From 7e7cdef88841fb3acd16ae61a57a1884588f3280 Mon Sep 17 00:00:00 2001 From: Simeon Bird Date: Mon, 11 Mar 2013 23:52:02 -0400 Subject: [PATCH 2/5] Make the initMutex a ReadWriteLock, so multiple threads can check initialisation at once, and protect creation of the ResourceWatcher with it. --- libnepomukcore/resource/resourcemanager.cpp | 35 ++++++++++++++++++----------- libnepomukcore/resource/resourcemanager_p.h | 3 ++- 2 files changed, 24 insertions(+), 14 deletions(-) diff --git a/libnepomukcore/resource/resourcemanager.cpp b/libnepomukcore/resource/resourcemanager.cpp index 03b7b58..257f1bb 100644 --- a/libnepomukcore/resource/resourcemanager.cpp +++ b/libnepomukcore/resource/resourcemanager.cpp @@ -284,7 +284,7 @@ Nepomuk2::ResourceManager* Nepomuk2::ResourceManager::instance() int Nepomuk2::ResourceManager::init() { - QMutexLocker lock( &d->initMutex ); + QWriteLocker lock( &d->initMutex ); if( d->overrideModel ) { return true; @@ -302,7 +302,7 @@ int Nepomuk2::ResourceManager::init() bool Nepomuk2::ResourceManager::initialized() const { - QMutexLocker lock( &d->initMutex ); + QReadLocker lock( &d->initMutex ); if( d->overrideModel ) return true; @@ -409,21 +409,30 @@ void Nepomuk2::ResourceManagerPrivate::addToWatcher( const QUrl& uri ) { if( uri.isEmpty() ) return; - + // Lock the init mutex to make sure we don't create multiple watchers + initMutex.lockForRead(); if( !m_watcher ) { - m_watcher = new ResourceWatcher(m_manager); - // - // The ResourceWatcher is not thread-safe. Thus, we need to ensure the safety ourselves. - // We do that by simply handling all RW related operations in the manager thread. - // This also means to invoke methods on the watcher through QMetaObject to make sure they - // get queued in case of calls between different threads. - // - m_watcher->moveToThread(m_manager->thread()); - QObject::connect( m_watcher, SIGNAL(propertyAdded(Nepomuk2::Resource, Nepomuk2::Types::Property, QVariant)), + // Lock the initMutex for write + initMutex.unlock(); + initMutex.lockForWrite(); + // check that nothing stole in and created + // a ResourceWatcher while we were unlocked. + if( !m_watcher ) { + m_watcher = new ResourceWatcher(m_manager); + // + // The ResourceWatcher is not thread-safe. Thus, we need to ensure the safety ourselves. + // We do that by simply handling all RW related operations in the manager thread. + // This also means to invoke methods on the watcher through QMetaObject to make sure they + // get queued in case of calls between different threads. + // + m_watcher->moveToThread(m_manager->thread()); + QObject::connect( m_watcher, SIGNAL(propertyAdded(Nepomuk2::Resource, Nepomuk2::Types::Property, QVariant)), m_manager, SLOT(slotPropertyAdded(Nepomuk2::Resource, Nepomuk2::Types::Property, QVariant)) ); - QObject::connect( m_watcher, SIGNAL(propertyRemoved(Nepomuk2::Resource, Nepomuk2::Types::Property, QVariant)), + QObject::connect( m_watcher, SIGNAL(propertyRemoved(Nepomuk2::Resource, Nepomuk2::Types::Property, QVariant)), m_manager, SLOT(slotPropertyRemoved(Nepomuk2::Resource, Nepomuk2::Types::Property, QVariant)) ); + } } + initMutex.unlock(); // add a resource and (re-)start the watcher in case this resource is the only one in the list of watched QMetaObject::invokeMethod( m_watcher, "addResourceStart", Qt::AutoConnection, Q_ARG(QUrl, uri) ); } diff --git a/libnepomukcore/resource/resourcemanager_p.h b/libnepomukcore/resource/resourcemanager_p.h index 68479d5..eeec948 100644 --- a/libnepomukcore/resource/resourcemanager_p.h +++ b/libnepomukcore/resource/resourcemanager_p.h @@ -22,6 +22,7 @@ #define _NEPOMUK2_RESOURCE_MANAGER_P_H_ #include +#include #include @@ -52,7 +53,7 @@ namespace Nepomuk2 { Soprano::Model* overrideModel; /// used to protect the initialization - QMutex initMutex; + QReadWriteLock initMutex; /// used to protect all data in ResourceManager QMutex mutex; -- 1.8.2