src/msw/thread.cpp

   1 /////////////////////////////////////////////////////////////////////////////
   2 // Name:        src/msw/thread.cpp
   3 // Purpose:     wxThread Implementation
   4 // Author:      Original from Wolfram Gloger/Guilhem Lavaux
   5 // Modified by: Vadim Zeitlin to make it work :-)
   6 // Created:     04/22/98
   7 // RCS-ID:      $Id$
   8 // Copyright:   (c) Wolfram Gloger (1996, 1997), Guilhem Lavaux (1998);
   9 //                  Vadim Zeitlin (1999-2002)
  10 // Licence:     wxWindows licence
  11 /////////////////////////////////////////////////////////////////////////////
  12
  13 #if defined(__GNUG__) && !defined(NO_GCC_PRAGMA)
  14     #pragma implementation "thread.h"
  15 #endif
  16
  17 // ----------------------------------------------------------------------------
  18 // headers
  19 // ----------------------------------------------------------------------------
  20
  21 // For compilers that support precompilation, includes "wx.h".
  22 #include "wx/wxprec.h"
  23
  24 #if defined(__BORLANDC__)
  25     #pragma hdrstop
  26 #endif
  27
  28 #ifndef WX_PRECOMP
  29     #include "wx/intl.h"
  30     #include "wx/app.h"
  31 #endif
  32
  33 #if wxUSE_THREADS
  34
  35 #include "wx/apptrait.h"
  36
  37 #include "wx/msw/private.h"
  38 #include "wx/msw/missing.h"
  39
  40 #include "wx/module.h"
  41 #include "wx/thread.h"
  42
  43 // must have this symbol defined to get _beginthread/_endthread declarations
  44 #ifndef _MT
  45     #define _MT
  46 #endif
  47
  48 #if defined(__BORLANDC__)
  49     #if !defined(__MT__)
  50         // I can't set -tWM in the IDE (anyone?) so have to do this
  51         #define __MT__
  52     #endif
  53
  54     #if !defined(__MFC_COMPAT__)
  55         // Needed to know about _beginthreadex etc..
  56         #define __MFC_COMPAT__
  57     #endif
  58 #endif // BC++
  59
  60 // define wxUSE_BEGIN_THREAD if the compiler has _beginthreadex() function
  61 // which should be used instead of Win32 ::CreateThread() if possible
  62 #if defined(__VISUALC__) || \
  63     (defined(__BORLANDC__) && (__BORLANDC__ >= 0x500)) || \
  64     (defined(__GNUG__) && defined(__MSVCRT__)) || \
  65     defined(__WATCOMC__) || defined(__MWERKS__)
  66
  67 #ifndef __WXWINCE__
  68     #undef wxUSE_BEGIN_THREAD
  69     #define wxUSE_BEGIN_THREAD
  70 #endif
  71
  72 #endif
  73
  74 #ifdef wxUSE_BEGIN_THREAD
  75     // this is where _beginthreadex() is declared
  76     #include <process.h>
  77
  78     // the return type of the thread function entry point
  79     typedef unsigned THREAD_RETVAL;
  80
  81     // the calling convention of the thread function entry point
  82     #define THREAD_CALLCONV __stdcall
  83 #else
  84     // the settings for CreateThread()
  85     typedef DWORD THREAD_RETVAL;
  86     #define THREAD_CALLCONV WINAPI
  87 #endif
  88
  89 // ----------------------------------------------------------------------------
  90 // constants
  91 // ----------------------------------------------------------------------------
  92
  93 // the possible states of the thread ("=>" shows all possible transitions from
  94 // this state)
  95 enum wxThreadState
  96 {
  97     STATE_NEW,          // didn't start execution yet (=> RUNNING)
  98     STATE_RUNNING,      // thread is running (=> PAUSED, CANCELED)
  99     STATE_PAUSED,       // thread is temporarily suspended (=> RUNNING)
 100     STATE_CANCELED,     // thread should terminate a.s.a.p. (=> EXITED)
 101     STATE_EXITED        // thread is terminating
 102 };
 103
 104 // ----------------------------------------------------------------------------
 105 // this module globals
 106 // ----------------------------------------------------------------------------
 107
 108 // TLS index of the slot where we store the pointer to the current thread
 109 static DWORD gs_tlsThisThread = 0xFFFFFFFF;
 110
 111 // id of the main thread - the one which can call GUI functions without first
 112 // calling wxMutexGuiEnter()
 113 static DWORD gs_idMainThread = 0;
 114
 115 // if it's false, some secondary thread is holding the GUI lock
 116 static bool gs_bGuiOwnedByMainThread = true;
 117
 118 // critical section which controls access to all GUI functions: any secondary
 119 // thread (i.e. except the main one) must enter this crit section before doing
 120 // any GUI calls
 121 static wxCriticalSection *gs_critsectGui = NULL;
 122
 123 // critical section which protects gs_nWaitingForGui variable
 124 static wxCriticalSection *gs_critsectWaitingForGui = NULL;
 125
 126 // critical section which serializes WinThreadStart() and WaitForTerminate()
 127 // (this is a potential bottleneck, we use a single crit sect for all threads
 128 // in the system, but normally time spent inside it should be quite short)
 129 static wxCriticalSection *gs_critsectThreadDelete = NULL;
 130
 131 // number of threads waiting for GUI in wxMutexGuiEnter()
 132 static size_t gs_nWaitingForGui = 0;
 133
 134 // are we waiting for a thread termination?
