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text append waits until hcitoo scan is finished

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  • JonBJ JonB

    @AnneRanch
    In addition to @ChrisW67's [and Now @SGaist too] excellent points, if you really want to write your code this way (it's not the Qt way) you could try putting qApp->processEvents() after each append() line, I think that will show your updates in the UI.

    J.HilkJ Offline
    J.HilkJ Offline
    J.Hilk
    Moderators
    wrote on last edited by
    #5

    @JonB don't hand out guns for people to shoot themselves with. It's easy enough in c++ 😜


    Be aware of the Qt Code of Conduct, when posting : https://forum.qt.io/topic/113070/qt-code-of-conduct


    Q: What's that?
    A: It's blue light.
    Q: What does it do?
    A: It turns blue.

    1 Reply Last reply
    1
    • SGaistS SGaist

      Hi,

      If you really want asynchronous handling, use QProcess rather than system.

      A Offline
      A Offline
      Anonymous_Banned275
      wrote on last edited by
      #6

      @ChrisW67As always, you are correct.
      So I found this example and it is sort of working.
      When I first run it I got "file not found" error - which was expected.
      (I think if I run this function only once , in push button event , I wdillw get the file erro back
      Now I have two problems - still getting the error BUT no longer includes the "file is missing message" . Then the hcitoll won't terminate and that gives another error.

      Printing the standard error..........

      QProcess: Destroyed while process ("hcitool") is still running.
      Form::ProcessCommand(QString command )

      . So I am not sure why hcotool won't terminate, but I think it is the dunction which won't finish the error message.
      Because it works just fine , without getting the full error when call the to function single.
      I really do not need to call all the commands in sequence as I am testin in now.

      So I'll work on the error.

      BTW
      How do I pass an empty "argument list ?
      .

      timer.start();
      

      // ProcessCommand("hcitool", {" "}); no arg list - does not work
      // ProcessCommand("hcitool",{ " "});
      ProcessCommand("hcitool",{ "dev"});
      ProcessCommand("hcitool", {"inq"});
      ProcessCommand("hcitool", {"scan "});

      Here is the current , UNDER CONSTRUCTION, version of the usage of QProcess

      int Form::ProcessCommand(QString Command, QStringList args  )
      {
          qDebug("Form::ProcessCommand(QString command ) ");
          std::cout<<"\n * Program to demonstrate the usage of linux commands in qt * \n";
          timer.elapsed();
          QString s = QString::number(timer.elapsed());
          s = "ProcessCommand START  elapsed time " + s;
          ui->textEdit_2->append(s);
          QProcess OProcess;
          //    QString Command;    //Contains the command to be executed
          //    QStringList args;   //Contains arguments of the command
          //    Command = "ls";
          //    args<<"-l"<<"/home/anil";
      
          OProcess.start(Command,args,QIODevice::ReadWrite); //Starts execution of command
          //QProcess.start(Command,)
          OProcess.waitForFinished();                       //Waits for execution to complete
      
          QString StdOut      =   OProcess.readAllStandardOutput();  //Reads standard output
          QString StdError    =   OProcess.readAllStandardError();   //Reads standard error
      
          std::cout<<"\n Printing the standard output..........\n";
          std::cout<<std::endl<<StdOut.toStdString();
          std::cout<<"\n Printing the standard error..........\n";
          std::cout<<std::endl<<StdError.toStdString();
      
          std::cout<<"\n\n";
          s = QString::number(timer.elapsed());
              s = "ProcessCommand END elapsed time " + s;
              ui->textEdit_2->append(s);
      
      
      
                  //system(Command.toStdString().c_str());  //>> log_file.txt);
                  return 0;
      };
      
      1 Reply Last reply
      0
      • SGaistS Offline
        SGaistS Offline
        SGaist
        Lifetime Qt Champion
        wrote on last edited by
        #7

        Using QProcess that way is more or less the same as calling system since you are blocking the event loop.

        Interested in AI ? www.idiap.ch
        Please read the Qt Code of Conduct - https://forum.qt.io/topic/113070/qt-code-of-conduct

        A 1 Reply Last reply
        0
        • A Offline
          A Offline
          Anonymous_Banned275
          wrote on last edited by
          #8

          My last post is little screwed-up.
          The error text is always executed and reason I do no have a real error - I did not add the "redirect " to file yet.

          Which is subject of this post

          1. what exactly is QIODevice as coded in an example ?

          2. QIODevice::Append append to file - so where in the "start" I add the file ?
            This adds file data to arg . Is that correct ?
            //Process.Start("cmd.exe", "/c foo.exe -arg >" + dumpDir + "\foo_arg.txt");

          3. How can I option to execute BOTH
            QIODevice::ReadWrite & QIODevice::Append)
            this did not work

          1 Reply Last reply
          0
          • SGaistS SGaist

            Using QProcess that way is more or less the same as calling system since you are blocking the event loop.

            A Offline
            A Offline
            Anonymous_Banned275
            wrote on last edited by
            #9

            @SGaist Good point, but it does not matter in my application. I am more concerned why I cannot run the function consecutively.
            Cheers

            1 Reply Last reply
            0
            • SGaistS Offline
              SGaistS Offline
              SGaist
              Lifetime Qt Champion
              wrote on last edited by
              #10
              1. it's the base class of QProcess
              2. No it's not, at best it will overwrite the file. If you want to append to a file in a shell you need to use >>
              3. You want to execute your process, then read the output it generated though QProcess API and then use a QFile to write what you want to the file. QProcess is not a full shell so the redirection that you try to use won't work.

