+/*******************************************************************************\r
+ * Copyright (c) 2007, 2010 Association for Decentralized Information Management\r
+ * in Industry THTH ry.\r
+ * All rights reserved. This program and the accompanying materials\r
+ * are made available under the terms of the Eclipse Public License v1.0\r
+ * which accompanies this distribution, and is available at\r
+ * http://www.eclipse.org/legal/epl-v10.html\r
+ *\r
+ * Contributors:\r
+ * VTT Technical Research Centre of Finland - initial API and implementation\r
+ *******************************************************************************/\r
+package org.simantics.browsing.ui.graph.impl;\r
+\r
+import java.util.function.Consumer;\r
+\r
+import org.simantics.browsing.ui.DataSource;\r
+import org.simantics.browsing.ui.NodeContext;\r
+import org.simantics.browsing.ui.NodeContext.PrimitiveQueryKey;\r
+import org.simantics.browsing.ui.PrimitiveQueryProcessor;\r
+import org.simantics.browsing.ui.PrimitiveQueryUpdater;\r
+import org.simantics.browsing.ui.graph.impl.request.ResourceQuery;\r
+import org.simantics.db.ReadGraph;\r
+import org.simantics.db.exception.DatabaseException;\r
+import org.simantics.db.procedure.Listener;\r
+import org.simantics.utils.Container;\r
+\r
+public abstract class LazyResourceQueryContainer<Result> implements Container<Result> {\r
+\r
+ final private ResourceQuery<Result> query;\r
+\r
+ final private PrimitiveQueryUpdater updater;\r
+\r
+ private final Listener<Result> procedure;\r
+\r
+ final protected NodeContext context;\r
+\r
+ private Result result;\r
+\r
+ private boolean computed = false;\r
+\r
+ /**\r
+ * Computes the graph query result. This will get called asynchronously.\r
+ * \r
+ * @param graph\r
+ * @return\r
+ */\r
+ protected abstract Result compute(ReadGraph graph) throws DatabaseException;\r
+\r
+ /**\r
+ * Needed for retrieving the actual primitive query key that is used to with\r
+ * {@link PrimitiveQueryUpdater#scheduleReplace(NodeContext, PrimitiveQueryKey, Object)}\r
+ * inside the {@link #query} that is initialized in the constructor\r
+ * {@link #LazyResourceQueryContainer(PrimitiveQueryUpdater, NodeContext, Object, Object)}\r
+ * .\r
+ * \r
+ * <p>\r
+ * This key should originally be received by the actual\r
+ * {@link PrimitiveQueryProcessor} that has been invoked to compute the\r
+ * result that will be stored in this {@link LazyResourceQueryContainer}.\r
+ * \r
+ * @return\r
+ */\r
+ protected abstract PrimitiveQueryKey<Container<Result>> getKey();\r
+\r
+ public LazyResourceQueryContainer(final PrimitiveQueryUpdater updater, final NodeContext context, Result initial) {\r
+\r
+ this.updater = updater;\r
+ this.context = context;\r
+ this.result = initial;\r
+\r
+ this.query = new ResourceQuery<Result>(getKey(), context) {\r
+\r
+ @Override\r
+ public Result perform(ReadGraph graph) throws DatabaseException {\r
+ return compute(graph);\r
+ }\r
+\r
+ };\r
+\r
+ procedure = new Listener<Result>() {\r
+\r
+ @Override\r
+ public void execute(Result result) {\r
+ setResult(result);\r
+ updater.scheduleReplace(context, getKey(), LazyResourceQueryContainer.this);\r
+ }\r
+\r
+ @Override\r
+ public boolean isDisposed() {\r
+ return updater.isDisposed();\r
+ }\r
+\r
+ public void exception(Throwable t) {\r
+ System.out.print("LazyResourceQueryContainer2.request failed: ");\r
+ t.printStackTrace();\r
+ }\r
+\r
+ };\r
+\r
+ }\r
+\r
+ protected PrimitiveQueryUpdater getUpdater() {\r
+ return updater;\r
+ }\r
+\r
+ private void setResult(Result result) {\r
+ this.result = result;\r
+ computed = true;\r
+ }\r
+\r
+ @Override\r
+ public Result get() {\r
+\r
+ if (!computed) {\r
+\r
+ final DataSource<ReadGraph> source = updater.getDataSource(ReadGraph.class);\r
+ assert(source != null);\r
+\r
+ source.schedule(new Consumer<ReadGraph>() {\r
+\r
+ @Override\r
+ public void accept(ReadGraph source) {\r
+\r
+ source.asyncRequest(query, procedure);\r
+\r
+ }\r
+\r
+ });\r
+\r
+ }\r
+\r
+ return result;\r
+\r
+ }\r
+\r
+}\r