bundles/org.simantics.db.common/src/org/simantics/db/common/GraphSemaphore.java

   1 package org.simantics.db.common;
   2
   3 import java.util.concurrent.Semaphore;
   4 import java.util.concurrent.TimeUnit;
   5
   6 import org.simantics.db.AsyncReadGraph;
   7 import org.simantics.db.exception.DatabaseException;
   8
   9 public class GraphSemaphore extends Semaphore {
  10
  11         private static final long serialVersionUID = 2114861433176831938L;
  12
  13         private final AsyncReadGraph graph;
  14
  15         public GraphSemaphore(AsyncReadGraph graph, int permits) {
  16                 super(permits);
  17                 this.graph = graph;
  18         }
  19
  20         public void waitFor(int permits) throws DatabaseException, InterruptedException {
  21
  22         boolean success = false;
  23         success = tryAcquire(permits);
  24         if(success) return;
  25
  26         while(!success) {
  27
  28                 if(graph.performPending()) {
  29                         // Some task was done
  30                         success = tryAcquire(permits);
  31                 } else {
  32                         // Nothing to do - just wait
  33                 try {
  34                                 success = tryAcquire(permits, 10, TimeUnit.SECONDS);
  35                                 if(!success) throw new DatabaseException("Timeout while waiting for async request to complete.");
  36                         } catch (InterruptedException e) {
  37                                 throw new DatabaseException(e);
  38                         }
  39                 }
  40
  41         }
  42
  43
  44         }
  45
  46
  47
  48 }