 135 static bool gs_waitingForThread = false;
 136
 137 // ============================================================================
 138 // Windows implementation of thread and related classes
 139 // ============================================================================
 140
 141 // ----------------------------------------------------------------------------
 142 // wxCriticalSection
 143 // ----------------------------------------------------------------------------
 144
 145 wxCriticalSection::wxCriticalSection()
 146 {
 147     wxCOMPILE_TIME_ASSERT( sizeof(CRITICAL_SECTION) <= sizeof(wxCritSectBuffer),
 148                            wxCriticalSectionBufferTooSmall );
 149
 150     ::InitializeCriticalSection((CRITICAL_SECTION *)m_buffer);
 151 }
 152
 153 wxCriticalSection::~wxCriticalSection()
 154 {
 155     ::DeleteCriticalSection((CRITICAL_SECTION *)m_buffer);
 156 }
 157
 158 void wxCriticalSection::Enter()
 159 {
 160     ::EnterCriticalSection((CRITICAL_SECTION *)m_buffer);
 161 }
 162
 163 void wxCriticalSection::Leave()
 164 {
 165     ::LeaveCriticalSection((CRITICAL_SECTION *)m_buffer);
 166 }
 167
 168 // ----------------------------------------------------------------------------
 169 // wxMutex
 170 // ----------------------------------------------------------------------------
 171
 172 class wxMutexInternal
 173 {
 174 public:
 175     wxMutexInternal(wxMutexType mutexType);
 176     ~wxMutexInternal();
 177
 178     bool IsOk() const { return m_mutex != NULL; }
 179
 180     wxMutexError Lock() { return LockTimeout(INFINITE); }
 181     wxMutexError TryLock() { return LockTimeout(0); }
 182     wxMutexError Unlock();
 183
 184 private:
 185     wxMutexError LockTimeout(DWORD milliseconds);
 186
 187     HANDLE m_mutex;
 188
 189     DECLARE_NO_COPY_CLASS(wxMutexInternal)
 190 };
 191
 192 // all mutexes are recursive under Win32 so we don't use mutexType
 193 wxMutexInternal::wxMutexInternal(wxMutexType WXUNUSED(mutexType))
 194 {
 195     // create a nameless (hence intra process and always private) mutex
 196     m_mutex = ::CreateMutex
 197                 (
 198                     NULL,       // default secutiry attributes
 199                     false,      // not initially locked
 200                     NULL        // no name
 201                 );
 202
 203     if ( !m_mutex )
 204     {
 205         wxLogLastError(_T("CreateMutex()"));
 206     }
 207 }
 208
 209 wxMutexInternal::~wxMutexInternal()
 210 {
 211     if ( m_mutex )
 212     {
 213         if ( !::CloseHandle(m_mutex) )
 214         {
 215             wxLogLastError(_T("CloseHandle(mutex)"));
 216         }
 217     }
 218 }
 219
 220 wxMutexError wxMutexInternal::LockTimeout(DWORD milliseconds)
 221 {
 222     DWORD rc = ::WaitForSingleObject(m_mutex, milliseconds);
 223     if ( rc == WAIT_ABANDONED )
 224     {
 225         // the previous caller died without releasing the mutex, but now we can
 226         // really lock it
 227         wxLogDebug(_T("WaitForSingleObject() returned WAIT_ABANDONED"));
 228
 229         // use 0 timeout, normally we should always get it
 230         rc = ::WaitForSingleObject(m_mutex, 0);
 231     }
 232
 233     switch ( rc )
 234     {
 235         case WAIT_OBJECT_0:
 236             // ok
 237             break;
 238
 239         case WAIT_TIMEOUT:
 240             return wxMUTEX_BUSY;
 241
 242         case WAIT_ABANDONED:        // checked for above
 243         default:
 244             wxFAIL_MSG(wxT("impossible return value in wxMutex::Lock"));
 245             // fall through
 246
 247         case WAIT_FAILED:
 248             wxLogLastError(_T("WaitForSingleObject(mutex)"));
 249             return wxMUTEX_MISC_ERROR;
 250     }
 251
 252     return wxMUTEX_NO_ERROR;
 253 }
 254
 255 wxMutexError wxMutexInternal::Unlock()
 256 {
 257     if ( !::ReleaseMutex(m_mutex) )
 258     {
 259         wxLogLastError(_T("ReleaseMutex()"));
 260
 261         return wxMUTEX_MISC_ERROR;
 262     }
 263
 264     return wxMUTEX_NO_ERROR;
 265 }
 266
 267 // --------------------------------------------------------------------------
 268 // wxSemaphore
 269 // --------------------------------------------------------------------------
 270
 271 // a trivial wrapper around Win32 semaphore
 272 class wxSemaphoreInternal
 273 {
 274 public:
 275     wxSemaphoreInternal(int initialcount, int maxcount);
 276     ~wxSemaphoreInternal();
 277
 278     bool IsOk() const { return m_semaphore != NULL; }
 279
 280     wxSemaError Wait() { return WaitTimeout(INFINITE); }
 281
 282     wxSemaError TryWait()
 283     {
 284         wxSemaError rc = WaitTimeout(0);
 285         if ( rc == wxSEMA_TIMEOUT )
 286             rc = wxSEMA_BUSY;
 287
 288         return rc;
 289     }
 290
 291     wxSemaError WaitTimeout(unsigned long milliseconds);
 292
 293     wxSemaError Post();
 294
 295 private:
 296     HANDLE m_semaphore;
 297
 298     DECLARE_NO_COPY_CLASS(wxSemaphoreInternal)
 299 };
 300
 301 wxSemaphoreInternal::wxSemaphoreInternal(int initialcount, int maxcount)
 302 {
 303 #ifndef __WXWINCE__
 304     if ( maxcount == 0 )
 305     {
 306         // make it practically infinite
 307         maxcount = INT_MAX;
 308     }
 309
 310     m_semaphore = ::CreateSemaphore
 311                     (
 312                         NULL,           // default security attributes
 313                         initialcount,
 314                         maxcount,
 315                         NULL            // no name
 316                     );
 317 #endif
 318     if ( !m_semaphore )
 319     {
 320         wxLogLastError(_T("CreateSemaphore()"));
