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         boolean success = false;
  22         success = tryAcquire(permits);
  23         if (success)
  24             return;
  25
  26         while (!success) {
  27             if (graph.performPending()) {
  28                 // Some task was done
  29                 success = tryAcquire(permits);
  30             } else {
  31                 // Nothing to do - just wait
  32                 try {
  33                     success = tryAcquire(permits, 10, TimeUnit.SECONDS);
  34                     if (!success)
  35                         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 }