QSessionManager Class Reference

The QSessionManager class provides access to the session manager. More...

#include <qsessionmanager.h>

Inheritance diagram for QSessionManager:

Public Types
enum	RestartHint { RestartIfRunning, RestartAnyway, RestartImmediately, RestartNever }
	This enum type defines the circumstances under which this application wants to be restarted by the session manager. More...

Public Functions
bool	allowsErrorInteraction ()
	Returns true if error interaction is permitted; otherwise returns false. More...
bool	allowsInteraction ()
	Asks the session manager for permission to interact with the user. More...
void	cancel ()
	Tells the session manager to cancel the shutdown process. More...
QStringList	discardCommand () const
	Returns the currently set discard command. More...
void *	handle () const
bool	isPhase2 () const
	Returns true if the session manager is currently performing a second session management phase; otherwise returns false. More...
void	release ()
	Releases the session manager's interaction semaphore after an interaction phase. More...
void	requestPhase2 ()
	Requests a second session management phase for the application. More...
QStringList	restartCommand () const
	Returns the currently set restart command. More...
RestartHint	restartHint () const
	Returns the application's current restart hint. More...
QString	sessionId () const
	Returns the identifier of the current session. More...
QString	sessionKey () const
	Returns the session key in the current session. More...
void	setDiscardCommand (const QStringList &)
	Sets the discard command to the given list. More...
void	setManagerProperty (const QString &name, const QString &value)
	Low-level write access to the application's identification and state records are kept in the session manager. More...
void	setManagerProperty (const QString &name, const QStringList &value)
	Low-level write access to the application's identification and state record are kept in the session manager. More...
void	setRestartCommand (const QStringList &)
	If the session manager is capable of restoring sessions it will execute command in order to restore the application. More...
void	setRestartHint (RestartHint)
	Sets the application's restart hint to hint. More...
Public Functions inherited from QObject
bool	blockSignals (bool b)
	If block is true, signals emitted by this object are blocked (i.e., emitting a signal will not invoke anything connected to it). More...
const QObjectList &	children () const
	Returns a list of child objects. More...
bool	connect (const QObject *sender, const char *signal, const char *member, Qt::ConnectionType type=Qt::AutoConnection) const
bool	disconnect (const char *signal=0, const QObject *receiver=0, const char *member=0)
bool	disconnect (const QObject *receiver, const char *member=0)
void	dumpObjectInfo ()
	Dumps information about signal connections, etc. More...
void	dumpObjectTree ()
	Dumps a tree of children to the debug output. More...
QList< QByteArray >	dynamicPropertyNames () const
	Returns the names of all properties that were dynamically added to the object using setProperty(). More...
virtual bool	event (QEvent *)
	This virtual function receives events to an object and should return true if the event e was recognized and processed. More...
virtual bool	eventFilter (QObject *, QEvent *)
	Filters events if this object has been installed as an event filter for the watched object. More...
template<typename T >
T	findChild (const QString &aName=QString()) const
	Returns the child of this object that can be cast into type T and that is called name, or 0 if there is no such object. More...
template<typename T >
QList< T >	findChildren (const QString &aName=QString()) const
	Returns all children of this object with the given name that can be cast to type T, or an empty list if there are no such objects. More...
template<typename T >
QList< T >	findChildren (const QRegExp &re) const
bool	inherits (const char *classname) const
	Returns true if this object is an instance of a class that inherits className or a QObject subclass that inherits className; otherwise returns false. More...
void	installEventFilter (QObject *)
	Installs an event filter filterObj on this object. More...
bool	isWidgetType () const
	Returns true if the object is a widget; otherwise returns false. More...
void	killTimer (int id)
	Kills the timer with timer identifier, id. More...
virtual const QMetaObject *	metaObject () const
	Returns a pointer to the meta-object of this object. More...
void	moveToThread (QThread *thread)
	Changes the thread affinity for this object and its children. More...
QString	objectName () const
QObject *	parent () const
	Returns a pointer to the parent object. More...
QVariant	property (const char *name) const
	Returns the value of the object's name property. More...
Q_INVOKABLE	QObject (QObject *parent=0)
	Constructs an object with parent object parent. More...
void	removeEventFilter (QObject *)
	Removes an event filter object obj from this object. More...
void	setObjectName (const QString &name)
void	setParent (QObject *)
	Makes the object a child of parent. More...
bool	setProperty (const char *name, const QVariant &value)
	Sets the value of the object's name property to value. More...
void	setUserData (uint id, QObjectUserData *data)
bool	signalsBlocked () const
	Returns true if signals are blocked; otherwise returns false. More...
int	startTimer (int interval)
	Starts a timer and returns a timer identifier, or returns zero if it could not start a timer. More...
QThread *	thread () const
	Returns the thread in which the object lives. More...
QObjectUserData *	userData (uint id) const
virtual	~QObject ()
	Destroys the object, deleting all its child objects. More...

