boost库中有一个boost::lockfree::queue类型的 队列，对于一般的需要队列的程序，其效率都算不错的了，下面使用一个用例来说明。
程序是一个典型的生产者与消费者的关系，都可以使用多线程，其效率要比使用上层的互斥锁要快很多，因为它直接使用底层的原子操作来进行同步数据的。
freedeque.h
1 #pragma once#ifndef INCLUDED_UTILS_LFRINGQUEUE
2 #define INCLUDED_UTILS_LFRINGQUEUE
3
4 #define _ENABLE_ATOMIC_ALIGNMENT_FIX
5 #define ATOMIC_FLAG_INIT 0
6
7
8 #pragma once
9
10
11 #include <vector>
12 #include <mutex>
13 #include <thread>
14 #include <atomic>
15 #include <chrono>
16 #include <cstring>
17 #include <iostream>
18
19 // Lock free ring queue
20
21 template < typename _TyData, long _uiCount = 100000 >
22 class lfringqueue
23 {
24 public:
25 lfringqueue(long uiCount = _uiCount) : m_lTailIterator(0), m_lHeadIterator(0), m_uiCount(uiCount)
26 {
27 m_queue = new _TyData*[m_uiCount];
28 memset(m_queue, 0, sizeof(_TyData*) * m_uiCount);
29 }
30
31 ~lfringqueue()
32 {
33 if (m_queue)
34 delete[] m_queue;
35 }
36
37 bool enqueue(_TyData *pdata, unsigned int uiRetries = 1000)
38 {
39 if (NULL == pdata)
40 {
41 // Null enqueues are not allowed
42 return false;
43 }
44
45 unsigned int uiCurrRetries = 0;
46 while (uiCurrRetries < uiRetries)
47 {
48 // Release fence in order to prevent memory reordering
49 // of any read or write with following write
50 std::atomic_thread_fence(std::memory_order_release);
51
52 long lHeadIterator = m_lHeadIterator;
53
54 if (NULL == m_queue[lHeadIterator])
55 {
56 long lHeadIteratorOrig = lHeadIterator;
57
58 ++lHeadIterator;
59 if (lHeadIterator >= m_uiCount)
60 lHeadIterator = 0;
61
62 // Don‘t worry if this CAS fails. It only means some thread else has
63 // already inserted an item and set it.
64 if (std::atomic_compare_exchange_strong(&m_lHeadIterator, &lHeadIteratorOrig, lHeadIterator))
65 {
66 // void* are always atomic (you wont set a partial pointer).
67 m_queue[lHeadIteratorOrig] = pdata;
68
69 if (m_lEventSet.test_and_set())
70 {
71 m_bHasItem.test_and_set();
72 }
73 return true;
74 }
75 }
76 else
77 {
78 // The queue is full. Spin a few times to check to see if an item is popped off.
79 ++uiCurrRetries;
80 }
81 }
82 return false;
83 }
84
85 bool dequeue(_TyData **ppdata)
86 {
87 if (!ppdata)
88 {
89 // Null dequeues are not allowed!
90 return false;
91 }
92
93 bool bDone = false;
94 bool bCheckQueue = true;
95
96 while (!bDone)
97 {
98 // Acquire fence in order to prevent memory reordering
99 // of any read or write with following read
100 std::atomic_thread_fence(std::memory_order_acquire);
101 //MemoryBarrier();
102 long lTailIterator = m_lTailIterator;
103 _TyData *pdata = m_queue[lTailIterator];
104 //volatile _TyData *pdata = m_queue[lTailIterator];
105 if (NULL != pdata)
106 {
107 bCheckQueue = true;
108 long lTailIteratorOrig = lTailIterator;
109
110 ++lTailIterator;
111 if (lTailIterator >= m_uiCount)
112 lTailIterator = 0;
113
114 //if ( lTailIteratorOrig == atomic_cas( (volatile long*)&m_lTailIterator, lTailIterator, lTailIteratorOrig ))
115 if (std::atomic_compare_exchange_strong(&m_lTailIterator, &lTailIteratorOrig, lTailIterator))
116 {
117 // Sets of sizeof(void*) are always atomic (you wont set a partial pointer).
118 m_queue[lTailIteratorOrig] = NULL;
119
120 // Gets of sizeof(void*) are always atomic (you wont get a partial pointer).
121 *ppdata = (_TyData*)pdata;
122
123 return true;
124 }
125 }
126 else
127 {
128 bDone = true;
129 m_lEventSet.clear();
130 }
131 }
132 *ppdata = NULL;
133 return false;
134 }
135
136
137 long countguess() const
138 {
139 long lCount = trycount();
140
141 if (0 != lCount)
142 return lCount;
143
144 // If the queue is full then the item right before the tail item will be valid. If it
145 // is empty then the item should be set to NULL.
