mcs/class/corlib/System.Threading/WaitHandle.cs

   1 //
   2 // System.Threading.WaitHandle.cs
   3 //
   4 // Author:
   5 //      Dick Porter (dick@ximian.com)
   6 //      Gonzalo Paniagua Javier (gonzalo@ximian.com
   7 //
   8 // (C) 2002,2003 Ximian, Inc.   (http://www.ximian.com)
   9 // Copyright (C) 2004-2005 Novell, Inc (http://www.novell.com)
  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.Reflection;
  33 using System.Runtime.CompilerServices;
  34 #if FEATURE_REMOTING
  35 using System.Runtime.Remoting.Contexts;
  36 #endif
  37 using System.Runtime.InteropServices;
  38 using Microsoft.Win32.SafeHandles;
  39 using System.Runtime.ConstrainedExecution;
  40
  41 namespace System.Threading
  42 {
  43         [StructLayout (LayoutKind.Sequential)]
  44         public abstract partial class WaitHandle
  45         {
  46                 protected static readonly IntPtr InvalidHandle = (IntPtr) (-1);
  47
  48                 internal const int MaxWaitHandles = 64;
  49
  50                 // We rely on the reference source implementation of WaitHandle, and it delegates to a function named
  51                 //  WaitOneNative to perform the actual operation of waiting on a handle.
  52                 // This native operation actually has to call back into managed code and invoke .Wait
  53                 //  on the current SynchronizationContext. As such, our implementation of this "native" method
  54                 //  is actually managed code, and the real native icall being used is Wait_internal.
  55                 static int WaitOneNative (SafeHandle waitableSafeHandle, uint millisecondsTimeout, bool hasThreadAffinity, bool exitContext)
  56                 {
  57                         bool release = false;
  58 #if !MONODROID
  59                         var context = SynchronizationContext.Current;
  60 #endif
  61                         try {
  62                                 waitableSafeHandle.DangerousAddRef (ref release);
  63
  64 #if FEATURE_REMOTING
  65                                 if (exitContext)
  66                                         SynchronizationAttribute.ExitContext ();
  67 #endif
  68
  69 #if !MONODROID
  70                                 // HACK: Documentation (and public posts by experts like Joe Duffy) suggests that
  71                                 //  users must first call SetWaitNotificationRequired to flag that a given synchronization
  72                                 //  context overrides .Wait. Because invoking the Wait method is somewhat expensive, we use
  73                                 //  the notification-required flag to determine whether or not we should invoke the managed
  74                                 //  wait method.
  75                                 // Another option would be to check whether this context uses the default Wait implementation,
  76                                 //  but I don't know of a cheap way to do this that handles derived types correctly.
  77                                 // If the thread does not have a synchronization context set at all, we can safely just
  78                                 //  jump directly to invoking Wait_internal.
  79                                 if ((context != null) && context.IsWaitNotificationRequired ()) {
  80                                         return context.Wait (
  81                                                 new IntPtr[] { waitableSafeHandle.DangerousGetHandle () },
  82                                                 false,
  83                                                 (int)millisecondsTimeout
  84                                         );
  85                                 } else
  86 #endif
  87                                 {
  88                                         unsafe {
  89                                                 IntPtr handle = waitableSafeHandle.DangerousGetHandle ();
  90                                                 return Wait_internal (&handle, 1, false, (int)millisecondsTimeout);
  91                                         }
  92                                 }
  93                         } finally {
  94                                 if (release)
  95                                         waitableSafeHandle.DangerousRelease ();
  96
  97 #if FEATURE_REMOTING
  98                                 if (exitContext)
  99                                         SynchronizationAttribute.EnterContext ();
 100 #endif
 101                         }
 102
 103                 }
 104
 105                 static int WaitMultiple(WaitHandle[] waitHandles, int millisecondsTimeout, bool exitContext, bool WaitAll)
 106                 {
 107                         if (waitHandles.Length > MaxWaitHandles)
 108                                 return WAIT_FAILED;
 109
 110                         int release_last = -1;
 111                         var context = SynchronizationContext.Current;