Private Functions
	QSessionManager (QApplication *app, QString &id, QString &key)
	~QSessionManager ()

Friends
class	QApplication
class	QApplicationPrivate
class	QBaseApplication

Additional Inherited Members
Public Slots inherited from QObject
void	deleteLater ()
	Schedules this object for deletion. More...
Signals inherited from QObject
void	destroyed (QObject *=0)
	This signal is emitted immediately before the object obj is destroyed, and can not be blocked. More...
Static Public Functions inherited from QObject
static bool	connect (const QObject *sender, const char *signal, const QObject *receiver, const char *member, Qt::ConnectionType=Qt::AutoConnection)
	Creates a connection of the given type from the signal in the sender object to the method in the receiver object. More...
static bool	connect (const QObject *sender, const QMetaMethod &signal, const QObject *receiver, const QMetaMethod &method, Qt::ConnectionType type=Qt::AutoConnection)
static bool	disconnect (const QObject *sender, const char *signal, const QObject *receiver, const char *member)
	Disconnects signal in object sender from method in object receiver. More...
static bool	disconnect (const QObject *sender, const QMetaMethod &signal, const QObject *receiver, const QMetaMethod &member)
static uint	registerUserData ()
static QString	tr (const char *sourceText, const char *comment=0, int n=-1)
static QString	trUtf8 (const char *sourceText, const char *comment=0, int n=-1)
Static Public Variables inherited from QObject
static const QMetaObject	staticMetaObject
	This variable stores the meta-object for the class. More...
Protected Functions inherited from QObject
virtual void	childEvent (QChildEvent *)
	This event handler can be reimplemented in a subclass to receive child events. More...
virtual void	connectNotify (const char *signal)
	This virtual function is called when something has been connected to signal in this object. More...
virtual void	customEvent (QEvent *)
	This event handler can be reimplemented in a subclass to receive custom events. More...
virtual void	disconnectNotify (const char *signal)
	This virtual function is called when something has been disconnected from signal in this object. More...
	QObject (QObjectPrivate &dd, QObject *parent=0)
int	receivers (const char *signal) const
	Returns the number of receivers connected to the signal. More...
QObject *	sender () const
	Returns a pointer to the object that sent the signal, if called in a slot activated by a signal; otherwise it returns 0. More...
int	senderSignalIndex () const
virtual void	timerEvent (QTimerEvent *)
	This event handler can be reimplemented in a subclass to receive timer events for the object. More...
Protected Variables inherited from QObject
QScopedPointer< QObjectData >	d_ptr
Static Protected Variables inherited from QObject
static const QMetaObject	staticQtMetaObject
Related Functions inherited from QObject
T	qFindChildqFindChildren (const QObject *obj, const QString &name)()
QList< T >	qFindChildrenqFindChildren (const QObject *obj, const QString &name)()
QList< T >	qFindChildrenqFindChildren (const QObject *obj, const QRegExp &regExp)()
T *	qobject_cast (QObject *object)
	QObjectList
void *	qt_find_obj_child (QObject *parent, const char *type, const QString &name)
	Returns a pointer to the object named name that inherits type and with a given parent. More...

Detailed Description

The QSessionManager class provides access to the session manager.

A session manager in a desktop environment (in which Qt GUI applications live) keeps track of a session, which is a group of running applications, each of which has a particular state. The state of an application contains (most notably) the documents the application has open and the position and size of its windows.

The session manager is used to save the session, e.g., when the machine is shut down, and to restore a session, e.g., when the machine is started up. We recommend that you use QSettings to save an application's settings, for example, window positions, recently used files, etc. When the application is restarted by the session manager, you can restore the settings.

QSessionManager provides an interface between the application and the session manager so that the program can work well with the session manager. In Qt, session management requests for action are handled by the two virtual functions QApplication::commitData() and QApplication::saveState(). Both provide a reference to a session manager object as argument, to allow the application to communicate with the session manager. The session manager can only be accessed through these functions.