              Interested in AI ? www.idiap.ch
              Please read the Qt Code of Conduct - https://forum.qt.io/topic/113070/qt-code-of-conduct

              A 1 Reply Last reply
              1
              • SGaistS SGaist
                1. it's the base class of QProcess
                2. No it's not, at best it will overwrite the file. If you want to append to a file in a shell you need to use >>
                3. You want to execute your process, then read the output it generated though QProcess API and then use a QFile to write what you want to the file. QProcess is not a full shell so the redirection that you try to use won't work.
                A Offline
                A Offline
                Anonymous_Banned275
                wrote on last edited by
                #11

                @SGaist It works as expected when I add the file redirection in "arg".
                I am back to need refresh course on "HCI".
                My process function is timing out because there is no response from "hcitool".
                I am really frustrated with this Bluetooth stuff - how low do I have to go to get it working / responding reliably and in time. I believe there is a spec somewhere to tell how long before the HCI commands timeout.

                I have no issue with local "dev" but it is the "scan" or "inq" which is killing the process .

                1 Reply Last reply
                0
                • C Offline
                  C Offline
                  ChrisW67
                  wrote on last edited by
                  #12

                  The blocking behaviour of hcitool is not a Qt problem. hcitool has options for controlling timeouts (at least the Bluez source code I am looking at does). However, you seem to be running something on Windows, so I have no idea what your hcittool really is.

                  Is there a reason that you are not using the Qt Bluetooth support?

                  A 1 Reply Last reply
                  0
                  • JamieghosalJ Offline
                    JamieghosalJ Offline
                    Jamieghosal
                    wrote on last edited by
                    #13

                    I am also facing some kind of erroneous things which I am sharing along with btconnect.h file -
                    This is my btconnect.h file

                    #ifndef BTCONNECT_H
                    #define BTCONNECT_H

                    #include "scandialog.h"

                    namespace Ui {
                    class BTConnect;
                    }

                    class BTConnect : public QWidget
                    {
                    Q_OBJECT

                    public:
                    explicit BTConnect(QWidget *parent = 0);
                    ~BTConnect();

                    private slots:
                    void on_ScanButton_clicked();

                    void ScanBTDevices();
                    
                    //some slots here
                    
                    void ScanDialogShow();
                    
                    void ScanDialogClose();
                    

                    public slots:
                    //some slots here

                    private:
                    Ui::BTConnect *ui;

                    QProcess BTscan_Process;
                    
                    scanDialog *scan;
                    

                    };

                    #endif // BTCONNECT_H
                    btconnect.cpp

                    BTConnect::BTConnect(QWidget *parent) :
                    QWidget(parent),
                    ui(new Ui::BTConnect)
                    {
                    //set the userinterface as BTConnect.ui
                    ui->setupUi(this);

                    scan = new scanDialog(this);
                    

                    }

                    void BTConnect::ScanDialogShow()
                    {
                    scan->show();
                    }

                    void BTConnect::ScanDialogClose()
                    {
                    scan->close();
                    }

                    void BTConnect::ScanBTDevices()
                    {
                    ScanDialogShow();

                    //Command to scan nearby bluetooth devices
                    //"hcitool scan"
                    QString cmd("hcitool scan");
                    
                    //start the process
                    BTscan_Process.start(cmd);
                    
                    //Wait for the processs to finish with a timeout of 20 seconds
                    if(BTscan_Process.waitForFinished(20000))
                    {
                        //Clear the list widget
                        this->ui->listWidget->clear();
                    
                        //Read the command line output and store it in QString out
                        QString out(BTscan_Process.readAllStandardOutput());
                    
                        //Split the QString every new line and save theve in a QStringList
                        QStringList OutSplit = out.split("\n");
                    
                        //Parse the QStringList in btCellsParser
                        btCellsParser cp(OutSplit);
                    
                        for(unsigned int i = 0; i<cp.count(); i++)
                        {
                           //writing in listwidget
                        }
                    
                    }
                    
                    ScanDialogClose();
                    

                    }

                    void BTConnect::on_ScanButton_clicked()
                    {
                    //Scan for available nearby bluetooth devices
                    ScanBTDevices();
                    }
                    if I use the above code, the qdialog scandialog does open when the process begins and closes when the data is loaded in qlistwidget, but the contents of qdialog scandialog are not displayed. If I were to change show() to exec(), the contents will be shown but the QProcess does not run until the dialog is closed.

                    I want the dialog to open when the Qprocess starts and close when the qlistwidget is loaded with data from the scan. And I want the contents of scandialog to be displayed. It has two labels. One with .GIF file and another with text saying scanning.

                    Any help is appreciated.

                    Answer - 1
                    0 arrow_circle_up 0 arrow_circle_down
                    The problem is that QDialog::exec and QProcess::waitForFinished functions block event loop. Never ever block event loop. So you just need to do things more asynchronously.

                    QProcess class can be handled asynchronously using signals like readReadStandardOutput. And QDialog can be shown asynchronously using open slot.

