src/os2/thread.cpp

   1 /////////////////////////////////////////////////////////////////////////////
   2 // Name:        thread.cpp
   3 // Purpose:     wxThread Implementation. For Unix ports, see e.g. src/gtk
   4 // Author:      Original from Wolfram Gloger/Guilhem Lavaux
   5 // Modified by: David Webster
   6 // Created:     04/22/98
   7 // RCS-ID:      $Id$
   8 // Copyright:   (c) Wolfram Gloger (1996, 1997); Guilhem Lavaux (1998)
   9 // Licence:     wxWindows licence
  10 /////////////////////////////////////////////////////////////////////////////
  11
  12 // ----------------------------------------------------------------------------
  13 // headers
  14 // ----------------------------------------------------------------------------
  15
  16 // For compilers that support precompilation, includes "wx.h".
  17 #include "wx/wxprec.h"
  18
  19 #if wxUSE_THREADS
  20
  21 #include <stdio.h>
  22
  23 #include "wx/module.h"
  24 #include "wx/thread.h"
  25
  26 #define INCL_DOSSEMAPHORES
  27 #define INCL_DOSPROCESS
  28 #define INCL_ERRORS
  29 #include <os2.h>
  30 #include <bseerr.h>
  31
  32 // the possible states of the thread ("=>" shows all possible transitions from
  33 // this state)
  34 enum wxThreadState
  35 {
  36     STATE_NEW,          // didn't start execution yet (=> RUNNING)
  37     STATE_RUNNING,      // thread is running (=> PAUSED, CANCELED)
  38     STATE_PAUSED,       // thread is temporarily suspended (=> RUNNING)
  39     STATE_CANCELED,     // thread should terminate a.s.a.p. (=> EXITED)
  40     STATE_EXITED        // thread is terminating
  41 };
  42
  43 // ----------------------------------------------------------------------------
  44 // static variables
  45 // ----------------------------------------------------------------------------
  46
  47 // id of the main thread - the one which can call GUI functions without first
  48 // calling wxMutexGuiEnter()
  49 static ULONG                        s_ulIdMainThread = 0;
  50 wxMutex*                            p_wxMainMutex;
  51
  52 // OS2 substitute for Tls pointer the current parent thread object
  53 wxThread*                           m_pThread;    // pointer to the wxWindows thread object
  54
  55 // if it's FALSE, some secondary thread is holding the GUI lock
  56 static bool s_bGuiOwnedByMainThread = TRUE;
  57
  58 // critical section which controls access to all GUI functions: any secondary
  59 // thread (i.e. except the main one) must enter this crit section before doing
  60 // any GUI calls
  61 static wxCriticalSection *s_pCritsectGui = NULL;
  62
  63 // critical section which protects s_nWaitingForGui variable
  64 static wxCriticalSection *s_pCritsectWaitingForGui = NULL;
  65
  66 // number of threads waiting for GUI in wxMutexGuiEnter()
  67 static size_t s_nWaitingForGui = 0;
  68
  69 // are we waiting for a thread termination?
  70 static bool s_bWaitingForThread = FALSE;
  71
  72 // ============================================================================
  73 // OS/2 implementation of thread classes
  74 // ============================================================================
  75
  76 // ----------------------------------------------------------------------------
  77 // wxMutex implementation
  78 // ----------------------------------------------------------------------------
  79 class wxMutexInternal
  80 {
  81 public:
  82     HMTX                            m_vMutex;
  83 };
  84
  85 wxMutex::wxMutex()
  86 {
  87     APIRET                          ulrc;
  88
  89     p_internal = new wxMutexInternal;
  90     ulrc = ::DosCreateMutexSem(NULL, &p_internal->m_vMutex, 0L, FALSE);
  91     if (ulrc != 0)
  92     {
  93         wxLogSysError(_("Can not create mutex."));
  94     }
  95     m_locked = 0;
  96 }
  97
  98 wxMutex::~wxMutex()
  99 {
 100     if (m_locked > 0)
 101         wxLogDebug(wxT("Warning: freeing a locked mutex (%d locks)."), m_locked);