 321     }
 322 }
 323
 324 wxSemaphoreInternal::~wxSemaphoreInternal()
 325 {
 326     if ( m_semaphore )
 327     {
 328         if ( !::CloseHandle(m_semaphore) )
 329         {
 330             wxLogLastError(_T("CloseHandle(semaphore)"));
 331         }
 332     }
 333 }
 334
 335 wxSemaError wxSemaphoreInternal::WaitTimeout(unsigned long milliseconds)
 336 {
 337     DWORD rc = ::WaitForSingleObject( m_semaphore, milliseconds );
 338
 339     switch ( rc )
 340     {
 341         case WAIT_OBJECT_0:
 342            return wxSEMA_NO_ERROR;
 343
 344         case WAIT_TIMEOUT:
 345            return wxSEMA_TIMEOUT;
 346
 347         default:
 348             wxLogLastError(_T("WaitForSingleObject(semaphore)"));
 349     }
 350
 351     return wxSEMA_MISC_ERROR;
 352 }
 353
 354 wxSemaError wxSemaphoreInternal::Post()
 355 {
 356 #ifndef __WXWINCE__
 357     if ( !::ReleaseSemaphore(m_semaphore, 1, NULL /* ptr to previous count */) )
 358 #endif
 359     {
 360         wxLogLastError(_T("ReleaseSemaphore"));
 361
 362         return wxSEMA_MISC_ERROR;
 363     }
 364
 365     return wxSEMA_NO_ERROR;
 366 }
 367
 368 // ----------------------------------------------------------------------------
 369 // wxThread implementation
 370 // ----------------------------------------------------------------------------
 371
 372 // wxThreadInternal class
 373 // ----------------------
 374
 375 class wxThreadInternal
 376 {
 377 public:
 378     wxThreadInternal(wxThread *thread)
 379     {
 380         m_thread = thread;
 381         m_hThread = 0;
 382         m_state = STATE_NEW;
 383         m_priority = WXTHREAD_DEFAULT_PRIORITY;
 384         m_nRef = 1;
 385     }
 386
 387     ~wxThreadInternal()
 388     {
 389         Free();
 390     }
 391
 392     void Free()
 393     {
 394         if ( m_hThread )
 395         {
 396             if ( !::CloseHandle(m_hThread) )
 397             {
 398                 wxLogLastError(wxT("CloseHandle(thread)"));
 399             }
 400
 401             m_hThread = 0;
 402         }
 403     }
 404
 405     // create a new (suspended) thread (for the given thread object)
 406     bool Create(wxThread *thread, unsigned int stackSize);
 407
 408     // wait for the thread to terminate, either by itself, or by asking it
 409     // (politely, this is not Kill()!) to do it
 410     wxThreadError WaitForTerminate(wxCriticalSection& cs,
 411                                    wxThread::ExitCode *pRc,
 412                                    wxThread *threadToDelete = NULL);
 413
 414     // kill the thread unconditionally
 415     wxThreadError Kill();
 416
 417     // suspend/resume/terminate
 418     bool Suspend();
 419     bool Resume();
 420     void Cancel() { m_state = STATE_CANCELED; }
 421
 422     // thread state
 423     void SetState(wxThreadState state) { m_state = state; }
 424     wxThreadState GetState() const { return m_state; }
 425
 426     // thread priority
 427     void SetPriority(unsigned int priority);
 428     unsigned int GetPriority() const { return m_priority; }
 429
 430     // thread handle and id
 431     HANDLE GetHandle() const { return m_hThread; }
 432     DWORD  GetId() const { return m_tid; }
 433
 434     // thread function
 435     static THREAD_RETVAL THREAD_CALLCONV WinThreadStart(void *thread);
 436
 437     void KeepAlive()
 438     {
 439         if ( m_thread->IsDetached() )
 440             ::InterlockedIncrement(&m_nRef);
 441     }
 442
 443     void LetDie()
 444     {
 445         if ( m_thread->IsDetached() && !::InterlockedDecrement(&m_nRef) )
 446             delete m_thread;
 447     }
 448
 449 private:
 450     // the thread we're associated with
 451     wxThread *m_thread;
 452
 453     HANDLE        m_hThread;    // handle of the thread
 454     wxThreadState m_state;      // state, see wxThreadState enum
 455     unsigned int  m_priority;   // thread priority in "wx" units
 456     DWORD         m_tid;        // thread id
 457
 458     // number of threads which need this thread to remain alive, when the count
 459     // reaches 0 we kill the owning wxThread -- and die ourselves with it
 460     LONG m_nRef;
 461
 462     DECLARE_NO_COPY_CLASS(wxThreadInternal)
 463 };
 464
 465 // small class which keeps a thread alive during its lifetime
 466 class wxThreadKeepAlive
 467 {
 468 public:
 469     wxThreadKeepAlive(wxThreadInternal& thrImpl) : m_thrImpl(thrImpl)
 470         { m_thrImpl.KeepAlive(); }
 471     ~wxThreadKeepAlive()
 472         { m_thrImpl.LetDie(); }
 473
 474 private:
 475     wxThreadInternal& m_thrImpl;
 476 };
 477
 478
 479 THREAD_RETVAL THREAD_CALLCONV wxThreadInternal::WinThreadStart(void *param)
 480 {
 481     THREAD_RETVAL rc;
 482
 483     wxThread * const thread = (wxThread *)param;
 484
 485     // first of all, check whether we hadn't been cancelled already and don't
 486     // start the user code at all then
 487     if ( thread->m_internal->GetState() == STATE_EXITED )
 488     {
 489         rc = (THREAD_RETVAL)-1;
 490     }
 491     else // do run thread
 492     {
 493         // store the thread object in the TLS
 494         if ( !::TlsSetValue(gs_tlsThisThread, thread) )
 495         {
 496             wxLogSysError(_("Can not start thread: error writing TLS."));
 497
 498             return (DWORD)-1;
 499         }
 500
 501         rc = (THREAD_RETVAL)thread->Entry();
 502
 503         // enter m_critsect before changing the thread state
 504         wxCriticalSectionLocker lock(thread->m_critsect);
 505
 506         thread->m_internal->SetState(STATE_EXITED);
 507     }
 508
 509     thread->OnExit();
 510