                    The example:

                    void ScanBTDevices() {
                    // Open dialog when process is started
                    connect(process, SIGNAL(started()), dialog, SLOT(open()));

                    // Read standard output asynchronously
                    connect(process, SIGNAL(readyReadStandardOutput()), SLOT(onReadyRead()));
                    
                    // Start process asynchronously (for example I use recursive ls)
                    process->start("ls -R /");
                    

                    }

                    void onReadyRead() {
                    // Write to list widget
                    dialog->appendText(QString(process->readAllStandardOutput()));
                    }
                    The data will be appended to the dialog during generating by process. Also using QProcess::finished signal and you can close the dialog.

                    by *
                    Answer - 2 verified
                    0 arrow_circle_up 0 arrow_circle_down
                    you never return to the event loop when you do show (because of waitForFinished) and you never continue to the processing code when you do exec

                    instead of the waitForFinished you should connect to the finished signal and handle it there and use a single shot timer that will cancel it:

                    void BTConnect::on_BTscanFinished()//new slot
                    {
                    //Clear the list widget
                    this->ui->listWidget->clear();

                    //Read the command line output and store it in QString out
                    QString out(BTscan_Process.readAllStandardOutput());
                    

                    After doing all of this I basically stuck on virtual onboarding software.
                    //Split the QString every new line and save theve in a QStringList
                    QStringList OutSplit = out.split("\n");

                    //Parse the QStringList in btCellsParser
                    btCellsParser cp(OutSplit);
                    
                    for(unsigned int i = 0; i<cp.count(); i++)
                    {
                       //writing in listwidget
                    }
                    ScanDialogClose();
                    

                    }

                    void BTConnect::ScanBTDevices()
                    {
                    ScanDialogShow();

                    //Command to scan nearby bluetooth devices
                    //"hcitool scan"
                    QString cmd("hcitool scan");
                    
                    //start the process
                    connect(BTscan_Process, SIGNAL(finished()), this, SLOT(on_BTscanFinished()));
                    BTscan_Process.start(cmd);
                    QTimer::singleShot(20000, scan, SLOT(close()));
                    

                    }

                    Hope this will properly help you.

                    Exactlly software is a leading software and solutions provider specializing in ERP, HRMS, CRM and PMS. The company operates globally through its operations in India, UAE, Oman, Singapore and Malaysia.

                    A 2 Replies Last reply
                    0
                    • JamieghosalJ Jamieghosal

                      I am also facing some kind of erroneous things which I am sharing along with btconnect.h file -
                      This is my btconnect.h file

                      #ifndef BTCONNECT_H
                      #define BTCONNECT_H

                      #include "scandialog.h"

                      namespace Ui {
                      class BTConnect;
                      }

                      class BTConnect : public QWidget
                      {
                      Q_OBJECT

                      public:
                      explicit BTConnect(QWidget *parent = 0);
                      ~BTConnect();

                      private slots:
                      void on_ScanButton_clicked();

                      void ScanBTDevices();
                      
                      //some slots here
                      
                      void ScanDialogShow();
                      
                      void ScanDialogClose();
                      

                      public slots:
                      //some slots here

                      private:
                      Ui::BTConnect *ui;

                      QProcess BTscan_Process;
                      
                      scanDialog *scan;
                      

                      };

                      #endif // BTCONNECT_H
                      btconnect.cpp

                      BTConnect::BTConnect(QWidget *parent) :
                      QWidget(parent),
                      ui(new Ui::BTConnect)
                      {
                      //set the userinterface as BTConnect.ui
                      ui->setupUi(this);

                      scan = new scanDialog(this);
                      

                      }

                      void BTConnect::ScanDialogShow()
                      {
                      scan->show();
                      }

                      void BTConnect::ScanDialogClose()
                      {
                      scan->close();
                      }

                      void BTConnect::ScanBTDevices()
                      {
                      ScanDialogShow();

                      //Command to scan nearby bluetooth devices
                      //"hcitool scan"
                      QString cmd("hcitool scan");
                      
                      //start the process
                      BTscan_Process.start(cmd);
                      
                      //Wait for the processs to finish with a timeout of 20 seconds
                      if(BTscan_Process.waitForFinished(20000))
                      {
                          //Clear the list widget
                          this->ui->listWidget->clear();
                      
                          //Read the command line output and store it in QString out
                          QString out(BTscan_Process.readAllStandardOutput());
                      
                          //Split the QString every new line and save theve in a QStringList
                          QStringList OutSplit = out.split("\n");
                      
                          //Parse the QStringList in btCellsParser
                          btCellsParser cp(OutSplit);
                      
                          for(unsigned int i = 0; i<cp.count(); i++)
                          {
                             //writing in listwidget
                          }
                      
                      }
                      
                      ScanDialogClose();
                      

                      }

                      void BTConnect::on_ScanButton_clicked()
                      {
                      //Scan for available nearby bluetooth devices
                      ScanBTDevices();
                      }
                      if I use the above code, the qdialog scandialog does open when the process begins and closes when the data is loaded in qlistwidget, but the contents of qdialog scandialog are not displayed. If I were to change show() to exec(), the contents will be shown but the QProcess does not run until the dialog is closed.

