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

   1 /*******************************************************************************\r
   2  * Copyright (c) 2012 Association for Decentralized Information Management in\r
   3  * Industry THTH ry.\r
   4  * All rights reserved. This program and the accompanying materials\r
   5  * are made available under the terms of the Eclipse Public License v1.0\r
   6  * which accompanies this distribution, and is available at\r
   7  * http://www.eclipse.org/legal/epl-v10.html\r
   8  *\r
   9  * Contributors:\r
  10  *     VTT Technical Research Centre of Finland - initial API and implementation\r
  11  *******************************************************************************/\r
  12 package org.simantics.utils.threads;\r
  13 \r
  14 import java.util.concurrent.TimeUnit;\r
  15 \r
  16 /**\r
  17  * @author Antti Villberg\r
  18  */\r
  19 public class Throttler implements Runnable {\r
  20 \r
  21         final private IThreadWorkQueue thread;\r
  22         final private int interval;\r
  23 \r
  24         private boolean isScheduling = false;\r
  25 \r
  26         private long[] dispatchTimes;\r
  27         private long lastQueueTime;\r
  28 \r
  29         private int dispatchTimePointer = 0;\r
  30 \r
  31         private Runnable todo;\r
  32 \r
  33         public Throttler(IThreadWorkQueue thread, int interval, int queueLength) {\r
  34 \r
  35                 this.thread = thread;\r
  36                 this.interval = interval;\r
  37 \r
  38                 long currentTime = System.currentTimeMillis();\r
  39 \r
  40                 dispatchTimes = new long[queueLength];\r
  41                 for(int i=0;i<dispatchTimes.length;i++)\r
  42                         dispatchTimes[i] = currentTime - interval;\r
  43 \r
  44                 lastQueueTime = Long.MAX_VALUE;\r
  45 \r
  46         }\r
  47 \r
  48         public synchronized void run() {\r
  49 \r
  50                 if(todo != null) {\r
  51                         thread.asyncExec(todo);\r
  52                         todo = null;\r
  53                         ThreadUtils.getTimer().schedule(this, interval, TimeUnit.MILLISECONDS);\r
  54                 } else {\r
  55                         isScheduling = false;\r
  56                 }\r
  57 \r
  58         }\r
  59         \r
  60         public synchronized void schedule(Runnable r) {\r
  61 \r
  62                 assert(thread.currentThreadAccess());\r
  63                 \r
  64                 dispatch(r);\r
  65 \r
  66                 if(getQueueTime() < interval) {\r
  67 \r
  68                         isScheduling = true;\r
  69                         ThreadUtils.getTimer().schedule(this, interval, TimeUnit.MILLISECONDS);\r
  70 \r
  71                 }\r
  72 \r
  73         }\r
  74 \r
  75         private long getQueueTime() {\r
  76                 return lastQueueTime;\r
  77         }\r
  78 \r
  79         private void dispatch(Runnable runnable) {\r
  80 \r
  81                 long time = System.currentTimeMillis();\r
  82                 lastQueueTime = time - dispatchTimes[dispatchTimePointer];\r
  83                 dispatchTimes[dispatchTimePointer] = time;\r
  84                 dispatchTimePointer = ((dispatchTimePointer+1) % dispatchTimes.length);\r
  85 \r
  86                 if(!isScheduling) {\r
  87                         todo = null;\r
  88                         runnable.run();\r
  89                 } else {\r
  90                         todo = runnable;\r
  91                 }\r
  92 \r
  93         }\r
  94 \r
  95 }\r