 511     // the thread may delete itself now if it wants, we don't need it any more
 512     thread->m_internal->LetDie();
 513
 514     return rc;
 515 }
 516
 517 void wxThreadInternal::SetPriority(unsigned int priority)
 518 {
 519     m_priority = priority;
 520
 521     // translate wxWindows priority to the Windows one
 522     int win_priority;
 523     if (m_priority <= 20)
 524         win_priority = THREAD_PRIORITY_LOWEST;
 525     else if (m_priority <= 40)
 526         win_priority = THREAD_PRIORITY_BELOW_NORMAL;
 527     else if (m_priority <= 60)
 528         win_priority = THREAD_PRIORITY_NORMAL;
 529     else if (m_priority <= 80)
 530         win_priority = THREAD_PRIORITY_ABOVE_NORMAL;
 531     else if (m_priority <= 100)
 532         win_priority = THREAD_PRIORITY_HIGHEST;
 533     else
 534     {
 535         wxFAIL_MSG(wxT("invalid value of thread priority parameter"));
 536         win_priority = THREAD_PRIORITY_NORMAL;
 537     }
 538
 539     if ( !::SetThreadPriority(m_hThread, win_priority) )
 540     {
 541         wxLogSysError(_("Can't set thread priority"));
 542     }
 543 }
 544
 545 bool wxThreadInternal::Create(wxThread *thread, unsigned int stackSize)
 546 {
 547     wxASSERT_MSG( m_state == STATE_NEW && !m_hThread,
 548                     _T("Create()ing thread twice?") );
 549
 550     // for compilers which have it, we should use C RTL function for thread
 551     // creation instead of Win32 API one because otherwise we will have memory
 552     // leaks if the thread uses C RTL (and most threads do)
 553 #ifdef wxUSE_BEGIN_THREAD
 554
 555     // Watcom is reported to not like 0 stack size (which means "use default"
 556     // for the other compilers and is also the default value for stackSize)
 557 #ifdef __WATCOMC__
 558     if ( !stackSize )
 559         stackSize = 10240;
 560 #endif // __WATCOMC__
 561
 562     m_hThread = (HANDLE)_beginthreadex
 563                         (
 564                           NULL,                             // default security
 565                           stackSize,
 566                           wxThreadInternal::WinThreadStart, // entry point
 567                           thread,
 568                           CREATE_SUSPENDED,
 569                           (unsigned int *)&m_tid
 570                         );
 571 #else // compiler doesn't have _beginthreadex
 572     m_hThread = ::CreateThread
 573                   (
 574                     NULL,                               // default security
 575                     stackSize,                          // stack size
 576                     wxThreadInternal::WinThreadStart,   // thread entry point
 577                     (LPVOID)thread,                     // parameter
 578                     CREATE_SUSPENDED,                   // flags
 579                     &m_tid                              // [out] thread id
 580                   );
 581 #endif // _beginthreadex/CreateThread
 582
 583     if ( m_hThread == NULL )
 584     {
 585         wxLogSysError(_("Can't create thread"));
 586
 587         return false;
 588     }
 589
 590     if ( m_priority != WXTHREAD_DEFAULT_PRIORITY )
 591     {
 592         SetPriority(m_priority);
 593     }
 594
 595     return true;
 596 }
 597
 598 wxThreadError wxThreadInternal::Kill()
 599 {
 600     if ( !::TerminateThread(m_hThread, (DWORD)-1) )
 601     {
 602         wxLogSysError(_("Couldn't terminate thread"));
 603
 604         return wxTHREAD_MISC_ERROR;
 605     }
 606
 607     Free();
 608
 609     return wxTHREAD_NO_ERROR;
 610 }
 611
 612 wxThreadError
 613 wxThreadInternal::WaitForTerminate(wxCriticalSection& cs,
 614                                    wxThread::ExitCode *pRc,
 615                                    wxThread *threadToDelete)
 616 {
 617     // prevent the thread C++ object from disappearing as long as we are using
 618     // it here
 619     wxThreadKeepAlive keepAlive(*this);
 620
 621
 622     // we may either wait passively for the thread to terminate (when called
 623     // from Wait()) or ask it to terminate (when called from Delete())
 624     bool shouldDelete = threadToDelete != NULL;
 625
 626     wxThread::ExitCode rc = 0;
 627
 628     // Delete() is always safe to call, so consider all possible states
 629
 630     // we might need to resume the thread, but we might also not need to cancel
 631     // it if it doesn't run yet
 632     bool shouldResume = false,
 633          isRunning = false;
 634
 635     // check if the thread already started to run
 636     {
 637         wxCriticalSectionLocker lock(cs);
 638
 639         if ( m_state == STATE_NEW )
 640         {
 641             if ( shouldDelete )
 642             {
 643                 // WinThreadStart() will see it and terminate immediately, no
 644                 // need to cancel the thread -- but we still need to resume it
 645                 // to let it run
 646                 m_state = STATE_EXITED;
 647
 648                 Resume();   // it knows about STATE_EXITED special case
 649
 650                 shouldDelete = false;
 651             }
 652
 653             isRunning = true;
 654
 655             // shouldResume is correctly set to false here
 656         }
 657         else if ( m_state == STATE_EXITED )
 658         {
 659             return wxTHREAD_NOT_RUNNING;
 660         }
 661         else // running (but maybe paused or cancelled)
 662         {
 663             shouldResume = m_state == STATE_PAUSED;
 664         }
 665     }
 666
 667     // resume the thread if it is paused
 668     if ( shouldResume )
 669         Resume();
 670
 671     // is it still running?
