尝试获取文件的 MD5 时 Qt 程序冻结

Posted 2023-02-16

【中文标题】尝试获取文件的 MD5 时 Qt 程序冻结

【英文标题】：Qt Program freeze when try to get MD5 of files

【发布时间】：2020-09-25 17:31:13

【问题描述】：

您好，我使用此代码在 QT 中生成文件的 MD5

QString Md5_gen(QString const &s)

    QString pakchunk_Md5;
    QCryptographicHash crypto(QCryptographicHash::Md5);
    QFile pakchunk("D:/Games/TDPA - Man of Medan" + s);
    if (pakchunk.open(QIODevice::ReadOnly))
    
        while(!pakchunk.atEnd())
        crypto.addData(pakchunk.read(8192));
        
     else
    
        qDebug() << "Can't open file.";
        pakchunk_Md5 = "nofile";
        return pakchunk_Md5;
    
    pakchunk_Md5 = crypto.result().toHex();
    return pakchunk_Md5;

我需要使用此代码生成 8 个大文件的 MD5 (1.5GB>) 问题是当我按下按钮开始生成 MD5 时，GUI 冻结直到所有 MD5生成 我用这种方式测试QFuture、QFutureWatcher、QtConcurrent，但是运气不好GUI还是每次都卡住

main.cpp

#include "user_def.h"
#include "mainwindow2.h"
#include...

QString Md5_gen(QString const &s)

    QString pakchunk_Md5;
    QCryptographicHash crypto(QCryptographicHash::Md5);
    QFile pakchunk("D:/Games/TDPA - Man of Medan" + s);
    if (pakchunk.open(QIODevice::ReadOnly))
    
        while(!pakchunk.atEnd())
        crypto.addData(pakchunk.read(8192));
        
     else
    
        qDebug() << "Can't open file.";
        pakchunk_Md5 = "nofile";
        return pakchunk_Md5;
    
    pakchunk_Md5 = crypto.result().toHex();
    return pakchunk_Md5;


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

  a.setStyle(new DarkStyle);

  FramelessWindow framelessWindow;
  framelessWindow.setWindowIcon(a.style()->standardIcon(QStyle::SP_DesktopIcon));

  MainWindow *mainWindow = new MainWindow;

  framelessWindow.setContent(mainWindow);
  framelessWindow.show();

  return a.exec();

user_def.h

#ifndef USER_DEF_H
#define USER_DEF_H
#include <QString>

QString Md5_gen(QString const &s);

#endif // USER_DEF_H

mainwindow2.h

#ifndef MAINWINDOW2_H
#define MAINWINDOW2_H

#include <QMainWindow>
#include <QtConcurrentRun>
#include <QFuture>
#include <QFutureWatcher>
#include <QThread>
#include <QThreadPool>
#include "user_def.h"

namespace Ui 
class MainWindow2;


class MainWindow2 : public QMainWindow

    Q_OBJECT

public:
    explicit MainWindow2(QWidget *parent = nullptr);
    ~MainWindow2();

public slots:
      void run_thread();
      void displayFinishedBox();

private slots:
    void on_pushButton_clicked();

private:
    Ui::MainWindow2 *ui;
    QFutureWatcher<QString> *watcher;
    QFuture<QString> *future;
;

#endif // MAINWINDOW2_H

mainwindow2.cpp

#include...

MainWindow2::MainWindow2(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow2)

    ui->setupUi(this);
    connect(ui->pushButton, &QPushButton::clicked,
               this, &MainWindow2::run_thread);


    // display a message box when the calculation has finished

    future = new QFuture<QString>;
    watcher = new QFutureWatcher<QString>;

    connect(watcher, SIGNAL(finished()),
            this, SLOT(displayFinishedBox()));



