mcs/class/System/System.Timers/Timer.cs

   1 //
   2 // System.Timers.Timer
   3 //
   4 // Authors:
   5 //      Gonzalo Paniagua Javier (gonzalo@ximian.com)
   6 //
   7 // (C) 2002 Ximian, Inc (http://www.ximian.com)
   8 //
   9 // The docs talk about server timers and such...
  10
  11 using System;
  12 using System.ComponentModel;
  13 using System.Threading;
  14
  15 namespace System.Timers
  16 {
  17         [DefaultEventAttribute("Elapsed")]
  18         [DefaultProperty("Interval")]
  19         public class Timer : Component, ISupportInitialize
  20         {
  21                 bool autoReset;
  22                 bool enabled;
  23                 double interval;
  24                 ISynchronizeInvoke so;
  25                 ManualResetEvent wait;
  26
  27                 [Category("Behavior")]
  28                 [TimersDescription("Occurs when the Interval has elapsed.")]
  29                 public event ElapsedEventHandler Elapsed;
  30
  31                 public Timer () : this (100)
  32                 {
  33                 }
  34
  35                 public Timer (double interval)
  36                 {
  37                         autoReset = true;
  38                         enabled = false;
  39                         Interval = interval;
  40                         so = null;
  41                         wait = null;
  42                 }
  43
  44
  45                 [Category("Behavior")]
  46                 [DefaultValue(true)]
  47                 [TimersDescription("Indicates whether the timer will be restarted when it is enabled.")]
  48                 public bool AutoReset
  49                 {
  50                         get { return autoReset; }
  51                         set { autoReset = value; }
  52                 }
  53
  54                 [Category("Behavior")]
  55                 [DefaultValue(false)]
  56                 [TimersDescription("Indicates whether the timer is enabled to fire events at a defined interval.")]
  57                 public bool Enabled
  58                 {
  59                         get { return enabled; }
  60                         set {
  61                                 if (enabled == value)
  62                                         return;
  63
  64                                 enabled = value;
  65                                 if (value) {
  66                                         Thread t = new Thread (new ThreadStart (StartTimer));
  67                                         t.Start ();
  68                                 } else {
  69                                         StopTimer ();
  70                                 }
  71                         }
  72                 }
  73
  74                 [Category("Behavior")]
  75                 [DefaultValue(100)]
  76                 [RecommendedAsConfigurable(true)]
  77                 [TimersDescription( "The number of milliseconds between timer events.")]
  78                 public double Interval
  79                 {
  80                         get { return interval; }
  81                         set {
  82                                 // The doc says 'less than 0', but 0 also throws the exception
  83                                 if (value <= 0)
  84                                         throw new ArgumentException ("Invalid value: " + interval, "interval");
  85
  86                                 interval = value;
  87                         }
  88                 }
  89
  90                 public override ISite Site
  91                 {
  92                         get { return base.Site; }
  93                         set { base.Site = value; }
  94                 }
  95
  96                 [DefaultValue(null)]
  97                 [TimersDescriptionAttribute("The object used to marshal the event handler calls issued " +
  98                                             "when an interval has elapsed.")]
  99                 public ISynchronizeInvoke SynchronizingObject
 100                 {
 101                         get { return so; }
 102                         set { so = value; }
 103                 }
 104
 105                 public void BeginInit ()
 106                 {
 107                         // Nothing to do
 108                 }
 109
 110                 public void Close ()
 111                 {
 112                         StopTimer ();
 113                 }
 114
 115                 public void EndInit ()
 116                 {
 117                         // Nothing to do
 118                 }
 119
 120                 public void Start ()
 121                 {
 122                         Enabled = true;
 123                 }
 124
 125                 public void Stop ()
 126                 {
 127                         Enabled = false;
 128                 }
 129
 130                 protected override void Dispose (bool disposing)
 131                 {
 132                         Close ();
 133                         base.Dispose (disposing);
 134                 }
 135
 136                 static void Callback (object state)
 137                 {
 138                         Timer timer = (Timer) state;
 139                         if (timer.Elapsed == null)
 140                                 return;
 141
 142                         ElapsedEventArgs arg = new ElapsedEventArgs (DateTime.Now);
 143
 144                         if (timer.so != null && timer.so.InvokeRequired) {
 145                                 timer.so.BeginInvoke (timer.Elapsed, new object [2] {timer, arg});
 146                         } else {
 147                                 timer.Elapsed (timer, arg);
 148                         }
 149                 }
 150
 151                 void StartTimer ()
 152                 {
 153                         wait = new ManualResetEvent (false);
 154
 155                         WaitCallback wc = new WaitCallback (Callback);
 156                         while (enabled && wait.WaitOne ((int) interval, false) == false) {
 157                                 if (autoReset == false)
 158                                         enabled = false;
 159
 160                                 ThreadPool.QueueUserWorkItem (wc, this);
 161                         }
 162
 163                         wc = null;
 164                         ((IDisposable) wait).Dispose ();
 165                         wait = null;
 166                 }
 167
 168                 void StopTimer ()
 169                 {
 170                         if (wait != null)
 171                                 wait.Set ();
 172                 }
 173         }
 174 }
 175