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 // ----------------------------------------------------------------------------
  14 // headers
  15 // ----------------------------------------------------------------------------
  16
  17 // For compilers that support precompilation, includes "wx.h".
  18 #include "wx/wxprec.h"
  19
  20 #if defined(__BORLANDC__)
  21     #pragma hdrstop
  22 #endif
  23
  24 #if wxUSE_THREADS
  25
  26 #include "wx/thread.h"
  27
  28 #ifndef WX_PRECOMP
  29     #include "wx/intl.h"
  30     #include "wx/app.h"
  31     #include "wx/module.h"
  32 #endif
  33
  34 #include "wx/apptrait.h"
  35 #include "wx/scopeguard.h"
  36
  37 #include "wx/msw/private.h"
  38 #include "wx/msw/missing.h"
  39 #include "wx/msw/seh.h"
  40
  41 #include "wx/except.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 wxUIntPtr 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 static const THREAD_RETVAL THREAD_ERROR_EXIT = (THREAD_RETVAL)-1;
  90
  91 // ----------------------------------------------------------------------------
  92 // constants
  93 // ----------------------------------------------------------------------------
  94
  95 // the possible states of the thread ("=>" shows all possible transitions from
  96 // this state)
  97 enum wxThreadState
  98 {
  99     STATE_NEW,          // didn't start execution yet (=> RUNNING)
 100     STATE_RUNNING,      // thread is running (=> PAUSED, CANCELED)
 101     STATE_PAUSED,       // thread is temporarily suspended (=> RUNNING)
 102     STATE_CANCELED,     // thread should terminate a.s.a.p. (=> EXITED)
 103     STATE_EXITED        // thread is terminating
 104 };
 105
 106 // ----------------------------------------------------------------------------
 107 // this module globals
 108 // ----------------------------------------------------------------------------
 109
 110 // TLS index of the slot where we store the pointer to the current thread
 111 static DWORD gs_tlsThisThread = 0xFFFFFFFF;
 112
 113 // id of the main thread - the one which can call GUI functions without first
 114 // calling wxMutexGuiEnter()
 115 static DWORD gs_idMainThread = 0;
 116
 117 // if it's false, some secondary thread is holding the GUI lock
 118 static bool gs_bGuiOwnedByMainThread = true;
 119
 120 // critical section which controls access to all GUI functions: any secondary
 121 // thread (i.e. except the main one) must enter this crit section before doing
 122 // any GUI calls
 123 static wxCriticalSection *gs_critsectGui = NULL;
 124
 125 // critical section which protects gs_nWaitingForGui variable
 126 static wxCriticalSection *gs_critsectWaitingForGui = NULL;
 127
 128 // critical section which serializes WinThreadStart() and WaitForTerminate()
 129 // (this is a potential bottleneck, we use a single crit sect for all threads
 130 // in the system, but normally time spent inside it should be quite short)
 131 static wxCriticalSection *gs_critsectThreadDelete = NULL;
 132
 133 // number of threads waiting for GUI in wxMutexGuiEnter()
 134 static size_t gs_nWaitingForGui = 0;
 135
 136 // are we waiting for a thread termination?
 137 static bool gs_waitingForThread = false;
 138
 139 // ============================================================================
 140 // Windows implementation of thread and related classes
 141 // ============================================================================
 142
 143 // ----------------------------------------------------------------------------
 144 // wxCriticalSection
 145 // ----------------------------------------------------------------------------
 146
 147 wxCriticalSection::wxCriticalSection()
 148 {
 149     wxCOMPILE_TIME_ASSERT( sizeof(CRITICAL_SECTION) <= sizeof(wxCritSectBuffer),
 150                            wxCriticalSectionBufferTooSmall );
 151
 152     ::InitializeCriticalSection((CRITICAL_SECTION *)m_buffer);
 153 }
 154
 155 wxCriticalSection::~wxCriticalSection()
 156 {
 157     ::DeleteCriticalSection((CRITICAL_SECTION *)m_buffer);
 158 }
 159
 160 void wxCriticalSection::Enter()
 161 {
 162     ::EnterCriticalSection((CRITICAL_SECTION *)m_buffer);
 163 }
 164
 165 void wxCriticalSection::Leave()
 166 {
 167     ::LeaveCriticalSection((CRITICAL_SECTION *)m_buffer);
 168 }
 169
 170 // ----------------------------------------------------------------------------
 171 // wxMutex
 172 // ----------------------------------------------------------------------------
 173
 174 class wxMutexInternal
 175 {
 176 public:
 177     wxMutexInternal(wxMutexType mutexType);
 178     ~wxMutexInternal();
 179
 180     bool IsOk() const { return m_mutex != NULL; }
 181
 182     wxMutexError Lock() { return LockTimeout(INFINITE); }
 183     wxMutexError Lock(unsigned long ms) { return LockTimeout(ms); }
 184     wxMutexError TryLock();
 185     wxMutexError Unlock();
 186
 187 private:
 188     wxMutexError LockTimeout(DWORD milliseconds);
 189
 190     HANDLE m_mutex;
 191
 192     DECLARE_NO_COPY_CLASS(wxMutexInternal)
 193 };
 194
 195 // all mutexes are recursive under Win32 so we don't use mutexType