                      I want the dialog to open when the Qprocess starts and close when the qlistwidget is loaded with data from the scan. And I want the contents of scandialog to be displayed. It has two labels. One with .GIF file and another with text saying scanning.

                      Any help is appreciated.

                      Answer - 1
                      0 arrow_circle_up 0 arrow_circle_down
                      The problem is that QDialog::exec and QProcess::waitForFinished functions block event loop. Never ever block event loop. So you just need to do things more asynchronously.

                      QProcess class can be handled asynchronously using signals like readReadStandardOutput. And QDialog can be shown asynchronously using open slot.

                      The example:

                      void ScanBTDevices() {
                      // Open dialog when process is started
                      connect(process, SIGNAL(started()), dialog, SLOT(open()));

                      // Read standard output asynchronously
                      connect(process, SIGNAL(readyReadStandardOutput()), SLOT(onReadyRead()));
                      
                      // Start process asynchronously (for example I use recursive ls)
                      process->start("ls -R /");
                      

                      }

                      void onReadyRead() {
                      // Write to list widget
                      dialog->appendText(QString(process->readAllStandardOutput()));
                      }
                      The data will be appended to the dialog during generating by process. Also using QProcess::finished signal and you can close the dialog.

                      by *
                      Answer - 2 verified
                      0 arrow_circle_up 0 arrow_circle_down
                      you never return to the event loop when you do show (because of waitForFinished) and you never continue to the processing code when you do exec

                      instead of the waitForFinished you should connect to the finished signal and handle it there and use a single shot timer that will cancel it:

                      void BTConnect::on_BTscanFinished()//new slot
                      {
                      //Clear the list widget
                      this->ui->listWidget->clear();

                      //Read the command line output and store it in QString out
                      QString out(BTscan_Process.readAllStandardOutput());
                      

                      After doing all of this I basically stuck on virtual onboarding software.
                      //Split the QString every new line and save theve in a QStringList
                      QStringList OutSplit = out.split("\n");

                      //Parse the QStringList in btCellsParser
                      btCellsParser cp(OutSplit);
                      
                      for(unsigned int i = 0; i<cp.count(); i++)
                      {
                         //writing in listwidget
                      }
                      ScanDialogClose();
                      

                      }

                      void BTConnect::ScanBTDevices()
                      {
                      ScanDialogShow();

                      //Command to scan nearby bluetooth devices
                      //"hcitool scan"
                      QString cmd("hcitool scan");
                      
                      //start the process
                      connect(BTscan_Process, SIGNAL(finished()), this, SLOT(on_BTscanFinished()));
                      BTscan_Process.start(cmd);
                      QTimer::singleShot(20000, scan, SLOT(close()));
                      

                      }

                      Hope this will properly help you.

                      A Offline
                      A Offline
                      Anonymous_Banned275
                      wrote on last edited by
                      #14

                      @Jamieghosal Many thanks for the post. I am glad I found somebody who does "Bluetooth" coding.
                      Your post is a big help, however at this time I have to fix "updating" QT.
                      The example function is OK , but it still keep QT from updating until it is finished. I need to work on that first.

                      Speaking of Bluetooth - I am very often experiencing a total "screw-up" - even using commands running terminal won't work. The only "solution" is to switch / reboot to another OS _ I am, running multi-boot - all Ubuntu.

                      I really believe "bluez" is the worst application and it is "part of the Linux kernel" - hence I am trying to bypass it using HCI directly.

                      1 Reply Last reply
                      0
                      • C ChrisW67

                        The blocking behaviour of hcitool is not a Qt problem. hcitool has options for controlling timeouts (at least the Bluez source code I am looking at does). However, you seem to be running something on Windows, so I have no idea what your hcittool really is.

                        Is there a reason that you are not using the Qt Bluetooth support?

                        A Offline
                        A Offline
                        Anonymous_Banned275
                        wrote on last edited by
                        #15

                        @ChrisW67 Yes, QTBluetooth "support" won't even recognize that I turned Bluetooth off in OS - and happily reports "finished " - no error.
                        I did try at lest two versions of QTCreator with same result.
                        FYI _ I am using Ubuntu.

                        1 Reply Last reply
                        0
                        • JamieghosalJ Jamieghosal

                          I am also facing some kind of erroneous things which I am sharing along with btconnect.h file -
                          This is my btconnect.h file

                          #ifndef BTCONNECT_H
                          #define BTCONNECT_H

                          #include "scandialog.h"

                          namespace Ui {
                          class BTConnect;
                          }

                          class BTConnect : public QWidget
                          {
                          Q_OBJECT

                          public:
                          explicit BTConnect(QWidget *parent = 0);
                          ~BTConnect();

                          private slots:
                          void on_ScanButton_clicked();

                          void ScanBTDevices();
                          
                          //some slots here
                          
                          void ScanDialogShow();
                          
                          void ScanDialogClose();
                          

                          public slots:
                          //some slots here

                          private:
                          Ui::BTConnect *ui;

                          QProcess BTscan_Process;
                          
                          scanDialog *scan;
                          

                          };

                          #endif // BTCONNECT_H
                          btconnect.cpp

                          BTConnect::BTConnect(QWidget *parent) :
                          QWidget(parent),
                          ui(new Ui::BTConnect)
                          {
                          //set the userinterface as BTConnect.ui
                          ui->setupUi(this);