No user interaction is possible unless the application gets explicit permission from the session manager. You ask for permission by calling allowsInteraction() or, if it is really urgent, allowsErrorInteraction(). Qt does not enforce this, but the session manager may.

You can try to abort the shutdown process by calling cancel(). The default commitData() function does this if some top-level window rejected its closeEvent().

For sophisticated session managers provided on Unix/X11, QSessionManager offers further possibilities to fine-tune an application's session management behavior: setRestartCommand(), setDiscardCommand(), setRestartHint(), setProperty(), requestPhase2(). See the respective function descriptions for further details.

See also

QApplication, {Session Management}

Definition at line 60 of file qsessionmanager.h.

Enumerations

RestartHint

enum QSessionManager::RestartHint

This enum type defines the circumstances under which this application wants to be restarted by the session manager.

The current values are:

• RestartIfRunning If the application is still running when the session is shut down, it wants to be restarted at the start of the next session.

• RestartAnyway The application wants to be started at the start of the next session, no matter what. (This is useful for utilities that run just after startup and then quit.)

• RestartImmediately The application wants to be started immediately whenever it is not running.

• RestartNever The application does not want to be restarted automatically.

The default hint is RestartIfRunning.

Enumerator
RestartIfRunning
RestartAnyway
RestartImmediately
RestartNever

Definition at line 79 of file qsessionmanager.h.

                     {
        RestartIfRunning,
        RestartAnyway,
        RestartImmediately,
        RestartNever
    };

Constructors and Destructors

QSessionManager()

QSessionManager::QSessionManager ( QApplication *  app, QString &  id, QString &  key  )

private

Definition at line 5054 of file qapplication.cpp.

Referenced by QSessionManagerPrivate::QSessionManagerPrivate(), and QSmSocketReceiver::socketActivated().

    : QObject(*new QSessionManagerPrivate, app)
{
    Q_D(QSessionManager);
    setObjectName(QLatin1String("qt_sessionmanager"));
    qt_session_manager_self = this;
#if defined(Q_WS_WIN)
    wchar_t guidstr[40];
    GUID guid;
    CoCreateGuid(&guid);
    StringFromGUID2(guid, guidstr, 40);
    id = QString::fromWCharArray(guidstr);
    CoCreateGuid(&guid);
    StringFromGUID2(guid, guidstr, 40);
    key = QString::fromWCharArray(guidstr);
#endif
    d->sessionId = id;
    d->sessionKey = key;
    d->restartHint = RestartIfRunning;
}

~QSessionManager()

QSessionManager::~QSessionManager ( )

private

Definition at line 5075 of file qapplication.cpp.

Referenced by QSessionManagerPrivate::QSessionManagerPrivate(), and QSmSocketReceiver::socketActivated().

{
    qt_session_manager_self = 0;
}

Functions

allowsErrorInteraction()

bool QSessionManager::allowsErrorInteraction

(

)

Returns true if error interaction is permitted; otherwise returns false.

This is similar to allowsInteraction(), but also enables the application to tell the user about any errors that occur. Session managers may give error interaction requests higher priority, which means that it is more likely that an error interaction is permitted. However, you are still not guaranteed that the session manager will allow interaction.

See also

allowsInteraction(), release(), cancel()

Definition at line 4170 of file qapplication_win.cpp.

Referenced by handle(), QSessionManagerPrivate::QSessionManagerPrivate(), and sm_performSaveYourself().

{
    sm_blockUserInput = false;
    return true;
}

allowsInteraction()

bool QSessionManager::allowsInteraction

(

)

Asks the session manager for permission to interact with the user.

Returns true if interaction is permitted; otherwise returns false.

The rationale behind this mechanism is to make it possible to synchronize user interaction during a shutdown. Advanced session managers may ask all applications simultaneously to commit their data, resulting in a much faster shutdown.

When the interaction is completed we strongly recommend releasing the user interaction semaphore with a call to release(). This way, other applications may get the chance to interact with the user while your application is still busy saving data. (The semaphore is implicitly released when the application exits.)

If the user decides to cancel the shutdown process during the interaction phase, you must tell the session manager that this has happened by calling cancel().