 196 wxMutexInternal::wxMutexInternal(wxMutexType WXUNUSED(mutexType))
 197 {
 198     // create a nameless (hence intra process and always private) mutex
 199     m_mutex = ::CreateMutex
 200                 (
 201                     NULL,       // default secutiry attributes
 202                     FALSE,      // not initially locked
 203                     NULL        // no name
 204                 );
 205
 206     if ( !m_mutex )
 207     {
 208         wxLogLastError(_T("CreateMutex()"));
 209     }
 210 }
 211
 212 wxMutexInternal::~wxMutexInternal()
 213 {
 214     if ( m_mutex )
 215     {
 216         if ( !::CloseHandle(m_mutex) )
 217         {
 218             wxLogLastError(_T("CloseHandle(mutex)"));
 219         }
 220     }
 221 }
 222
 223 wxMutexError wxMutexInternal::TryLock()
 224 {
 225     const wxMutexError rc = LockTimeout(0);
 226
 227     // we have a special return code for timeout in this case
 228     return rc == wxMUTEX_TIMEOUT ? wxMUTEX_BUSY : rc;
 229 }
 230
 231 wxMutexError wxMutexInternal::LockTimeout(DWORD milliseconds)
 232 {
 233     DWORD rc = ::WaitForSingleObject(m_mutex, milliseconds);
 234     if ( rc == WAIT_ABANDONED )
 235     {
 236         // the previous caller died without releasing the mutex, but now we can
 237         // really lock it
 238         wxLogDebug(_T("WaitForSingleObject() returned WAIT_ABANDONED"));
 239
 240         // use 0 timeout, normally we should always get it
 241         rc = ::WaitForSingleObject(m_mutex, 0);
 242     }
 243
 244     switch ( rc )
 245     {
 246         case WAIT_OBJECT_0:
 247             // ok
 248             break;
 249
 250         case WAIT_TIMEOUT:
 251             return wxMUTEX_TIMEOUT;
 252
 253         case WAIT_ABANDONED:        // checked for above
 254         default:
 255             wxFAIL_MSG(wxT("impossible return value in wxMutex::Lock"));
 256             // fall through
 257
 258         case WAIT_FAILED:
 259             wxLogLastError(_T("WaitForSingleObject(mutex)"));
 260             return wxMUTEX_MISC_ERROR;
 261     }
 262
 263     return wxMUTEX_NO_ERROR;
 264 }
 265
 266 wxMutexError wxMutexInternal::Unlock()
 267 {
 268     if ( !::ReleaseMutex(m_mutex) )
 269     {
 270         wxLogLastError(_T("ReleaseMutex()"));
 271
 272         return wxMUTEX_MISC_ERROR;
 273     }
 274
 275     return wxMUTEX_NO_ERROR;
 276 }
 277
 278 // --------------------------------------------------------------------------
 279 // wxSemaphore
 280 // --------------------------------------------------------------------------
 281
 282 // a trivial wrapper around Win32 semaphore
 283 class wxSemaphoreInternal
 284 {
 285 public:
 286     wxSemaphoreInternal(int initialcount, int maxcount);
 287     ~wxSemaphoreInternal();
 288
 289     bool IsOk() const { return m_semaphore != NULL; }
 290
 291     wxSemaError Wait() { return WaitTimeout(INFINITE); }
 292
 293     wxSemaError TryWait()
 294     {
 295         wxSemaError rc = WaitTimeout(0);
 296         if ( rc == wxSEMA_TIMEOUT )
 297             rc = wxSEMA_BUSY;
 298
 299         return rc;
 300     }
 301
 302     wxSemaError WaitTimeout(unsigned long milliseconds);
 303
 304     wxSemaError Post();
 305
 306 private:
 307     HANDLE m_semaphore;
 308
 309     DECLARE_NO_COPY_CLASS(wxSemaphoreInternal)
 310 };
 311
 312 wxSemaphoreInternal::wxSemaphoreInternal(int initialcount, int maxcount)
 313 {
 314 #if !defined(_WIN32_WCE) || (_WIN32_WCE >= 300)
 315     if ( maxcount == 0 )
 316     {
 317         // make it practically infinite
 318         maxcount = INT_MAX;
 319     }
 320
 321     m_semaphore = ::CreateSemaphore
 322                     (
 323                         NULL,           // default security attributes
 324                         initialcount,
 325                         maxcount,
 326                         NULL            // no name
 327                     );
 328 #endif
 329     if ( !m_semaphore )
 330     {
 331         wxLogLastError(_T("CreateSemaphore()"));
 332     }
 333 }
 334
 335 wxSemaphoreInternal::~wxSemaphoreInternal()
 336 {
 337     if ( m_semaphore )
 338     {
 339         if ( !::CloseHandle(m_semaphore) )
 340         {
 341             wxLogLastError(_T("CloseHandle(semaphore)"));
 342         }
 343     }
 344 }
 345
 346 wxSemaError wxSemaphoreInternal::WaitTimeout(unsigned long milliseconds)
 347 {
 348     DWORD rc = ::WaitForSingleObject( m_semaphore, milliseconds );
 349
 350     switch ( rc )
 351     {
 352         case WAIT_OBJECT_0:
 353            return wxSEMA_NO_ERROR;
 354
 355         case WAIT_TIMEOUT:
 356            return wxSEMA_TIMEOUT;
 357
 358         default:
 359             wxLogLastError(_T("WaitForSingleObject(semaphore)"));
 360     }
 361
 362     return wxSEMA_MISC_ERROR;
 363 }
 364
 365 wxSemaError wxSemaphoreInternal::Post()
 366 {
 367 #if !defined(_WIN32_WCE) || (_WIN32_WCE >= 300)
 368     if ( !::ReleaseSemaphore(m_semaphore, 1, NULL /* ptr to previous count */) )
 369     {
 370         if ( GetLastError() == ERROR_TOO_MANY_POSTS )
 371         {
 372             return wxSEMA_OVERFLOW;
 373         }
 374         else
 375         {