 102     ::DosCloseMutexSem(p_internal->m_vMutex);
 103     p_internal->m_vMutex = NULL;
 104 }
 105
 106 wxMutexError wxMutex::Lock()
 107 {
 108     APIRET                          ulrc;
 109
 110     ulrc = ::DosRequestMutexSem(p_internal->m_vMutex, SEM_INDEFINITE_WAIT);
 111
 112     switch (ulrc)
 113     {
 114         case ERROR_TOO_MANY_SEM_REQUESTS:
 115             return wxMUTEX_BUSY;
 116
 117         case NO_ERROR:
 118             // ok
 119             break;
 120
 121         case ERROR_INVALID_HANDLE:
 122         case ERROR_INTERRUPT:
 123         case ERROR_SEM_OWNER_DIED:
 124             wxLogSysError(_("Couldn't acquire a mutex lock"));
 125             return wxMUTEX_MISC_ERROR;
 126
 127         case ERROR_TIMEOUT:
 128         default:
 129             wxFAIL_MSG(wxT("impossible return value in wxMutex::Lock"));
 130     }
 131     m_locked++;
 132     return wxMUTEX_NO_ERROR;
 133 }
 134
 135 wxMutexError wxMutex::TryLock()
 136 {
 137     ULONG                           ulrc;
 138
 139     ulrc = ::DosRequestMutexSem(p_internal->m_vMutex, SEM_IMMEDIATE_RETURN /*0L*/);
 140     if (ulrc == ERROR_TIMEOUT || ulrc == ERROR_TOO_MANY_SEM_REQUESTS)
 141         return wxMUTEX_BUSY;
 142
 143     m_locked++;
 144     return wxMUTEX_NO_ERROR;
 145 }
 146
 147 wxMutexError wxMutex::Unlock()
 148 {
 149     APIRET                          ulrc;
 150
 151     if (m_locked > 0)
 152         m_locked--;
 153
 154     ulrc = ::DosReleaseMutexSem(p_internal->m_vMutex);
 155     if (ulrc != 0)
 156     {
 157         wxLogSysError(_("Couldn't release a mutex"));
 158         return wxMUTEX_MISC_ERROR;
 159     }
 160     return wxMUTEX_NO_ERROR;
 161 }
 162
 163 // ----------------------------------------------------------------------------
 164 // wxCondition implementation
 165 // ----------------------------------------------------------------------------
 166
 167 class wxConditionInternal
 168 {
 169 public:
 170     HEV                             m_vEvent;
 171     int                             m_nWaiters;
 172 };
 173
 174 wxCondition::wxCondition()
 175 {
 176     APIRET                          ulrc;
 177     ULONG                           ulCount;
 178
 179     p_internal = new wxConditionInternal;
 180     ulrc = ::DosCreateEventSem(NULL, &p_internal->m_vEvent, 0L, FALSE);
 181     if (ulrc != 0)
 182     {
 183         wxLogSysError(_("Can not create event object."));
 184     }
 185     p_internal->m_nWaiters = 0;
 186     // ?? just for good measure?
 187     ::DosResetEventSem(p_internal->m_vEvent, &ulCount);
 188 }
 189
 190 wxCondition::~wxCondition()
 191 {
 192     ::DosCloseEventSem(p_internal->m_vEvent);
 193     delete p_internal;
 194     p_internal = NULL;
 195 }
 196
 197 void wxCondition::Wait(
 198   wxMutex&                          rMutex
 199 )
 200 {
 201     rMutex.Unlock();
 202     p_internal->m_nWaiters++;
 203     ::DosWaitEventSem(p_internal->m_vEvent, SEM_INDEFINITE_WAIT);
 204     p_internal->m_nWaiters--;
 205     rMutex.Lock();
 206 }
 207
 208 bool wxCondition::Wait(
 209   wxMutex&                          rMutex
 210 , unsigned long                     ulSec
 211 , unsigned long                     ulMillisec)
 212 {
 213     APIRET                          ulrc;
 214
 215     rMutex.Unlock();
 216     p_internal->m_nWaiters++;
 217     ulrc = ::DosWaitEventSem(p_internal->m_vEvent, ULONG((ulSec * 1000L) + ulMillisec));
 218     p_internal->m_nWaiters--;
 219     rMutex.Lock();
 220
 221     return (ulrc != ERROR_TIMEOUT);
 222 }
 223
 224 void wxCondition::Signal()
 225 {
 226     ::DosPostEventSem(p_internal->m_vEvent);
 227 }
 228
 229 void wxCondition::Broadcast()
 230 {
 231     int                             i;
 232
 233     for (i = 0; i < p_internal->m_nWaiters; i++)
 234     {
 235         if (::DosPostEventSem(p_internal->m_vEvent) != 0)
 236         {
 237             wxLogSysError(_("Couldn't change the state of event object."));
 238         }
 239     }
 240 }
