QgsConnectionPoolGroup< T > Class Template Reference

Template that stores data related to a connection to a single server or datasource. More...

#include <qgsconnectionpool.h>

Classes
struct	Item

Public Member Functions
	QgsConnectionPoolGroup (const QgsConnectionPoolGroup &other)=delete
	QgsConnectionPoolGroup (const QString &ci)
	Constructor for QgsConnectionPoolGroup, with the specified connection info.
	~QgsConnectionPoolGroup ()
T	acquire (int timeout, bool requestMayBeNested)
	Try to acquire a connection for a maximum of timeout milliseconds.
void	invalidateConnections ()
QgsConnectionPoolGroup &	operator= (const QgsConnectionPoolGroup &other)=delete
void	release (T conn)

Protected Member Functions
template<typename U>
void	initTimer (U *parent)
	Initializes the connection timeout handling.
void	onConnectionExpired ()

Protected Attributes
QList< T >	acquiredConns
QString	connInfo
QMutex	connMutex
QStack< Item >	conns
QTimer *	expirationTimer = nullptr
QSemaphore	sem

Detailed Description

template<typename T>
class QgsConnectionPoolGroup< T >

Template that stores data related to a connection to a single server or datasource.

It is assumed that following functions exist:

• void qgsConnectionPool_ConnectionCreate(QString name, T& c) ... create a new connection
• void qgsConnectionPool_ConnectionDestroy(T c) ... destroy the connection
• QString qgsConnectionPool_ConnectionToName(T c) ... lookup connection's name (path)
• void qgsConnectionPool_InvalidateConnection(T c) ... flag a connection as invalid
• bool qgsConnectionPool_ConnectionIsValid(T c) ... return whether a connection is valid

Because of issues with templates and QObject's signals and slots, this class only provides helper functions for QObject-related functionality - the place which uses the template is resonsible for:

• being derived from QObject
• calling initTimer( this ) in constructor
• having handleConnectionExpired() slot that calls onConnectionExpired()
• having startExpirationTimer(), stopExpirationTimer() slots to start/stop the expiration timer

For an example on how to use the template class, have a look at the implementation in Postgres/SpatiaLite providers.

Note

not available in Python bindings

Definition at line 64 of file qgsconnectionpool.h.

Constructor & Destructor Documentation

QgsConnectionPoolGroup() [1/2]

template<typename T>

QgsConnectionPoolGroup< T >::QgsConnectionPoolGroup ( const QString & ci )

inline

Constructor for QgsConnectionPoolGroup, with the specified connection info.

Definition at line 77 of file qgsconnectionpool.h.

~QgsConnectionPoolGroup()

template<typename T>

QgsConnectionPoolGroup< T >::~QgsConnectionPoolGroup ( )

inline

Definition at line 83 of file qgsconnectionpool.h.

QgsConnectionPoolGroup() [2/2]

template<typename T>

QgsConnectionPoolGroup< T >::QgsConnectionPoolGroup ( const QgsConnectionPoolGroup< T > & other )

delete

Member Function Documentation

acquire()

template<typename T>

T QgsConnectionPoolGroup< T >::acquire ( int timeout, bool requestMayBeNested )

inline

Try to acquire a connection for a maximum of timeout milliseconds.

If timeout is a negative value the calling thread will be blocked until a connection becomes available. This is the default behavior.

Returns

initialized connection or nullptr if unsuccessful

Definition at line 102 of file qgsconnectionpool.h.

initTimer()

template<typename T>

template<typename U>

void QgsConnectionPoolGroup< T >::initTimer ( U * parent )

inlineprotected

Initializes the connection timeout handling.

Should be called from subclasses within their constructors, passing themselves as the parent.

Definition at line 226 of file qgsconnectionpool.h.

invalidateConnections()

template<typename T>

void QgsConnectionPoolGroup< T >::invalidateConnections ( )

inline

Definition at line 203 of file qgsconnectionpool.h.

onConnectionExpired()

template<typename T>

void QgsConnectionPoolGroup< T >::onConnectionExpired ( )

inlineprotected

Definition at line 237 of file qgsconnectionpool.h.

operator=()

template<typename T>

QgsConnectionPoolGroup & QgsConnectionPoolGroup< T >::operator= ( const QgsConnectionPoolGroup< T > & other )

delete

release()

template<typename T>

void QgsConnectionPoolGroup< T >::release ( T conn )

inline

Definition at line 174 of file qgsconnectionpool.h.

Member Data Documentation

acquiredConns

template<typename T>

QList<T> QgsConnectionPoolGroup< T >::acquiredConns

protected

Definition at line 269 of file qgsconnectionpool.h.

connInfo

template<typename T>

QString QgsConnectionPoolGroup< T >::connInfo

protected

Definition at line 267 of file qgsconnectionpool.h.

connMutex

template<typename T>

QMutex QgsConnectionPoolGroup< T >::connMutex

protected

Definition at line 270 of file qgsconnectionpool.h.

conns

template<typename T>

QStack<Item> QgsConnectionPoolGroup< T >::conns

protected

Definition at line 268 of file qgsconnectionpool.h.

expirationTimer

template<typename T>

QTimer* QgsConnectionPoolGroup< T >::expirationTimer = nullptr

protected

Definition at line 272 of file qgsconnectionpool.h.

sem

template<typename T>

QSemaphore QgsConnectionPoolGroup< T >::sem

protected

Definition at line 271 of file qgsconnectionpool.h.

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

• /build/qgis-3.99.0+git20251207+21b3aa880ba+99sid/src/core/qgsconnectionpool.h