Migrated source code from Simantics SVN

[simantics/platform.git] / bundles / org.simantics.db.common / src / org / simantics / db / common / changeset / GenericChangeListener.java

diff --git a/bundles/org.simantics.db.common/src/org/simantics/db/common/changeset/GenericChangeListener.java b/bundles/org.simantics.db.common/src/org/simantics/db/common/changeset/GenericChangeListener.java
new file mode 100644 (file)
index 0000000..f0d28cd
--- /dev/null
+++ b/bundles/org.simantics.db.common/src/org/simantics/db/common/changeset/GenericChangeListener.java
@@ -0,0 +1,92 @@
+/*******************************************************************************\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.db.common.changeset;\r
+\r
+import java.lang.reflect.Constructor;\r
+import java.lang.reflect.InvocationTargetException;\r
+\r
+import org.simantics.db.ChangeSet;\r
+import org.simantics.db.MetadataI;\r
+import org.simantics.db.ReadGraph;\r
+import org.simantics.db.Session;\r
+import org.simantics.db.common.procedure.adapter.TransientCacheListener;\r
+import org.simantics.db.common.utils.Logger;\r
+import org.simantics.db.event.ChangeEvent;\r
+import org.simantics.db.event.ChangeListener;\r
+import org.simantics.db.exception.DatabaseException;\r
+import org.simantics.db.request.Read;\r
+import org.simantics.utils.ReflectionUtils;\r
+\r
+/**\r
+ * A listener added to a Session for receiving notifications for completed\r
+ * write transactions.\r
+ * \r
+ * @see GraphChangeEvent\r
+ * @see Session\r
+ */\r
+abstract public class GenericChangeListener<Request, Result> implements ChangeListener {\r
+\r
+    private final Constructor<Read<Result>> constructor;\r
+\r
+    public GenericChangeListener() {\r
+\r
+        try {\r
+            Class<Read<Result>> clazz = ReflectionUtils.getSingleParameterTypeExtending(getClass());\r
+            this.constructor = clazz.getConstructor(ChangeSet.class);\r
+            return;\r
+        } catch (SecurityException e) {\r
+            Logger.defaultLogError(e);\r
+        } catch (NoSuchMethodException e) {\r
+            Logger.defaultLogError(e);\r
+        }\r
+        throw new IllegalArgumentException();\r
+\r
+    }\r
+\r
+    final public void graphChanged(ChangeEvent e) throws DatabaseException {\r
+\r
+        try {\r
+            if (!preEventRequest())\r
+                return;\r
+\r
+            Result event = e.getGraph().syncRequest(constructor.newInstance(e.getChanges()), TransientCacheListener.<Result>instance());\r
+            onEvent(e.getGraph(), e.getMetadataI(), event);\r
+        } catch (IllegalArgumentException e1) {\r
+            Logger.defaultLogError(e1);\r
+        } catch (InstantiationException e1) {\r
+            Logger.defaultLogError(e1);\r
+        } catch (IllegalAccessException e1) {\r
+            Logger.defaultLogError(e1);\r
+        } catch (InvocationTargetException e1) {\r
+            Logger.defaultLogError(e1);\r
+        }\r
+\r
+    }\r
+\r
+    /**\r
+     * Invoked before performing the event request with the received change\r
+     * event and sending the result to {@link #onEvent(ReadGraph, Object)}. Can\r
+     * be used to veto processing of an event.\r
+     * \r
+     * @return <code>true</code> if the event request shall be performed and the\r
+     *         result sent to {@link #onEvent(ReadGraph, Object)},\r
+     *         <code>false</code> to disable any further processing of the\r
+     *         received db {@link ChangeEvent}\r
+     * @since 1.8\r
+     */\r
+    public boolean preEventRequest() {\r
+        return true;\r
+    }\r
+\r
+    public abstract void onEvent(ReadGraph graph, MetadataI metadata, Result event) throws DatabaseException;\r
+\r
+}\r