 672     if ( isRunning || m_state == STATE_RUNNING )
 673     {
 674         if ( wxThread::IsMain() )
 675         {
 676             // set flag for wxIsWaitingForThread()
 677             gs_waitingForThread = true;
 678         }
 679
 680         // ask the thread to terminate
 681         if ( shouldDelete )
 682         {
 683             wxCriticalSectionLocker lock(cs);
 684
 685             Cancel();
 686         }
 687
 688         // we can't just wait for the thread to terminate because it might be
 689         // calling some GUI functions and so it will never terminate before we
 690         // process the Windows messages that result from these functions
 691         // (note that even in console applications we might have to process
 692         // messages if we use wxExecute() or timers or ...)
 693         DWORD result = 0;       // suppress warnings from broken compilers
 694         do
 695         {
 696             if ( wxThread::IsMain() )
 697             {
 698                 // give the thread we're waiting for chance to do the GUI call
 699                 // it might be in
 700                 if ( (gs_nWaitingForGui > 0) && wxGuiOwnedByMainThread() )
 701                 {
 702                     wxMutexGuiLeave();
 703                 }
 704             }
 705
 706             result = ::MsgWaitForMultipleObjects
 707                      (
 708                        1,              // number of objects to wait for
 709                        &m_hThread,     // the objects
 710                        false,          // don't wait for all objects
 711                        INFINITE,       // no timeout
 712                        QS_ALLINPUT |   // return as soon as there are any events
 713                        QS_ALLPOSTMESSAGE
 714                      );
 715
 716             switch ( result )
 717             {
 718                 case 0xFFFFFFFF:
 719                     // error
 720                     wxLogSysError(_("Can not wait for thread termination"));
 721                     Kill();
 722                     return wxTHREAD_KILLED;
 723
 724                 case WAIT_OBJECT_0:
 725                     // thread we're waiting for terminated
 726                     break;
 727
 728                 case WAIT_OBJECT_0 + 1:
 729                     // new message arrived, process it -- but only if we're the
 730                     // main thread as we don't support processing messages in
 731                     // the other ones
 732                     //
 733                     // NB: we still must include QS_ALLINPUT even when waiting
 734                     //     in a secondary thread because if it had created some
 735                     //     window somehow (possible not even using wxWindows)
 736                     //     the system might dead lock then
 737                     if ( wxThread::IsMain() )
 738                     {
 739                         // it looks that sometimes WAIT_OBJECT_0 + 1 is
 740                         // returned but there are no messages in the thread
 741                         // queue -- prevent DoMessageFromThreadWait() from
 742                         // blocking inside ::GetMessage() forever in this case
 743                         ::PostMessage(NULL, WM_NULL, 0, 0);
 744
 745                         wxAppTraits *traits = wxTheApp ? wxTheApp->GetTraits()
 746                                                        : NULL;
 747
 748                         if ( traits && !traits->DoMessageFromThreadWait() )
 749                         {
 750                             // WM_QUIT received: kill the thread
 751                             Kill();
 752
 753                             return wxTHREAD_KILLED;
 754                         }
 755                     }
 756                     break;
 757
 758                 default:
 759                     wxFAIL_MSG(wxT("unexpected result of MsgWaitForMultipleObject"));
 760             }
 761         } while ( result != WAIT_OBJECT_0 );
 762
 763         if ( wxThread::IsMain() )
 764         {
 765             gs_waitingForThread = false;
 766         }
 767     }
 768
 769     // although the thread might be already in the EXITED state it might not
 770     // have terminated yet and so we are not sure that it has actually
 771     // terminated if the "if" above hadn't been taken
 772     do
 773     {
 774         if ( !::GetExitCodeThread(m_hThread, (LPDWORD)&rc) )
 775         {
 776             wxLogLastError(wxT("GetExitCodeThread"));
 777
 778             rc = (wxThread::ExitCode)-1;
 779         }
 780     } while ( (DWORD)rc == STILL_ACTIVE );
 781
 782     if ( pRc )
 783         *pRc = rc;
 784
 785     // we don't need the thread handle any more in any case
 786     Free();
 787
 788
 789     return rc == (wxThread::ExitCode)-1 ? wxTHREAD_MISC_ERROR
 790                                         : wxTHREAD_NO_ERROR;
 791 }
 792
 793 bool wxThreadInternal::Suspend()
 794 {
 795     DWORD nSuspendCount = ::SuspendThread(m_hThread);
 796     if ( nSuspendCount == (DWORD)-1 )
 797     {
 798         wxLogSysError(_("Can not suspend thread %x"), m_hThread);
 799
 800         return false;
 801     }
 802
 803     m_state = STATE_PAUSED;
 804
 805     return true;
 806 }
 807
 808 bool wxThreadInternal::Resume()
 809 {
 810     DWORD nSuspendCount = ::ResumeThread(m_hThread);
 811     if ( nSuspendCount == (DWORD)-1 )
 812     {
 813         wxLogSysError(_("Can not resume thread %x"), m_hThread);
 814
 815         return false;
 816     }
 817
 818     // don't change the state from STATE_EXITED because it's special and means
 819     // we are going to terminate without running any user code - if we did it,
 820     // the codei n Delete() wouldn't work
 821     if ( m_state != STATE_EXITED )
 822     {
 823         m_state = STATE_RUNNING;
 824     }
 825
 826     return true;
 827 }
 828
 829 // static functions
 830 // ----------------
 831
 832 wxThread *wxThread::This()
 833 {
 834     wxThread *thread = (wxThread *)::TlsGetValue(gs_tlsThisThread);
 835
 836     // be careful, 0 may be a valid return value as well
 837     if ( !thread && (::GetLastError() != NO_ERROR) )
 838     {
 839         wxLogSysError(_("Couldn't get the current thread pointer"));
 840
 841         // return NULL...