MainWindow2::~MainWindow2()

    delete ui;


void MainWindow2::run_thread()

    int file_ok = 0;
    //file pak33
    QString loc33 = "/SM/test1.pak";
    QFuture<QString> future33 = QtConcurrent::run(QThreadPool::globalInstance(), Md5_gen, loc33);
    watcher->setFuture(future33);
    QString pakchunk33 = future33.result();

    qDebug() << pakchunk33;
    if (pakchunk33 == "f7002d4419cd235a87746715ba6fb2ea")
    
        qDebug() << "OK";
        file_ok++;
        ui->label_8->setText("OK");
        ui->label_8->setStyleSheet("QLabel  color : green; ");
     else if (pakchunk33 == "nofile")
    
        qDebug() << "no file found";
        ui->label_8->setText("not found");
        ui->label_8->setStyleSheet("QLabel  color : red; ");
     else
    
        qDebug() << "file is diffrent";
        ui->label_8->setText("wrong");
        ui->label_8->setStyleSheet("QLabel  color : red; ");
    
    ui->progressBar->setValue(12);

    //file pak34
    QString loc34 = "/SM/test2.pak";
    QFuture<QString> future34 = QtConcurrent::run(QThreadPool::globalInstance(), Md5_gen, loc34);
    watcher->setFuture(future34);
    QString pakchunk34 = future34.result();
    qDebug() << pakchunk34;

    if (pakchunk34 == "64c77598586b6c3cb60beed0b0750620")
    
        qDebug() << "OK";
        file_ok++;
        ui->label->setText("OK");
        ui->label->setStyleSheet("QLabel  color : green; ");
     else if (pakchunk34 == "nofile")
    
        qDebug() << "no file found";
        ui->label->setText("not found");
        ui->label->setStyleSheet("QLabel  color : red; ");
     else
    
        qDebug() << "file is diffrent";
        ui->label->setText("wrong");
        ui->label->setStyleSheet("QLabel  color : red; ");
    
    ui->progressBar->setValue(25);

    //file pak35
    QString loc35 = "/SM/test3.pak";
    QFuture<QString> future35 = QtConcurrent::run(QThreadPool::globalInstance(), Md5_gen, loc35);
    watcher->setFuture(future35);
    QString pakchunk35 = future35.result();

    qDebug() << pakchunk35;
    if (pakchunk35 == "ee53f7a7656a32b5278c460baec46f16")
    
        qDebug() << "OK";
        file_ok++;
        ui->label_7->setText("OK");
        ui->label_7->setStyleSheet("QLabel  color : green; ");
     else if (pakchunk35 == "nofile")
    
        qDebug() << "no file found";
        ui->label_7->setText("not found");
        ui->label_7->setStyleSheet("QLabel  color : red; ");
     else
    
        qDebug() << "file is diffrent";
        ui->label_7->setText("wrong");
        ui->label_7->setStyleSheet("QLabel  color : red; ");
    
    ui->progressBar->setValue(38);

    /*Some other code*/

谁能说出我的问题是什么，我该如何解决？ 编辑 1

我以这种方式编辑我的代码 没有冻结gui它工作得很好 在编码方面这个代码是标准的吗？

mainwindow2.cpp

MainWindow2::MainWindow2(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow2)

    ui->setupUi(this);
    connect(ui->pushButton_3, &QPushButton::clicked, this, &MainWindow2::MD5_thread_1);

    future = new QFuture<QString>;
    watcher1 = new QFutureWatcher<QString>;
    watcher2 = new QFutureWatcher<QString>;
    watcher3 = new QFutureWatcher<QString>;

    connect(watcher1, &QFutureWatcher<QString>::finished, this, &MainWindow2::MD5_thread_2);
    connect(watcher2, &QFutureWatcher<QString>::finished, this, &MainWindow2::MD5_thread_3);
    connect(watcher3, &QFutureWatcher<QString>::finished, this, &MainWindow2::MD5_thread_4);
    //some other code


void MainWindow2::MD5_thread_1()

    ui->pushButton->setEnabled(false);
    ui->pushButton->setText("procces started");
    ui->pushButton->setStyleSheet("QPushButton  color : white; background-color: rgb(73, 80, 93); ");
    ui->label->setText("checking");
    ui->label_2->setText("checking");
    ui->label_3->setText("checking");
    ui->label_4->setText("checking");
    ui->label_5->setText("checking");
    ui->label_6->setText("checking");
    ui->label_7->setText("checking");
    ui->label_8->setText("checking");
    ui->label_14->setText("waiting for end of check");
    ui->progressBar->setRange(0, 100);
    ui->progressBar_2->setRange(0, 100);
    ui->progressBar->setValue(0);
    ui->progressBar_2->setValue(0);