 241
 242 // ----------------------------------------------------------------------------
 243 // wxCriticalSection implementation
 244 // ----------------------------------------------------------------------------
 245
 246 class wxCriticalSectionInternal
 247 {
 248 public:
 249     // init the critical section object
 250     wxCriticalSectionInternal()
 251         { }
 252
 253     // free the associated ressources
 254     ~wxCriticalSectionInternal()
 255         { }
 256
 257 private:
 258 };
 259
 260 // ----------------------------------------------------------------------------
 261 // wxCriticalSection implementation
 262 // ----------------------------------------------------------------------------
 263
 264 wxCriticalSection::wxCriticalSection()
 265 {
 266     m_critsect = new wxCriticalSectionInternal;
 267 }
 268
 269 wxCriticalSection::~wxCriticalSection()
 270 {
 271     delete m_critsect;
 272 }
 273
 274 void wxCriticalSection::Enter()
 275 {
 276     ::DosEnterCritSec();
 277 }
 278
 279 void wxCriticalSection::Leave()
 280 {
 281     ::DosExitCritSec();
 282 }
 283
 284 // ----------------------------------------------------------------------------
 285 // wxThread implementation
 286 // ----------------------------------------------------------------------------
 287
 288 // wxThreadInternal class
 289 // ----------------------
 290
 291 class wxThreadInternal
 292 {
 293 public:
 294     inline wxThreadInternal()
 295     {
 296         m_hThread = 0;
 297         m_eState = STATE_NEW;
 298         m_nPriority = 0;
 299     }
 300
 301     // create a new (suspended) thread (for the given thread object)
 302     bool Create(wxThread* pThread);
 303
 304     // suspend/resume/terminate
 305     bool Suspend();
 306     bool Resume();
 307     inline void Cancel() { m_eState = STATE_CANCELED; }
 308
 309     // thread state
 310     inline void SetState(wxThreadState eState) { m_eState = eState; }
 311     inline wxThreadState GetState() const { return m_eState; }
 312
 313     // thread priority
 314     inline void SetPriority(unsigned int nPriority) { m_nPriority = nPriority; }
 315     inline unsigned int GetPriority() const { return m_nPriority; }
 316
 317     // thread handle and id
 318     inline TID GetHandle() const { return m_hThread; }
 319     TID  GetId() const { return m_hThread; }
 320
 321     // thread function
 322     static DWORD OS2ThreadStart(wxThread *thread);
 323
 324 private:
 325     // Threads in OS/2 have only an ID, so m_hThread is both it's handle and ID
 326     // PM also has no real Tls mechanism to index pointers by so we'll just
 327     // keep track of the wxWindows parent object here.
 328     TID                             m_hThread;    // handle and ID of the thread
 329     wxThreadState                   m_eState;     // state, see wxThreadState enum
 330     unsigned int                    m_nPriority;  // thread priority in "wx" units
 331 };
 332
 333 ULONG wxThreadInternal::OS2ThreadStart(
 334   wxThread*                         pThread
 335 )
 336 {
 337     m_pThread = pThread;
 338
 339     DWORD                           dwRet = (DWORD)pThread->Entry();
 340
 341     pThread->p_internal->SetState(STATE_EXITED);
 342     pThread->OnExit();
 343
 344     delete pThread;
 345     m_pThread = NULL;
 346     return dwRet;
 347 }
 348
 349 bool wxThreadInternal::Create(
 350   wxThread*                         pThread
 351 )
 352 {
 353     APIRET                          ulrc;
 354
 355     ulrc = ::DosCreateThread( &m_hThread
 356                              ,(PFNTHREAD)wxThreadInternal::OS2ThreadStart
 357                              ,(ULONG)pThread
 358                              ,CREATE_SUSPENDED | STACK_SPARSE
 359                              ,8192L
 360                             );
 361     if(ulrc != 0)
 362     {
 363         wxLogSysError(_("Can't create thread"));
 364
 365         return FALSE;
 366     }
 367