 842     }
 843
 844     return thread;
 845 }
 846
 847 bool wxThread::IsMain()
 848 {
 849     return ::GetCurrentThreadId() == gs_idMainThread;
 850 }
 851
 852 void wxThread::Yield()
 853 {
 854     // 0 argument to Sleep() is special and means to just give away the rest of
 855     // our timeslice
 856     ::Sleep(0);
 857 }
 858
 859 void wxThread::Sleep(unsigned long milliseconds)
 860 {
 861     ::Sleep(milliseconds);
 862 }
 863
 864 int wxThread::GetCPUCount()
 865 {
 866     SYSTEM_INFO si;
 867     GetSystemInfo(&si);
 868
 869     return si.dwNumberOfProcessors;
 870 }
 871
 872 unsigned long wxThread::GetCurrentId()
 873 {
 874     return (unsigned long)::GetCurrentThreadId();
 875 }
 876
 877 bool wxThread::SetConcurrency(size_t level)
 878 {
 879 #ifndef __WXWINCE__
 880     wxASSERT_MSG( IsMain(), _T("should only be called from the main thread") );
 881
 882     // ok only for the default one
 883     if ( level == 0 )
 884         return 0;
 885
 886     // get system affinity mask first
 887     HANDLE hProcess = ::GetCurrentProcess();
 888     DWORD dwProcMask, dwSysMask;
 889     if ( ::GetProcessAffinityMask(hProcess, &dwProcMask, &dwSysMask) == 0 )
 890     {
 891         wxLogLastError(_T("GetProcessAffinityMask"));
 892
 893         return false;
 894     }
 895
 896     // how many CPUs have we got?
 897     if ( dwSysMask == 1 )
 898     {
 899         // don't bother with all this complicated stuff - on a single
 900         // processor system it doesn't make much sense anyhow
 901         return level == 1;
 902     }
 903
 904     // calculate the process mask: it's a bit vector with one bit per
 905     // processor; we want to schedule the process to run on first level
 906     // CPUs
 907     DWORD bit = 1;
 908     while ( bit )
 909     {
 910         if ( dwSysMask & bit )
 911         {
 912             // ok, we can set this bit
 913             dwProcMask |= bit;
 914
 915             // another process added
 916             if ( !--level )
 917             {
 918                 // and that's enough
 919                 break;
 920             }
 921         }
 922
 923         // next bit
 924         bit <<= 1;
 925     }
 926
 927     // could we set all bits?
 928     if ( level != 0 )
 929     {
 930         wxLogDebug(_T("bad level %u in wxThread::SetConcurrency()"), level);
 931
 932         return false;
 933     }
 934
 935     // set it: we can't link to SetProcessAffinityMask() because it doesn't
 936     // exist in Win9x, use RT binding instead
 937
 938     typedef BOOL (*SETPROCESSAFFINITYMASK)(HANDLE, DWORD);
 939
 940     // can use static var because we're always in the main thread here
 941     static SETPROCESSAFFINITYMASK pfnSetProcessAffinityMask = NULL;
 942
 943     if ( !pfnSetProcessAffinityMask )
 944     {
 945         HMODULE hModKernel = ::LoadLibrary(_T("kernel32"));
 946         if ( hModKernel )
 947         {
 948             pfnSetProcessAffinityMask = (SETPROCESSAFFINITYMASK)
 949                 ::GetProcAddress(hModKernel, "SetProcessAffinityMask");
 950         }
 951
 952         // we've discovered a MT version of Win9x!
