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 QString &ci)
	QgsConnectionPoolGroup (const QgsConnectionPoolGroup &other)=delete
	QgsConnectionPoolGroup cannot be copied. More...
	~QgsConnectionPoolGroup ()
T	acquire (int timeout, bool requestMayBeNested)
	Try to acquire a connection for a maximum of timeout milliseconds. More...
void	invalidateConnections ()
QgsConnectionPoolGroup &	operator= (const QgsConnectionPoolGroup &other)=delete
	QgsConnectionPoolGroup cannot be copied. More...
void	release (T conn)

Protected Member Functions
void	initTimer (QObject *parent)
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 59 of file qgsconnectionpool.h.

Constructor & Destructor Documentation

template<typename T >

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

inline

Definition at line 69 of file qgsconnectionpool.h.

template<typename T >

QgsConnectionPoolGroup< T >::~QgsConnectionPoolGroup ( )

inline

Definition at line 75 of file qgsconnectionpool.h.

template<typename T >

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

delete

QgsConnectionPoolGroup cannot be copied.

Member Function Documentation

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 95 of file qgsconnectionpool.h.

template<typename T >

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

inlineprotected

Definition at line 198 of file qgsconnectionpool.h.

template<typename T >

void QgsConnectionPoolGroup< T >::invalidateConnections ( )

inline

Definition at line 183 of file qgsconnectionpool.h.

template<typename T >

void QgsConnectionPoolGroup< T >::onConnectionExpired ( )

inlineprotected

Definition at line 209 of file qgsconnectionpool.h.

template<typename T >

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

delete

QgsConnectionPoolGroup cannot be copied.

template<typename T >

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

inline

Definition at line 156 of file qgsconnectionpool.h.

Member Data Documentation

template<typename T >

QList<T> QgsConnectionPoolGroup< T >::acquiredConns

protected

Definition at line 241 of file qgsconnectionpool.h.

template<typename T >

QString QgsConnectionPoolGroup< T >::connInfo

protected

Definition at line 239 of file qgsconnectionpool.h.

template<typename T >

QMutex QgsConnectionPoolGroup< T >::connMutex

protected

Definition at line 242 of file qgsconnectionpool.h.

template<typename T >

QStack<Item> QgsConnectionPoolGroup< T >::conns

protected

Definition at line 240 of file qgsconnectionpool.h.

template<typename T >

QTimer* QgsConnectionPoolGroup< T >::expirationTimer = nullptr

protected

Definition at line 244 of file qgsconnectionpool.h.

template<typename T >

QSemaphore QgsConnectionPoolGroup< T >::sem

protected

Definition at line 243 of file qgsconnectionpool.h.

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

• /build/qgis-3.4.15+24xenial/src/core/qgsconnectionpool.h