Here's an example of how an application's QApplication::commitData() might be implemented:

void MyApplication::commitData(QSessionManager& manager)
{
    if (manager.allowsInteraction()) {
        int ret = QMessageBox::warning(
                    mainWindow,
                    tr("My Application"),
                    tr("Save changes to document?"),
                    QMessageBox::Save | QMessageBox::Discard | QMessageBox::Cancel);

        switch (ret) {
        case QMessageBox::Save:
            manager.release();
            if (!saveDocument())
                manager.cancel();
            break;
        case QMessageBox::Discard:
            break;
        case QMessageBox::Cancel:
        default:
            manager.cancel();
        }
    } else {
        // we did not get permission to interact, then
        // do something reasonable instead
    }
}

If an error occurred within the application while saving its data, you may want to try allowsErrorInteraction() instead.

See also

QApplication::commitData(), release(), cancel()

Definition at line 4164 of file qapplication_win.cpp.

Referenced by QApplication::commitData(), handle(), QSessionManagerPrivate::QSessionManagerPrivate(), and QSmSocketReceiver::socketActivated().

{
    sm_blockUserInput = false;
    return true;
}

cancel()

void QSessionManager::cancel

(

)

Tells the session manager to cancel the shutdown process.

Applications should not call this function without asking the user first.

See also

allowsInteraction(), allowsErrorInteraction()

Definition at line 4182 of file qapplication_win.cpp.

Referenced by QApplication::commitData(), handle(), and QSessionManagerPrivate::QSessionManagerPrivate().

{
    sm_cancel = true;
}

discardCommand()

QStringList QSessionManager::discardCommand

(

)

const

Returns the currently set discard command.

To iterate over the list, you can use the foreach pseudo-keyword:

foreach (const QString &command, mySession.discardCommand())
    do_something(command);

See also

setDiscardCommand(), restartCommand(), setRestartCommand()

Definition at line 5150 of file qapplication.cpp.

Referenced by QSessionManagerPrivate::QSessionManagerPrivate(), and sm_performSaveYourself().

{
    Q_D(const QSessionManager);
    return d->discardCommand;
}

handle()

void * QSessionManager::handle

(

)

const

Warning

This function is not part of the public interface.

Definition at line 5094 of file qapplication.cpp.

Referenced by QSmSocketReceiver::socketActivated().

{
    return 0;
}

isPhase2()

bool QSessionManager::isPhase2

(

)

const

Returns true if the session manager is currently performing a second session management phase; otherwise returns false.

See also

requestPhase2()

Definition at line 5164 of file qapplication.cpp.

Referenced by QSessionManagerPrivate::QSessionManagerPrivate().

{
    return false;
}

release()

void QSessionManager::release

(

)

Releases the session manager's interaction semaphore after an interaction phase.

See also

allowsInteraction(), allowsErrorInteraction()

Definition at line 4176 of file qapplication_win.cpp.

Referenced by handle(), and QSessionManagerPrivate::QSessionManagerPrivate().

{
    if (sm_smActive)
        sm_blockUserInput = true;
}

requestPhase2()

void QSessionManager::requestPhase2

(

)

Requests a second session management phase for the application.

The application may then return immediately from the QApplication::commitData() or QApplication::saveState() function, and they will be called again once most or all other applications have finished their session management.

The two phases are useful for applications such as the X11 window manager that need to store information about another application's windows and therefore have to wait until these applications have completed their respective session management tasks.

Note

If another application has requested a second phase it may get called before, simultaneously with, or after your application's second phase.

See also

isPhase2()

Definition at line 5169 of file qapplication.cpp.

Referenced by QSessionManagerPrivate::QSessionManagerPrivate().

{
}

restartCommand()

QStringList QSessionManager::restartCommand

(

)

const

Returns the currently set restart command.

To iterate over the list, you can use the foreach pseudo-keyword:

foreach (const QString &command, mySession.restartCommand())
    do_something(command);

See also

setRestartCommand(), restartHint()

Definition at line 5138 of file qapplication.cpp.

Referenced by QSessionManagerPrivate::QSessionManagerPrivate(), and sm_performSaveYourself().

{
    Q_D(const QSessionManager);
    return d->restartCommand;
}

restartHint()

QSessionManager::RestartHint QSessionManager::restartHint

(

)

const

Returns the application's current restart hint.

The default is RestartIfRunning.

See also

setRestartHint()

Definition at line 5126 of file qapplication.cpp.

Referenced by QSessionManagerPrivate::QSessionManagerPrivate(), and sm_performSaveYourself().