 953         wxASSERT_MSG( pfnSetProcessAffinityMask,
 954                       _T("this system has several CPUs but no SetProcessAffinityMask function?") );
 955     }
 956
 957     if ( !pfnSetProcessAffinityMask )
 958     {
 959         // msg given above - do it only once
 960         return false;
 961     }
 962
 963     if ( pfnSetProcessAffinityMask(hProcess, dwProcMask) == 0 )
 964     {
 965         wxLogLastError(_T("SetProcessAffinityMask"));
 966
 967         return false;
 968     }
 969 #endif
 970     return true;
 971 }
 972
 973 // ctor and dtor
 974 // -------------
 975
 976 wxThread::wxThread(wxThreadKind kind)
 977 {
 978     m_internal = new wxThreadInternal(this);
 979
 980     m_isDetached = kind == wxTHREAD_DETACHED;
 981 }
 982
 983 wxThread::~wxThread()
 984 {
 985     delete m_internal;
 986 }
 987
 988 // create/start thread
 989 // -------------------
 990
 991 wxThreadError wxThread::Create(unsigned int stackSize)
 992 {
 993     wxCriticalSectionLocker lock(m_critsect);
 994
 995     if ( !m_internal->Create(this, stackSize) )
 996         return wxTHREAD_NO_RESOURCE;
 997
 998     return wxTHREAD_NO_ERROR;
 999 }
1000
1001 wxThreadError wxThread::Run()
1002 {
1003     wxCriticalSectionLocker lock(m_critsect);
1004
1005     if ( m_internal->GetState() != STATE_NEW )
1006     {
1007         // actually, it may be almost any state at all, not only STATE_RUNNING
1008         return wxTHREAD_RUNNING;
1009     }
1010
1011     // the thread has just been created and is still suspended - let it run
1012     return Resume();
1013 }
1014
1015 // suspend/resume thread
1016 // ---------------------
1017
1018 wxThreadError wxThread::Pause()
1019 {
1020     wxCriticalSectionLocker lock(m_critsect);
1021
1022     return m_internal->Suspend() ? wxTHREAD_NO_ERROR : wxTHREAD_MISC_ERROR;
1023 }
1024
1025 wxThreadError wxThread::Resume()
1026 {
1027     wxCriticalSectionLocker lock(m_critsect);
1028
1029     return m_internal->Resume() ? wxTHREAD_NO_ERROR : wxTHREAD_MISC_ERROR;
1030 }
1031
1032 // stopping thread
1033 // ---------------
1034
1035 wxThread::ExitCode wxThread::Wait()
1036 {
1037     // although under Windows we can wait for any thread, it's an error to
1038     // wait for a detached one in wxWin API
1039     wxCHECK_MSG( !IsDetached(), (ExitCode)-1,
1040                  _T("wxThread::Wait(): can't wait for detached thread") );
1041
1042     ExitCode rc = (ExitCode)-1;
1043
1044     (void)m_internal->WaitForTerminate(m_critsect, &rc);
1045
1046     return rc;
1047 }
1048
1049 wxThreadError wxThread::Delete(ExitCode *pRc)
1050 {
1051     return m_internal->WaitForTerminate(m_critsect, pRc, this);
1052 }
1053
1054 wxThreadError wxThread::Kill()
1055 {
1056     if ( !IsRunning() )
1057         return wxTHREAD_NOT_RUNNING;
1058
1059     wxThreadError rc = m_internal->Kill();
1060
1061     if ( IsDetached() )
1062     {
1063         delete this;
1064     }
1065     else // joinable
1066     {
1067         // update the status of the joinable thread
1068         wxCriticalSectionLocker lock(m_critsect);
1069         m_internal->SetState(STATE_EXITED);
1070     }
1071
1072     return rc;
1073 }
1074
1075 void wxThread::Exit(ExitCode status)
1076 {
1077     m_internal->Free();
1078
1079     if ( IsDetached() )
1080     {
1081         delete this;
1082     }
1083     else // joinable
1084     {
1085         // update the status of the joinable thread
1086         wxCriticalSectionLocker lock(m_critsect);
1087         m_internal->SetState(STATE_EXITED);
1088     }
1089
1090 #ifdef wxUSE_BEGIN_THREAD
1091     _endthreadex((unsigned)status);
1092 #else // !VC++
1093     ::ExitThread((DWORD)status);
1094 #endif // VC++/!VC++
1095
1096     wxFAIL_MSG(wxT("Couldn't return from ExitThread()!"));
1097 }
1098
1099 // priority setting
1100 // ----------------
1101
1102 void wxThread::SetPriority(unsigned int prio)
1103 {
1104     wxCriticalSectionLocker lock(m_critsect);
1105
1106     m_internal->SetPriority(prio);
1107 }
1108
1109 unsigned int wxThread::GetPriority() const
1110 {
1111     wxCriticalSectionLocker lock((wxCriticalSection &)m_critsect); // const_cast
1112
1113     return m_internal->GetPriority();
1114 }
1115
1116 unsigned long wxThread::GetId() const
1117 {
1118     wxCriticalSectionLocker lock((wxCriticalSection &)m_critsect); // const_cast
1119
1120     return (unsigned long)m_internal->GetId();
1121 }
1122
1123 bool wxThread::IsRunning() const
1124 {
1125     wxCriticalSectionLocker lock((wxCriticalSection &)m_critsect); // const_cast
1126
1127     return m_internal->GetState() == STATE_RUNNING;
1128 }
1129
1130 bool wxThread::IsAlive() const
1131 {
1132     wxCriticalSectionLocker lock((wxCriticalSection &)m_critsect); // const_cast
1133
1134     return (m_internal->GetState() == STATE_RUNNING) ||
1135            (m_internal->GetState() == STATE_PAUSED);
1136 }
1137
1138 bool wxThread::IsPaused() const
1139 {
1140     wxCriticalSectionLocker lock((wxCriticalSection &)m_critsect); // const_cast
1141
1142     return m_internal->GetState() == STATE_PAUSED;
1143 }
1144
1145 bool wxThread::TestDestroy()
1146 {
1147     wxCriticalSectionLocker lock((wxCriticalSection &)m_critsect); // const_cast
1148
1149     return m_internal->GetState() == STATE_CANCELED;
1150 }
1151
1152 // ----------------------------------------------------------------------------
1153 // Automatic initialization for thread module
1154 // ----------------------------------------------------------------------------
1155
1156 class wxThreadModule : public wxModule
1157 {
1158 public:
1159     virtual bool OnInit();