 376             wxLogLastError(_T("ReleaseSemaphore"));
 377             return wxSEMA_MISC_ERROR;
 378         }
 379     }
 380
 381     return wxSEMA_NO_ERROR;
 382 #else
 383     return wxSEMA_MISC_ERROR;
 384 #endif
 385 }
 386
 387 // ----------------------------------------------------------------------------
 388 // wxThread implementation
 389 // ----------------------------------------------------------------------------
 390
 391 // wxThreadInternal class
 392 // ----------------------
 393
 394 class wxThreadInternal
 395 {
 396 public:
 397     wxThreadInternal(wxThread *thread)
 398     {
 399         m_thread = thread;
 400         m_hThread = 0;
 401         m_state = STATE_NEW;
 402         m_priority = WXTHREAD_DEFAULT_PRIORITY;
 403         m_nRef = 1;
 404     }
 405
 406     ~wxThreadInternal()
 407     {
 408         Free();
 409     }
 410
 411     void Free()
 412     {
 413         if ( m_hThread )
 414         {
 415             if ( !::CloseHandle(m_hThread) )
 416             {
 417                 wxLogLastError(wxT("CloseHandle(thread)"));
 418             }
 419
 420             m_hThread = 0;
 421         }
 422     }
 423
 424     // create a new (suspended) thread (for the given thread object)
 425     bool Create(wxThread *thread, unsigned int stackSize);
 426
 427     // wait for the thread to terminate, either by itself, or by asking it
 428     // (politely, this is not Kill()!) to do it
 429     wxThreadError WaitForTerminate(wxCriticalSection& cs,
 430                                    wxThread::ExitCode *pRc,
 431                                    wxThread *threadToDelete = NULL);
 432
 433     // kill the thread unconditionally
 434     wxThreadError Kill();
 435
 436     // suspend/resume/terminate
 437     bool Suspend();
 438     bool Resume();
 439     void Cancel() { m_state = STATE_CANCELED; }
 440
 441     // thread state
 442     void SetState(wxThreadState state) { m_state = state; }
 443     wxThreadState GetState() const { return m_state; }
 444
 445     // thread priority
 446     void SetPriority(unsigned int priority);
 447     unsigned int GetPriority() const { return m_priority; }
 448
 449     // thread handle and id
 450     HANDLE GetHandle() const { return m_hThread; }
 451     DWORD  GetId() const { return m_tid; }
 452
 453     // the thread function forwarding to DoThreadStart
 454     static THREAD_RETVAL THREAD_CALLCONV WinThreadStart(void *thread);
 455
 456     // really start the thread (if it's not already dead)
 457     static THREAD_RETVAL DoThreadStart(wxThread *thread);
 458
 459     // call OnExit() on the thread
 460     static void DoThreadOnExit(wxThread *thread);
 461
 462
 463     void KeepAlive()
 464     {
 465         if ( m_thread->IsDetached() )
 466             ::InterlockedIncrement(&m_nRef);
 467     }
 468
 469     void LetDie()
 470     {
 471         if ( m_thread->IsDetached() && !::InterlockedDecrement(&m_nRef) )
 472             delete m_thread;
 473     }
 474
 475 private:
 476     // the thread we're associated with
 477     wxThread *m_thread;
 478
 479     HANDLE        m_hThread;    // handle of the thread
 480     wxThreadState m_state;      // state, see wxThreadState enum
 481     unsigned int  m_priority;   // thread priority in "wx" units
 482     DWORD         m_tid;        // thread id
 483
 484     // number of threads which need this thread to remain alive, when the count
 485     // reaches 0 we kill the owning wxThread -- and die ourselves with it
 486     LONG m_nRef;
 487
 488     DECLARE_NO_COPY_CLASS(wxThreadInternal)
 489 };
 490
 491 // small class which keeps a thread alive during its lifetime
 492 class wxThreadKeepAlive
 493 {
 494 public:
 495     wxThreadKeepAlive(wxThreadInternal& thrImpl) : m_thrImpl(thrImpl)
 496         { m_thrImpl.KeepAlive(); }
 497     ~wxThreadKeepAlive()
 498         { m_thrImpl.LetDie(); }
 499
 500 private:
 501     wxThreadInternal& m_thrImpl;
 502 };
 503
 504 /* static */
 505 void wxThreadInternal::DoThreadOnExit(wxThread *thread)
 506 {
 507     wxTRY
 508     {
 509         thread->OnExit();
 510     }
 511     wxCATCH_ALL( wxTheApp->OnUnhandledException(); )
 512 }
 513
 514 /* static */
 515 THREAD_RETVAL wxThreadInternal::DoThreadStart(wxThread *thread)
 516 {
 517     wxON_BLOCK_EXIT1(DoThreadOnExit, thread);
 518
 519     THREAD_RETVAL rc = THREAD_ERROR_EXIT;
 520
 521     wxTRY
 522     {
 523         // store the thread object in the TLS
 524         if ( !::TlsSetValue(gs_tlsThisThread, thread) )
 525         {
 526             wxLogSysError(_("Can not start thread: error writing TLS."));
 527
 528             return THREAD_ERROR_EXIT;
 529         }
 530
 531         rc = (THREAD_RETVAL)thread->Entry();
 532     }
 533     wxCATCH_ALL( wxTheApp->OnUnhandledException(); )
 534
 535     return rc;
 536 }
 537
 538 /* static */
 539 THREAD_RETVAL THREAD_CALLCONV wxThreadInternal::WinThreadStart(void *param)
 540 {
 541     THREAD_RETVAL rc = THREAD_ERROR_EXIT;
 542
 543     wxThread * const thread = (wxThread *)param;
 544
 545     // each thread has its own SEH translator so install our own a.s.a.p.
