bundles/org.simantics.db.common/src/org/simantics/db/common/request/TransientResourceRead.java

   1 /*******************************************************************************
   2  * Copyright (c) 2007, 2010 Association for Decentralized Information Management
   3  * in Industry THTH ry.
   4  * All rights reserved. This program and the accompanying materials
   5  * are made available under the terms of the Eclipse Public License v1.0
   6  * which accompanies this distribution, and is available at
   7  * http://www.eclipse.org/legal/epl-v10.html
   8  *
   9  * Contributors:
  10  *     VTT Technical Research Centre of Finland - initial API and implementation
  11  *******************************************************************************/
  12 package org.simantics.db.common.request;
  13
  14 import org.simantics.db.ReadGraph;
  15 import org.simantics.db.Resource;
  16 import org.simantics.db.exception.DatabaseException;
  17 import org.simantics.db.request.ReadExt;
  18 import org.simantics.db.service.QueryControl;
  19
  20 abstract public class TransientResourceRead<R> extends BinaryRead<Object,Resource,R> implements ReadExt {
  21
  22     protected static final Object WITH_PARENT = new Object();
  23
  24     public TransientResourceRead(ReadGraph graph, Resource parameter) throws DatabaseException {
  25         this(graph, graph.getService(QueryControl.class), parameter);
  26     }
  27
  28     public TransientResourceRead(ReadGraph graph, QueryControl qc, Resource parameter) throws DatabaseException {
  29         super(resolveFirstParameter(graph, qc), parameter);
  30     }
  31
  32     final private static Object resolveFirstParameter(ReadGraph graph, QueryControl qc) throws DatabaseException {
  33         if(qc.hasParentRequest(graph)) return WITH_PARENT;
  34         else return graph.getModificationCounter();
  35     }
  36
  37     @Override
  38     final public R perform(ReadGraph _graph) throws DatabaseException {
  39         if(parameter == WITH_PARENT) {
  40             return perform(_graph, parameter2);
  41         } else {
  42             QueryControl qc = _graph.getService(QueryControl.class);
  43             return qc.syncRequestIndependent(_graph, new UniqueRead<R>() {
  44                 @Override
  45                 public R perform(ReadGraph graph) throws DatabaseException {
  46                     return TransientResourceRead.this.perform(graph, parameter2);
  47                 }
  48             });
  49         }
  50     }
  51
  52     abstract public R perform(ReadGraph graph, Resource parameter) throws DatabaseException;
  53
  54     @Override
  55     public boolean isImmutable(ReadGraph graph) throws DatabaseException {
  56         return graph.isImmutable(parameter2);
  57     }
  58
  59 }