bundles/org.simantics.db.common/src/org/simantics/db/common/processor/MergingDelayedWriteProcessor.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.processor;
  13
  14 import java.util.concurrent.ConcurrentLinkedQueue;
  15
  16 import org.simantics.db.AsyncRequestProcessor;
  17 import org.simantics.db.WriteGraph;
  18 import org.simantics.db.common.request.DelayedWriteRequest;
  19 import org.simantics.db.common.utils.Logger;
  20 import org.simantics.db.exception.DatabaseException;
  21 import org.simantics.db.request.DelayedWrite;
  22
  23 final public class MergingDelayedWriteProcessor extends ProcessorBase {
  24
  25     final long transactionKeepalivePeriod;
  26     final ConcurrentLinkedQueue<DelayedWrite> queue = new ConcurrentLinkedQueue<DelayedWrite>();
  27     final private AsyncRequestProcessor processor;
  28
  29     boolean hasAlreadyRequest = false;
  30
  31     public MergingDelayedWriteProcessor(AsyncRequestProcessor processor, long transactionKeepalivePeriod) {
  32         this.processor = processor;
  33         this.transactionKeepalivePeriod = transactionKeepalivePeriod;
  34     }
  35
  36     class MergedWrite extends DelayedWriteRequest {
  37
  38         @Override
  39         public void perform(WriteGraph graph) throws DatabaseException {
  40
  41 //            System.out.println("MergedWrite begins");
  42
  43             while (true) {
  44
  45                 DelayedWrite next = queue.poll();
  46                 if(next == null) {
  47                     synchronized (MergingDelayedWriteProcessor.this) {
  48                         if (transactionKeepalivePeriod > 0) {
  49                             try {
  50                                 MergingDelayedWriteProcessor.this.wait(transactionKeepalivePeriod);
  51                             } catch (InterruptedException e) {
  52                                         Logger.defaultLogError(e);
  53                             }
  54                             next = queue.poll();
  55                         }
  56                         if(next == null) {
  57                             hasAlreadyRequest = false;
  58 //                            System.out.println("MergedWrite ends");
  59                             return;
  60                         }
  61                     }
  62                 }
  63
  64 //                System.out.println("MergedWrite executes " + next);
  65                 try {
  66                     next.perform(graph);
  67                 } catch(Throwable t) {
  68                         Logger.defaultLogError(t);
  69                 }
  70
  71             }
  72
  73         }
  74
  75     }
  76
  77     @Override
  78     public void asyncRequest(DelayedWrite request) {
  79
  80         queue.add(request);
  81
  82         synchronized (this) {
  83
  84           if (!hasAlreadyRequest) {
  85               processor.asyncRequest(new MergedWrite());
  86               hasAlreadyRequest = true;
  87           } else {
  88               notify();
  89           }
  90
  91         }
  92
  93     }
  94
  95     @Override
  96     public String toString() {
  97         return "MergingDelayedWriteProcessor@" + System.identityHashCode(this) + " (based on " + processor + ")";
  98     }
  99
 100 }