1160     virtual void OnExit();
1161
1162 private:
1163     DECLARE_DYNAMIC_CLASS(wxThreadModule)
1164 };
1165
1166 IMPLEMENT_DYNAMIC_CLASS(wxThreadModule, wxModule)
1167
1168 bool wxThreadModule::OnInit()
1169 {
1170     // allocate TLS index for storing the pointer to the current thread
1171     gs_tlsThisThread = ::TlsAlloc();
1172     if ( gs_tlsThisThread == 0xFFFFFFFF )
1173     {
1174         // in normal circumstances it will only happen if all other
1175         // TLS_MINIMUM_AVAILABLE (>= 64) indices are already taken - in other
1176         // words, this should never happen
1177         wxLogSysError(_("Thread module initialization failed: impossible to allocate index in thread local storage"));
1178
1179         return false;
1180     }
1181
1182     // main thread doesn't have associated wxThread object, so store 0 in the
1183     // TLS instead
1184     if ( !::TlsSetValue(gs_tlsThisThread, (LPVOID)0) )
1185     {
1186         ::TlsFree(gs_tlsThisThread);
1187         gs_tlsThisThread = 0xFFFFFFFF;
1188
1189         wxLogSysError(_("Thread module initialization failed: can not store value in thread local storage"));
1190
1191         return false;
1192     }
1193
1194     gs_critsectWaitingForGui = new wxCriticalSection();
1195
1196     gs_critsectGui = new wxCriticalSection();
1197     gs_critsectGui->Enter();
1198
1199     gs_critsectThreadDelete = new wxCriticalSection;
1200
1201     // no error return for GetCurrentThreadId()
1202     gs_idMainThread = ::GetCurrentThreadId();
1203
1204     return true;
1205 }
1206
1207 void wxThreadModule::OnExit()
1208 {
1209     if ( !::TlsFree(gs_tlsThisThread) )
1210     {
1211         wxLogLastError(wxT("TlsFree failed."));
1212     }
1213
1214     delete gs_critsectThreadDelete;
1215     gs_critsectThreadDelete = NULL;
1216
1217     if ( gs_critsectGui )
1218     {
1219         gs_critsectGui->Leave();
1220         delete gs_critsectGui;
1221         gs_critsectGui = NULL;
1222     }
1223
1224     delete gs_critsectWaitingForGui;
1225     gs_critsectWaitingForGui = NULL;
1226 }
1227
1228 // ----------------------------------------------------------------------------
1229 // under Windows, these functions are implemented using a critical section and
1230 // not a mutex, so the names are a bit confusing
1231 // ----------------------------------------------------------------------------
1232
1233 void WXDLLIMPEXP_BASE wxMutexGuiEnter()
1234 {
1235     // this would dead lock everything...
1236     wxASSERT_MSG( !wxThread::IsMain(),
1237                   wxT("main thread doesn't want to block in wxMutexGuiEnter()!") );
1238
1239     // the order in which we enter the critical sections here is crucial!!
1240
1241     // set the flag telling to the main thread that we want to do some GUI
1242     {
1243         wxCriticalSectionLocker enter(*gs_critsectWaitingForGui);
1244
1245         gs_nWaitingForGui++;
1246     }
1247
1248     wxWakeUpMainThread();
1249
1250     // now we may block here because the main thread will soon let us in
1251     // (during the next iteration of OnIdle())
1252     gs_critsectGui->Enter();
1253 }
1254
1255 void WXDLLIMPEXP_BASE wxMutexGuiLeave()
1256 {
1257     wxCriticalSectionLocker enter(*gs_critsectWaitingForGui);
1258
1259     if ( wxThread::IsMain() )
1260     {
1261         gs_bGuiOwnedByMainThread = false;
1262     }
1263     else
1264     {
1265         // decrement the number of threads waiting for GUI access now
1266         wxASSERT_MSG( gs_nWaitingForGui > 0,
1267                       wxT("calling wxMutexGuiLeave() without entering it first?") );
1268
1269         gs_nWaitingForGui--;
1270
1271         wxWakeUpMainThread();
1272     }
1273
1274     gs_critsectGui->Leave();
1275 }
1276
1277 void WXDLLIMPEXP_BASE wxMutexGuiLeaveOrEnter()
1278 {
1279     wxASSERT_MSG( wxThread::IsMain(),
1280                   wxT("only main thread may call wxMutexGuiLeaveOrEnter()!") );
1281
1282     wxCriticalSectionLocker enter(*gs_critsectWaitingForGui);
1283
1284     if ( gs_nWaitingForGui == 0 )
1285     {
1286         // no threads are waiting for GUI - so we may acquire the lock without
1287         // any danger (but only if we don't already have it)
1288         if ( !wxGuiOwnedByMainThread() )
1289         {
1290             gs_critsectGui->Enter();
1291
1292             gs_bGuiOwnedByMainThread = true;
1293         }
1294         //else: already have it, nothing to do
1295     }
1296     else
1297     {
1298         // some threads are waiting, release the GUI lock if we have it
1299         if ( wxGuiOwnedByMainThread() )
1300         {
1301             wxMutexGuiLeave();
1302         }
1303         //else: some other worker thread is doing GUI
1304     }
1305 }
1306
1307 bool WXDLLIMPEXP_BASE wxGuiOwnedByMainThread()
1308 {
1309     return gs_bGuiOwnedByMainThread;
1310 }
1311
1312 // wake up the main thread if it's in ::GetMessage()
1313 void WXDLLIMPEXP_BASE wxWakeUpMainThread()
1314 {
1315     // sending any message would do - hopefully WM_NULL is harmless enough
1316     if ( !::PostThreadMessage(gs_idMainThread, WM_NULL, 0, 0) )
1317     {
1318         // should never happen
1319         wxLogLastError(wxT("PostThreadMessage(WM_NULL)"));
1320     }
1321 }
1322
1323 bool WXDLLIMPEXP_BASE wxIsWaitingForThread()
1324 {
1325     return gs_waitingForThread;
1326 }
1327
1328 // ----------------------------------------------------------------------------
1329 // include common implementation code
1330 // ----------------------------------------------------------------------------
1331
1332 #include "wx/thrimpl.cpp"
1333
1334 #endif // wxUSE_THREADS
1335