 546     DisableAutomaticSETranslator();
 547
 548     // first of all, check whether we hadn't been cancelled already and don't
 549     // start the user code at all then
 550     const bool hasExited = thread->m_internal->GetState() == STATE_EXITED;
 551
 552     // run the thread function itself inside a SEH try/except block
 553     wxSEH_TRY
 554     {
 555         if ( hasExited )
 556             DoThreadOnExit(thread);
 557         else
 558             rc = DoThreadStart(thread);
 559     }
 560     wxSEH_HANDLE(THREAD_ERROR_EXIT)
 561
 562
 563     // save IsDetached because thread object can be deleted by joinable
 564     // threads after state is changed to STATE_EXITED.
 565     const bool isDetached = thread->IsDetached();
 566     if ( !hasExited )
 567     {
 568         // enter m_critsect before changing the thread state
 569         //
 570         // NB: can't use wxCriticalSectionLocker here as we use SEH and it's
 571         //     incompatible with C++ object dtors
 572         thread->m_critsect.Enter();
 573         thread->m_internal->SetState(STATE_EXITED);
 574         thread->m_critsect.Leave();
 575     }
 576
 577     // the thread may delete itself now if it wants, we don't need it any more
 578     if ( isDetached )
 579         thread->m_internal->LetDie();
 580
 581     return rc;
 582 }
 583
 584 void wxThreadInternal::SetPriority(unsigned int priority)
 585 {
 586     m_priority = priority;
 587
 588     // translate wxWidgets priority to the Windows one
 589     int win_priority;
 590     if (m_priority <= 20)
 591         win_priority = THREAD_PRIORITY_LOWEST;
 592     else if (m_priority <= 40)
 593         win_priority = THREAD_PRIORITY_BELOW_NORMAL;
 594     else if (m_priority <= 60)
 595         win_priority = THREAD_PRIORITY_NORMAL;
 596     else if (m_priority <= 80)
 597         win_priority = THREAD_PRIORITY_ABOVE_NORMAL;
 598     else if (m_priority <= 100)
 599         win_priority = THREAD_PRIORITY_HIGHEST;
 600     else
 601     {
 602         wxFAIL_MSG(wxT("invalid value of thread priority parameter"));
 603         win_priority = THREAD_PRIORITY_NORMAL;
 604     }
 605
 606     if ( !::SetThreadPriority(m_hThread, win_priority) )
 607     {
 608         wxLogSysError(_("Can't set thread priority"));
 609     }
 610 }
 611
 612 bool wxThreadInternal::Create(wxThread *thread, unsigned int stackSize)
 613 {
 614     wxASSERT_MSG( m_state == STATE_NEW && !m_hThread,
 615                     _T("Create()ing thread twice?") );
 616
 617     // for compilers which have it, we should use C RTL function for thread
 618     // creation instead of Win32 API one because otherwise we will have memory
 619     // leaks if the thread uses C RTL (and most threads do)
 620 #ifdef wxUSE_BEGIN_THREAD
 621
 622     // Watcom is reported to not like 0 stack size (which means "use default"
 623     // for the other compilers and is also the default value for stackSize)
 624 #ifdef __WATCOMC__
 625     if ( !stackSize )
 626         stackSize = 10240;
 627 #endif // __WATCOMC__
 628
 629     m_hThread = (HANDLE)_beginthreadex
 630                         (
 631                           NULL,                             // default security
 632                           stackSize,
 633                           wxThreadInternal::WinThreadStart, // entry point
 634                           thread,
 635                           CREATE_SUSPENDED,
 636                           (unsigned int *)&m_tid
 637                         );
 638 #else // compiler doesn't have _beginthreadex
 639     m_hThread = ::CreateThread
 640                   (
 641                     NULL,                               // default security
 642                     stackSize,                          // stack size
 643                     wxThreadInternal::WinThreadStart,   // thread entry point
 644                     (LPVOID)thread,                     // parameter
 645                     CREATE_SUSPENDED,                   // flags
 646                     &m_tid                              // [out] thread id
 647                   );
 648 #endif // _beginthreadex/CreateThread
 649
 650     if ( m_hThread == NULL )
 651     {
 652         wxLogSysError(_("Can't create thread"));
 653
 654         return false;
 655     }
 656
 657     if ( m_priority != WXTHREAD_DEFAULT_PRIORITY )
 658     {
 659         SetPriority(m_priority);
 660     }
 661
 662     return true;
 663 }
 664
 665 wxThreadError wxThreadInternal::Kill()
 666 {
 667     if ( !::TerminateThread(m_hThread, THREAD_ERROR_EXIT) )
 668     {
 669         wxLogSysError(_("Couldn't terminate thread"));
 670
 671         return wxTHREAD_MISC_ERROR;
 672     }
 673
 674     Free();
 675
 676     return wxTHREAD_NO_ERROR;
 677 }
 678
 679 wxThreadError
 680 wxThreadInternal::WaitForTerminate(wxCriticalSection& cs,
 681                                    wxThread::ExitCode *pRc,
 682                                    wxThread *threadToDelete)
 683 {
 684     // prevent the thread C++ object from disappearing as long as we are using
 685     // it here
 686     wxThreadKeepAlive keepAlive(*this);
 687
 688
 689     // we may either wait passively for the thread to terminate (when called
 690     // from Wait()) or ask it to terminate (when called from Delete())
 691     bool shouldDelete = threadToDelete != NULL;
 692
 693     DWORD rc = 0;
 694
 695     // we might need to resume the thread if it's currently stopped
 696     bool shouldResume = false;
 697
 698     // as Delete() (which calls us) is always safe to call we need to consider
 699     // all possible states
 700     {
 701         wxCriticalSectionLocker lock(cs);
 702
 703         if ( m_state == STATE_NEW )
 704         {
 705             if ( shouldDelete )
 706             {
 707                 // WinThreadStart() will see it and terminate immediately, no
 708                 // need to cancel the thread -- but we still need to resume it
 709                 // to let it run
 710                 m_state = STATE_EXITED;
 711
 712                 // we must call Resume() as the thread hasn't been initially
 713                 // resumed yet (and as Resume() it knows about STATE_EXITED
 714                 // special case, it won't touch it and WinThreadStart() will
 715                 // just exit immediately)
 716                 shouldResume = true;
 717                 shouldDelete = false;
 718             }
 719             //else: shouldResume is correctly set to false here, wait until
 720             //      someone else runs the thread and it finishes
 721         }
 722         else // running, paused, cancelled or even exited
 723         {
 724             shouldResume = m_state == STATE_PAUSED;
 725         }
 726     }
 727
 728     // resume the thread if it is paused
 729     if ( shouldResume )
 730         Resume();
 731
 732     // ask the thread to terminate
 733     if ( shouldDelete )
 734     {
 735         wxCriticalSectionLocker lock(cs);
 736
 737         Cancel();
 738     }
 739
 740
 741     // now wait for thread to finish
 742     if ( wxThread::IsMain() )
 743     {
 744         // set flag for wxIsWaitingForThread()
 745         gs_waitingForThread = true;
 746     }
 747
 748     // we can't just wait for the thread to terminate because it might be
 749     // calling some GUI functions and so it will never terminate before we
 750     // process the Windows messages that result from these functions
 751     // (note that even in console applications we might have to process
 752     // messages if we use wxExecute() or timers or ...)
