1. 引用进阶
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| #include <iostream>
#include <vector>
using namespace std;
class Student {
private:
string info = "AAA";
public:
string getInfo() {
return this->info;
}
public:
string & getInfo_front() {
return this->info;
}
};
int main() {
Student student;
student.getInfo() = "九阳神功";
string result = student.getInfo();
cout << "第一种情况:" << result << endl;
student.getInfo_front() = "三分归元气";
result = student.getInfo_front();
cout << "第二种情况:" << result << endl;
}
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2. thread
thread是C++ 11引入的一个线程类，主要也是封装pthread类，用起来更简单，但是阉割了部分功能，日常开发中主要还是使用pthread。
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| #include <iostream>
#include <thread>
#include <unistd.h>
using namespace std;
void runAction(int number) {
for (int i = 0; i < 10; ++i) {
cout << "runAction：" << number << endl;
sleep(1);
}
}
int main() {
thread thread2(runAction, 100);
thread2.join();
cout << "main弹栈了" << endl;
return 0;
}
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3. pthread用法
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| #include <iostream>
#include <pthread.h> // Cygwin 有 pthreads支持
using namespace std;
void * customPthreadTask(void * pVoid) {
int * number = static_cast<int *>(pVoid);
cout << "异步线程执行了:" << *number << endl;
return 0;
}
int main() {
int number = 9527;
pthread_t pthreadID;
pthread_create(&pthreadID, 0, customPthreadTask, &number);
return 0;
}
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4. pthread的三种状态
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#include <iostream>
#include <pthread.h> // Derry Cygwin 有 pthreads支持
#include <unistd.h>
using namespace std;
void * runTask(void * pVoid) {
int number = *static_cast<int *>(pVoid);
cout << "异步线程执行了:" << number << endl;
for (int i = 0; i < 10; ++i) {
cout << "run:" << i << endl;
sleep(1);
}
return 0;
}
int main() {
int number = 999;
pthread_t pthreadID;
pthread_create(&pthreadID, 0, runTask, &number);
pthread_join(pthreadID, 0);
cout << "main函数即将弹栈..." << endl;
return 0;
}
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5. 分离线程与非分离线程区别
- 分离线程： 各个线程都是自己运行自己的，老死不相往来，例如：main函数结束，全部结束，不会等待异步线程 【多线程独立计算情况下场景】
- 非分离线程： 线程有协作的能力，例如：main函数线程会等待 异步线程执行完成后，我再执行 后面main函数的代码【协作，顺序执行 场景】
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| #include <iostream>
#include <pthread.h> // Derry Cygwin 有 pthreads支持
#include <unistd.h>
using namespace std;
void * runTask(void * pVoid) {
int number = *static_cast<int *>(pVoid);
cout << "异步线程执行了:" << number << endl;
for (int i = 0; i < 10; ++i) {
cout << "run:" << i << endl;
sleep(1);
}
return 0;
}
int main() {
int number = 999;
pthread_t pthreadID;
pthread_create(&pthreadID, 0, runTask, &number);
pthread_join(pthreadID, 0);
cout << "main函数即将弹栈..." << endl;
return 0;
}
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6. 互斥锁
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| #include <iostream>
#include <pthread.h>
#include <queue>
#include <unistd.h> // sleep（秒）
using namespace std;
queue<int> queueData;
pthread_mutex_t mutex;
void *task(void *pVoid) {
pthread_mutex_lock(&mutex);
cout << "异步线程-当前线程的标记是:" << *static_cast<int *>(pVoid) << "异步线程" << endl;
if (!queueData.empty()) {
printf("异步线程-获取队列的数据:%d\n", queueData.front());
queueData.pop();
} else {
printf("异步线程-队列中没有数据了\n");
}
sleep(0.2);
pthread_mutex_unlock(&mutex);
return 0;
}
int main() {
pthread_mutex_init(&mutex, NULL);
for (int i = 10001; i < 10011; ++i) {
queueData.push(i);
}
pthread_t pthreadIDArray[10];
for (int i = 0; i < 10; ++i) {
pthread_create(&pthreadIDArray[i], 0, task, &i);
}
sleep(12);
pthread_mutex_destroy(&mutex);
cout << "main函数即将弹栈..." << endl;
return 0;
}
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7. 多线程通知机制实现生产者消费者模型
建立一个队列，在get()，set()方法中使用互斥锁对队列存元素和元素进行加锁。
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|
#ifndef CPPCLIONPROJECT_SAFE_QUEUE_TOO_H
#define CPPCLIONPROJECT_SAFE_QUEUE_TOO_H
#endif
#pragma once
#include <iostream>
#include <string>
#include <pthread.h>
#include <string>
#include <queue>
using namespace std;
template<typename T>
class SafeQueueClass {
private:
queue<T> queue;
pthread_mutex_t mutex;
pthread_cond_t cond;
public:
SafeQueueClass() {
pthread_mutex_init(&mutex, 0);
pthread_cond_init(&cond, 0);
}
~SafeQueueClass() {
pthread_mutex_destroy(&mutex);
pthread_cond_destroy(&cond);
}
void add(T t) {
pthread_mutex_lock(&mutex);
queue.push(t);
pthread_cond_broadcast(&cond);
cout << "add queue.push 我已经notifyAll所有等待线程了" << endl;
pthread_mutex_unlock(&mutex);
}
void get(T & t) {
pthread_mutex_lock(&mutex);
while (queue.empty()) {
cout << "get empty 我已经乖乖等待中.." << endl;
pthread_cond_wait(&cond, &mutex);
}
t = queue.front();
queue.pop();
pthread_mutex_unlock(&mutex);
}
};
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| #pragma once
#include <iostream>
#include "safe_queue_too.h"
using namespace std;
SafeQueueClass<int> sq;
void * getMethod(void *) {
while (true) {
printf("getMethod\n");
int value;
sq.get(value);
printf("消费者get 得到的数据:%d\n", value);
if (-1 == value) {
printf("消费者get 全部执行完毕\n");
break;
}
}
return 0;
}
void * setMethod(void *) {
while (true) {
printf("setMethod\n");
int value;
printf("请输入你要生成的信息:\n");
cin >> value;
if (-1 == value) {
sq.add(value);
printf("消费者get 全部执行完毕\n");
break;
}
sq.add(value);
}
return 0;
}
int main() {
pthread_t pthreadGet;
pthread_create(&pthreadGet, 0, getMethod, 0);
pthread_t pthreadSet;
pthread_create(&pthreadSet, 0, setMethod, 0);
pthread_join(pthreadGet, 0);
pthread_join(pthreadSet, 0);
return 0;
}
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