beagled/Shutdown.cs

   1 //
   2 // Shutdown.cs
   3 //
   4 // Copyright (C) 2004 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.Threading;
  29 using System.Collections;
  30 using Beagle.Util;
  31
  32 namespace Beagle.Daemon {
  33
  34         public class Shutdown {
  35
  36                 static public bool Debug = false;
  37
  38                 static object shutdownLock = new object ();
  39                 static Hashtable workers = new Hashtable ();
  40                 static Hashtable workers_names = new Hashtable ();
  41                 static bool shutdownRequested = false;
  42
  43                 public delegate void ShutdownHandler ();
  44                 public static event ShutdownHandler ShutdownEvent;
  45
  46                 public static bool WorkerStart (object o, string name)
  47                 {
  48                         lock (shutdownLock) {
  49                                 if (shutdownRequested) {
  50                                         return false;
  51                                 }
  52                                 int refcount = 0;
  53                                 if (workers.Contains (o))
  54                                         refcount = (int)workers[o];
  55                                 ++refcount;
  56                                 workers[o] = refcount;
  57                                 workers_names[o] = name;
  58
  59                                 if (Debug)
  60                                         Logger.Log.Debug ("worker added: name={0} refcount={1}", name, refcount);
  61                         }
  62                         return true;
  63                 }
  64
  65                 public static bool WorkerStart (object o)
  66                 {
  67                         return WorkerStart (o, o.ToString ());
  68                 }
  69
  70                 public static void WorkerFinished (object o)
  71                 {
  72                         lock (shutdownLock) {
  73                                 if (!workers.Contains (o)) {
  74                                         Logger.Log.Warn ("extra WorkerFinished called for {0}", o);
  75                                         return;
  76                                 }
  77
  78                                 int refcount = (int)workers[o];
  79                                 --refcount;
  80                                 if (refcount == 0) {
  81                                         if (Debug)
  82                                                 Logger.Log.Debug ("worker removed: name={0}", workers_names[o]);
  83                                         workers.Remove (o);
  84                                         workers_names.Remove (o);
  85                                 } else {
  86                                         if (Debug)
  87                                                 Logger.Log.Debug ("worker finished: name={0} refcount={1}", workers_names[o], refcount);
  88                                         workers[o] = refcount;
  89                                 }
  90
  91                                 Monitor.Pulse (shutdownLock);
  92                         }
  93                 }
  94
  95                 static public bool ShutdownRequested {
  96                         get { return shutdownRequested; }
  97                         set {
  98                                 lock (shutdownLock)
  99                                         shutdownRequested = value;
 100                         }
 101                 }
 102
 103                 private static GLib.MainLoop main_loop = null;
 104
 105                 public static void RegisterMainLoop (GLib.MainLoop loop)
 106                 {
 107                         main_loop = loop;
 108                 }
 109
 110                 // Our handler triggers an orderly shutdown when it receives a signal.
 111                 // However, this can be annoying if the process gets wedged during
 112                 // shutdown.  To deal with that case, we make a note of the time when
 113                 // the first signal comes in, and we allow signals to unconditionally
 114                 // kill the process after 5 seconds have passed.
 115
 116                 static DateTime signal_time = DateTime.MinValue;
 117
 118                 public static void BeginShutdown ()
 119                 {
 120                         lock (shutdownLock) {
 121                                 shutdownRequested = true;
 122                         }
 123
 124                         // FIXME: This whole "unconditional killing after 5 seconds because
 125                         // beagled can hang while shutting down" thing should not occur. Any such
 126                         // incident should be immediately investigated and fixed. Hint: Sending
 127                         // kill -quit `pidof beagled` will probably reveal that beagled got locked
 128                         // when signal handler was called and some thread was executing some native
 129                         // method.
 130                         bool first_signal = false;
 131                         if (signal_time == DateTime.MinValue) {
 132                                 signal_time = DateTime.Now;
 133                                 first_signal = true;
 134                         }
 135
 136                         if (! first_signal) {
 137                                 double t = (DateTime.Now - signal_time).TotalSeconds;
 138                                 const double min_t = 5;
 139
 140                                 if (t < min_t) {
 141                                         Logger.Log.Debug ("Signals can force an immediate shutdown in {0:0.00}s", min_t-t);
 142                                         return;
 143                                 } else {
 144                                         Logger.Log.Debug ("Forcing immediate shutdown.");
 145                                         Environment.Exit (0);
 146                                 }
 147                         }
 148
 149                         if (ShutdownEvent != null) {
 150                                 try {
 151                                         ShutdownEvent ();
 152                                 } catch (Exception ex) {
 153                                         Logger.Log.Warn (ex, "Caught unhandled exception during shutdown event");
 154                                 }
 155                         }
 156
 157                         int count = 0;
 158
 159                         lock (shutdownLock) {
 160                                 while (workers.Count > 0) {
 161                                         ++count;
 162                                         Logger.Log.Debug ("({0}) Waiting for {1} worker{2}...",
 163                                                           count,
 164                                                           workers.Count,
 165                                                           workers.Count > 1 ? "s" : "");
 166                                         foreach (object o in workers.Keys)
 167                                                 Logger.Log.Debug ("waiting for {0}", workers_names[o]);
 168                                         Monitor.Wait (shutdownLock);
 169                                 }
 170                         }
 171
 172                         Logger.Log.Info ("All workers have finished.  Exiting main loop.");
 173                         main_loop.Quit ();
 174                 }
 175         }
 176 }