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| /*************************************************************************** | ||
| qgspostgresconnpool.cpp | ||
| --------------------- | ||
| begin : January 2014 | ||
| copyright : (C) 2014 by Martin Dobias | ||
| email : wonder dot sk at gmail dot com | ||
| *************************************************************************** | ||
| * * | ||
| * This program is free software; you can redistribute it and/or modify * | ||
| * it under the terms of the GNU General Public License as published by * | ||
| * the Free Software Foundation; either version 2 of the License, or * | ||
| * (at your option) any later version. * | ||
| * * | ||
| ***************************************************************************/ | ||
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| #include "qgspostgresconnpool.h" | ||
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| #include "qgspostgresconn.h" | ||
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| #include <QCoreApplication> | ||
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| #define POSTGRES_MAX_CONCURRENT_CONNS 4 | ||
| #define POSTGRES_CONN_EXPIRATION 10 // in seconds | ||
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| QgsPostgresConnPoolGroup::QgsPostgresConnPoolGroup( const QString& ci ) | ||
| : connInfo( ci ) | ||
| , sem( POSTGRES_MAX_CONCURRENT_CONNS ) | ||
| , expirationTimer( this ) | ||
| { | ||
| // just to make sure the object belongs to main thread and thus will get events | ||
| moveToThread( qApp->thread() ); | ||
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| expirationTimer.setInterval( POSTGRES_CONN_EXPIRATION * 1000 ); | ||
| connect( &expirationTimer, SIGNAL( timeout() ), this, SLOT( handleConnectionExpired() ) ); | ||
| } | ||
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| QgsPostgresConnPoolGroup::~QgsPostgresConnPoolGroup() | ||
| { | ||
| foreach ( Item item, conns ) | ||
| item.c->disconnect(); | ||
| } | ||
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| QgsPostgresConn* QgsPostgresConnPoolGroup::acquire() | ||
| { | ||
| // we are going to acquire a resource - if no resource is available, we will block here | ||
| sem.acquire(); | ||
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| // quick (preferred) way - use cached connection | ||
| { | ||
| QMutexLocker locker( &connMutex ); | ||
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| if ( !conns.isEmpty() ) | ||
| { | ||
| Item i = conns.pop(); | ||
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| // no need to run if nothing can expire | ||
| if ( conns.isEmpty() ) | ||
| expirationTimer.stop(); | ||
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| return i.c; | ||
| } | ||
| } | ||
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| QgsPostgresConn* c = QgsPostgresConn::connectDb( connInfo, true, false ); // TODO: read-only | ||
| if ( !c ) | ||
| { | ||
| // we didn't get connection for some reason, so release the lock | ||
| sem.release(); | ||
| return 0; | ||
| } | ||
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| return c; | ||
| } | ||
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| void QgsPostgresConnPoolGroup::release( QgsPostgresConn* conn ) | ||
| { | ||
| connMutex.lock(); | ||
| Item i; | ||
| i.c = conn; | ||
| i.lastUsedTime = QTime::currentTime(); | ||
| conns.push( i ); | ||
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| if ( !expirationTimer.isActive() ) | ||
| expirationTimer.start(); | ||
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| connMutex.unlock(); | ||
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| sem.release(); // this can unlock a thread waiting in acquire() | ||
| } | ||
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| void QgsPostgresConnPoolGroup::handleConnectionExpired() | ||
| { | ||
| connMutex.lock(); | ||
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| QTime now = QTime::currentTime(); | ||
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| // what connections have expired? | ||
| QList<int> toDelete; | ||
| for ( int i = 0; i < conns.count(); ++i ) | ||
| { | ||
| if ( conns.at( i ).lastUsedTime.secsTo( now ) >= POSTGRES_CONN_EXPIRATION ) | ||
| toDelete.append( i ); | ||
| } | ||
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| // delete expired connections | ||
| for ( int j = toDelete.count() - 1; j >= 0; --j ) | ||
| { | ||
| int index = toDelete[j]; | ||
| conns[index].c->disconnect(); | ||
| conns.remove( index ); | ||
| } | ||
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| if ( conns.isEmpty() ) | ||
| expirationTimer.stop(); | ||
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| connMutex.unlock(); | ||
| } | ||
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| // ---- | ||
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| QgsPostgresConnPool* QgsPostgresConnPool::mInstance = 0; | ||
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| QgsPostgresConnPool* QgsPostgresConnPool::instance() | ||
| { | ||
| if ( !mInstance ) | ||
| mInstance = new QgsPostgresConnPool; | ||
| return mInstance; | ||
| } | ||
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| QgsPostgresConn* QgsPostgresConnPool::acquireConnection( const QString& connInfo ) | ||
| { | ||
| mMutex.lock(); | ||
| QgsPostgresConnPoolGroups::iterator it = mGroups.find( connInfo ); | ||
| if ( it == mGroups.end() ) | ||
| { | ||
| it = mGroups.insert( connInfo, new QgsPostgresConnPoolGroup( connInfo ) ); | ||
| } | ||
| QgsPostgresConnPoolGroup* group = *it; | ||
| mMutex.unlock(); | ||
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| return group->acquire(); | ||
| } | ||
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| void QgsPostgresConnPool::releaseConnection( QgsPostgresConn* conn ) | ||
| { | ||
| mMutex.lock(); | ||
| QgsPostgresConnPoolGroups::iterator it = mGroups.find( conn->connInfo() ); | ||
| Q_ASSERT( it != mGroups.end() ); | ||
| QgsPostgresConnPoolGroup* group = *it; | ||
| mMutex.unlock(); | ||
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| group->release( conn ); | ||
| } |
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