QCA::SyncThread

#include <QtCrypto>

Inheritance diagram for QCA::SyncThread:

[legend]

Public Member Functions
	SyncThread (QObject *parent=nullptr)

	~SyncThread () override

QVariant	call (QObject obj, const QByteArray &method, const QVariantList &args=QVariantList(), bool ok=nullptr)

void	start ()

void	stop ()

Public Member Functions inherited from QThread
	QThread (QObject *parent)

virtual bool	event (QEvent *event) override

QAbstractEventDispatcher *	eventDispatcher () const const

void	exit (int returnCode)

void	finished ()

bool	isFinished () const const

bool	isInterruptionRequested () const const

bool	isRunning () const const

int	loopLevel () const const

Priority	priority () const const

void	quit ()

void	requestInterruption ()

void	setEventDispatcher (QAbstractEventDispatcher *eventDispatcher)

void	setPriority (Priority priority)

void	setStackSize (uint stackSize)

uint	stackSize () const const

void	start (Priority priority)

void	started ()

void	terminate ()

bool	wait (QDeadlineTimer deadline)

bool	wait (unsigned long time)

Public Member Functions inherited from QObject
	QObject (QObject *parent)

QBindable< QString >	bindableObjectName ()

bool	blockSignals (bool block)

const QObjectList &	children () const const

QMetaObject::Connection	connect (const QObject sender, const char signal, const char *method, Qt::ConnectionType type) const const

void	deleteLater ()

void	destroyed (QObject *obj)

bool	disconnect (const char signal, const QObject receiver, const char *method) const const

bool	disconnect (const QObject receiver, const char method) const const

void	dumpObjectInfo () const const

void	dumpObjectTree () const const

QList< QByteArray >	dynamicPropertyNames () const const

virtual bool	eventFilter (QObject watched, QEvent event)

T	findChild (const QString &name, Qt::FindChildOptions options) const const

QList< T >	findChildren (const QRegularExpression &re, Qt::FindChildOptions options) const const

QList< T >	findChildren (const QString &name, Qt::FindChildOptions options) const const

QList< T >	findChildren (Qt::FindChildOptions options) const const

bool	inherits (const char *className) const const

void	installEventFilter (QObject *filterObj)

bool	isQuickItemType () const const

bool	isWidgetType () const const

bool	isWindowType () const const

void	killTimer (int id)

virtual const QMetaObject *	metaObject () const const

void	moveToThread (QThread *targetThread)

QString	objectName () const const

void	objectNameChanged (const QString &objectName)

QObject *	parent () const const

QVariant	property (const char *name) const const

	Q_CLASSINFO (Name, Value)

	Q_EMIT Q_EMIT

	Q_ENUM (...)

	Q_ENUM_NS (...)

	Q_ENUMS (...)

	Q_FLAG (...)

	Q_FLAG_NS (...)

	Q_FLAGS (...)

	Q_GADGET Q_GADGET

	Q_GADGET_EXPORT (EXPORT_MACRO)

	Q_INTERFACES (...)

	Q_INVOKABLE Q_INVOKABLE

	Q_MOC_INCLUDE Q_MOC_INCLUDE

	Q_NAMESPACE Q_NAMESPACE

	Q_NAMESPACE_EXPORT (EXPORT_MACRO)

	Q_OBJECT Q_OBJECT

	Q_PROPERTY (...)

	Q_REVISION Q_REVISION

	Q_SET_OBJECT_NAME (Object)

	Q_SIGNAL Q_SIGNAL

	Q_SIGNALS Q_SIGNALS

	Q_SLOT Q_SLOT

	Q_SLOTS Q_SLOTS

T	qobject_cast (const QObject *object)

T	qobject_cast (QObject *object)

	QT_NO_NARROWING_CONVERSIONS_IN_CONNECT QT_NO_NARROWING_CONVERSIONS_IN_CONNECT

void	removeEventFilter (QObject *obj)

void	setObjectName (const QString &name)

void	setObjectName (QAnyStringView name)

void	setParent (QObject *parent)

bool	setProperty (const char *name, const QVariant &value)

bool	setProperty (const char *name, QVariant &&value)

bool	signalsBlocked () const const

int	startTimer (int interval, Qt::TimerType timerType)

int	startTimer (std::chrono::milliseconds interval, Qt::TimerType timerType)

QThread *	thread () const const

Protected Member Functions
virtual void	atEnd ()=0

virtual void	atStart ()=0

void	run () override

Protected Member Functions inherited from QThread
int	exec ()

Protected Member Functions inherited from QObject
virtual void	childEvent (QChildEvent *event)

virtual void	connectNotify (const QMetaMethod &signal)

virtual void	customEvent (QEvent *event)

virtual void	disconnectNotify (const QMetaMethod &signal)

bool	isSignalConnected (const QMetaMethod &signal) const const

int	receivers (const char *signal) const const

QObject *	sender () const const

int	senderSignalIndex () const const

virtual void	timerEvent (QTimerEvent *event)

Related Symbols
(Note that these are not member symbols.)
QCA_EXPORT bool	invokeMethodWithVariants (QObject obj, const QByteArray &method, const QVariantList &args, QVariant ret, Qt::ConnectionType type=Qt::AutoConnection)

