dep/src/zthread/win32/Monitor.cxx

   1 /*
   2  * Copyright (c) 2005, Eric Crahen
   3  *
   4  * Permission is hereby granted, free of charge, to any person obtaining a copy
   5  * of this software and associated documentation files (the "Software"), to deal
   6  * in the Software without restriction, including without limitation the rights
   7  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
   8  * copies of the Software, and to permit persons to whom the Software is furnished
   9  * to do so, subject to the following conditions:
  10  *
  11  * The above copyright notice and this permission notice shall be included in all
  12  * copies or substantial portions of the Software.
  13  *
  14  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  15  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  16  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  17  * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
  18  * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
  19  * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  20  *
  21  */
  22
  23 #include "Monitor.h"
  24
  25 #ifdef HAVE_CONFIG_H
  26 #include "config.h"
  27 #endif
  28
  29 using namespace ZThread;
  30
  31 Monitor::Monitor() : _owner(0), _waiting(false) {
  32
  33   _handle = ::CreateEvent(0, TRUE, FALSE, 0);
  34   if(_handle == NULL) {
  35     assert(0);
  36   }
  37
  38 }
  39
  40 Monitor::~Monitor() {
  41
  42   assert(!_waiting);
  43
  44   ::CloseHandle(_handle);
  45
  46 }
  47
  48 Monitor::STATE Monitor::wait(unsigned long ms) {
  49
  50   // Update the owner on first use. The owner will not change, each
  51   // thread waits only on a single Monitor and a Monitor is never
  52   // shared
  53   if(_owner == 0)
  54     _owner = ::GetCurrentThreadId();
  55
  56   STATE state; //(INVALID);
  57
  58   // Serialize access to the state of the Monitor
  59   // and test the state to determine if a wait is needed.
  60   _waitLock.acquire();
  61
  62   if(pending(ANYTHING)) {
  63
  64     // Return without waiting when possible
  65     state = next();
  66
  67     _waitLock.release();
  68     return state;
  69
  70   }
  71   // Unlock the external lock if a wait() is probably needed.
  72   // Access to the state is still serial.
  73   _lock.release();
  74
  75   // Wait for a transition in the state that is of interest, this
  76   // allows waits to exclude certain flags (e.g. INTERRUPTED)
  77   // for a single wait() w/o actually discarding those flags -
  78   // they will remain set until a wait interested in those flags
  79   // occurs.
  80   //  if(!currentState(interest)) {
  81
  82   // Wait, ignoring signals
  83   _waiting = true;
  84
  85   // Block until the event is set.
  86   _waitLock.release();
  87
  88   // The event is manual reset so this lack of atmoicity will not
  89   // be an issue
  90
  91   DWORD dwResult =
  92     ::WaitForSingleObject(_handle, ((ms == 0) ? INFINITE : (DWORD)ms));
  93
  94   // Reacquire serialized access to the state
  95   _waitLock.acquire();
  96
  97   // Awaken only when the event is set or the timeout expired
  98   assert(dwResult == WAIT_OBJECT_0 || dwResult == WAIT_TIMEOUT);
  99
 100   if(dwResult == WAIT_TIMEOUT)
 101     push(TIMEDOUT);
 102
 103   // Get the next available STATE
 104   state = next();
 105   _waiting = false;
 106
 107   ::ResetEvent(_handle);
 108
 109   // Acquire the internal lock & release the external lock
 110   _waitLock.release();
 111
 112   // Reaquire the external lock, keep from deadlocking threads calling
 113   // notify(), interrupt(), etc.
 114   _lock.acquire();
 115
 116   return state;
 117
 118 }
 119
 120
 121 bool Monitor::interrupt() {
 122
 123   // Serialize access to the state
 124   _waitLock.acquire();
 125
 126   bool wasInterruptable = !pending(INTERRUPTED);
 127   bool hadWaiter = _waiting;
 128
 129   if(wasInterruptable) {
 130
 131     // Update the state & wake the waiter if there is one
 132     push(INTERRUPTED);
 133
 134     wasInterruptable = false;
 135
 136     if(hadWaiter && !masked(Monitor::INTERRUPTED)) {
 137
 138       // Blocked on a synchronization object
 139       if(::SetEvent(_handle) == FALSE) {
 140         assert(0);
 141       }
 142
 143     } else
 144       wasInterruptable = !(_owner == ::GetCurrentThreadId());
 145
 146   }
 147
 148   _waitLock.release();
 149
 150   // Only returns true when an interrupted thread is not currently blocked
 151   return wasInterruptable;
 152
 153 }
 154
 155 bool Monitor::isInterrupted() {
 156
 157   // Serialize access to the state
 158   _waitLock.acquire();
 159
 160   bool wasInterrupted = pending(INTERRUPTED);
 161   clear(INTERRUPTED);
 162
 163   _waitLock.release();
 164
 165   return wasInterrupted;
 166
 167 }
 168
 169
 170 bool Monitor::notify() {
 171
 172   // Serialize access to the state
 173   _waitLock.acquire();
 174
 175   bool wasNotifyable = !pending(INTERRUPTED);
 176
 177   if(wasNotifyable) {
 178
 179     // Set the flag and wake the waiter if there
 180     // is one
 181     push(SIGNALED);
 182
 183     // If there is a waiter then send the signal.
 184     if(_waiting)
 185       if(::SetEvent(_handle) == FALSE) {
 186         assert(0);
 187       }
 188
 189   }
 190
 191   _waitLock.release();
 192
 193   return wasNotifyable;
 194
 195 }
 196
 197
 198 bool Monitor::cancel() {
 199
 200   // Serialize access to the state
 201   _waitLock.acquire();
 202
 203   bool wasInterrupted = !pending(INTERRUPTED);
 204   bool hadWaiter = _waiting;
 205
 206   push(CANCELED);
 207
 208   if(wasInterrupted) {
 209
 210     // Update the state & wake the waiter if there is one
 211     push(INTERRUPTED);
 212
 213     // If there is a waiter then send the signal.
 214     if(hadWaiter && !masked(Monitor::INTERRUPTED))
 215       if(::SetEvent(_handle) == FALSE) {
 216         assert(0);
 217       }
 218
 219   }
 220
 221   _waitLock.release();
 222
 223   return wasInterrupted;
 224
 225 }
 226
 227 bool Monitor::isCanceled() {
 228
 229   // Serialize access to the state
 230   _waitLock.acquire();
 231
 232   bool wasCanceled = examine(CANCELED);
 233
 234   if(_owner == ::GetCurrentThreadId())
 235     clear(INTERRUPTED);
 236
 237   _waitLock.release();
 238
 239   return wasCanceled;
 240
 241 }
 242