146 long lLastInsert = m_lTailIterator - 1;
147 if (lLastInsert < 0)
148 lLastInsert = m_uiCount - 1;
149
150 _TyData *pdata = m_queue[lLastInsert];
151 if (pdata != NULL)
152 return m_uiCount;
153
154 return 0;
155 }
156
157 long getmaxsize() const
158 {
159 return m_uiCount;
160 }
161
162 bool HasItem()
163 {
164 return m_bHasItem.test_and_set();
165 }
166
167 void SetItemFlagBack()
168 {
169 m_bHasItem.clear();
170 }
171
172 private:
173 long trycount() const
174 {
175 long lHeadIterator = m_lHeadIterator;
176 long lTailIterator = m_lTailIterator;
177
178 if (lTailIterator > lHeadIterator)
179 return m_uiCount - lTailIterator + lHeadIterator;
180
181 // This has a bug where it returns 0 if the queue is full.
182 return lHeadIterator - lTailIterator;
183 }
184
185 private:
186 std::atomic<long> m_lHeadIterator; // enqueue index
187 std::atomic<long> m_lTailIterator; // dequeue index
188 _TyData **m_queue; // array of pointers to the data
189 long m_uiCount; // size of the array
190 std::atomic_flag m_lEventSet = ATOMIC_FLAG_INIT; // a flag to use whether we should change the item flag
191 std::atomic_flag m_bHasItem = ATOMIC_FLAG_INIT; // a flag to indicate whether there is an item enqueued
192 };
193
194 #endif //INCLUDED_UTILS_LFRINGQUEUE
/*
* File: main.cpp
* Author: Peng
*
* Created on February 22, 2014, 9:55 PM
*/
#include <iostream>
#include <string>
#include "freedeque.h"
#include <sstream>
#include <boost/thread/thread.hpp>
#include <boost/lockfree/queue.hpp>
#include <boost/atomic.hpp>
#include<boost/thread/lock_guard.hpp>
#include<boost/thread/mutex.hpp>
#include<boost/date_time/posix_time/posix_time.hpp>
const int NUM_ENQUEUE_THREAD = 5;
const int NUM_DEQUEUE_THREAD = 10;
const long NUM_ITEM = 50000;
const long NUM_DATA = NUM_ENQUEUE_THREAD * NUM_ITEM;
class Data {
public:
Data(int i = 0) : m_iData(i)
{
std::stringstream ss;
ss << i;
m_szDataString = ss.str();
}
bool operator< (const Data & aData) const
{
if (m_iData < aData.m_iData)
return true;
else
return false;
}
int& GetData()
{
return m_iData;
}
private:
int m_iData;
std::string m_szDataString;
};
Data* g_arrData = new Data[NUM_DATA];
boost::mutex mtx;
constexpr long size = 0.5 * NUM_DATA;
lfringqueue < Data, 10000> LockFreeQueue;
boost::lockfree::queue<Data*> BoostQueue(10000);
bool GenerateRandomNumber_FindPointerToTheNumber_EnQueue(int n)
{
for (long i = 0; i < NUM_ITEM; i++)
{
int x = i + NUM_ITEM * n;
Data* pData = g_arrData + x;
LockFreeQueue.enqueue(pData);
}
return true;
}
void print(Data* pData) {
if (!pData)
return;
boost::lock_guard<boost::mutex> lock(mtx);
std::cout << pData->GetData() << std::endl;
}
bool Dequeue()
{
Data *pData = NULL;
while (true)
{
if (LockFreeQueue.dequeue(&pData) && pData)
{
print(pData);
}
else {
boost::thread::sleep(boost::get_system_time() + boost::posix_time::milliseconds(5));
}
}
return true;
}
int main(int argc, char** argv)
{
for (int i = 0; i < NUM_DATA; ++i)
{
Data data(i);
//DataArray[i] = data;
*(g_arrData + i) = data;
}
std::thread PublishThread[NUM_ENQUEUE_THREAD];
std::thread ConsumerThread[NUM_DEQUEUE_THREAD];
std::chrono::duration<double> elapsed_seconds;
for (int i = 0; i < NUM_ENQUEUE_THREAD; i++)
{
PublishThread[i] = std::thread(GenerateRandomNumber_FindPointerToTheNumber_EnQueue, i);
}
for (int i = 0; i < NUM_DEQUEUE_THREAD; i++)
{
ConsumerThread[i] = std::thread{ Dequeue };
}
for (int i = 0; i < NUM_DEQUEUE_THREAD; i++)
{
ConsumerThread[i].join();
}
for (int i = 0; i < NUM_ENQUEUE_THREAD; i++)
{
PublishThread[i].join();
}
delete[] g_arrData;
return 0;
}
说明：模板文件是原作者写的，为了验证其正确性，后面的测试程序我改写了一下，最后测试程序是无法退出来的，这里只是测试，没有进一步完善了。
在测试中发现deque应该是大小限制的，再增大data的数据程序会阻塞在某个地方没有进一步再查找原因了，以后有时候再做修改，对于一般的工程都够用了。
原文地址：https://www.cnblogs.com/hbright/p/9508032.html
时间： 2024-08-26 08:36:33