include/wx/thrimpl.cpp

   1 /////////////////////////////////////////////////////////////////////////////
   2 // Name:        wx/thrimpl.cpp
   3 // Purpose:     common part of wxThread Implementations
   4 // Author:      Vadim Zeitlin
   5 // Modified by:
   6 // Created:     04.06.02 (extracted from src/*/thread.cpp files)
   7 // Copyright:   (c) Vadim Zeitlin (2002)
   8 // Licence:     wxWindows licence
   9 /////////////////////////////////////////////////////////////////////////////
  10
  11 // this file is supposed to be included only by the various thread.cpp
  12
  13 // ----------------------------------------------------------------------------
  14 // wxMutex
  15 // ----------------------------------------------------------------------------
  16
  17 wxMutex::wxMutex(wxMutexType mutexType)
  18 {
  19     m_internal = new wxMutexInternal(mutexType);
  20
  21     if ( !m_internal->IsOk() )
  22     {
  23         delete m_internal;
  24         m_internal = NULL;
  25     }
  26 }
  27
  28 wxMutex::~wxMutex()
  29 {
  30     delete m_internal;
  31 }
  32
  33 bool wxMutex::IsOk() const
  34 {
  35     return m_internal != NULL;
  36 }
  37
  38 wxMutexError wxMutex::Lock()
  39 {
  40     wxCHECK_MSG( m_internal, wxMUTEX_INVALID,
  41                  wxT("wxMutex::Lock(): not initialized") );
  42
  43     return m_internal->Lock();
  44 }
  45
  46 wxMutexError wxMutex::LockTimeout(unsigned long ms)
  47 {
  48     wxCHECK_MSG( m_internal, wxMUTEX_INVALID,
  49                  wxT("wxMutex::Lock(): not initialized") );
  50
  51     return m_internal->Lock(ms);
  52 }
  53
  54 wxMutexError wxMutex::TryLock()
  55 {
  56     wxCHECK_MSG( m_internal, wxMUTEX_INVALID,
  57                  wxT("wxMutex::TryLock(): not initialized") );
  58
  59     return m_internal->TryLock();
  60 }
  61
  62 wxMutexError wxMutex::Unlock()
  63 {
  64     wxCHECK_MSG( m_internal, wxMUTEX_INVALID,
  65                  wxT("wxMutex::Unlock(): not initialized") );
  66
  67     return m_internal->Unlock();
  68 }
  69
  70 // --------------------------------------------------------------------------
  71 // wxConditionInternal
  72 // --------------------------------------------------------------------------
  73
  74 // Win32 and OS/2 don't have explicit support for the POSIX condition
  75 // variables and their events/event semaphores have quite different semantics,
  76 // so we reimplement the conditions from scratch using the mutexes and
  77 // semaphores
  78 #if defined(__WINDOWS__) || defined(__OS2__) || defined(__EMX__)
  79
  80 class wxConditionInternal
  81 {
  82 public:
  83     wxConditionInternal(wxMutex& mutex);
  84
  85     bool IsOk() const { return m_mutex.IsOk() && m_semaphore.IsOk(); }
  86
  87     wxCondError Wait();
  88     wxCondError WaitTimeout(unsigned long milliseconds);
  89
  90     wxCondError Signal();
  91     wxCondError Broadcast();
  92
  93 private:
  94     // the number of threads currently waiting for this condition
  95     LONG m_numWaiters;
  96
  97     // the critical section protecting m_numWaiters
  98     wxCriticalSection m_csWaiters;
  99
 100     wxMutex& m_mutex;
 101     wxSemaphore m_semaphore;
 102
 103     wxDECLARE_NO_COPY_CLASS(wxConditionInternal);
 104 };
 105
 106 wxConditionInternal::wxConditionInternal(wxMutex& mutex)
 107                    : m_mutex(mutex)
 108 {
 109     // another thread can't access it until we return from ctor, so no need to