 368     // translate wxWindows priority to the PM one
 369     ULONG                           ulOS2_Priority;
 370
 371     if (m_nPriority <= 20)
 372         ulOS2_Priority = PRTYC_NOCHANGE;
 373     else if (m_nPriority <= 40)
 374         ulOS2_Priority = PRTYC_IDLETIME;
 375     else if (m_nPriority <= 60)
 376         ulOS2_Priority = PRTYC_REGULAR;
 377     else if (m_nPriority <= 80)
 378         ulOS2_Priority = PRTYC_TIMECRITICAL;
 379     else if (m_nPriority <= 100)
 380         ulOS2_Priority = PRTYC_FOREGROUNDSERVER;
 381     else
 382     {
 383         wxFAIL_MSG(wxT("invalid value of thread priority parameter"));
 384         ulOS2_Priority = PRTYC_REGULAR;
 385     }
 386     ulrc = ::DosSetPriority( PRTYS_THREAD
 387                             ,ulOS2_Priority
 388                             ,0
 389                             ,(ULONG)m_hThread
 390                            );
 391     if (ulrc != 0)
 392     {
 393         wxLogSysError(_("Can't set thread priority"));
 394     }
 395     return TRUE;
 396 }
 397
 398 bool wxThreadInternal::Suspend()
 399 {
 400     ULONG                           ulrc = ::DosSuspendThread(m_hThread);
 401
 402     if (ulrc != 0)
 403     {
 404         wxLogSysError(_("Can not suspend thread %lu"), m_hThread);
 405         return FALSE;
 406     }
 407     m_eState = STATE_PAUSED;
 408     return TRUE;
 409 }
 410
 411 bool wxThreadInternal::Resume()
 412 {
 413     ULONG                           ulrc = ::DosResumeThread(m_hThread);
 414
 415     if (ulrc != 0)
 416     {
 417         wxLogSysError(_("Can not suspend thread %lu"), m_hThread);
 418         return FALSE;
 419     }
 420     m_eState = STATE_PAUSED;
 421     return TRUE;
 422 }
 423
 424 // static functions
 425 // ----------------
 426
 427 wxThread *wxThread::This()
 428 {
 429     wxThread*                       pThread = m_pThread;
 430     return pThread;
 431 }
 432
 433 bool wxThread::IsMain()
 434 {
 435     PTIB                            ptib;
 436     PPIB                            ppib;
 437
 438     ::DosGetInfoBlocks(&ptib, &ppib);
 439
 440     if (ptib->tib_ptib2->tib2_ultid == s_ulIdMainThread)
 441         return TRUE;
 442     return FALSE;
 443 }
 444
 445 #ifdef Yield
 446     #undef Yield
 447 #endif
 448
 449 void wxThread::Yield()
 450 {
 451     ::DosSleep(0);
 452 }
 453
 454 void wxThread::Sleep(
 455   unsigned long                     ulMilliseconds
 456 )
 457 {
 458     ::DosSleep(ulMilliseconds);
 459 }
 460
 461 // create/start thread
 462 // -------------------
 463
 464 wxThreadError wxThread::Create()
 465 {
 466     if ( !p_internal->Create(this) )
 467         return wxTHREAD_NO_RESOURCE;
 468
 469     return wxTHREAD_NO_ERROR;
 470 }
 471
 472 wxThreadError wxThread::Run()
 473 {
 474     wxCriticalSectionLocker         lock((wxCriticalSection &)m_critsect);
 475
 476     if ( p_internal->GetState() != STATE_NEW )
 477     {
 478         // actually, it may be almost any state at all, not only STATE_RUNNING
 479         return wxTHREAD_RUNNING;
 480     }
 481     return Resume();
 482 }
 483
 484 // suspend/resume thread
 485 // ---------------------
 486
 487 wxThreadError wxThread::Pause()
 488 {
 489     wxCriticalSectionLocker         lock((wxCriticalSection &)m_critsect);
 490
 491     return p_internal->Suspend() ? wxTHREAD_NO_ERROR : wxTHREAD_MISC_ERROR;
 492 }
 493
 494 wxThreadError wxThread::Resume()
 495 {
 496     wxCriticalSectionLocker         lock((wxCriticalSection &)m_critsect);
 497
 498     return p_internal->Resume() ? wxTHREAD_NO_ERROR : wxTHREAD_MISC_ERROR;
 499 }
 500
 501 // stopping thread
 502 // ---------------
 503
 504 wxThread::ExitCode wxThread::Delete()
 505 {
 506     ExitCode                        rc = 0;
 507     ULONG                           ulrc;
 508
 509     // Delete() is always safe to call, so consider all possible states
 510     if (IsPaused())
 511         Resume();
 512
 513     if (IsRunning())
 514     {
