Util/ThreadPond.cs

   1 //
   2 // ThreadPond.cs
   3 //
   4 // Copyright (C) 2005 Novell, Inc.
   5 //
   6
   7 //
   8 // Permission is hereby granted, free of charge, to any person obtaining a
   9 // copy of this software and associated documentation files (the "Software"),
  10 // to deal in the Software without restriction, including without limitation
  11 // the rights to use, copy, modify, merge, publish, distribute, sublicense,
  12 // and/or sell copies of the Software, and to permit persons to whom the
  13 // Software is furnished to do so, subject to the following conditions:
  14 //
  15 // The above copyright notice and this permission notice shall be included in
  16 // all copies or substantial portions of the Software.
  17 //
  18 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  19 // IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  20 // FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  21 // AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  22 // LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
  23 // FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
  24 // DEALINGS IN THE SOFTWARE.
  25 //
  26
  27 using System;
  28 using System.Collections;
  29 using System.Threading;
  30
  31 namespace Beagle.Util {
  32
  33         public class ThreadPond {
  34
  35                 private object queue_lock = new object ();
  36                 private Queue queue = new Queue ();
  37                 private Thread [] threads;
  38                 private bool running;
  39
  40                 public ThreadPond (int N)
  41                 {
  42                         queue_lock = new object ();
  43
  44                         queue = new Queue ();
  45
  46                         ThreadStart worker;
  47                         worker = new ThreadStart (Worker);
  48
  49                         threads = new Thread [N];
  50                         for (int i = 0; i < N; ++i)
  51                                 threads [i] = new Thread (worker);
  52
  53                         running = false;
  54                 }
  55
  56                 public void Add (ThreadStart start)
  57                 {
  58                         lock (queue_lock) {
  59                                 queue.Enqueue (start);
  60                                 Monitor.Pulse (queue_lock);
  61                         }
  62                 }
  63
  64                 public void Start ()
  65                 {
  66                         running = true;
  67                         Log.Debug ("Starting {0} threads in pond", threads.Length);
  68                         for (int i = 0; i < threads.Length; ++i)
  69                                 threads [i].Start ();
  70                 }
  71
  72                 public void Stop ()
  73                 {
  74                         running = false;
  75
  76                         // We need to pulse the lock once per thread, so that they
  77                         // will all have an opportunity to wake up and terminate.
  78                         for (int i = 0; i < threads.Length; ++i)
  79                                 lock (queue_lock)
  80                                         Monitor.Pulse (queue_lock);
  81                 }
  82
  83                 private void Worker ()
  84                 {
  85                         while (running) {
  86
  87                                 ThreadStart start = null;
  88
  89                                 lock (queue_lock) {
  90                                         if (! running)
  91                                                 return;
  92                                         if (queue.Count == 0) {
  93                                                 Monitor.Wait (queue_lock);
  94                                                 continue;
  95                                         }
  96                                         start = queue.Dequeue () as ThreadStart;
  97                                 }
  98
  99                                 if (start == null)
 100                                         continue;
 101
 102                                 try {
 103                                         start ();
 104                                 } catch (Exception ex) {
 105                                         Logger.Log.Warn ("Caught exception in ThreadPond worker");
 106                                         Logger.Log.Warn (ex);
 107                                 }
 108                         }
 109                 }
 110
 111         }
 112
 113 }