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Qt线程的简单使用--QReadWriteLock的用法_qt的读写锁怎么应用-CSDN博客
应用场景#xff1a;多个线程同时进行读操作。
比如#xff1a;100个线程进行读操作#xff0c;1个线程进行写操作。
示例1#xff1a;
#include QObject
#include
Qt线程的简单使用--QReadWriteLock的用法_qt的读写锁怎么应用-CSDN博客
应用场景多个线程同时进行读操作。
比如100个线程进行读操作1个线程进行写操作。
示例1
#include QObject
#include QThread
class Read_thread : public QThread
{Q_OBJECT
public:explicit Read_thread(QObject *parent nullptr);
protected:void run();
};class Write_thread : public QThread
{Q_OBJECT
public:explicit Write_thread(QObject *parent nullptr);
protected:void run();
};
#include QReadWriteLock
int counter0;
QReadWriteLock lock;void Read_thread::run()
{lock.lockForRead();for(int i0;i5;i){this-msleep(10);qDebug()Read_thread:QThread::currentThreadId() counter;}lock.unlock();
}
void Write_thread::run()
{lock.lockForWrite();for(int i0;i5;i){counter;this-msleep(10);qDebug()Write_thread:QThread::currentThreadId() counter;}lock.unlock();
}
Widget::Widget(QWidget *parent) :QWidget(parent),ui(new Ui::Widget)
{ui-setupUi(this);qDebug()main:QThread::currentThreadId();connect(this,SIGNAL(destroyed()),this,SLOT(quitThreadSlot()));tnew Read_thread(this);t-start();t1new Read_thread(this);t1-start();t2new Write_thread(this);t2-start();t3new Write_thread(this);t3-start();
}void Widget::quitThreadSlot()
{t1-quit();t1-wait();t-quit();t-wait();t2-quit();t2-wait();t3-quit();t3-wait();
}输出结果 main: 0x5a08 Read_thread: 0x4f30 0 Read_thread: 0x62d8 0 Read_thread: 0x4f30 0 Read_thread: 0x62d8 0 Read_thread: 0x62d8 0 Read_thread: 0x4f30 0 Read_thread: 0x4f30 0 Read_thread: 0x62d8 0 Read_thread: 0x4f30 0 Read_thread: 0x62d8 0 Write_thread: 0x339c 1 Write_thread: 0x339c 2 Write_thread: 0x339c 3 Write_thread: 0x339c 4 Write_thread: 0x339c 5 Write_thread: 0x60b0 6 Write_thread: 0x60b0 7 Write_thread: 0x60b0 8 Write_thread: 0x60b0 9 Write_thread: 0x60b0 10 分析结果 可以看到允许不同的线程同时读counter,这里就是在交替地读counter, 之后进行写操作不是交替进行的 而是先执行Write_thread: 0x339c 再执行Write_thread: 0x60b0。 即可以同时读不可以同时写。 示例2修改部分代码 tnew Read_thread(this);t-start();QThread::msleep(1000);t2new Write_thread(this);t2-start();t3new Write_thread(this);t3-start();t1new Read_thread(this);t1-start(); 输出结果 main: 0x5c84 Read_thread: 0xb60 0 Read_thread: 0xb60 0 Read_thread: 0xb60 0 Read_thread: 0xb60 0 Read_thread: 0xb60 0 Write_thread: 0x3aa0 1 Write_thread: 0x3aa0 2 Write_thread: 0x3aa0 3 Write_thread: 0x3aa0 4 Write_thread: 0x3aa0 5 Write_thread: 0x4788 6 Write_thread: 0x4788 7 Write_thread: 0x4788 8 Write_thread: 0x4788 9 Write_thread: 0x4788 10 Read_thread: 0x38b0 10 Read_thread: 0x38b0 10 Read_thread: 0x38b0 10 Read_thread: 0x38b0 10 Read_thread: 0x38b0 10 分析Read_thread: 0xb60先进行读操作 主线程阻塞1s Write_thread: 0x3aa0进行写操作 Write_thread:0x4788进行写操作 Read_thread: 0x38b0进行读操作 示例3QReadLocker和QWriteLocker的使用
void Read_thread::run()
{QReadLocker locker(lock);for(int i0;i5;i){this-msleep(10);qDebug()Read_thread:QThread::currentThreadId() counter;}
}void Write_thread::run()
{QWriteLocker locker(lock);for(int i0;i5;i){counter;this-msleep(10);qDebug()Write_thread:QThread::currentThreadId() counter;}
}这样写只是更简单了一些不需要再locked(),unlocked()了。