 110     // protect access to m_numWaiters here
 111     m_numWaiters = 0;
 112 }
 113
 114 wxCondError wxConditionInternal::Wait()
 115 {
 116     // increment the number of waiters
 117     {
 118         wxCriticalSectionLocker lock(m_csWaiters);
 119         m_numWaiters++;
 120     }
 121
 122     m_mutex.Unlock();
 123
 124     // after unlocking the mutex other threads may Signal() us, but it is ok
 125     // now as we had already incremented m_numWaiters so Signal() will post the
 126     // semaphore and decrement m_numWaiters back even if it is called before we
 127     // start to Wait()
 128     const wxSemaError err = m_semaphore.Wait();
 129
 130     m_mutex.Lock();
 131
 132     if ( err == wxSEMA_NO_ERROR )
 133     {
 134         // m_numWaiters was decremented by Signal()
 135         return wxCOND_NO_ERROR;
 136     }
 137
 138     // but in case of an error we need to do it manually
 139     {
 140         wxCriticalSectionLocker lock(m_csWaiters);
 141         m_numWaiters--;
 142     }
 143
 144     return err == wxSEMA_TIMEOUT ? wxCOND_TIMEOUT : wxCOND_MISC_ERROR;
 145 }
 146
 147 wxCondError wxConditionInternal::WaitTimeout(unsigned long milliseconds)
 148 {
 149     {
 150         wxCriticalSectionLocker lock(m_csWaiters);
 151         m_numWaiters++;
 152     }
 153
 154     m_mutex.Unlock();
 155
 156     wxSemaError err = m_semaphore.WaitTimeout(milliseconds);
 157
 158     m_mutex.Lock();
 159
 160     if ( err == wxSEMA_NO_ERROR )
 161         return wxCOND_NO_ERROR;
 162
 163     if ( err == wxSEMA_TIMEOUT )
 164     {
 165         // a potential race condition exists here: it happens when a waiting
 166         // thread times out but doesn't have time to decrement m_numWaiters yet
 167         // before Signal() is called in another thread
 168         //
 169         // to handle this particular case, check the semaphore again after
 170         // acquiring m_csWaiters lock -- this will catch the signals missed
 171         // during this window
 172         wxCriticalSectionLocker lock(m_csWaiters);
 173
 174         err = m_semaphore.WaitTimeout(0);
 175         if ( err == wxSEMA_NO_ERROR )
 176             return wxCOND_NO_ERROR;
 177
 178         // we need to decrement m_numWaiters ourselves as it wasn't done by
 179         // Signal()
 180         m_numWaiters--;
 181
 182         return err == wxSEMA_TIMEOUT ? wxCOND_TIMEOUT : wxCOND_MISC_ERROR;
 183     }
 184
 185     // undo m_numWaiters++ above in case of an error
 186     {
 187         wxCriticalSectionLocker lock(m_csWaiters);
 188         m_numWaiters--;
 189     }
 190
 191     return wxCOND_MISC_ERROR;
 192 }
 193
 194 wxCondError wxConditionInternal::Signal()
 195 {
 196     wxCriticalSectionLocker lock(m_csWaiters);
 197
 198     if ( m_numWaiters > 0 )
 199     {
 200         // increment the semaphore by 1
 201         if ( m_semaphore.Post() != wxSEMA_NO_ERROR )
 202             return wxCOND_MISC_ERROR;
 203
 204         m_numWaiters--;
 205     }
 206
 207     return wxCOND_NO_ERROR;
 208 }
 209
 210 wxCondError wxConditionInternal::Broadcast()
 211 {
 212     wxCriticalSectionLocker lock(m_csWaiters);
 213
 214     while ( m_numWaiters > 0 )
 215     {
 216         if ( m_semaphore.Post() != wxSEMA_NO_ERROR )
 217             return wxCOND_MISC_ERROR;
 218
 219         m_numWaiters--;
 220     }
 221
 222     return wxCOND_NO_ERROR;
 223 }
 224
 225 #endif // __WINDOWS__ || __OS2__ || __EMX__
