Home

Contribute

Source code


1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142

/***************************************************************************
 * Copyright (c) 2004 - 2007 Eike Stepper, Germany.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 * 
 * Contributors:
 *    Eike Stepper - initial API and implementation
 **************************************************************************/
package org.eclipse.internal.net4j.util.concurrent;

import org.eclipse.net4j.util.concurrent.IWorkSerializer;
import org.eclipse.net4j.util.om.trace.ContextTracer;

import org.eclipse.internal.net4j.bundle.Net4j;

import java.util.Queue;
import java.util.concurrent.ConcurrentLinkedQueue;
import java.util.concurrent.ExecutorService;

/**
 * @author Eike Stepper
 */
public class AsynchronousWorkSerializer implements IWorkSerializer, Runnable
{
  private static final ContextTracer TRACER = new ContextTracer(Net4j.DEBUG_CONCURRENCY,
      AsynchronousWorkSerializer.class);

  private ExecutorService executorService;

  private Queue<Runnable> workQueue;

  private Occupation occupation = new Occupation();

  public AsynchronousWorkSerializer(ExecutorService executorService, Queue<Runnable> workQueue)
  {
    if (executorService == null)
    {
      throw new IllegalArgumentException("executorService == null"); //$NON-NLS-1$
    }

    this.executorService = executorService;
    this.workQueue = workQueue;
  }

  public AsynchronousWorkSerializer(ExecutorService executorService)
  {
    this(executorService, new ConcurrentLinkedQueue());
  }

  public ExecutorService getExecutorService()
  {
    return executorService;
  }

  public void addWork(Runnable work)
  {
    workQueue.add(work);

    // isOccupied can (and must) be called unsynchronized here
    if (!occupation.isOccupied())
    {
      synchronized (occupation)
      {
        occupation.setOccupied(true);
      }

      if (TRACER.isEnabled())
      {
        TRACER.trace("Notifying executor service"); //$NON-NLS-1$
      }

      executorService.execute(this);
    }
  }

  /**
   * Executed in the context of the
   * {@link #getExecutorService() executor service}.
   * <p>
   */
  public void run()
  {
    synchronized (occupation)
    {
      Runnable work;
      while (occupation.isOccupied() && (work = workQueue.poll()) != null)
      {
        try
        {
          work.run();
        }
        catch (RuntimeException ex)
        {
          if (TRACER.isEnabled())
          {
            TRACER.trace(ex);
          }
        }
      }

      occupation.setOccupied(false);
    }
  }

  public void dispose()
  {
    if (occupation.isOccupied())
    {
      occupation.setOccupied(false);
    }

    workQueue.clear();
    workQueue = null;
    executorService = null;
  }

  @Override
  public String toString()
  {
    return "AsynchronousWorkSerializer[" + executorService + "]"; //$NON-NLS-1$ //$NON-NLS-2$
  }

  /**
   * @author Eike Stepper
   */
  private static final class Occupation
  {
    private boolean occupied = false;

    public boolean isOccupied()
    {
      return occupied;
    }

    public void setOccupied(boolean occupied)
    {
      this.occupied = occupied;
    }
  }
}