代码之家 › 专栏 › 技术社区 › Erik Johnson

将qmutex添加到类后“尝试引用已删除的函数”

qmutex qt5 qt c++

Erik Johnson · 技术社区 · 7 年前

我正在用qt5构建一个应用程序。我的程序构建和运行良好,但访问数据结构的两个线程之间存在冲突。我有一个canmessage对象的qlist,我想使用qmutex保护其中的一些数据。但是,一旦我将qmutex添加到类定义中,就会出现错误:

QList.h: `error: C2280: 
'CanMessage::CanMessage(const CanMessage &)': attempting to reference a deleted function`.

这是我的 canmessage.h 文件:

#ifndef CANMESSAGE_H
#define CANMESSAGE_H

#include <QObject>
#include <QMutex>
#include "cansignal.h"

class CanMessage
{
public:
    CanMessage();
    /* snip - public function prototypes */

private:
    /* snip - private prototypes and data */
    QMutex m_messageMutex;
};

#endif // CANMESSAGE_H

和 cansignal.h 以下内容:

#ifndef CANSIGNAL_H
#define CANSIGNAL_H

#include <QObject>
#include <QDebug>
#include <QByteArray>

class CanSignal
{
public:
    CanSignal();

    CanSignal(QString &signalName, quint8 &signalLength, quint8 &signalStartBit,
                   float &offset, float &factor, bool &isBigEndian, bool &isFloat, bool &isSigned)
    {
        this->m_name = signalName;
        this->m_length = signalLength;
        this->m_startBit = signalStartBit;
        this->m_offset = offset;
        this->m_factor = factor;
        this->m_isBigEndian = isBigEndian;
        this->m_isFloat = isFloat;
        this->m_isSigned = isSigned;
    }

    bool setName(QString &signalName);
    bool setBitLength(quint8 &length);
    bool setStartBit(quint8 &startBit);
    bool setOffset(float &offset);
    bool setFactor(float &factor);
    bool setEndianess(bool &isBigEndian);
    bool setIsFloat(bool &isFloat);
    bool setIsSigned(bool &isSigned);
    void setValid();
    void setInvalid();
    void setEngineeringData(float data);

    QString getName();
    quint8 getBitLength();
    quint8 getStartBit();
    float getOffset();
    float getFactor();
    float getData();
    bool isBigEndian();
    bool isFloat();
    bool isSigned();
    bool getSignalValidity();


private:
    QString m_name;
    quint8 m_length;
    quint8 m_startBit;
    float m_offset;
    float m_factor;
    float m_data_float = 0;
    bool m_isBigEndian;
    bool m_isFloat;
    bool m_isSigned;
    // Set After everything in signal is filled
    bool m_isSignalValid = false;
};

#endif // CANSIGNAL_H

1 回复 | 直到 7 年前

cbuchart 7 年前

CanMessage::CanMessage(const CanMessage &)

是复制构造函数,显然用于将项放入列表中。从那以后就没用了 QMutex 事实上

CanMessage 所以它有一个动态互斥体(当然是在构造函数中创建的)。

来源目标对象中的互斥体。

不 (a)

下面的代码是一个显示问题的完整的简单代码段,如果您离开 QMutex m_mutex;

#include <QList>
#include <QMutex>

#include <iostream>

class Xyzzy {
private:
    int m_xyzzy;
    //QMutex m_mutex;
public:
    Xyzzy() : m_xyzzy(0) {};
    Xyzzy(int val) : m_xyzzy(val) {};
};

int main() {
    QList<Xyzzy> myList;
    Xyzzy plugh;
    myList.push_back(plugh);
    return 0;
}

一旦你

 error: use of deleted function 'Xyzzy::Xyzzy(const Xyzzy&)'

在解决问题方面,您可以执行以下操作:

#include <QList>
#include <QMutex>

#include <iostream>

class Xyzzy {
private:
    int m_xyzzy;
    QMutex *m_mutex; // Now a pointer
public:
    Xyzzy() : m_xyzzy(0) {
        m_mutex = new QMutex(); // Need to create in constructor.
        std::cout << "constructor " << m_mutex << '\n';
    };
    ~Xyzzy() {
        std::cout << "destructor " << m_mutex << '\n';
        delete m_mutex; // Need to delete in destructor.
    }
    Xyzzy(const Xyzzy &old) {
        old.m_mutex->lock();
        m_mutex = new QMutex(); // Need to make new one here.
        std::cout << "copy constructor from " << old.m_mutex
                  << " to " << m_mutex << '\n';
        old.m_mutex->unlock();
    }
};

int main() {
    QList<Xyzzy> myList;
    Xyzzy plugh;
    myList.push_back(plugh);
    return 0;
}

constructor 0x21c9e50
copy constructor from 0x21c9e50 to 0x21c9ec0
destructor 0x21c9e50
destructor 0x21c9ec0

new/delete Xyzzy &operator=(const Xyzzy &old)