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

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