blob: 1d14d922c6480849b461c7bc3d93f909f8da16d7 (
plain)
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
|
/*
* Copyright (c) 2016-present, Facebook, Inc.
* All rights reserved.
*
* This source code is licensed under both the BSD-style license (found in the
* LICENSE file in the root directory of this source tree) and the GPLv2 (found
* in the COPYING file in the root directory of this source tree).
*/
#pragma once
#include "utils/Buffer.h"
#include <atomic>
#include <cassert>
#include <cstddef>
#include <condition_variable>
#include <cstddef>
#include <functional>
#include <mutex>
#include <queue>
namespace pzstd {
/// Unbounded thread-safe work queue.
template <typename T>
class WorkQueue {
// Protects all member variable access
std::mutex mutex_;
std::condition_variable readerCv_;
std::condition_variable writerCv_;
std::condition_variable finishCv_;
std::queue<T> queue_;
bool done_;
std::size_t maxSize_;
// Must have lock to call this function
bool full() const {
if (maxSize_ == 0) {
return false;
}
return queue_.size() >= maxSize_;
}
public:
/**
* Constructs an empty work queue with an optional max size.
* If `maxSize == 0` the queue size is unbounded.
*
* @param maxSize The maximum allowed size of the work queue.
*/
WorkQueue(std::size_t maxSize = 0) : done_(false), maxSize_(maxSize) {}
/**
* Push an item onto the work queue. Notify a single thread that work is
* available. If `finish()` has been called, do nothing and return false.
* If `push()` returns false, then `item` has not been moved from.
*
* @param item Item to push onto the queue.
* @returns True upon success, false if `finish()` has been called. An
* item was pushed iff `push()` returns true.
*/
bool push(T&& item) {
{
std::unique_lock<std::mutex> lock(mutex_);
while (full() && !done_) {
writerCv_.wait(lock);
}
if (done_) {
return false;
}
queue_.push(std::move(item));
}
readerCv_.notify_one();
return true;
}
/**
* Attempts to pop an item off the work queue. It will block until data is
* available or `finish()` has been called.
*
* @param[out] item If `pop` returns `true`, it contains the popped item.
* If `pop` returns `false`, it is unmodified.
* @returns True upon success. False if the queue is empty and
* `finish()` has been called.
*/
bool pop(T& item) {
{
std::unique_lock<std::mutex> lock(mutex_);
while (queue_.empty() && !done_) {
readerCv_.wait(lock);
}
if (queue_.empty()) {
assert(done_);
return false;
}
item = std::move(queue_.front());
queue_.pop();
}
writerCv_.notify_one();
return true;
}
/**
* Sets the maximum queue size. If `maxSize == 0` then it is unbounded.
*
* @param maxSize The new maximum queue size.
*/
void setMaxSize(std::size_t maxSize) {
{
std::lock_guard<std::mutex> lock(mutex_);
maxSize_ = maxSize;
}
writerCv_.notify_all();
}
/**
* Promise that `push()` won't be called again, so once the queue is empty
* there will never any more work.
*/
void finish() {
{
std::lock_guard<std::mutex> lock(mutex_);
assert(!done_);
done_ = true;
}
readerCv_.notify_all();
writerCv_.notify_all();
finishCv_.notify_all();
}
/// Blocks until `finish()` has been called (but the queue may not be empty).
void waitUntilFinished() {
std::unique_lock<std::mutex> lock(mutex_);
while (!done_) {
finishCv_.wait(lock);
}
}
};
/// Work queue for `Buffer`s that knows the total number of bytes in the queue.
class BufferWorkQueue {
WorkQueue<Buffer> queue_;
std::atomic<std::size_t> size_;
public:
BufferWorkQueue(std::size_t maxSize = 0) : queue_(maxSize), size_(0) {}
void push(Buffer buffer) {
size_.fetch_add(buffer.size());
queue_.push(std::move(buffer));
}
bool pop(Buffer& buffer) {
bool result = queue_.pop(buffer);
if (result) {
size_.fetch_sub(buffer.size());
}
return result;
}
void setMaxSize(std::size_t maxSize) {
queue_.setMaxSize(maxSize);
}
void finish() {
queue_.finish();
}
/**
* Blocks until `finish()` has been called.
*
* @returns The total number of bytes of all the `Buffer`s currently in the
* queue.
*/
std::size_t size() {
queue_.waitUntilFinished();
return size_.load();
}
};
}
|