                          scan = new scanDialog(this);
                          

                          }

                          void BTConnect::ScanDialogShow()
                          {
                          scan->show();
                          }

                          void BTConnect::ScanDialogClose()
                          {
                          scan->close();
                          }

                          void BTConnect::ScanBTDevices()
                          {
                          ScanDialogShow();

                          //Command to scan nearby bluetooth devices
                          //"hcitool scan"
                          QString cmd("hcitool scan");
                          
                          //start the process
                          BTscan_Process.start(cmd);
                          
                          //Wait for the processs to finish with a timeout of 20 seconds
                          if(BTscan_Process.waitForFinished(20000))
                          {
                              //Clear the list widget
                              this->ui->listWidget->clear();
                          
                              //Read the command line output and store it in QString out
                              QString out(BTscan_Process.readAllStandardOutput());
                          
                              //Split the QString every new line and save theve in a QStringList
                              QStringList OutSplit = out.split("\n");
                          
                              //Parse the QStringList in btCellsParser
                              btCellsParser cp(OutSplit);
                          
                              for(unsigned int i = 0; i<cp.count(); i++)
                              {
                                 //writing in listwidget
                              }
                          
                          }
                          
                          ScanDialogClose();
                          

                          }

                          void BTConnect::on_ScanButton_clicked()
                          {
                          //Scan for available nearby bluetooth devices
                          ScanBTDevices();
                          }
                          if I use the above code, the qdialog scandialog does open when the process begins and closes when the data is loaded in qlistwidget, but the contents of qdialog scandialog are not displayed. If I were to change show() to exec(), the contents will be shown but the QProcess does not run until the dialog is closed.

                          I want the dialog to open when the Qprocess starts and close when the qlistwidget is loaded with data from the scan. And I want the contents of scandialog to be displayed. It has two labels. One with .GIF file and another with text saying scanning.

                          Any help is appreciated.

                          Answer - 1
                          0 arrow_circle_up 0 arrow_circle_down
                          The problem is that QDialog::exec and QProcess::waitForFinished functions block event loop. Never ever block event loop. So you just need to do things more asynchronously.

                          QProcess class can be handled asynchronously using signals like readReadStandardOutput. And QDialog can be shown asynchronously using open slot.

                          The example:

                          void ScanBTDevices() {
                          // Open dialog when process is started
                          connect(process, SIGNAL(started()), dialog, SLOT(open()));

                          // Read standard output asynchronously
                          connect(process, SIGNAL(readyReadStandardOutput()), SLOT(onReadyRead()));
                          
                          // Start process asynchronously (for example I use recursive ls)
                          process->start("ls -R /");
                          

                          }

                          void onReadyRead() {
                          // Write to list widget
                          dialog->appendText(QString(process->readAllStandardOutput()));
                          }
                          The data will be appended to the dialog during generating by process. Also using QProcess::finished signal and you can close the dialog.

                          by *
                          Answer - 2 verified
                          0 arrow_circle_up 0 arrow_circle_down
                          you never return to the event loop when you do show (because of waitForFinished) and you never continue to the processing code when you do exec

                          instead of the waitForFinished you should connect to the finished signal and handle it there and use a single shot timer that will cancel it:

                          void BTConnect::on_BTscanFinished()//new slot
                          {
                          //Clear the list widget
                          this->ui->listWidget->clear();

                          //Read the command line output and store it in QString out
                          QString out(BTscan_Process.readAllStandardOutput());
                          

                          After doing all of this I basically stuck on virtual onboarding software.
                          //Split the QString every new line and save theve in a QStringList
                          QStringList OutSplit = out.split("\n");

                          //Parse the QStringList in btCellsParser
                          btCellsParser cp(OutSplit);
                          
                          for(unsigned int i = 0; i<cp.count(); i++)
                          {
                             //writing in listwidget
                          }
                          ScanDialogClose();
                          

                          }

                          void BTConnect::ScanBTDevices()
                          {
                          ScanDialogShow();

                          //Command to scan nearby bluetooth devices
                          //"hcitool scan"
                          QString cmd("hcitool scan");
                          
                          //start the process
                          connect(BTscan_Process, SIGNAL(finished()), this, SLOT(on_BTscanFinished()));
                          BTscan_Process.start(cmd);
                          QTimer::singleShot(20000, scan, SLOT(close()));
                          

                          }

                          Hope this will properly help you.

                          A Offline
                          A Offline
                          Anonymous_Banned275
                          wrote on last edited by
                          #16

                          @Jamieghosal I think the basic "problem" is

                          OProcess.waitForFinished(60000);

                          I do not get how QT executes basic C function by "waiting" for it to return "true".
                          That basically blocks the rest of the code and I expect "process" not to do that.
                          So it back to finding out how to make "process" NOT to block the rest of the code. Long time ago I used QProgressBar and it is the time to try it again - I should be able to "update" the QProgressBar on each second - hence the QProcess needs to be convinced to do so.