    //file pak33
    QString loc33 = "/SMG0/editor.pak";
    *future= QtConcurrent::run(QThreadPool::globalInstance(), Md5_gen, loc33);
    watcher1->setFuture(*future);


void MainWindow2::MD5_thread_2()

    QString pakchunk33 = future->result();

    qDebug() << pakchunk33;
    if (pakchunk33 == "f7002d4419cd235a87746715ba6fb2ea")
    
        qDebug() << "OK";
        file_ok++;
        ui->label_8->setText("OK");
        ui->label_8->setStyleSheet("QLabel  color : green; ");
     else if (pakchunk33 == "nofile")
    
        qDebug() << "no file found";
        ui->label_8->setText("not found");
        ui->label_8->setStyleSheet("QLabel  color : red; ");
     else
    
        qDebug() << "file is diffrent";
        ui->label_8->setText("wrong");
        ui->label_8->setStyleSheet("QLabel  color : red; ");
    
    ui->progressBar->setValue(12);
    watcher1->deleteLater();

    //file pak34
    QString loc34 = "/SMG0/2Editor.pak";
    *future = QtConcurrent::run(QThreadPool::globalInstance(), Md5_gen, loc34);
    watcher2->setFuture(*future);


void MainWindow2::MD5_thread_3()

    QString pakchunk34 = future->result();
    qDebug() << pakchunk34;

    if (pakchunk34 == "64c77598586b6c3cb60beed0b0750620")
    
        qDebug() << "OK";
        file_ok++;
        ui->label->setText("OK");
        ui->label->setStyleSheet("QLabel  color : green; ");
     else if (pakchunk34 == "nofile")
    
        qDebug() << "no file found";
        ui->label->setText("not found");
        ui->label->setStyleSheet("QLabel  color : red; ");
     else
    
        qDebug() << "file is diffrent";
        ui->label->setText("wrong");
        ui->label->setStyleSheet("QLabel  color : red; ");
    
    ui->progressBar->setValue(25);
    watcher2->deleteLater();

    //file pak35
    QString loc35 = "/SMG0/3Editor.pak";
    *future = QtConcurrent::run(QThreadPool::globalInstance(), Md5_gen, loc35);
    watcher3->setFuture(*future);



void MainWindow2::core_install

    QString pakchunk35 = future->result();

    qDebug() << pakchunk40;
    if (pakchunk40 == "49e0440340044f424caeb82bade1301f")
    
        qDebug() << "OK";
        file_ok++;
        ui->label_2->setText("OK");
        ui->label_2->setStyleSheet("QLabel  color : green; ");
     else if (pakchunk40 == "nofile")
    
        qDebug() << "no file found";
        ui->label_2->setText("not found");
        ui->label_2->setStyleSheet("QLabel  color : red; ");
     else
    
        qDebug() << "file is diffrent";
        ui->label_2->setText("wrong");
        ui->label_2->setStyleSheet("QLabel  color : red; ");
    
    ui->progressBar->setValue(100);
    watcher3->deleteLater();

    //check if game is okey or not
    if (file_ok == 8)
    
        ui->label_14->setText("O");
        ui->label_14->setStyleSheet("QLabel  color : green; ");
     else
    
        ui->label_14->setText("X");
        ui->label_14->setStyleSheet("QLabel  color : red; ");
    

mainwindow2.h

#ifndef MAINWINDOW2_H
#define MAINWINDOW2_H

#include <QMainWindow>
#include <QtConcurrentRun>
#include <QFuture>
#include <QFutureWatcher>
#include <QThread>
#include <QThreadPool>
#include "user_def.h"

namespace Ui 
class MainWindow2;


class MainWindow2 : public QMainWindow

    Q_OBJECT

public:
    explicit MainWindow2(QWidget *parent = nullptr);
    ~MainWindow2();

public slots:
      void MD5_thread_1();
      void MD5_thread_2();
      void MD5_thread_3();
      void core_install();

private slots:
    void on_pushButton_clicked();

    void on_pushButton_2_clicked();

    void on_radioButton_2_clicked();

    void on_radioButton_4_clicked();

    void on_radioButton_3_clicked();

    void on_radioButton_clicked();

private:
    Ui::MainWindow2 *ui;
    QFutureWatcher<QString> *watcher1;
    QFutureWatcher<QString> *watcher2;
    QFutureWatcher<QString> *watcher3;
    QFuture<QString> *future;
    int file_ok = 0;
;

