XQueryContext has helpless synchronization

[alebastrov]

method:

• public synchronized ExistRepository getRepository(){...}
• usage of updateListener field may need sync (if there are several threads which add/remove listeners)
  Also
  inner class (should be static) class ContextUpdateListener does too long synchronization when documentUpdated() and unsubscribe() called, and of course debug() and nodeMoved() should use syncronization
  I would suggest such realization

private static class ContextUpdateListener implements UpdateListener {

    private List<UpdateListener> listeners = new ArrayList<UpdateListener>();

    public void addListener( UpdateListener listener )
    {
        synchronized( this ) {
                       listeners.add( listener );
        }
    }


    public void documentUpdated( DocumentImpl document, int event )
    {
        List<UpdateListener> copyOfListeners = null;
        synchronized( this ) { 
            copyOfListeners = new ArrayList(listeners);
                    }
            for( final UpdateListener listener : copyOfListeners ) {

                if( listener != null ) {
                    listener.documentUpdated( document, event );
                }
            }

    }


    public void unsubscribe()
    {
        List<UpdateListener> copyOfListeners = null;
        synchronized( this ) { 
            copyOfListeners = new ArrayList(listeners);
            listeners = new ArrayList();
                    }
            for( final UpdateListener listener : copyOfListeners ) {

                if( listener != null ) {
                    listener.unsubscribe();
                }
            }
    }


    public void nodeMoved( NodeId oldNodeId, StoredNode newNode )
    {
        List<UpdateListener> copyOfListeners = null;
        synchronized( this ) { 
            copyOfListeners = new ArrayList(listeners);
                    }
        for( int i = 0; i < copyOfListeners.size(); i++ ) {
            final UpdateListener listener = (UpdateListener)copyOfListeners.get( i );

            if( listener != null ) {
                listener.nodeMoved( oldNodeId, newNode );
            }
        }
    }


    public void debug() {
        List<UpdateListener> copyOfListeners = null;
        synchronized( this ) { 
            copyOfListeners = new ArrayList(listeners);
                    }
        LOG.debug(String.format("XQueryContext: %s document update listeners", copyOfListeners.size()));
        for (int i = 0; i < copyOfListeners.size(); i++) {
            ((UpdateListener) copyOfListeners.get(i)).debug();
        }
    }

}

[shabanovd]

@alebastrov will you able to make PR?

[alebastrov]

Of course yes, but it may take some time

[alebastrov]

added PR: #853

[duncdrum]

closed by rebased #886