bundles/org.simantics.utils.thread/src/org/simantics/utils/threads/Throttler.java

   1 /*******************************************************************************
   2  * Copyright (c) 2012 Association for Decentralized Information Management in
   3  * 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.utils.threads;
  13
  14 import java.util.concurrent.TimeUnit;
  15
  16 /**
  17  * @author Antti Villberg
  18  */
  19 public class Throttler implements Runnable {
  20
  21         final private IThreadWorkQueue thread;
  22         final private int interval;
  23
  24         private boolean isScheduling = false;
  25
  26         private long[] dispatchTimes;
  27         private long lastQueueTime;
  28
  29         private int dispatchTimePointer = 0;
  30
  31         private Runnable todo;
  32
  33         public Throttler(IThreadWorkQueue thread, int interval, int queueLength) {
  34
  35                 this.thread = thread;
  36                 this.interval = interval;
  37
  38                 long currentTime = System.currentTimeMillis();
  39
  40                 dispatchTimes = new long[queueLength];
  41                 for(int i=0;i<dispatchTimes.length;i++)
  42                         dispatchTimes[i] = currentTime - interval;
  43
  44                 lastQueueTime = Long.MAX_VALUE;
  45
  46         }
  47
  48         public synchronized void run() {
  49
  50                 if(todo != null) {
  51                         thread.asyncExec(todo);
  52                         todo = null;
  53                         ThreadUtils.getTimer().schedule(this, interval, TimeUnit.MILLISECONDS);
  54                 } else {
  55                         isScheduling = false;
  56                 }
  57
  58         }
  59
  60         public synchronized void schedule(Runnable r) {
  61
  62                 assert(thread.currentThreadAccess());
  63
  64                 dispatch(r);
  65
  66                 if(getQueueTime() < interval) {
  67
  68                         isScheduling = true;
  69                         ThreadUtils.getTimer().schedule(this, interval, TimeUnit.MILLISECONDS);
  70
  71                 }
  72
  73         }
  74
  75         private long getQueueTime() {
  76                 return lastQueueTime;
  77         }
  78
  79         private void dispatch(Runnable runnable) {
  80
  81                 long time = System.currentTimeMillis();
  82                 lastQueueTime = time - dispatchTimes[dispatchTimePointer];
  83                 dispatchTimes[dispatchTimePointer] = time;
  84                 dispatchTimePointer = ((dispatchTimePointer+1) % dispatchTimes.length);
  85
  86                 if(!isScheduling) {
  87                         todo = null;
  88                         runnable.run();
  89                 } else {
  90                         todo = runnable;
  91                 }
  92
  93         }
  94
  95 }