 753     DWORD result wxDUMMY_INITIALIZE(0);
 754     do
 755     {
 756         if ( wxThread::IsMain() )
 757         {
 758             // give the thread we're waiting for chance to do the GUI call
 759             // it might be in
 760             if ( (gs_nWaitingForGui > 0) && wxGuiOwnedByMainThread() )
 761             {
 762                 wxMutexGuiLeave();
 763             }
 764         }
 765
 766         wxAppTraits *traits = wxTheApp ? wxTheApp->GetTraits() : NULL;
 767         if ( traits )
 768         {
 769             result = traits->WaitForThread(m_hThread);
 770         }
 771         else // can't wait for the thread
 772         {
 773             // so kill it below
 774             result = 0xFFFFFFFF;
 775         }
 776
 777         switch ( result )
 778         {
 779             case 0xFFFFFFFF:
 780                 // error
 781                 wxLogSysError(_("Can not wait for thread termination"));
 782                 Kill();
 783                 return wxTHREAD_KILLED;
 784
 785             case WAIT_OBJECT_0:
 786                 // thread we're waiting for terminated
 787                 break;
 788
 789             case WAIT_OBJECT_0 + 1:
 790                 // new message arrived, process it -- but only if we're the
 791                 // main thread as we don't support processing messages in
 792                 // the other ones
 793                 //
 794                 // NB: we still must include QS_ALLINPUT even when waiting
 795                 //     in a secondary thread because if it had created some
 796                 //     window somehow (possible not even using wxWidgets)
 797                 //     the system might dead lock then
 798                 if ( wxThread::IsMain() )
 799                 {
 800                     if ( traits && !traits->DoMessageFromThreadWait() )
 801                     {
 802                         // WM_QUIT received: kill the thread
 803                         Kill();
 804
 805                         return wxTHREAD_KILLED;
 806                     }
 807                 }
 808                 break;
 809
 810             default:
 811                 wxFAIL_MSG(wxT("unexpected result of MsgWaitForMultipleObject"));
 812         }
 813     } while ( result != WAIT_OBJECT_0 );
 814
 815     if ( wxThread::IsMain() )
 816     {
 817         gs_waitingForThread = false;
 818     }
 819
 820
 821     // although the thread might be already in the EXITED state it might not
 822     // have terminated yet and so we are not sure that it has actually
 823     // terminated if the "if" above hadn't been taken
 824     for ( ;; )
 825     {
 826         if ( !::GetExitCodeThread(m_hThread, &rc) )
 827         {
 828             wxLogLastError(wxT("GetExitCodeThread"));
 829
 830             rc = THREAD_ERROR_EXIT;
 831
 832             break;
 833         }
 834
 835         if ( rc != STILL_ACTIVE )
 836             break;
 837
 838         // give the other thread some time to terminate, otherwise we may be
 839         // starving it
 840         ::Sleep(1);
 841     }
 842
 843     if ( pRc )
 844         *pRc = wxUIntToPtr(rc);
 845
 846     // we don't need the thread handle any more in any case
 847     Free();
 848
 849
 850     return rc == THREAD_ERROR_EXIT ? wxTHREAD_MISC_ERROR : wxTHREAD_NO_ERROR;
 851 }
 852
 853 bool wxThreadInternal::Suspend()
 854 {
 855     DWORD nSuspendCount = ::SuspendThread(m_hThread);
 856     if ( nSuspendCount == (DWORD)-1 )
 857     {
 858         wxLogSysError(_("Can not suspend thread %x"), m_hThread);
 859
 860         return false;
 861     }
 862
 863     m_state = STATE_PAUSED;
 864
 865     return true;
 866 }
 867
 868 bool wxThreadInternal::Resume()
 869 {
 870     DWORD nSuspendCount = ::ResumeThread(m_hThread);
 871     if ( nSuspendCount == (DWORD)-1 )
 872     {
 873         wxLogSysError(_("Can not resume thread %x"), m_hThread);
 874
 875         return false;
 876     }
 877
 878     // don't change the state from STATE_EXITED because it's special and means
 879     // we are going to terminate without running any user code - if we did it,
 880     // the code in WaitForTerminate() wouldn't work
 881     if ( m_state != STATE_EXITED )
 882     {
 883         m_state = STATE_RUNNING;
 884     }
 885
 886     return true;
 887 }
 888
 889 // static functions
 890 // ----------------
 891
 892 wxThread *wxThread::This()
 893 {
 894     wxThread *thread = (wxThread *)::TlsGetValue(gs_tlsThisThread);
 895
 896     // be careful, 0 may be a valid return value as well
 897     if ( !thread && (::GetLastError() != NO_ERROR) )
 898     {
 899         wxLogSysError(_("Couldn't get the current thread pointer"));
 900
 901         // return NULL...
