bundles/org.simantics.browsing.ui.graph.impl/src/org/simantics/browsing/ui/graph/impl/LazyResourceQueryContainer.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.browsing.ui.graph.impl;\r
  13 \r
  14 import java.util.function.Consumer;\r
  15 \r
  16 import org.simantics.browsing.ui.DataSource;\r
  17 import org.simantics.browsing.ui.NodeContext;\r
  18 import org.simantics.browsing.ui.NodeContext.PrimitiveQueryKey;\r
  19 import org.simantics.browsing.ui.PrimitiveQueryProcessor;\r
  20 import org.simantics.browsing.ui.PrimitiveQueryUpdater;\r
  21 import org.simantics.browsing.ui.graph.impl.request.ResourceQuery;\r
  22 import org.simantics.db.ReadGraph;\r
  23 import org.simantics.db.exception.DatabaseException;\r
  24 import org.simantics.db.procedure.Listener;\r
  25 import org.simantics.utils.Container;\r
  26 \r
  27 public abstract class LazyResourceQueryContainer<Result> implements Container<Result> {\r
  28 \r
  29     final private ResourceQuery<Result> query;\r
  30 \r
  31     final private PrimitiveQueryUpdater updater;\r
  32 \r
  33     private final Listener<Result> procedure;\r
  34 \r
  35     final protected NodeContext        context;\r
  36 \r
  37     private Result                      result;\r
  38 \r
  39     private boolean                     computed = false;\r
  40 \r
  41     /**\r
  42      * Computes the graph query result. This will get called asynchronously.\r
  43      * \r
  44      * @param graph\r
  45      * @return\r
  46      */\r
  47     protected abstract Result compute(ReadGraph graph) throws DatabaseException;\r
  48 \r
  49     /**\r
  50      * Needed for retrieving the actual primitive query key that is used to with\r
  51      * {@link PrimitiveQueryUpdater#scheduleReplace(NodeContext, PrimitiveQueryKey, Object)}\r
  52      * inside the {@link #query} that is initialized in the constructor\r
  53      * {@link #LazyResourceQueryContainer(PrimitiveQueryUpdater, NodeContext, Object, Object)}\r
  54      * .\r
  55      * \r
  56      * <p>\r
  57      * This key should originally be received by the actual\r
  58      * {@link PrimitiveQueryProcessor} that has been invoked to compute the\r
  59      * result that will be stored in this {@link LazyResourceQueryContainer}.\r
  60      * \r
  61      * @return\r
  62      */\r
  63     protected abstract PrimitiveQueryKey<Container<Result>> getKey();\r
  64 \r
  65     public LazyResourceQueryContainer(final PrimitiveQueryUpdater updater, final NodeContext context, Result initial) {\r
  66 \r
  67         this.updater = updater;\r
  68         this.context = context;\r
  69         this.result = initial;\r
  70 \r
  71         this.query = new ResourceQuery<Result>(getKey(), context) {\r
  72 \r
  73             @Override\r
  74             public Result perform(ReadGraph graph) throws DatabaseException {\r
  75                 return compute(graph);\r
  76             }\r
  77 \r
  78         };\r
  79 \r
  80         procedure = new Listener<Result>() {\r
  81 \r
  82             @Override\r
  83             public void execute(Result result) {\r
  84                 setResult(result);\r
  85                 updater.scheduleReplace(context, getKey(), LazyResourceQueryContainer.this);\r
  86             }\r
  87 \r
  88             @Override\r
  89             public boolean isDisposed() {\r
  90                 return updater.isDisposed();\r
  91             }\r
  92 \r
  93             public void exception(Throwable t) {\r
  94                 System.out.print("LazyResourceQueryContainer2.request failed: ");\r
  95                 t.printStackTrace();\r
  96             }\r
  97 \r
  98         };\r
  99 \r
 100     }\r
 101 \r
 102     protected PrimitiveQueryUpdater getUpdater() {\r
 103         return updater;\r
 104     }\r
 105 \r
 106     private void setResult(Result result) {\r
 107         this.result = result;\r
 108         computed = true;\r
 109     }\r
 110 \r
 111     @Override\r
 112     public Result get() {\r
 113 \r
 114         if (!computed) {\r
 115 \r
 116             final DataSource<ReadGraph> source = updater.getDataSource(ReadGraph.class);\r
 117             assert(source != null);\r
 118 \r
 119             source.schedule(new Consumer<ReadGraph>() {\r
 120 \r
 121                 @Override\r
 122                 public void accept(ReadGraph source) {\r
 123 \r
 124                     source.asyncRequest(query, procedure);\r
 125 \r
 126                 }\r
 127 \r
 128             });\r
 129 \r
 130         }\r
 131 \r
 132         return result;\r
 133 \r
 134     }\r
 135 \r
 136 }\r