QCA_EXPORT int	methodReturnType (const QMetaObject *obj, const QByteArray &method, const QList< QByteArray > &argTypes)

Additional Inherited Members
Public Types inherited from QThread
enum	Priority

Properties inherited from QObject
	objectName

Static Public Member Functions inherited from QThread
QThread *	create (Function &&f, Args &&... args)

QThread *	currentThread ()

Qt::HANDLE	currentThreadId ()

int	idealThreadCount ()

void	msleep (unsigned long msecs)

void	sleep (std::chrono::nanoseconds nsecs)

void	sleep (unsigned long secs)

void	usleep (unsigned long usecs)

void	yieldCurrentThread ()

Static Public Member Functions inherited from QObject
QMetaObject::Connection	connect (const QObject sender, const char signal, const QObject receiver, const char method, Qt::ConnectionType type)

QMetaObject::Connection	connect (const QObject sender, const QMetaMethod &signal, const QObject receiver, const QMetaMethod &method, Qt::ConnectionType type)

QMetaObject::Connection	connect (const QObject sender, PointerToMemberFunction signal, const QObject context, Functor functor, Qt::ConnectionType type)

QMetaObject::Connection	connect (const QObject sender, PointerToMemberFunction signal, const QObject receiver, PointerToMemberFunction method, Qt::ConnectionType type)

QMetaObject::Connection	connect (const QObject *sender, PointerToMemberFunction signal, Functor functor)

bool	disconnect (const QMetaObject::Connection &connection)

bool	disconnect (const QObject sender, const char signal, const QObject receiver, const char method)

bool	disconnect (const QObject sender, const QMetaMethod &signal, const QObject receiver, const QMetaMethod &method)

bool	disconnect (const QObject sender, PointerToMemberFunction signal, const QObject receiver, PointerToMemberFunction method)

QString	tr (const char sourceText, const char disambiguation, int n)

Public Attributes inherited from QThread
	HighestPriority

	HighPriority

	IdlePriority

	InheritPriority

	LowestPriority

	LowPriority

	NormalPriority

	TimeCriticalPriority

Public Attributes inherited from QObject
typedef	QObjectList

Static Protected Member Functions inherited from QThread
void	setTerminationEnabled (bool enabled)

Detailed Description

Convenience class to run a thread and interact with it synchronously.

SyncThread makes it easy to perform the common practice of starting a thread, running some objects in that thread, and then interacting with those objects safely. Often, there is no need to directly use threading primitives (e.g. QMutex), resulting in very clean multi-threaded code.

Note: The following is an excerpt from http://delta.affinix.com/2006/11/13/synchronized-threads-part-3/

—
With SyncThread, you can start, stop, and call a method in another thread while the main thread sleeps. The only requirement is that the methods be declared as slots.

Below is a contrived example, where we have an object in another thread that increments a counter over a some interval, using the Qt event loop, and provides a method to inspect the value.

First, the Counter object:

class Counter : public QObject
{
    Q_OBJECT
private:
    int x;
    QTimer timer;
 
public:
    Counter() : timer(this)
    {
        x = 0;
        connect(&timer, &QTimer::timeout, this, &Counter::t_timeout);
    }
 
public slots:
    void start(int seconds)
    {
        timer.setInterval(seconds * 1000);
        timer.start();
    }
 
    int value() const
    {
        return x;
    }
 
private Q_SLOTS:
    void t_timeout()
    {
        ++x;
    }
};

Looks like a typical object, no surprises.

Now to wrap Counter with SyncThread. We went over how to do this in the first article, and it is very straightforward:

class CounterThread : public SyncThread
{
    Q_OBJECT
public:
    Counter *counter;
 
    CounterThread(QObject *parent) : SyncThread(parent)
    {
        counter = 0;
    }
 
    ~CounterThread()
    {
        // SyncThread will stop the thread on destruct, but since our
        //   atStop() function makes references to CounterThread's
        //   members, we need to shutdown here, before CounterThread
        //   destructs.
        stop();
    }
 
protected:
    virtual void atStart()
    {
        counter = new Counter;
    }
 
    virtual void atStop()
    {
        delete counter;
    }
};

We can then use it like this:

CounterThread *thread = new CounterThread;
 
// after this call, the thread is started and the Counter is ready
thread->start();
 
// let's start the counter with a 1 second interval
thread->call(thread->counter, "start", QVariantList() << 1);
...
 
// after some time passes, let's check on the value
int x = thread->call(thread->counter, "value").toInt();
 
// we're done with this thing
delete thread;

Even without the call() function, SyncThread is still very useful for preparing objects in another thread, which you can then QObject::connect() to and use signals and slots like normal.

Definition at line 279 of file qca_support.h.

Constructor & Destructor Documentation

◆ SyncThread()

QCA::SyncThread::SyncThread ( QObject * parent = nullptr )

Standard constructor.

Parameters

parent the parent object for this parent.

◆ ~SyncThread()

QCA::SyncThread::~SyncThread ( )

override

Calls stop() and then destructs.