 515         if (IsMain())
 516         {
 517             // set flag for wxIsWaitingForThread()
 518             s_bWaitingForThread = TRUE;
 519             wxBeginBusyCursor();
 520         }
 521
 522         TID                         hThread;
 523
 524         {
 525             wxCriticalSectionLocker         lock((wxCriticalSection &)m_critsect);
 526
 527             p_internal->Cancel();
 528             hThread = p_internal->GetHandle();
 529         }
 530
 531         // we can't just wait for the thread to terminate because it might be
 532         // calling some GUI functions and so it will never terminate before we
 533         // process the Windows messages that result from these functions
 534
 535         do
 536         {
 537             ulrc = ::DosWaitThread( &hThread
 538                                    ,DCWW_NOWAIT
 539                                   );
 540             switch (ulrc)
 541             {
 542                 case ERROR_INTERRUPT:
 543                 case ERROR_INVALID_THREADID:
 544                     // error
 545                     wxLogSysError(_("Can not wait for thread termination"));
 546                     Kill();
 547                     return (ExitCode)-1;
 548
 549                 case 0:
 550                     // thread we're waiting for terminated
 551                     break;
 552
 553                 case ERROR_THREAD_NOT_TERMINATED:
 554                     // new message arrived, process it
 555                     if (!wxTheApp->DoMessage())
 556                     {
 557                         // WM_QUIT received: kill the thread
 558                         Kill();
 559                         return (ExitCode)-1;
 560                     }
 561                     if (IsMain())
 562                     {
 563                         // give the thread we're waiting for chance to exit
 564                         // from the GUI call it might have been in
 565                         if ((s_nWaitingForGui > 0) && wxGuiOwnedByMainThread())
 566                         {
 567                             wxMutexGuiLeave();
 568                         }
 569                     }
 570                     break;
 571
 572                 default:
 573                     wxFAIL_MSG(wxT("unexpected result of DosWatiThread"));
 574             }
 575         } while (ulrc != 0);
 576
 577         if (IsMain())
 578         {
 579             s_bWaitingForThread = FALSE;
 580             wxEndBusyCursor();
 581         }
 582
 583         ::DosExit(EXIT_THREAD, ulrc);
 584     }
 585     rc = (ExitCode)ulrc;
 586     return rc;
 587 }
 588
 589 wxThreadError wxThread::Kill()
 590 {
 591     if (!IsRunning())
 592         return wxTHREAD_NOT_RUNNING;
 593
 594     ::DosKillThread(p_internal->GetHandle());
 595     delete this;
 596     return wxTHREAD_NO_ERROR;
 597 }
 598
 599 void wxThread::Exit(
 600   void*                             pStatus
 601 )
 602 {
 603     delete this;
 604     ::DosExit(EXIT_THREAD, ULONG(pStatus));
 605     wxFAIL_MSG(wxT("Couldn't return from DosExit()!"));
 606 }
 607
 608 void wxThread::SetPriority(
 609   unsigned int                      nPrio
 610 )
 611 {
 612     wxCriticalSectionLocker         lock((wxCriticalSection &)m_critsect);
 613
 614     p_internal->SetPriority(nPrio);
 615 }
 616
 617 unsigned int wxThread::GetPriority() const
 618 {
 619     wxCriticalSectionLocker         lock((wxCriticalSection &)m_critsect);
 620
 621     return p_internal->GetPriority();
 622 }
 623
 624 unsigned long wxThread::GetID() const
 625 {
 626     wxCriticalSectionLocker         lock((wxCriticalSection &)m_critsect);
 627
 628     return (unsigned long)p_internal->GetId();
 629 }
 630
 631 bool wxThread::IsRunning() const
 632 {
 633     wxCriticalSectionLocker         lock((wxCriticalSection &)m_critsect);
 634
 635     return p_internal->GetState() == STATE_RUNNING;
 636 }
 637
 638 bool wxThread::IsAlive() const
