bundles/org.simantics.db.common/src/org/simantics/db/common/request/DelayedWriteRequest.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 java.util.Map;
  15
  16 import org.simantics.db.AsyncRequestProcessor;
  17 import org.simantics.db.ChangeSetIdentifier;
  18 import org.simantics.db.Operation;
  19 import org.simantics.db.RequestProcessor;
  20 import org.simantics.db.exception.DatabaseException;
  21 import org.simantics.db.procedure.Procedure;
  22 import org.simantics.db.request.DelayedWrite;
  23 import org.simantics.db.request.UndoTraits;
  24 import org.simantics.db.request.WriteInterface;
  25 import org.simantics.utils.datastructures.Callback;
  26
  27
  28 /**
  29  * Usage samples:
  30  *
  31  * <p>
  32  * Synchronous read without checked exceptions:
  33  * </p>
  34  * <pre>
  35  * Resource r = new SimpleReadGraphRequest&lt;Resource&gt;(session) {
  36  *     {@code @Override}
  37  *     public Resource run(Graph g) {
  38  *         Resource r = doSomethingThatMayFail();
  39  *         return r;
  40  *     }
  41  * }.sync();
  42  * </pre>
  43  *
  44  * <p>
  45  * Synchronous read with a selected checked exception that may be thrown:
  46  * </p>
  47  * <pre>
  48  * Resource r = new SimpleReadGraphRequest&lt;Resource&gt;(session) {
  49  *     {@code @Override}
  50  *     public Resource run(Graph g) throws CheckedException {
  51  *         Resource r = doSomethingThatMayFailWithCheckedException();
  52  *         return r;
  53  *     }
  54  * }.sync(CheckedException.class);
  55  * </pre>
  56  *
  57  * <p>
  58  * Asynchronous read with a completed() method for examining the result:
  59  * </p>
  60  * <pre>
  61  * Resource r = new SimpleReadGraphRequest&lt;Resource&gt;(session) {
  62  *     {@code @Override}
  63  *     public Resource run(Graph g) {
  64  *         Resource r = doSomethingThatMayFail();
  65  *         return r;
  66  *     }
  67  *     public void completed(Resource result) {
  68  *         // quickly dispatch the result somewhere, do nothing serious in this code.
  69  *     }
  70  * }.async();
  71  * </pre>
  72  *
  73  * @param <T> the result type
  74  */
  75 public abstract class DelayedWriteRequest implements DelayedWrite, UndoTraits, WriteInterface<Object> {
  76
  77     @Override
  78     public ChangeSetIdentifier getIdentifier() {
  79         return null;
  80     }
  81
  82     @Override
  83     public void fillMetadata(Map<String, String> metadata) {
  84         metadata.put("class=", this.getClass().getName());
  85     }
  86
  87     @Override
  88     public void commitOk(Operation op) {
  89     }
  90
  91     @Override
  92     public void request(AsyncRequestProcessor processor, final Procedure<Object> procedure) {
  93         processor.asyncRequest(this, new Callback<DatabaseException>() {
  94
  95                         @Override
  96                         public void run(DatabaseException parameter) {
  97                                 if(parameter != null) procedure.exception(parameter);
  98                                 else procedure.execute(null);
  99                         }
 100
 101                 });
 102     }
 103
 104     @Override
 105     public Object request(RequestProcessor processor) throws DatabaseException {
 106         processor.syncRequest(this);
 107         return null;
 108     }
 109
 110 }