Note: Subclasses should call stop() in their own destructor

Member Function Documentation

◆ atEnd()

virtual void QCA::SyncThread::atEnd ( )

protectedpure virtual

Reimplement this to perform your deinitialization.

◆ atStart()

virtual void QCA::SyncThread::atStart ( )

protectedpure virtual

Reimplement this to perform your initialization.

◆ call()

QVariant QCA::SyncThread::call	(	QObject *	obj,
		const QByteArray &	method,
		const QVariantList &	args = QVariantList(),
		bool *	ok = nullptr )

Calls a slot of an object in the thread.

This function will block until the slot has returned.

It is possible for the call to fail, for example if the method does not exist.

The arguments and return value of the call use QVariant. If the method has no return value (returns void), then the returned QVariant will be null.

Parameters

obj	the object to call the method on
method	the name of the method (without the arguments or brackets)
args	the list of arguments to use in the method call
ok	if not 0, true is stored here if the call succeeds, otherwise false is stored here.

◆ run()

void QCA::SyncThread::run ( )

overrideprotectedvirtual

Starts the event loop and calls atStart and atStop as necessary.

Reimplemented from QThread.

◆ start()

void QCA::SyncThread::start ( )

Starts the thread, begins the event loop the thread, and then calls atStart() in the thread.

This function will block until atStart() has returned.

◆ stop()

void QCA::SyncThread::stop ( )

Stops the event loop of the thread, calls atStop() in the thread, and instructs the thread to finish.

This function will block until the thread has finished.

Friends And Related Symbol Documentation

◆ invokeMethodWithVariants()

QCA_EXPORT bool invokeMethodWithVariants	(	QObject *	obj,
		const QByteArray &	method,
		const QVariantList &	args,
		QVariant *	ret,
		Qt::ConnectionType	type = Qt::AutoConnection )

Convenience method to invoke a method by name, using a variant list of arguments.

This function can be used as shown:

class TestClass : public QObject
{
    Q_OBJECT
    // ...
public slots:
    QString qstringMethod()  { return QString( "the result" ); };
    bool boolMethod( const QString & )  { return true; };
};
 
TestClass *testClass = new TestClass;
QVariantList args;
 
QVariant stringRes;
// calls testClass->qstringMethod() with no arguments ( since args is an empty list)
bool ret = QCA::invokeMethodWithVariants( testClass, QByteArray( "qstringMethod" ), args, &stringRes );
// ret is true (since call succeeded), stringRes.toString() is a string - "the result"
 
QVariant boolResult;
QString someString( "not important" );
args << someString;
// calls testClass->boolMethod( someString ), returning result in boolResult
ret = QCA::invokeMethodWithVariants( testClass1, QByteArray( "boolMethod" ), args, &boolResult );
// ret is true (since call succeeded), boolResult.toBool() is true.

Parameters

obj	the object to call the method on
method	the name of the method (without the arguments or brackets)
args	the list of arguments to use in the method call
ret	the return value of the method (unchanged if the call fails)
type	the type of connection to use

Returns: true if the call succeeded, otherwise false

◆ methodReturnType()

QCA_EXPORT int methodReturnType	(	const QMetaObject *	obj,
		const QByteArray &	method,
		const QList< QByteArray > &	argTypes )

Convenience method to determine the return type of a method.

This function identifies the return type of a specified method. This function can be used as shown:

class TestClass : public QObject
{
    Q_OBJECT
    // ...
public slots:
    QString qstringMethod()  { return QString(); };
    bool boolMethod( const QString & )  { return true; };
};
 
QByteArray myTypeName;
 
TestClass testClass;
QList<QByteArray> argsList; // empty list, since no args
 
myTypeName = QCA::methodReturnType( testClass.metaObject(), QByteArray( "qstringMethod" ), argsList );
// myTypeName is "QString"
 
myTypeName = QCA::methodReturnType( testClass.metaObject(), QByteArray( "boolMethod" ), argsList );
// myTypeName is "", because there is no method called "boolMethod" that has no arguments
 
argsList << "QString"; // now we have one argument
myTypeName = QCA::methodReturnType( testClass.metaObject(), QByteArray( "boolMethod" ), argsList );
// myTypeName is "bool"

The return type name of a method returning void is an empty string, not "void"

Note: This function is not normally required for use with QCA. It is provided for use in your code, if required.

Parameters

obj	the QMetaObject for the object
method	the name of the method (without the arguments or brackets)
argTypes	the list of argument types of the method

Returns: the name of the type that this method will return with the specified argument types.

See also: QMetaType for more information on the Qt meta type system.

The documentation for this class was generated from the following file:

qca_support.h

KDE's Doxygen guidelines are available online.

Class Picker

Quick Links

About QCA

QCA::SyncThread

Public Member Functions

Protected Member Functions

Related Symbols

Additional Inherited Members

Detailed Description

Constructor & Destructor Documentation

◆ SyncThread()

◆ ~SyncThread()

Member Function Documentation

◆ atEnd()

◆ atStart()

◆ call()

◆ run()

◆ start()

◆ stop()

Friends And Related Symbol Documentation

◆ invokeMethodWithVariants()

◆ methodReturnType()