Fix TWK-1395

We now queue DatabaseCommand_SetPlaylistRevision in a playlist-local
queue before we send them to the Database Queue to ensure that only
one DatabaseCommand_SetPlaylistRevision is run per playlist at a time.

src/libtomahawk/Playlist.cpp

@@ -354,7 +354,17 @@ Playlist::createNewRevision( const QString& newrev, const QString& oldrev, const
                                                      added,
                                                      entries );
 
-    Database::instance()->enqueue( Tomahawk::dbcmd_ptr( cmd ) );
+    connect( cmd, SIGNAL( finished() ),
+             this, SLOT( setPlaylistRevisionFinished() ) );
+    if ( d->queuedSetPlaylistRevision )
+    {
+        d->queuedSetPlaylistRevisionCmds.enqueue( cmd );
+    }
+    else
+    {
+        d->queuedSetPlaylistRevision = true;
+        Database::instance()->enqueue( Tomahawk::dbcmd_ptr( cmd ) );
+    }
 }
 
 
@@ -389,7 +399,17 @@ Playlist::updateEntries( const QString& newrev, const QString& oldrev, const QLi
                                              orderedguids,
                                              entries );
 
-    Database::instance()->enqueue( Tomahawk::dbcmd_ptr( cmd ) );
+    connect( cmd, SIGNAL( finished() ),
+             this, SLOT( setPlaylistRevisionFinished() ) );
+    if ( d->queuedSetPlaylistRevision )
+    {
+        d->queuedSetPlaylistRevisionCmds.enqueue( cmd );
+    }
+    else
+    {
+        d->queuedSetPlaylistRevision = true;
+        Database::instance()->enqueue( Tomahawk::dbcmd_ptr( cmd ) );
+    }
 }
 
 
@@ -561,6 +581,22 @@ Playlist::onResolvingFinished()
 }
 
 
+void
+Playlist::setPlaylistRevisionFinished()
+{
+    Q_D( Playlist );
+    if ( d->queuedSetPlaylistRevisionCmds.length() > 0 )
+    {
+        DatabaseCommand_SetPlaylistRevision* cmd = d->queuedSetPlaylistRevisionCmds.dequeue();
+        Database::instance()->enqueue( Tomahawk::dbcmd_ptr( cmd ) );
+    }
+    else
+    {
+        d->queuedSetPlaylistRevision = false;
+    }
+}
+
+
 void
 Playlist::addEntry( const query_ptr& query )
 {

src/libtomahawk/Playlist.h

@@ -272,6 +272,7 @@ protected:
 private slots:
     void onResultsChanged();
     void onResolvingFinished();
+    void setPlaylistRevisionFinished();
 
 private:
     Playlist();

src/libtomahawk/Playlist_p.h

@@ -26,6 +26,8 @@
 
 #include "playlist/RevisionQueueItem.h"
 
+class DatabaseCommand_SetPlaylistRevision;
+
 namespace Tomahawk
 {
 
@@ -35,6 +37,7 @@ class PlaylistPrivate
 public:
     PlaylistPrivate( Playlist* q )
         : q_ptr( q )
+        , queuedSetPlaylistRevision( false )
     {
     }
 
@@ -42,6 +45,7 @@ public:
         : q_ptr( q )
         , source( _author )
         , lastmodified( 0 )
+        , queuedSetPlaylistRevision( false )
     {
     }
 
@@ -63,6 +67,7 @@ public:
         , creator( _creator )
         , lastmodified( _lastmod )
         , createdOn( _createdOn )
+        , queuedSetPlaylistRevision( false )
         , shared( _shared )
     {
     }
@@ -82,6 +87,7 @@ public:
         , creator( _creator )
         , lastmodified( 0 )
         , createdOn( 0 ) // will be set by db command
+        , queuedSetPlaylistRevision( false )
         , shared( _shared )
         , initEntries( _entries )
     {
@@ -100,10 +106,12 @@ private:
     QString creator;
     unsigned int lastmodified;
     unsigned int createdOn;
+    bool queuedSetPlaylistRevision;
     bool shared;
     bool loaded;
 
     QQueue<_detail::Closure*> queuedOps;
+    QQueue<DatabaseCommand_SetPlaylistRevision*> queuedSetPlaylistRevisionCmds;
     QList< plentry_ptr > initEntries;
     QList< plentry_ptr > entries;
 

src/libtomahawk/database/DatabaseCommand_SetPlaylistRevision.cpp

@@ -274,7 +274,7 @@ DatabaseCommand_SetPlaylistRevision::exec( DatabaseImpl* lib )
         tDebug() << "Not updating current revision, optimistic locking fail" << currentRevision << m_oldrev;
 
         // This will fail if we run two SetPlaylistRevisions commands on the same playlist concurrently
-        // Q_ASSERT( !source()->isLocal() );
+        Q_ASSERT( !source()->isLocal() );
     }
 }
 

src/libtomahawk/playlist/dynamic/DynamicPlaylist.cpp

@@ -244,7 +244,18 @@ DynamicPlaylist::createNewRevision( const QString& newrev,
     if ( !d->autoLoad )
         cmd->setPlaylist( d->weakSelf );
 
-    Database::instance()->enqueue( Tomahawk::dbcmd_ptr( cmd ) );
+    connect( cmd, SIGNAL( finished() ),
+             this, SLOT( setPlaylistRevisionFinished() ) );
+
+    if ( d->queuedSetPlaylistRevision )
+    {
+        d->queuedSetPlaylistRevisionCmds.enqueue( cmd );
+    }
+    else
+    {
+        d->queuedSetPlaylistRevision = true;
+        Database::instance()->enqueue( Tomahawk::dbcmd_ptr( cmd ) );
+    }
 }
 
 
@@ -280,7 +291,18 @@ DynamicPlaylist::createNewRevision( const QString& newrev,
     if ( !d->autoLoad )
         cmd->setPlaylist( d->weakSelf );
 
-    Database::instance()->enqueue( Tomahawk::dbcmd_ptr( cmd ) );
+    connect( cmd, SIGNAL( finished() ),
+             this, SLOT( setPlaylistRevisionFinished() ) );
+
+    if ( d->queuedSetPlaylistRevision )
+    {
+        d->queuedSetPlaylistRevisionCmds.enqueue( cmd );
+    }
+    else
+    {
+        d->queuedSetPlaylistRevision = true;
+        Database::instance()->enqueue( Tomahawk::dbcmd_ptr( cmd ) );
+    }
 }