 639 {
 640     wxCriticalSectionLocker         lock((wxCriticalSection &)m_critsect);
 641
 642     return (p_internal->GetState() == STATE_RUNNING) ||
 643            (p_internal->GetState() == STATE_PAUSED);
 644 }
 645
 646 bool wxThread::IsPaused() const
 647 {
 648     wxCriticalSectionLocker         lock((wxCriticalSection &)m_critsect);
 649
 650     return (p_internal->GetState() == STATE_PAUSED);
 651 }
 652
 653 bool wxThread::TestDestroy()
 654 {
 655     wxCriticalSectionLocker         lock((wxCriticalSection &)m_critsect);
 656
 657     return p_internal->GetState() == STATE_CANCELED;
 658 }
 659
 660 wxThread::wxThread()
 661 {
 662     p_internal = new wxThreadInternal();
 663 }
 664
 665 wxThread::~wxThread()
 666 {
 667     delete p_internal;
 668 }
 669
 670 // ----------------------------------------------------------------------------
 671 // Automatic initialization for thread module
 672 // ----------------------------------------------------------------------------
 673
 674 class wxThreadModule : public wxModule
 675 {
 676 public:
 677     virtual bool OnInit();
 678     virtual void OnExit();
 679
 680 private:
 681     DECLARE_DYNAMIC_CLASS(wxThreadModule)
 682 };
 683
 684 IMPLEMENT_DYNAMIC_CLASS(wxThreadModule, wxModule)
 685
 686 bool wxThreadModule::OnInit()
 687 {
 688     s_pCritsectWaitingForGui = new wxCriticalSection();
 689
 690     s_pCritsectGui = new wxCriticalSection();
 691     s_pCritsectGui->Enter();
 692
 693     PTIB                            ptib;
 694     PPIB                            ppib;
 695
 696     ::DosGetInfoBlocks(&ptib, &ppib);
 697
 698     s_ulIdMainThread = ptib->tib_ptib2->tib2_ultid;
 699     return TRUE;
 700 }
 701
 702 void wxThreadModule::OnExit()
 703 {
 704     if (s_pCritsectGui)
 705     {
 706         s_pCritsectGui->Leave();
 707         delete s_pCritsectGui;
 708         s_pCritsectGui = NULL;
 709     }
 710
 711     wxDELETE(s_pCritsectWaitingForGui);
 712 }
 713
 714 // ----------------------------------------------------------------------------
 715 // Helper functions
 716 // ----------------------------------------------------------------------------
 717
 718 // Does nothing under OS/2 [for now]
 719 void WXDLLEXPORT wxWakeUpMainThread()
 720 {
 721 }
 722
 723 void WXDLLEXPORT wxMutexGuiLeave()
 724 {
 725     wxCriticalSectionLocker enter(*s_pCritsectWaitingForGui);
 726
 727     if ( wxThread::IsMain() )
 728     {
 729         s_bGuiOwnedByMainThread = FALSE;
 730     }
 731     else
 732     {
 733         // decrement the number of waiters now
 734         wxASSERT_MSG( s_nWaitingForGui > 0,
 735                       wxT("calling wxMutexGuiLeave() without entering it first?") );
 736
 737         s_nWaitingForGui--;
 738
 739         wxWakeUpMainThread();
 740     }
 741
 742     s_pCritsectGui->Leave();
 743 }
 744
 745 void WXDLLEXPORT wxMutexGuiLeaveOrEnter()
 746 {
 747     wxASSERT_MSG( wxThread::IsMain(),
 748                   wxT("only main thread may call wxMutexGuiLeaveOrEnter()!") );
 749
 750     wxCriticalSectionLocker enter(*s_pCritsectWaitingForGui);
 751
 752     if ( s_nWaitingForGui == 0 )
 753     {
 754         // no threads are waiting for GUI - so we may acquire the lock without
 755         // any danger (but only if we don't already have it)
 756         if (!wxGuiOwnedByMainThread())
 757         {
 758             s_pCritsectGui->Enter();
 759
 760             s_bGuiOwnedByMainThread = TRUE;
 761         }
 762         //else: already have it, nothing to do
 763     }
 764     else
 765     {
 766         // some threads are waiting, release the GUI lock if we have it
 767         if (wxGuiOwnedByMainThread())
 768         {
 769             wxMutexGuiLeave();
 770         }
 771         //else: some other worker thread is doing GUI
 772     }
 773 }
 774
 775 bool WXDLLEXPORT wxGuiOwnedByMainThread()
 776 {
 777     return s_bGuiOwnedByMainThread;
 778 }
 779
 780 #endif
 781   // wxUSE_THREADS