commit 979b0436510e7807c054e79c40c3753834ac2863
Author: Sebastian Trueg <trueg@kde.org>
Date:   Thu Mar 15 09:14:35 2012 +0100

    Thread-safe ResourceWatcher handling.
    
    We simply perform all RW operations in the manager thread.
    
    BUG: 295474
    FIXED-IN: 4.8.2

diff --git a/nepomuk/core/resourcedata.cpp b/nepomuk/core/resourcedata.cpp
index abe55ea..9d45228 100644
--- a/nepomuk/core/resourcedata.cpp
+++ b/nepomuk/core/resourcedata.cpp
@@ -175,7 +175,8 @@ void Nepomuk::ResourceData::resetAll( bool isDelete )
     if( !m_uri.isEmpty() ) {
         m_rm->m_initializedData.remove( m_uri );
         if( m_rm->m_watcher && m_addedToWatcher ) {
-            m_rm->m_watcher->removeResource(Resource::fromResourceUri(m_uri));
+            // See load() for an explanation of the QMetaObject call
+            QMetaObject::invokeMethod(m_rm->m_watcher, "removeResource", Qt::AutoConnection, Q_ARG(Nepomuk::Resource, Resource::fromResourceUri(m_uri)));
             m_addedToWatcher = false;
         }
     }
@@ -393,16 +394,23 @@ bool Nepomuk::ResourceData::load()
         m_cache.clear();
 
         if(!m_rm->m_watcher) {
+            //
+            // 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_rm->m_watcher = new ResourceWatcher(m_rm->m_manager);
+            m_rm->m_watcher->moveToThread(m_rm->m_manager->thread());
             QObject::connect( m_rm->m_watcher, SIGNAL(propertyAdded(Nepomuk::Resource, Nepomuk::Types::Property, QVariant)),
                               m_rm->m_manager, SLOT(slotPropertyAdded(Nepomuk::Resource, Nepomuk::Types::Property, QVariant)) );
             QObject::connect( m_rm->m_watcher, SIGNAL(propertyRemoved(Nepomuk::Resource, Nepomuk::Types::Property, QVariant)),
                               m_rm->m_manager, SLOT(slotPropertyRemoved(Nepomuk::Resource, Nepomuk::Types::Property, QVariant)) );
             m_rm->m_watcher->addResource( Nepomuk::Resource::fromResourceUri(m_uri) );
-            m_rm->m_watcher->start();
+            QMetaObject::invokeMethod(m_rm->m_watcher, "start", Qt::AutoConnection);
         }
         else {
-            m_rm->m_watcher->addResource( Nepomuk::Resource::fromResourceUri(m_uri) );
+            QMetaObject::invokeMethod(m_rm->m_watcher, "addResource", Qt::AutoConnection, Q_ARG(Nepomuk::Resource, Nepomuk::Resource::fromResourceUri(m_uri)) );
         }
         m_addedToWatcher = true;
 
diff --git a/nepomuk/core/resourcewatcher.h b/nepomuk/core/resourcewatcher.h
index 06b9622..92b12f5 100644
--- a/nepomuk/core/resourcewatcher.h
+++ b/nepomuk/core/resourcewatcher.h
@@ -93,6 +93,7 @@ namespace Nepomuk {
          */
         virtual ~ResourceWatcher();
 
+    public Q_SLOTS:
         /**
          * \brief Add a type to be watched.
          *
@@ -204,7 +205,6 @@ namespace Nepomuk {
          */
         QList<Types::Property> properties() const;
 
-    public Q_SLOTS:
         /**
          * \brief Start the signalling of changes.
          *