Add file monitoring and conflict handling in case of pending changed in

Akonadi while the file was changed on disk.

Basically works but shows that we lack a way to invalidate the Akonadi
cache in case we only deliver partial items in retrieveItems().

svn path=/trunk/KDE/kdepim/akonadi/; revision=875748

resources/ical/icalresource.cpp

@@ -93,7 +93,7 @@ void ICalResource::configure( WId windowId )
   dlg.setFilter( "*.ics *.ical|" + i18nc("Filedialog filter for *.ics *.ical", "iCal Calendar File" ) );
   dlg.setCaption( i18n("Select Calendar") );
   if ( dlg.exec() == QDialog::Accepted ) {
-    readFile();
+    reloadFile();
     synchronize();
   }
 }

resources/shared/singlefileresource.h

@@ -25,6 +25,7 @@
 
 #include <akonadi/collectiondisplayattribute.h>
 
+#include <KDirWatch>
 #include <KLocale>
 
 #include <QFile>
@@ -59,9 +60,8 @@ class SingleFileResource : public SingleFileResourceBase
      */
     void readFile()
     {
-      // if we have something loaded already, make sure we write that back in case the settings changed
-      if ( !mCurrentUrl.isEmpty() )
-        writeFile();
+      if ( KDirWatch::self()->contains( mCurrentUrl.path() ) )
+        KDirWatch::self()->removeFile( mCurrentUrl.path() );
 
       const bool nameWasChanged = mCurrentUrl.fileName() != name() && !mCurrentUrl.isEmpty();
 
@@ -95,6 +95,8 @@ class SingleFileResource : public SingleFileResourceBase
         return;
       }
 
+      if ( Settings::self()->monitorFile() )
+        KDirWatch::self()->addFile( mCurrentUrl.path() );
       emit status( Idle, i18n( "Data loaded from '%1'.", mCurrentUrl.prettyUrl() ) );
     }
 
@@ -119,7 +121,10 @@ class SingleFileResource : public SingleFileResourceBase
         return;
       }
 
-      if ( !writeToFile( mCurrentUrl.path() ) )
+      KDirWatch::self()->stopScan();
+      const bool writeResult = writeToFile( mCurrentUrl.path() );
+      KDirWatch::self()->startScan();
+      if ( !writeResult )
         return;
 
       emit status( Idle, i18n( "Data successfully saved to '%1'.", mCurrentUrl.prettyUrl() ) );

resources/shared/singlefileresourcebase.cpp

@@ -24,6 +24,13 @@
 #include <akonadi/collectiondisplayattribute.h>
 #include <akonadi/itemfetchscope.h>
 
+#include <KDebug>
+#include <KDirWatch>
+#include <KLocale>
+#include <KStandardDirs>
+
+#include <QDir>
+
 using namespace Akonadi;
 
 SingleFileResourceBase::SingleFileResourceBase( const QString & id ) :
@@ -32,11 +39,13 @@ SingleFileResourceBase::SingleFileResourceBase( const QString & id ) :
   connect( &mDirtyTimer, SIGNAL(timeout()), SLOT(writeFile()) );
   mDirtyTimer.setSingleShot( true );
 
-  connect( this, SIGNAL(reloadConfiguration()), SLOT(readFile()) );
+  connect( this, SIGNAL(reloadConfiguration()), SLOT(reloadFile()) );
   QTimer::singleShot( 0, this, SLOT(readFile()) );
 
   changeRecorder()->itemFetchScope().fetchFullPayload();
   changeRecorder()->fetchCollection( true );
+
+  connect( KDirWatch::self(), SIGNAL(dirty(QString)), SLOT(fileChanged(QString)) );
 }
 
 void SingleFileResourceBase::setSupportedMimetypes(const QStringList & mimeTypes, const QString &icon)
@@ -58,4 +67,38 @@ void SingleFileResourceBase::collectionChanged(const Akonadi::Collection & colle
     setName( newName );
 }
 
+void SingleFileResourceBase::reloadFile()
+{
+  // if we have something loaded already, make sure we write that back in case the settings changed
+  if ( !mCurrentUrl.isEmpty() )
+    writeFile();
+ readFile();
+}
+
+void SingleFileResourceBase::fileChanged(const QString & fileName)
+{
+  if ( fileName != mCurrentUrl.path() )
+    return;
+
+  // handle conflicts
+  if ( mDirtyTimer.isActive() && !mCurrentUrl.isEmpty() ) {
+    const KUrl prevUrl = mCurrentUrl;
+    int i = 0;
+    QString lostFoundFileName;
+    do {
+      lostFoundFileName = KStandardDirs::locateLocal( "data", identifier() + QDir::separator()
+          + prevUrl.fileName() + "-" + QString::number( ++i ) );
+    } while ( KStandardDirs::exists( lostFoundFileName ) );
+    mCurrentUrl = KUrl( lostFoundFileName );
+    writeFile();
+    emit warning( i18n( "The file '%1' was changed on disk while there were still pending changes in Akonadi. "
+        "To avoid dataloss, a backup of the internal changes has been created at '%2'.",
+         prevUrl.prettyUrl(), mCurrentUrl.prettyUrl() ) );
+    mCurrentUrl = prevUrl;
+  }
+
+  readFile();
+  synchronize();
+}
+
 #include "singlefileresourcebase.moc"

resources/shared/singlefileresourcebase.h

@@ -47,6 +47,7 @@ class SingleFileResourceBase : public ResourceBase, public Akonadi::AgentBase::O
     void collectionChanged( const Akonadi::Collection &collection );
 
   public Q_SLOTS:
+    void reloadFile();
     virtual void readFile() = 0;
     virtual void writeFile() = 0;
 
@@ -70,6 +71,9 @@ class SingleFileResourceBase : public ResourceBase, public Akonadi::AgentBase::O
     KUrl mCurrentUrl;
     QStringList mSupportedMimetypes;
     QString mCollectionIcon;
+
+  private Q_SLOTS:
+    void fileChanged( const QString &fileName );
 };
 
 }

resources/vcard/vcardresource.cpp

@@ -71,7 +71,7 @@ void VCardResource::configure( WId windowId )
   dlg.setFilter( "*.vcf|" + i18nc("Filedialog filter for *.vcf", "vCard Addressbook File" ) );
   dlg.setCaption( i18n("Select Addressbook") );
   if ( dlg.exec() == QDialog::Accepted ) {
-    readFile();
+    reloadFile();
     synchronize();
   }
 }