 902     }
 903
 904     return thread;
 905 }
 906
 907 bool wxThread::IsMain()
 908 {
 909     return ::GetCurrentThreadId() == gs_idMainThread || gs_idMainThread == 0;
 910 }
 911
 912 void wxThread::Yield()
 913 {
 914     // 0 argument to Sleep() is special and means to just give away the rest of
 915     // our timeslice
 916     ::Sleep(0);
 917 }
 918
 919 int wxThread::GetCPUCount()
 920 {
 921     SYSTEM_INFO si;
 922     GetSystemInfo(&si);
 923
 924     return si.dwNumberOfProcessors;
 925 }
 926
 927 unsigned long wxThread::GetCurrentId()
 928 {
 929     return (unsigned long)::GetCurrentThreadId();
 930 }
 931
 932 bool wxThread::SetConcurrency(size_t WXUNUSED_IN_WINCE(level))
 933 {
 934 #ifdef __WXWINCE__
 935     return false;
 936 #else
 937     wxASSERT_MSG( IsMain(), _T("should only be called from the main thread") );
 938
 939     // ok only for the default one
 940     if ( level == 0 )
 941         return 0;
 942
 943     // get system affinity mask first
 944     HANDLE hProcess = ::GetCurrentProcess();
 945     DWORD_PTR dwProcMask, dwSysMask;
 946     if ( ::GetProcessAffinityMask(hProcess, &dwProcMask, &dwSysMask) == 0 )
 947     {
 948         wxLogLastError(_T("GetProcessAffinityMask"));
 949
 950         return false;
 951     }
 952
 953     // how many CPUs have we got?
 954     if ( dwSysMask == 1 )
 955     {
 956         // don't bother with all this complicated stuff - on a single
 957         // processor system it doesn't make much sense anyhow
 958         return level == 1;
 959     }
 960
 961     // calculate the process mask: it's a bit vector with one bit per
 962     // processor; we want to schedule the process to run on first level
 963     // CPUs
 964     DWORD bit = 1;
 965     while ( bit )
 966     {
 967         if ( dwSysMask & bit )
 968         {
 969             // ok, we can set this bit
 970             dwProcMask |= bit;
 971
 972             // another process added
 973             if ( --level == 0 )
 974             {
 975                 // and that's enough
 976                 break;
 977             }
 978         }
 979
 980         // next bit
 981         bit <<= 1;
 982     }
 983
 984     // could we set all bits?
 985     if ( level != 0 )
 986     {
 987         wxLogDebug(_T("bad level %u in wxThread::SetConcurrency()"), level);
 988
 989         return false;
 990     }
 991
 992     // set it: we can't link to SetProcessAffinityMask() because it doesn't
 993     // exist in Win9x, use RT binding instead
 994
 995     typedef BOOL (WINAPI *SETPROCESSAFFINITYMASK)(HANDLE, DWORD_PTR);
 996
 997     // can use static var because we're always in the main thread here
 998     static SETPROCESSAFFINITYMASK pfnSetProcessAffinityMask = NULL;
 999
1000     if ( !pfnSetProcessAffinityMask )
1001     {
1002         HMODULE hModKernel = ::LoadLibrary(_T("kernel32"));
1003         if ( hModKernel )
1004         {
1005             pfnSetProcessAffinityMask = (SETPROCESSAFFINITYMASK)
1006                 ::GetProcAddress(hModKernel, "SetProcessAffinityMask");
1007         }
1008
1009         // we've discovered a MT version of Win9x!
