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List:       kde-devel
Subject:    Re: KProcess and KPart
From:       Gary Cramblitt <garycramblitt () comcast ! net>
Date:       2003-08-09 1:57:44
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On Thu, 7 Aug 2003 19:28:09 -0400
Gary Cramblitt <garycramblitt@comcast.net> wrote:

> I need some suggestions for a problem I've having involving KProcess and
> KParts.  I've written a KPart that uses KProcess to start a child
> process when user clicks a play button.  User can click stop button and
> I call KProcess->kill() to stop the child process.  All this is working
> great.  Here's the problem.  If user clicks play to start the child
> process, then closes my part without clicking stop button, I need to
> call KProcess->kill() to stop the child process.  I tried putting
> KProcess->kill() in my part's destructor but this doesn't work.  Another
> thread here explained that KProcess has a helper object called
> KProcessController.  When my part's destructor is called, KProcessController
> has already been destroyed, so I can't call KProcess->kill().
> 
> To work around this problem, I need some way for my kpart to know that
> the part is closing before object destruction begins.  So my question
> is: How can a KPart know that it is about to exit?  A normal KMainWindow
> gets a queryClose() event, but KParts do not receive this.  Whatever
> method I use needs to work whether user clicks File | Close on the menu,
> or clicks back button in Konqueror, or clicks the close button in the
> control box.

Here's a temporary solution I've come up with, but it still would be
better to have a chance to kill the child process BEFORE objects start
getting destroyed.  Can anyone help me please?

kspeakPart::~kspeakPart()
{
    if (m_process != NULL)
    {
        // TODO: Bug in KProcess (KDE 3.1-11).  When this destructor is called, the
        // KProcessController has already been destroyed, therefore, the following
        // statement accomplishes nothing.
        if (m_process->isRunning())
            m_process->kill(SIGTERM);
        
        // We have to terminate the child ourselves and wait for an exit status.
        // This solution is less than optimal because it still leaves a kdeinit process
        // running.
        pid_t pid = m_process->pid();
        if (pid)
        {
            int status;
            kill(pid, SIGTERM);
            waitpid(pid, &status, 0);
        }
        
        // When a KProcess is destroyed, it sends a SIGKILL to the child process.
        // In our case, that won't stop speaking, because the signal handler in child process
        // won't get a chance to signal the grandchild processes.
        delete m_process;
    }
}

 
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