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> Le Sunday 18 November 2007, Marcel Wiesweg a =E9crit :
> > I have a bit more for you:
> > For testing, I have added this call to the UI thread, before the worker
> > thread starts.
> >
> > >From the worker thread, when the call is executed again, I then get
> > > about 8 of
> >
> > these error messages:
> >
> > QObject: Cannot create children for a parent that is in a different
> > thread. (Parent is Solid::Backends::Hal::HalDevice(0x83f4f88), parent's
> > thread is QThread(0x82e33f8), current thread is
> > Digikam::ScanController(0x83ddbc0)
>
> Once again, would you mind making a test case for this?

The attached test case is an attempt to isolate the Solid code that was=20
causing the problem. The part is copied from digikam source without change.=
=20
With this case, I can reproduce the "Cannot create children for a parent th=
at=20
is in a different thread" problem; this is caused when the call is executed=
=20
in two threads at the same time. If you exchange the two lines t.start() an=
d=20
t.solid(), then it does not occur.

I have not been able to reproduce the original few-seconds-lockup problem w=
ith=20
this testcase though. I don't know what is needed to trigger this.
In the meantime, I have worked around the problem by moving the actual Soli=
d=20
call to the main thread with a blocking queued signal in digikam, so it's n=
ot=20
causing trouble at the moment.

>
> I can't seem to reproduce your issues.
>
> Now just curious, why do you use a thread in the first place? If that's
> only for a call to Device::list* that looks like overkill.

It's a worker thread that initializes the database and scans the collection=
=2E=20
To find out which parts of the collection are available, it needs to know t=
he=20
hardware situation. The UI thread is displaying progress info in the time.

Marcel

>
> Regards.



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#include <QThread>
#include <QDebug>
#include <QApplication>
#include <QList>

#include "kapplication.h"

#include <solid/device.h>
#include <solid/deviceinterface.h>
#include <solid/deviceinterface.h>
#include <solid/devicenotifier.h>
#include <solid/storageaccess.h>
#include <solid/storagedrive.h>
#include <solid/storagevolume.h>
#include <solid/opticaldisc.h>
#include <solid/predicate.h>


class SolidVolumeInfo
{
public:
    QString path; // mount path of volume, with trailing slash
    QString uuid; // UUID as from Solid
    QString label; // volume label (think of CDs)
    bool isRemovable; // may be removed
    bool isOpticalDisc;

    bool isNull() const { return path.isNull(); }
};

class Thread : public QThread
{
public:

    Thread()
    {
    }

    void run()
    {
        solid();
    }

    void solid()
    {
        QList<SolidVolumeInfo> volumes;
        qDebug() << "Starting list operation";
        QList<Solid::Device> devices = Solid::Device::listFromType(Solid::DeviceInterface::StorageAccess);
        qDebug() << "got listFromType" << endl;

        foreach(Solid::Device accessDevice, devices)
        {
            // check for StorageAccess
            if (!accessDevice.is<Solid::StorageAccess>())
                continue;

            Solid::StorageAccess *access = accessDevice.as<Solid::StorageAccess>();

            if (!access->isAccessible())
                continue;

            // check for StorageDrive
            Solid::Device driveDevice;
            for (Solid::Device currentDevice = accessDevice; currentDevice.isValid(); currentDevice = currentDevice.parent())
            {
                if (currentDevice.is<Solid::StorageDrive>())
                {
                    driveDevice = currentDevice;
                    break;
                }
            }
            if (!driveDevice.isValid())
                continue;

            Solid::StorageDrive *drive = driveDevice.as<Solid::StorageDrive>();

            // check for StorageVolume
            Solid::Device volumeDevice;
            for (Solid::Device currentDevice = accessDevice; currentDevice.isValid(); currentDevice = currentDevice.parent())
            {
                if (currentDevice.is<Solid::StorageVolume>())
                {
                    volumeDevice = currentDevice;
                    break;
                }
            }
            if (!volumeDevice.isValid())
                continue;

            Solid::StorageVolume *volume = volumeDevice.as<Solid::StorageVolume>();

            SolidVolumeInfo info;
            info.path = access->filePath();
            if (!info.path.endsWith("/"))
                info.path += "/";
            info.uuid = volume->uuid();
            info.label = volume->label();
            info.isRemovable = drive->isRemovable();
            info.isOpticalDisc = volumeDevice.is<Solid::OpticalDisc>();

            volumes << info;
        }
    }
};

int main(int argc, char **argv)
{
    QApplication app(argc, argv);

    Thread t;

    t.start();
    t.solid();

    QEventLoop l;
    l.exec();
}

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PROJECT(testsolid)
FIND_PACKAGE(KDE4 REQUIRED)
INCLUDE_DIRECTORIES( ${KDE4_INCLUDES} )

SET(KDE4ProjectSources testsolid.cpp )

KDE4_ADD_EXECUTABLE(testsolid ${KDE4ProjectSources} )

TARGET_LINK_LIBRARIES(testsolid ${KDE4_KDECORE_LIBS} ${KDE4_KDEUI_LIBS} ${KDE4_SOLID_LIBS} )
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