1010         wxASSERT_MSG( pfnSetProcessAffinityMask,
1011                       _T("this system has several CPUs but no SetProcessAffinityMask function?") );
1012     }
1013
1014     if ( !pfnSetProcessAffinityMask )
1015     {
1016         // msg given above - do it only once
1017         return false;
1018     }
1019
1020     if ( pfnSetProcessAffinityMask(hProcess, dwProcMask) == 0 )
1021     {
1022         wxLogLastError(_T("SetProcessAffinityMask"));
1023
1024         return false;
1025     }
1026
1027     return true;
1028 #endif // __WXWINCE__/!__WXWINCE__
1029 }
1030
1031 // ctor and dtor
1032 // -------------
1033
1034 wxThread::wxThread(wxThreadKind kind)
1035 {
1036     m_internal = new wxThreadInternal(this);
1037
1038     m_isDetached = kind == wxTHREAD_DETACHED;
1039 }
1040
1041 wxThread::~wxThread()
1042 {
1043     delete m_internal;
1044 }
1045
1046 // create/start thread
1047 // -------------------
1048
1049 wxThreadError wxThread::Create(unsigned int stackSize)
1050 {
1051     wxCriticalSectionLocker lock(m_critsect);
1052
1053     if ( !m_internal->Create(this, stackSize) )
1054         return wxTHREAD_NO_RESOURCE;
1055
1056     return wxTHREAD_NO_ERROR;
1057 }
1058
1059 wxThreadError wxThread::Run()
1060 {
1061     wxCriticalSectionLocker lock(m_critsect);
1062
1063     if ( m_internal->GetState() != STATE_NEW )
1064     {
1065         // actually, it may be almost any state at all, not only STATE_RUNNING
1066         return wxTHREAD_RUNNING;
1067     }
1068
1069     // the thread has just been created and is still suspended - let it run
1070     return Resume();
1071 }
1072
1073 // suspend/resume thread
1074 // ---------------------
1075
1076 wxThreadError wxThread::Pause()
1077 {
1078     wxCriticalSectionLocker lock(m_critsect);
1079
1080     return m_internal->Suspend() ? wxTHREAD_NO_ERROR : wxTHREAD_MISC_ERROR;
1081 }
1082
1083 wxThreadError wxThread::Resume()
1084 {
1085     wxCriticalSectionLocker lock(m_critsect);
1086
1087     return m_internal->Resume() ? wxTHREAD_NO_ERROR : wxTHREAD_MISC_ERROR;
1088 }
1089
1090 // stopping thread
1091 // ---------------
1092
1093 wxThread::ExitCode wxThread::Wait()
1094 {
1095     ExitCode rc = (ExitCode)THREAD_ERROR_EXIT;
1096
1097     // although under Windows we can wait for any thread, it's an error to
1098     // wait for a detached one in wxWin API
1099     wxCHECK_MSG( !IsDetached(), rc,
1100                  _T("wxThread::Wait(): can't wait for detached thread") );
1101
1102     (void)m_internal->WaitForTerminate(m_critsect, &rc);
1103
1104     return rc;
1105 }
1106
1107 wxThreadError wxThread::Delete(ExitCode *pRc)
1108 {
1109     return m_internal->WaitForTerminate(m_critsect, pRc, this);
1110 }
1111
1112 wxThreadError wxThread::Kill()
1113 {
1114     if ( !IsRunning() )
1115         return wxTHREAD_NOT_RUNNING;
1116
1117     wxThreadError rc = m_internal->Kill();
1118
1119     if ( IsDetached() )
1120     {
1121         delete this;
1122     }
1123     else // joinable
1124     {
1125         // update the status of the joinable thread
1126         wxCriticalSectionLocker lock(m_critsect);
1127         m_internal->SetState(STATE_EXITED);
1128     }
1129
1130     return rc;
1131 }
1132
1133 void wxThread::Exit(ExitCode status)
1134 {
1135     m_internal->Free();
1136
1137     if ( IsDetached() )
1138     {
1139         delete this;
1140     }
1141     else // joinable
1142     {
1143         // update the status of the joinable thread
1144         wxCriticalSectionLocker lock(m_critsect);
1145         m_internal->SetState(STATE_EXITED);
1146     }
1147
1148 #ifdef wxUSE_BEGIN_THREAD
1149     _endthreadex(wxPtrToUInt(status));
1150 #else // !VC++
1151     ::ExitThread((DWORD)status);
1152 #endif // VC++/!VC++
1153
1154     wxFAIL_MSG(wxT("Couldn't return from ExitThread()!"));
1155 }
1156
1157 // priority setting
1158 // ----------------
1159
1160 void wxThread::SetPriority(unsigned int prio)
1161 {
1162     wxCriticalSectionLocker lock(m_critsect);
1163
1164     m_internal->SetPriority(prio);
1165 }
1166
1167 unsigned int wxThread::GetPriority() const
1168 {
1169     wxCriticalSectionLocker lock((wxCriticalSection &)m_critsect); // const_cast
1170
1171     return m_internal->GetPriority();
1172 }
1173
1174 unsigned long wxThread::GetId() const
1175 {
1176     wxCriticalSectionLocker lock((wxCriticalSection &)m_critsect); // const_cast
1177
1178     return (unsigned long)m_internal->GetId();
1179 }
1180
1181 bool wxThread::IsRunning() const
1182 {
1183     wxCriticalSectionLocker lock((wxCriticalSection &)m_critsect); // const_cast
1184
1185     return m_internal->GetState() == STATE_RUNNING;
1186 }
1187
1188 bool wxThread::IsAlive() const
1189 {
1190     wxCriticalSectionLocker lock((wxCriticalSection &)m_critsect); // const_cast
1191
1192     return (m_internal->GetState() == STATE_RUNNING) ||
1193            (m_internal->GetState() == STATE_PAUSED);
1194 }
1195
1196 bool wxThread::IsPaused() const
1197 {
1198     wxCriticalSectionLocker lock((wxCriticalSection &)m_critsect); // const_cast
1199
1200     return m_internal->GetState() == STATE_PAUSED;
1201 }
1202
1203 bool wxThread::TestDestroy()
1204 {
1205     wxCriticalSectionLocker lock((wxCriticalSection &)m_critsect); // const_cast
1206
1207     return m_internal->GetState() == STATE_CANCELED;
1208 }
1209
1210 // ----------------------------------------------------------------------------
1211 // Automatic initialization for thread module
1212 // ----------------------------------------------------------------------------
1213
1214 class wxThreadModule : public wxModule
1215 {
