Qt：用 __thread 关键字让每个线程有自己的全局变量

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本文链接：https://blog.csdn.net/wsj18808050/article/details/51603006
在GUN标准中，提供了__thread关键字，配合static后，可以实现让一个线程拥有自己的全局变量。

我对__thread进行了简单的封装，可以用于存储class。并且防止了内存泄露（如果使用Qt线程类）。

测试中，我一共开启了两个线程，从输出可以得知每个线程都拥有自己的变量，并且在线程退出后被正常释放。

测试代码：

// Qt lib import
#include <QtCore>
#include <QtConcurrent>

class MyClass
{
public:
MyClass()
{
qDebug() << "MyClass" << this << QThread::currentThread();
}

~MyClass()
{
qDebug() << "~MyClass" << this << QThread::currentThread();
}
};

template< class T >
class ThreadStore
{
public:
T &getQuote()
{
if ( !t )
{
t = new T;

auto thread = qobject_cast< QThread * >( QThread::currentThread() );
if ( thread && thread->isRunning() )
{
QObject::connect( QThread::currentThread(), &QThread::finished, [ this ]()
{
if ( t )
{
delete t;
t = nullptr;
}
} );
}
}

return *t;
}

private:
T *t;
};

int main(int argc, char *argv[])
{
QCoreApplication a(argc, argv);

auto myTest = []()
{
static __thread ThreadStore< MyClass > threadStore;

auto &myData = threadStore.getQuote();

qDebug() << "myData:" << &myData;

QThread::sleep( 1 );
};

QThreadPool::globalInstance()->setMaxThreadCount( 2 );

QtConcurrent::run( myTest );
QtConcurrent::run( myTest );
QtConcurrent::run( myTest );
QtConcurrent::run( myTest );

QThreadPool::globalInstance()->waitForDone();

return a.exec();
}
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输出结果：

MyClass 0x7fe842e09b10 QThread(0x7fe842d0cbe0, name = "Thread (pooled)")
MyClass 0x7fe842c1d6a0 QThread(0x7fe842d0df60, name = "Thread (pooled)")
myData: 0x7fe842e09b10
myData: 0x7fe842c1d6a0
myData: 0x7fe842e09b10
myData: 0x7fe842c1d6a0
~MyClass 0x7fe842e09b10 QThread(0x7fe842d0cbe0, name = "Thread (pooled)")
~MyClass 0x7fe842c1d6a0 QThread(0x7fe842d0df60, name = "Thread (pooled)")
————————————————
版权声明：本文为CSDN博主「Jason188080501」的原创文章，遵循 CC 4.0 BY-SA 版权协议，转载请附上原文出处链接及本声明。
原文链接：https://blog.csdn.net/wsj18808050/article/details/51603006