                          SGaistS 1 Reply Last reply
                          0
                          • A Anonymous_Banned275

                            @Jamieghosal I think the basic "problem" is

                            OProcess.waitForFinished(60000);

                            I do not get how QT executes basic C function by "waiting" for it to return "true".
                            That basically blocks the rest of the code and I expect "process" not to do that.
                            So it back to finding out how to make "process" NOT to block the rest of the code. Long time ago I used QProgressBar and it is the time to try it again - I should be able to "update" the QProgressBar on each second - hence the QProcess needs to be convinced to do so.

                            SGaistS Offline
                            SGaistS Offline
                            SGaist
                            Lifetime Qt Champion
                            wrote on last edited by
                            #17

                            @AnneRanch QProcess is asynchronous as already explained. Learn how to use it that way.

                            Interested in AI ? www.idiap.ch
                            Please read the Qt Code of Conduct - https://forum.qt.io/topic/113070/qt-code-of-conduct

                            A 1 Reply Last reply
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                            • SGaistS SGaist

                              @AnneRanch QProcess is asynchronous as already explained. Learn how to use it that way.

                              A Offline
                              A Offline
                              Anonymous_Banned275
                              wrote on last edited by
                              #18

                              @SGaist And what do you think I am doing ? I do not need such comments.
                              Cheers

                              1 Reply Last reply
                              0
                              • SGaistS Offline
                                SGaistS Offline
                                SGaist
                                Lifetime Qt Champion
                                wrote on last edited by
                                #19

                                Well, you are using the blocking API, hence my suggestion. Stop doing that and use signals and slots to manage your QProcess object.

                                Make a list of the commands you want to execute. Pick the first, start it, then when it is done (use the finished signal to know), start the next on the list and so on until they are all done. No freeze will happen.

                                Interested in AI ? www.idiap.ch
                                Please read the Qt Code of Conduct - https://forum.qt.io/topic/113070/qt-code-of-conduct

                                A 1 Reply Last reply
                                3
                                • SGaistS SGaist

                                  Well, you are using the blocking API, hence my suggestion. Stop doing that and use signals and slots to manage your QProcess object.

                                  Make a list of the commands you want to execute. Pick the first, start it, then when it is done (use the finished signal to know), start the next on the list and so on until they are all done. No freeze will happen.

                                  A Offline
                                  A Offline
                                  Anonymous_Banned275
                                  wrote on last edited by
                                  #20

                                  @SGaist Tep, that is what I am doing and as usual I am stuck on "connect".
                                  Sure could use a real example of connect to get me going...
                                  This "wait for completion" sure was of no help to really understand QProcess...

                                  J.HilkJ 1 Reply Last reply
                                  0
                                  • SGaistS Offline
                                    SGaistS Offline
                                    SGaist
                                    Lifetime Qt Champion
                                    wrote on last edited by
                                    #21

                                    There's an example in the finished signal documentation using a lambda.
                                    There's a chapter dedicated to the explanation on how signal and slots work.

                                    Interested in AI ? www.idiap.ch
                                    Please read the Qt Code of Conduct - https://forum.qt.io/topic/113070/qt-code-of-conduct

                                    1 Reply Last reply
                                    1
                                    • A Anonymous_Banned275

                                      @SGaist Tep, that is what I am doing and as usual I am stuck on "connect".
                                      Sure could use a real example of connect to get me going...
                                      This "wait for completion" sure was of no help to really understand QProcess...

                                      J.HilkJ Offline
                                      J.HilkJ Offline
                                      J.Hilk
                                      Moderators
                                      wrote on last edited by
                                      #22

                                      @AnneRanch said in text append waits until hcitoo scan is finished:

                                      Tep, that is what I am doing and as usual I am stuck on "connect".
                                      Sure could use a real example of connect to get me going...
                                      This "wait for completion" sure was of no help to really understand QProcess...

                                      does this help?

                                      #ifndef HCITOOLPROCESS_H
                                      #define HCITOOLPROCESS_H
                                      
                                      #include <QObject>
                                      #include <QProcess>
                                      #include <QElapsedTimer>
                                      #include <iostream>
                                      
                                      class HciToolProcess : public QObject
                                      {
                                          Q_OBJECT
                                      public:
                                          enum HciCommands : uint8_t {
                                              Dev,
                                              Inq,
                                              Scan,
                                          };
                                      
                                          explicit HciToolProcess(QObject *parent = nullptr) : QObject(parent), m_currentCommand{HciCommands::Dev}
                                          {
                                              connect(&m_process, QOverload<int,QProcess::ExitStatus>::of(&QProcess::finished), this, &HciToolProcess::nextCommand);
                                          }
                                      
                                          bool startProcess(){
                                              if(m_currentCommand != HciCommands::Dev)
                                                  return false;
                                      
                                              m_elapsedTime.start();
                                      
                                              m_process.start(QStringLiteral("hcitool"), QStringList(HciCommandToString(m_currentCommand)), QIODevice::ReadWrite);
                                      
                                              return true;
                                          }
                                      
                                      signals:
                                          void timeElapsed(const QString &time); // to update your textEdit_2
                                          void allProcessesDone();
                                      
                                      private:
                                          void nextCommand(int exitCode, QProcess::ExitStatus exitStatus){
                                              std::cout<<"\n * Program to demonstrate the usage of linux commands in qt * \n";
                                      
                                              QString StdOut      =   m_process.readAllStandardOutput();  //Reads standard output
                                              QString StdError    =   m_process.readAllStandardError();   //Reads standard error
                                      