#endif // MAINWINDOW2_H

【问题讨论】：

这段代码可以工作，但是： 1) 它不是很容易维护：检查文件的代码重复了好几次，并且为这些文件进行了硬编码； 2）您使用的是 Qt4 信号槽语法； 3) 你失去了并行检查文件的能力。

我用新的 Qt 信号槽语法编辑了代码，还添加了watcher->deleteLater(); \你能指导我如何摆脱每个代码的代码吗？ ，以及关于并行检查如何修复代码以并行检查所有文件？谢谢

【参考方案1】：

result 方法阻塞了你的 UI 线程，使整个并发/未来的舞蹈毫无用处。

为每个未来创建一个观察者，并将其 finished 信号链接到一个 lambda，该 lambda 将文件名和结果内容传递给窗口上的 onHashCalculated 方法。在该方法中，您可以检查哈希是否与您的预定义哈希之一匹配，并更新 UI。

或者，将您当前的 run_thread 函数移动到在单独线程上运行的单独 QObject 中，并让它发出一个 hashCalculated(name, hash) 信号，您的主窗口使用类似于我上面描述的 onHashCalculated 槽订阅该信号.

这是封装这两种方法的 HashChecker 的代码。

注意静态 QMap 将文件名映射到哈希，doneFile 链接到 checkDone 的方式。

enum class Status  Ok, NotOk, Missing ;

class HashChecker : public QObject 
    Q_OBJECT

public:
    QMap<QString, Status> done;

    HashChecker(QObject *parent = nullptr) : QObject(parent) 
        QObject::connect(this, &HashChecker::doneFile, this, &HashChecker::checkDone);
    

    inline static const QMap<QString, QString> hashes = 
        "/SM/test1.pak", "f7002d4419cd235a87746715ba6fb2ea",
        "/SM/test2.pak", "64c77598586b6c3cb60beed0b0750620",
        "/SM/test3.pak", "ee53f7a7656a32b5278c460baec46f16",
    ;

signals:
    void finished();
    void doneFile(const QString& fname, Status s);

private slots:
    void checkDone(const QString& fname, Status s) 
        done[fname] = s;
        if (done.size() == hashes.size())
            emit finished();
    

public slots:
    void check_parallel() 
        for (auto it = hashes.cbegin(); it != hashes.cend(); it++) 
            auto fname = it.key();
            auto hash = it.value();

            QFuture<Status> fut = QtConcurrent::run(do_hash, fname, hash);
            QFutureWatcher<Status> *fw = new QFutureWatcher<Status>(this);
            fw->setFuture(fut);
            QObject::connect(fw, &QFutureWatcher<Status>::finished, this,
                    [=]() 
                    fw->deleteLater();
                    emit doneFile(fname, fut.result());
            );
        
    

    void check_sequential() 
        for (auto it = hashes.cbegin(); it != hashes.cend(); it++) 
            auto fname = it.key();
            auto hash = it.value();

            auto result = do_hash(fname, hash);
            emit doneFile(fname, result);
        
    
;

如果要并行检查文件：

HashChecker *hc = new HashChecker();
QObject::connect(hc, &HashChecker::doneFile, this, &MainWindow2::onHashCalculated);
hc->check_parallel();

不同线程中的顺序几乎相同：

QThread *t = new QThread(this);
HashChecker *hc = new HashChecker();
hc->moveToThread(t);
QObject::connect(t, &QThread::started, hc, &HashChecker::check_sequential);
QObject::connect(hc, &HashChecker::doneFile, this, &MainWindow2::onHashCalculated);
QObject::connect(hc, &HashChecker::finished, t, &QThread::quit);
t->start();

【讨论】：

要等到星期一，现在不能用电脑。

这只是一个我自己定义但忘记添加的枚举。现在添加。

这些是Status 值的三个可接受值。请参阅enum class

上的文档

例如，是的。或者你可以在它周围写一个包装器来检查提供的哈希值和计算出来的哈希值。

我在测试时没有看到那个错误信息，但是你需要在你的main函数中do what it says。您可能还需要致电Q_DECLARE_METATYPE(Status)