mcs/class/System.Runtime.Remoting/System.Runtime.Remoting.Channels/RemotingThreadPool.cs

   1 //
   2 // System.Runtime.Remoting.Channels.RemotingThreadPool.cs
   3 //
   4 // Author: Lluis Sanchez Gual (lluis@ximian.com)
   5 //
   6 // 2005 (C) Copyright, Novell, Inc.
   7 //
   8
   9 //
  10 // Permission is hereby granted, free of charge, to any person obtaining
  11 // a copy of this software and associated documentation files (the
  12 // "Software"), to deal in the Software without restriction, including
  13 // without limitation the rights to use, copy, modify, merge, publish,
  14 // distribute, sublicense, and/or sell copies of the Software, and to
  15 // permit persons to whom the Software is furnished to do so, subject to
  16 // the following conditions:
  17 //
  18 // The above copyright notice and this permission notice shall be
  19 // included in all copies or substantial portions of the Software.
  20 //
  21 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  22 // EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  23 // MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  24 // NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
  25 // LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
  26 // OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
  27 // WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  28 //
  29
  30 using System;
  31 using System.Collections;
  32 using System.Threading;
  33
  34 namespace System.Runtime.Remoting.Channels
  35 {
  36         internal class RemotingThreadPool
  37         {
  38                 const int ThreadLimit = 1000;
  39                 const int ThreadWaitTime = 20000; //ms
  40                 const int PoolGrowDelay = 500; // ms
  41                 const int MinThreads = 3;
  42
  43                 int freeThreads;
  44                 int poolUsers;
  45                 Queue workItems = new Queue ();
  46                 AutoResetEvent threadDone = new AutoResetEvent (false);
  47                 ArrayList runningThreads = new ArrayList ();
  48
  49                 bool stopped = false;
  50
  51                 static object globalLock = new object ();
  52                 static RemotingThreadPool sharedPool;
  53
  54                 public static RemotingThreadPool GetSharedPool ()
  55                 {
  56                         lock (globalLock) {
  57                                 if (sharedPool == null)
  58                                         sharedPool = new RemotingThreadPool ();
  59                                 sharedPool.poolUsers++;
  60                         }
  61                         return sharedPool;
  62                 }
  63
  64                 public void Free ()
  65                 {
  66                         lock (globalLock) {
  67                                 if (--poolUsers > 0)
  68                                         return;
  69
  70                                 lock (workItems) {
  71                                         stopped = true;
  72                                         threadDone.Set ();
  73                                         workItems.Clear ();
  74                                         foreach (Thread t in runningThreads)
  75                                                 t.Abort ();
  76                                         runningThreads.Clear ();
  77                                 }
  78                                 if (this == sharedPool)
  79                                         sharedPool = null;
  80                         }
  81                 }
  82
  83                 public bool RunThread (ThreadStart threadStart)
  84                 {
  85                         lock (workItems) {
  86                                 if (stopped)
  87                                         throw new RemotingException ("Server channel stopped.");
  88
  89                                 if (freeThreads > 0) {
  90                                         freeThreads--;
  91                                         workItems.Enqueue (threadStart);
  92                                         Monitor.Pulse (workItems);
  93                                         return true;
  94                                 } else if (runningThreads.Count < MinThreads) {
  95                                         workItems.Enqueue (threadStart);
  96                                         StartPoolThread ();
  97                                         return true;
  98                                 }
  99                         }
 100
 101                         // Try again some ms later, and if there are still no free threads,
 102                         // then create a new one
 103
 104                         threadDone.WaitOne (PoolGrowDelay, false);
 105
 106                         lock (workItems) {
 107                                 if (stopped)
 108                                         throw new RemotingException ("Server channel stopped.");
 109
 110                                 if (freeThreads > 0) {
 111                                         freeThreads--;
 112                                         workItems.Enqueue (threadStart);
 113                                         Monitor.Pulse (workItems);
 114                                 } else {
 115                                         if (runningThreads.Count >= ThreadLimit)
 116                                                 return false;
 117                                         workItems.Enqueue (threadStart);
 118                                         StartPoolThread ();
 119                                 }
 120                         }
 121                         return true;
 122                 }
 123
 124                 void StartPoolThread ()
 125                 {
 126                         Thread thread = new Thread (new ThreadStart (PoolThread));
 127                         runningThreads.Add (thread);
 128                         thread.IsBackground = true;
 129                         thread.Start ();
 130                 }
 131
 132                 void PoolThread ()
 133                 {
 134                         while (true) {
 135                                 ThreadStart work = null;
 136                                 do {
 137                                         lock (workItems) {
 138                                                 if (workItems.Count > 0)
 139                                                         work = (ThreadStart) workItems.Dequeue ();
 140                                                 else {
 141                                                         freeThreads ++;
 142                                                         threadDone.Set ();
 143                                                         if (!Monitor.Wait (workItems, ThreadWaitTime)) {
 144                                                                 // Maybe it timed out when the work was being queued.
 145                                                                 if (workItems.Count > 0) {
 146                                                                         work = (ThreadStart) workItems.Dequeue ();
 147                                                                 } else {
 148                                                                         freeThreads --;
 149                                                                         if (freeThreads == 0) threadDone.Reset ();
 150                                                                         runningThreads.Remove (Thread.CurrentThread);
 151                                                                         return;
 152                                                                 }
 153                                                         }
 154                                                 }
 155                                         }
 156                                 } while (work == null);
 157                                 try {
 158                                         work ();
 159                                 }
 160                                 catch (Exception ex)
 161                                 {
 162 #if DEBUG
 163                                         Console.WriteLine("The exception was caught during RemotingThreadPool.PoolThread - work: {0}, {1}", ex.GetType(), ex.Message);
 164 #endif
 165                                 }
 166                         }
 167                 }
 168         }
 169 }
 170