                                              std::cout<<"\n Printing the standard output..........\n";
                                              std::cout<<std::endl<<StdOut.toStdString();
                                              std::cout<<"\n Printing the standard error..........\n";
                                              std::cout<<std::endl<<StdError.toStdString();
                                              std::cout<<"\n Printing exit code..........\n";
                                              std::cout<<std::endl<<exitCode;
                                              std::cout<<"\n Printing exitStatus..........\n";
                                              std::cout<<std::endl<<exitStatus;
                                              std::cout<<"\n\n";
                                      
                                              QString elapsedTime = QString::number(m_elapsedTime.restart());
                                              emit timeElapsed(elapsedTime);
                                      
                                              m_currentCommand = static_cast<HciCommands>(m_currentCommand + 1);
                                              if(static_cast<uint8_t>(m_currentCommand) <= static_cast<uint8_t>(HciCommands::Scan)){
                                                  m_process.start(QStringLiteral("hcitool"), QStringList(HciCommandToString(m_currentCommand)), QIODevice::ReadWrite);
                                              } else {
                                                  m_currentCommand = HciCommands::Dev;
                                                  emit allProcessesDone();
                                              }
                                          }
                                      
                                          QString HciCommandToString( HciCommands cmd) {
                                              switch (cmd) {
                                              case HciCommands::Dev: return QStringLiteral("dev");
                                              case HciCommands::Inq: return QStringLiteral("inq");
                                              case HciCommands::Scan: return QStringLiteral("scan");
                                              default:
                                                  Q_UNREACHABLE();
                                                  return QLatin1String();
                                              }
                                          }
                                      
                                      private:
                                          QElapsedTimer m_elapsedTime;
                                          HciCommands m_currentCommand;
                                          QProcess m_process;
                                      };
                                      
                                      #endif // HCITOOLPROCESS_H
                                      
                                      

                                      Be aware of the Qt Code of Conduct, when posting : https://forum.qt.io/topic/113070/qt-code-of-conduct


                                      Q: What's that?
                                      A: It's blue light.
                                      Q: What does it do?
                                      A: It turns blue.

                                      JonBJ 1 Reply Last reply
                                      2
                                      • J.HilkJ J.Hilk

                                        @AnneRanch said in text append waits until hcitoo scan is finished:

                                        Tep, that is what I am doing and as usual I am stuck on "connect".
                                        Sure could use a real example of connect to get me going...
                                        This "wait for completion" sure was of no help to really understand QProcess...

                                        does this help?

                                        #ifndef HCITOOLPROCESS_H
                                        #define HCITOOLPROCESS_H
                                        
                                        #include <QObject>
                                        #include <QProcess>
                                        #include <QElapsedTimer>
                                        #include <iostream>
                                        
                                        class HciToolProcess : public QObject
                                        {
                                            Q_OBJECT
                                        public:
                                            enum HciCommands : uint8_t {
                                                Dev,
                                                Inq,
                                                Scan,
                                            };
                                        
                                            explicit HciToolProcess(QObject *parent = nullptr) : QObject(parent), m_currentCommand{HciCommands::Dev}
                                            {
                                                connect(&m_process, QOverload<int,QProcess::ExitStatus>::of(&QProcess::finished), this, &HciToolProcess::nextCommand);
                                            }
                                        
                                            bool startProcess(){
                                                if(m_currentCommand != HciCommands::Dev)
                                                    return false;
                                        
                                                m_elapsedTime.start();
                                        
                                                m_process.start(QStringLiteral("hcitool"), QStringList(HciCommandToString(m_currentCommand)), QIODevice::ReadWrite);
                                        
                                                return true;
                                            }
                                        
                                        signals:
                                            void timeElapsed(const QString &time); // to update your textEdit_2
                                            void allProcessesDone();
                                        
                                        private:
                                            void nextCommand(int exitCode, QProcess::ExitStatus exitStatus){
                                                std::cout<<"\n * Program to demonstrate the usage of linux commands in qt * \n";
                                        
                                                QString StdOut      =   m_process.readAllStandardOutput();  //Reads standard output
                                                QString StdError    =   m_process.readAllStandardError();   //Reads standard error
                                        
                                                std::cout<<"\n Printing the standard output..........\n";
                                                std::cout<<std::endl<<StdOut.toStdString();
                                                std::cout<<"\n Printing the standard error..........\n";
                                                std::cout<<std::endl<<StdError.toStdString();
                                                std::cout<<"\n Printing exit code..........\n";
                                                std::cout<<std::endl<<exitCode;
                                                std::cout<<"\n Printing exitStatus..........\n";
                                                std::cout<<std::endl<<exitStatus;
                                                std::cout<<"\n\n";
                                        
                                                QString elapsedTime = QString::number(m_elapsedTime.restart());
                                                emit timeElapsed(elapsedTime);
                                        
                                                m_currentCommand = static_cast<HciCommands>(m_currentCommand + 1);
                                                if(static_cast<uint8_t>(m_currentCommand) <= static_cast<uint8_t>(HciCommands::Scan)){
                                                    m_process.start(QStringLiteral("hcitool"), QStringList(HciCommandToString(m_currentCommand)), QIODevice::ReadWrite);
                                                } else {
                                                    m_currentCommand = HciCommands::Dev;
                                                    emit allProcessesDone();
                                                }
                                            }
                                        