 112
 113                         try {
 114 #if FEATURE_REMOTING
 115                                 if (exitContext)
 116                                         SynchronizationAttribute.ExitContext ();
 117 #endif
 118
 119                                 for (int i = 0; i < waitHandles.Length; ++i) {
 120                                         try {} finally {
 121                                                 /* we have to put it in a finally block, to avoid having a ThreadAbortException
 122                                                  * between the return from DangerousAddRef and the assignement to release_last */
 123                                                 bool release = false;
 124                                                 waitHandles [i].SafeWaitHandle.DangerousAddRef (ref release);
 125                                                 release_last = i;
 126                                         }
 127                                 }
 128
 129                                 if ((context != null) && context.IsWaitNotificationRequired ()) {
 130                                         IntPtr[] handles = new IntPtr[waitHandles.Length];
 131                                         for (int i = 0; i < waitHandles.Length; ++i)
 132                                                 handles[i] = waitHandles[i].SafeWaitHandle.DangerousGetHandle ();
 133
 134                                         return context.Wait (
 135                                                 handles,
 136                                                 false,
 137                                                 (int)millisecondsTimeout
 138                                         );
 139                                 } else {
 140                                         unsafe {
 141                                                 IntPtr* handles = stackalloc IntPtr[waitHandles.Length];
 142
 143                                                 for (int i = 0; i < waitHandles.Length; ++i)
 144                                                         handles[i] = waitHandles[i].SafeWaitHandle.DangerousGetHandle ();
 145
 146                                                 return Wait_internal (handles, waitHandles.Length, WaitAll, millisecondsTimeout);
 147                                         }
 148                                 }
 149                         } finally {
 150                                 for (int i = release_last; i >= 0; --i) {
 151                                         waitHandles [i].SafeWaitHandle.DangerousRelease ();
 152                                 }
 153
 154 #if FEATURE_REMOTING
 155                                 if (exitContext)
 156                                         SynchronizationAttribute.EnterContext ();
 157 #endif
 158                         }
 159                 }
 160
 161                 [MethodImplAttribute(MethodImplOptions.InternalCall)]
 162                 internal unsafe static extern int Wait_internal(IntPtr* handles, int numHandles, bool waitAll, int ms);
 163
 164                 static int SignalAndWaitOne (SafeWaitHandle waitHandleToSignal,SafeWaitHandle waitHandleToWaitOn, int millisecondsTimeout, bool hasThreadAffinity,  bool exitContext)
 165                 {
 166                         bool releaseHandleToSignal = false, releaseHandleToWaitOn = false;
 167                         try {
 168                                 waitHandleToSignal.DangerousAddRef (ref releaseHandleToSignal);
 169                                 waitHandleToWaitOn.DangerousAddRef (ref releaseHandleToWaitOn);
 170
 171                                 return SignalAndWait_Internal (waitHandleToSignal.DangerousGetHandle (), waitHandleToWaitOn.DangerousGetHandle (), millisecondsTimeout);
 172                         } finally {
 173                                 if (releaseHandleToSignal)
 174                                         waitHandleToSignal.DangerousRelease ();
 175                                 if (releaseHandleToWaitOn)
 176                                         waitHandleToWaitOn.DangerousRelease ();
 177                         }
 178                 }
 179
 180                 [MethodImplAttribute(MethodImplOptions.InternalCall)]
 181                 static extern int SignalAndWait_Internal (IntPtr toSignal, IntPtr toWaitOn, int ms);
 182
 183                 internal static int ToTimeoutMilliseconds(TimeSpan timeout)
 184                 {
 185                         var timeoutMilliseconds = (long)timeout.TotalMilliseconds;
 186                         if (timeoutMilliseconds < -1 || timeoutMilliseconds > int.MaxValue)
 187                         {
 188                                 throw new ArgumentOutOfRangeException(nameof(timeout), SR.ArgumentOutOfRange_NeedNonNegOrNegative1);
 189                         }
 190                         return (int)timeoutMilliseconds;
 191                 }
 192         }
 193 }