 226
 227 // ----------------------------------------------------------------------------
 228 // wxCondition
 229 // ----------------------------------------------------------------------------
 230
 231 wxCondition::wxCondition(wxMutex& mutex)
 232 {
 233     m_internal = new wxConditionInternal(mutex);
 234
 235     if ( !m_internal->IsOk() )
 236     {
 237         delete m_internal;
 238         m_internal = NULL;
 239     }
 240 }
 241
 242 wxCondition::~wxCondition()
 243 {
 244     delete m_internal;
 245 }
 246
 247 bool wxCondition::IsOk() const
 248 {
 249     return m_internal != NULL;
 250 }
 251
 252 wxCondError wxCondition::Wait()
 253 {
 254     wxCHECK_MSG( m_internal, wxCOND_INVALID,
 255                  wxT("wxCondition::Wait(): not initialized") );
 256
 257     return m_internal->Wait();
 258 }
 259
 260 wxCondError wxCondition::WaitTimeout(unsigned long milliseconds)
 261 {
 262     wxCHECK_MSG( m_internal, wxCOND_INVALID,
 263                  wxT("wxCondition::Wait(): not initialized") );
 264
 265     return m_internal->WaitTimeout(milliseconds);
 266 }
 267
 268 wxCondError wxCondition::Signal()
 269 {
 270     wxCHECK_MSG( m_internal, wxCOND_INVALID,
 271                  wxT("wxCondition::Signal(): not initialized") );
 272
 273     return m_internal->Signal();
 274 }
 275
 276 wxCondError wxCondition::Broadcast()
 277 {
 278     wxCHECK_MSG( m_internal, wxCOND_INVALID,
 279                  wxT("wxCondition::Broadcast(): not initialized") );
 280
 281     return m_internal->Broadcast();
 282 }
 283
 284 // --------------------------------------------------------------------------
 285 // wxSemaphore
 286 // --------------------------------------------------------------------------
 287
 288 wxSemaphore::wxSemaphore(int initialcount, int maxcount)
 289 {
 290     m_internal = new wxSemaphoreInternal( initialcount, maxcount );
 291     if ( !m_internal->IsOk() )
 292     {
 293         delete m_internal;
 294         m_internal = NULL;
 295     }
 296 }
 297
 298 wxSemaphore::~wxSemaphore()
 299 {
 300     delete m_internal;
 301 }
 302
 303 bool wxSemaphore::IsOk() const
 304 {
 305     return m_internal != NULL;
 306 }
 307
 308 wxSemaError wxSemaphore::Wait()
 309 {
 310     wxCHECK_MSG( m_internal, wxSEMA_INVALID,
 311                  wxT("wxSemaphore::Wait(): not initialized") );
 312
 313     return m_internal->Wait();
 314 }
 315
 316 wxSemaError wxSemaphore::TryWait()
 317 {
 318     wxCHECK_MSG( m_internal, wxSEMA_INVALID,
 319                  wxT("wxSemaphore::TryWait(): not initialized") );
 320
 321     return m_internal->TryWait();
 322 }
 323
 324 wxSemaError wxSemaphore::WaitTimeout(unsigned long milliseconds)
 325 {
 326     wxCHECK_MSG( m_internal, wxSEMA_INVALID,
 327                  wxT("wxSemaphore::WaitTimeout(): not initialized") );
 328
 329     return m_internal->WaitTimeout(milliseconds);
 330 }
 331
 332 wxSemaError wxSemaphore::Post()
 333 {
 334     wxCHECK_MSG( m_internal, wxSEMA_INVALID,
 335                  wxT("wxSemaphore::Post(): not initialized") );
 336
 337     return m_internal->Post();
 338 }
 339
 340 // ----------------------------------------------------------------------------
 341 // wxThread
 342 // ----------------------------------------------------------------------------
 343
 344 #include "wx/utils.h"
 345
 346 void wxThread::Sleep(unsigned long milliseconds)
 347 {
 348     wxMilliSleep(milliseconds);
 349 }