                                            QString HciCommandToString( HciCommands cmd) {
                                                switch (cmd) {
                                                case HciCommands::Dev: return QStringLiteral("dev");
                                                case HciCommands::Inq: return QStringLiteral("inq");
                                                case HciCommands::Scan: return QStringLiteral("scan");
                                                default:
                                                    Q_UNREACHABLE();
                                                    return QLatin1String();
                                                }
                                            }
                                        
                                        private:
                                            QElapsedTimer m_elapsedTime;
                                            HciCommands m_currentCommand;
                                            QProcess m_process;
                                        };
                                        
                                        #endif // HCITOOLPROCESS_H
                                        
                                        
                                        JonBJ Online
                                        JonBJ Online
                                        JonB
                                        wrote on last edited by
                                        #23

                                        @J-Hilk
                                        I was thinking about writing something like this, but assumed the effort would be ignored.

                                        If you were to get rid of your enumeration/switch statement and instead create some list of the commands (plus parameters) to be used, which the caller passes/sets on the class, it would be a generic "execute any arbitrary list of commands sequentially" class.

                                        J.HilkJ 1 Reply Last reply
                                        0
                                        • JonBJ JonB

                                          @J-Hilk
                                          I was thinking about writing something like this, but assumed the effort would be ignored.

                                          If you were to get rid of your enumeration/switch statement and instead create some list of the commands (plus parameters) to be used, which the caller passes/sets on the class, it would be a generic "execute any arbitrary list of commands sequentially" class.

                                          J.HilkJ Offline
                                          J.HilkJ Offline
                                          J.Hilk
                                          Moderators
                                          wrote on last edited by J.Hilk
                                          #24

                                          @JonB sure, here ya go :D

                                          #ifndef HCITOOLPROCESS_H
                                          #define HCITOOLPROCESS_H
                                          
                                          #include <QObject>
                                          #include <QProcess>
                                          #include <QElapsedTimer>
                                          #include <iostream>
                                          
                                          class HciToolProcess : public QObject
                                          {
                                              Q_OBJECT
                                          public:
                                          
                                              struct CommandAndArguments{
                                                  QString command;
                                                  QStringList arguments;
                                              };
                                          
                                              explicit HciToolProcess(QObject *parent = nullptr) : QObject(parent), m_index{-1}
                                              {
                                                  connect(&m_process, QOverload<int,QProcess::ExitStatus>::of(&QProcess::finished), this, &HciToolProcess::onProcessFinished);
                                              }
                                          
                                              bool startProcess(QList<CommandAndArguments> commands){
                                                  if(m_index != -1 || commands.isEmpty())
                                                      return false;
                                          
                                                  m_cmdAndArgs = commands;
                                          
                                                  m_elapsedTime.start();
                                          
                                                  //m_index is -1 so the function will set it to 0
                                                  processCommandAndArguments();
                                          
                                                  return true;
                                              }
                                          
                                          signals:
                                              void timeElapsed(const QString &time); // to update your textEdit_2
                                              void allProcessesDone();
                                          
                                          private:
                                              void processCommandAndArguments(){
                                                  m_index++;
                                                  if(m_index < m_cmdAndArgs.size()){
                                                      m_process.start(m_cmdAndArgs.at(m_index).command, m_cmdAndArgs.at(m_index).arguments, QIODevice::ReadWrite);
                                                  } else {
                                                      m_index = -1;
                                                      emit allProcessesDone();
                                                  }
                                              }
                                          
                                              void onProcessFinished(int exitCode, QProcess::ExitStatus exitStatus){
                                                  std::cout<<"\n * Program to demonstrate the usage of linux commands in qt * \n";
                                          
                                                  QString StdOut      =   m_process.readAllStandardOutput();  //Reads standard output
                                                  QString StdError    =   m_process.readAllStandardError();   //Reads standard error
                                          
                                                  std::cout<<"\n Printing the standard output..........\n";
                                                  std::cout<<std::endl<<StdOut.toStdString();
                                                  std::cout<<"\n Printing the standard error..........\n";
                                                  std::cout<<std::endl<<StdError.toStdString();
                                                  std::cout<<"\n Printing exit code..........\n";
                                                  std::cout<<std::endl<<exitCode;
                                                  std::cout<<"\n Printing exitStatus..........\n";
                                                  std::cout<<std::endl<<exitStatus;
                                                  std::cout<<"\n\n";
                                          
                                                  QString elapsedTime = QString::number(m_elapsedTime.restart());
                                                  emit timeElapsed(elapsedTime);
                                          
                                                  processCommandAndArguments();
                                              }
                                          
                                          private:
                                              QElapsedTimer m_elapsedTime;
                                              QProcess m_process;
                                              QList<CommandAndArguments> m_cmdAndArgs;
                                              int32_t m_index;
                                          };
                                          
                                          #endif // HCITOOLPROCESS_H
                                          

                                          Be aware of the Qt Code of Conduct, when posting : https://forum.qt.io/topic/113070/qt-code-of-conduct


                                          Q: What's that?
                                          A: It's blue light.
                                          Q: What does it do?
                                          A: It turns blue.

                                          1 Reply Last reply
                                          3

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