mcs/class/System.Web/System.Web/QueueManager.cs

   1 //
   2 // System.Web.QueueManager
   3 //
   4 // Authors:
   5 //      Gonzalo Paniagua Javier (gonzalo@ximian.com)
   6 //
   7 // (C) 2003-2009 Novell, Inc (http://www.novell.com)
   8 //
   9
  10 //
  11 // Permission is hereby granted, free of charge, to any person obtaining
  12 // a copy of this software and associated documentation files (the
  13 // "Software"), to deal in the Software without restriction, including
  14 // without limitation the rights to use, copy, modify, merge, publish,
  15 // distribute, sublicense, and/or sell copies of the Software, and to
  16 // permit persons to whom the Software is furnished to do so, subject to
  17 // the following conditions:
  18 //
  19 // The above copyright notice and this permission notice shall be
  20 // included in all copies or substantial portions of the Software.
  21 //
  22 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  23 // EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  24 // MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  25 // NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
  26 // LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
  27 // OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
  28 // WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  29 //
  30
  31 using System;
  32 using System.Collections;
  33 using System.Diagnostics;
  34 using System.Text;
  35 using System.Threading;
  36 using System.Web.Configuration;
  37
  38 namespace System.Web
  39 {
  40         sealed class QueueManager
  41         {
  42                 // keep the defaults in sync with the ones in HttpRuntimeSection.cs
  43                 int minFree = 8;
  44                 int minLocalFree = 4;
  45                 int queueLimit = 5000;
  46                 Queue queue;
  47                 bool disposing;
  48                 Exception initialException;
  49                 PerformanceCounter requestsQueuedCounter;
  50
  51                 public QueueManager ()
  52                 {
  53                         Exception ex = null;
  54
  55                         try {
  56                                 HttpRuntimeSection config;
  57
  58                                 config = (HttpRuntimeSection) WebConfigurationManager.GetWebApplicationSection ("system.web/httpRuntime");
  59                                 minFree = config.MinFreeThreads;
  60                                 minLocalFree = config.MinLocalRequestFreeThreads;
  61                                 queueLimit = config.AppRequestQueueLimit;
  62                         } catch (Exception e) {
  63                                 ex = e;
  64                         }
  65
  66                         try {
  67                                 queue = new Queue (queueLimit);
  68                         } catch (Exception e) {
  69                                 if (ex == null) {
  70                                         initialException = e;
  71                                 } else {
  72                                         StringBuilder sb = new StringBuilder ("Several exceptions occurred:\n");
  73                                         sb.AppendFormat ("--- Exception Q1:\n{0}\n", ex.ToString ());
  74                                         sb.AppendFormat ("--- Exception Q2:\n{0}\n", e.ToString ());
  75                                         initialException = new Exception (sb.ToString ());
  76                                 }
  77                         }
  78
  79                         if (initialException == null && ex != null)
  80                                 initialException = ex;
  81
  82                         requestsQueuedCounter = new PerformanceCounter ("ASP.NET", "Requests Queued");
  83                         requestsQueuedCounter.RawValue = 0;
  84                 }
  85
  86                 public bool HasException {
  87                         get { return initialException != null; }
  88                 }
  89
  90                 public Exception InitialException {
  91                         get { return initialException; }
  92                 }
  93
  94                 bool CanExecuteRequest (HttpWorkerRequest req)
  95                 {
  96                         if (disposing)
  97                                 return false;
  98
  99 #if TARGET_J2EE
 100                         return true; // The J2EE app server manages the thread pool
 101 #else
 102                         int threads, cports;
 103                         ThreadPool.GetAvailableThreads (out threads, out cports);
 104                         bool local = (req != null && req.GetLocalAddress () == "127.0.0.1");
 105                         return (threads > minFree) || (local && threads > minLocalFree);
 106 #endif
 107                 }
 108
 109                 public HttpWorkerRequest GetNextRequest (HttpWorkerRequest req)
 110                 {
 111                         if (!CanExecuteRequest (req)) {
 112                                 if (!disposing && req != null) {
 113                                         lock (queue) {
 114                                                 Queue (req);
 115                                         }
 116                                 }
 117
 118                                 return null;
 119                         }
 120
 121                         HttpWorkerRequest result;
 122                         lock (queue) {
 123                                 result = Dequeue ();
 124                                 if (result != null) {
 125                                         if (req != null)
 126                                                 Queue (req);
 127                                 } else {
 128                                         result = req;
 129                                 }
 130                         }
 131
 132                         return result;
 133                 }
 134
 135                 void Queue (HttpWorkerRequest wr)
 136                 {
 137                         if (queue.Count < queueLimit) {
 138                                 queue.Enqueue (wr);
 139                                 requestsQueuedCounter.Increment ();
 140                                 return;
 141                         }
 142
 143                         HttpRuntime.FinishUnavailable (wr);
 144                 }
 145
 146                 HttpWorkerRequest Dequeue ()
 147                 {
 148                         if (queue.Count > 0) {
 149                                 HttpWorkerRequest request = (HttpWorkerRequest) queue.Dequeue ();
 150                                 requestsQueuedCounter.Decrement ();
 151                                 return request;
 152                         }
 153
 154                         return null;
 155                 }
 156
 157                 public void Dispose ()
 158                 {
 159                         if (disposing)
 160                                 return;
 161
 162                         disposing = true;
 163                         HttpWorkerRequest wr;
 164                         while ((wr = GetNextRequest (null)) != null)
 165                                 HttpRuntime.FinishUnavailable (wr);
 166
 167                         queue = null;
 168                 }
 169         }
 170 }
 171