{
    Q_D(const QSessionManager);
    return d->restartHint;
}

sessionId()

QString QSessionManager::sessionId

(

)

const

Returns the identifier of the current session.

If the application has been restored from an earlier session, this identifier is the same as it was in the earlier session.

See also

sessionKey(), QApplication::sessionId()

Definition at line 5080 of file qapplication.cpp.

Referenced by QSessionManagerPrivate::QSessionManagerPrivate(), and QSmSocketReceiver::socketActivated().

{
    Q_D(const QSessionManager);
    return d->sessionId;
}

sessionKey()

QString QSessionManager::sessionKey

(

)

const

Returns the session key in the current session.

If the application has been restored from an earlier session, this key is the same as it was when the previous session ended.

The session key changes with every call of commitData() or saveState().

See also

sessionId(), QApplication::sessionKey()

Definition at line 5086 of file qapplication.cpp.

Referenced by QSessionManagerPrivate::QSessionManagerPrivate(), and QSmSocketReceiver::socketActivated().

{
    Q_D(const QSessionManager);
    return d->sessionKey;
}

setDiscardCommand()

void QSessionManager::setDiscardCommand

(

const QStringList &

list

)

Sets the discard command to the given list.

See also

discardCommand(), setRestartCommand()

Definition at line 5144 of file qapplication.cpp.

Referenced by QSessionManagerPrivate::QSessionManagerPrivate(), and sm_performSaveYourself().

{
    Q_D(QSessionManager);
    d->discardCommand = command;
}

setManagerProperty() [1/2]

void QSessionManager::setManagerProperty	(	const QString &	name,
		const QString &	value
	)

Low-level write access to the application's identification and state records are kept in the session manager.

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

The property called name has its value set to the string value.

Definition at line 5156 of file qapplication.cpp.

Referenced by QSessionManagerPrivate::QSessionManagerPrivate().

{
}

setManagerProperty() [2/2]

void QSessionManager::setManagerProperty	(	const QString &	name,
		const QStringList &	value
	)

Low-level write access to the application's identification and state record are kept in the session manager.

The property called name has its value set to the string list value.

Definition at line 5160 of file qapplication.cpp.

{
}

setRestartCommand()

void QSessionManager::setRestartCommand

(

const QStringList &

command

)

If the session manager is capable of restoring sessions it will execute command in order to restore the application.

The command defaults to

appname -session id

The -session option is mandatory; otherwise QApplication cannot tell whether it has been restored or what the current session identifier is. See QApplication::isSessionRestored() and QApplication::sessionId() for details.

If your application is very simple, it may be possible to store the entire application state in additional command line options. This is usually a very bad idea because command lines are often limited to a few hundred bytes. Instead, use QSettings, temporary files, or a database for this purpose. By marking the data with the unique sessionId(), you will be able to restore the application in a future session.

See also

restartCommand(), setDiscardCommand(), setRestartHint()

Definition at line 5132 of file qapplication.cpp.

Referenced by QSessionManagerPrivate::QSessionManagerPrivate(), and sm_performSaveYourself().

{
    Q_D(QSessionManager);
    d->restartCommand = command;
}

setRestartHint()

void QSessionManager::setRestartHint

(

QSessionManager::RestartHint

hint

)

Sets the application's restart hint to hint.

On application startup, the hint is set to RestartIfRunning.

Note

These flags are only hints, a session manager may or may not respect them.

We recommend setting the restart hint in QApplication::saveState() because most session managers perform a checkpoint shortly after an application's startup.

See also

restartHint()

Definition at line 5120 of file qapplication.cpp.

Referenced by QSessionManagerPrivate::QSessionManagerPrivate().

{
    Q_D(QSessionManager);
    d->restartHint = hint;
}

Friends and Related Functions

QApplication

friend class QApplication

friend

Definition at line 100 of file qsessionmanager.h.

QApplicationPrivate

friend class QApplicationPrivate

friend

Definition at line 101 of file qsessionmanager.h.

QBaseApplication

friend class QBaseApplication

friend

Definition at line 102 of file qsessionmanager.h.

---

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

• /src/gui/kernel/qsessionmanager.h
• /src/gui/kernel/qapplication.cpp
• /src/gui/kernel/qapplication_win.cpp
• /src/gui/kernel/qapplication_x11.cpp
• /src/gui/kernel/qsessionmanager_qpa.cpp
• /src/gui/kernel/qsessionmanager_qws.cpp