){return m_capacity > m_data.size();});
GAPI_Assert(m_capacity > m_data.size());
}
m_data.push(t);
lock.unlock();
m_cond_empty.notify_one();
}
// Pop an element from the queue. Blocking if there's no items
template<typename T>
void concurrent_bounded_queue<T>::pop(T &t) {
std::unique_lock<std::mutex> lock(m_mutex);
if (m_data.empty()) {
// if there is no data, wait
m_cond_empty.wait(lock, [&](){return !m_data.empty();});
}
unsafe_pop(t);
lock.unlock();
m_cond_full.notify_one();
}
// Try pop an element from the queue. Returns false if queue is empty
template<typename T>
bool concurrent_bounded_queue<T>::try_pop(T &t) {
std::unique_lock<std::mutex> lock(m_mutex);
if (m_data.empty()) {
// if there is no data, return
return false;
}
unsafe_pop(t);
lock.unlock();
m_cond_full.notify_one();
return true;
}
// Specify the upper limit to the queue. Assumed to be called after
// queue construction but before any real use, any other case is UB
template<typename T>
void concurrent_bounded_queue<T>::set_capacity(std::size_t capacity) {
GAPI_Assert(m_data.empty());
GAPI_Assert(m_capacity == 0u);
GAPI_Assert(capacity != 0u);
m_capacity = capacity;
}
// Clear the queue. Similar to the TBB version, this method is not
// thread-safe.
template<typename T>
void concurrent_bounded_queue<T>::clear() {
m_data = std::queue<T>{};
}
}}} // namespace cv::gapi::own
#endif // OPENCV_GAPI_EXECUTOR_CONC_QUEUE_HPP