1216 public:
1217     virtual bool OnInit();
1218     virtual void OnExit();
1219
1220 private:
1221     DECLARE_DYNAMIC_CLASS(wxThreadModule)
1222 };
1223
1224 IMPLEMENT_DYNAMIC_CLASS(wxThreadModule, wxModule)
1225
1226 bool wxThreadModule::OnInit()
1227 {
1228     // allocate TLS index for storing the pointer to the current thread
1229     gs_tlsThisThread = ::TlsAlloc();
1230     if ( gs_tlsThisThread == 0xFFFFFFFF )
1231     {
1232         // in normal circumstances it will only happen if all other
1233         // TLS_MINIMUM_AVAILABLE (>= 64) indices are already taken - in other
1234         // words, this should never happen
1235         wxLogSysError(_("Thread module initialization failed: impossible to allocate index in thread local storage"));
1236
1237         return false;
1238     }
1239
1240     // main thread doesn't have associated wxThread object, so store 0 in the
1241     // TLS instead
1242     if ( !::TlsSetValue(gs_tlsThisThread, (LPVOID)0) )
1243     {
1244         ::TlsFree(gs_tlsThisThread);
1245         gs_tlsThisThread = 0xFFFFFFFF;
1246
1247         wxLogSysError(_("Thread module initialization failed: can not store value in thread local storage"));
1248
1249         return false;
1250     }
1251
1252     gs_critsectWaitingForGui = new wxCriticalSection();
1253
1254     gs_critsectGui = new wxCriticalSection();
1255     gs_critsectGui->Enter();
1256
1257     gs_critsectThreadDelete = new wxCriticalSection;
1258
1259     // no error return for GetCurrentThreadId()
1260     gs_idMainThread = ::GetCurrentThreadId();
1261
1262     return true;
1263 }
1264
1265 void wxThreadModule::OnExit()
1266 {
1267     if ( !::TlsFree(gs_tlsThisThread) )
1268     {
1269         wxLogLastError(wxT("TlsFree failed."));
1270     }
1271
1272     delete gs_critsectThreadDelete;
1273     gs_critsectThreadDelete = NULL;
1274
1275     if ( gs_critsectGui )
1276     {
1277         gs_critsectGui->Leave();
1278         delete gs_critsectGui;
1279         gs_critsectGui = NULL;
1280     }
1281
1282     delete gs_critsectWaitingForGui;
1283     gs_critsectWaitingForGui = NULL;
1284 }
1285
1286 // ----------------------------------------------------------------------------
1287 // under Windows, these functions are implemented using a critical section and
1288 // not a mutex, so the names are a bit confusing
1289 // ----------------------------------------------------------------------------
1290
1291 void wxMutexGuiEnterImpl()
1292 {
1293     // this would dead lock everything...
1294     wxASSERT_MSG( !wxThread::IsMain(),
1295                   wxT("main thread doesn't want to block in wxMutexGuiEnter()!") );
1296
1297     // the order in which we enter the critical sections here is crucial!!
1298
1299     // set the flag telling to the main thread that we want to do some GUI
1300     {
1301         wxCriticalSectionLocker enter(*gs_critsectWaitingForGui);
1302
1303         gs_nWaitingForGui++;
1304     }
1305
1306     wxWakeUpMainThread();
1307
1308     // now we may block here because the main thread will soon let us in
1309     // (during the next iteration of OnIdle())
1310     gs_critsectGui->Enter();
1311 }
1312
1313 void wxMutexGuiLeaveImpl()
1314 {
1315     wxCriticalSectionLocker enter(*gs_critsectWaitingForGui);
1316
1317     if ( wxThread::IsMain() )
1318     {
1319         gs_bGuiOwnedByMainThread = false;
1320     }
1321     else
1322     {
1323         // decrement the number of threads waiting for GUI access now
1324         wxASSERT_MSG( gs_nWaitingForGui > 0,
1325                       wxT("calling wxMutexGuiLeave() without entering it first?") );
1326
1327         gs_nWaitingForGui--;
1328
1329         wxWakeUpMainThread();
1330     }
1331
1332     gs_critsectGui->Leave();
1333 }
1334
1335 void WXDLLIMPEXP_BASE wxMutexGuiLeaveOrEnter()
1336 {
1337     wxASSERT_MSG( wxThread::IsMain(),
1338                   wxT("only main thread may call wxMutexGuiLeaveOrEnter()!") );
1339
1340     wxCriticalSectionLocker enter(*gs_critsectWaitingForGui);
1341
1342     if ( gs_nWaitingForGui == 0 )
1343     {
1344         // no threads are waiting for GUI - so we may acquire the lock without
1345         // any danger (but only if we don't already have it)
1346         if ( !wxGuiOwnedByMainThread() )
1347         {
1348             gs_critsectGui->Enter();
1349
1350             gs_bGuiOwnedByMainThread = true;
1351         }
1352         //else: already have it, nothing to do
1353     }
1354     else
1355     {
1356         // some threads are waiting, release the GUI lock if we have it
1357         if ( wxGuiOwnedByMainThread() )
1358         {
1359             wxMutexGuiLeave();
1360         }
1361         //else: some other worker thread is doing GUI
1362     }
1363 }
1364
1365 bool WXDLLIMPEXP_BASE wxGuiOwnedByMainThread()
1366 {
1367     return gs_bGuiOwnedByMainThread;
1368 }
1369
1370 // wake up the main thread if it's in ::GetMessage()
1371 void WXDLLIMPEXP_BASE wxWakeUpMainThread()
1372 {
1373     // sending any message would do - hopefully WM_NULL is harmless enough
1374     if ( !::PostThreadMessage(gs_idMainThread, WM_NULL, 0, 0) )
1375     {
1376         // should never happen
1377         wxLogLastError(wxT("PostThreadMessage(WM_NULL)"));
1378     }
1379 }
1380
1381 bool WXDLLIMPEXP_BASE wxIsWaitingForThread()
1382 {
1383     return gs_waitingForThread;
1384 }
1385
1386 // ----------------------------------------------------------------------------
1387 // include common implementation code
1388 // ----------------------------------------------------------------------------
1389
1390 #include "wx/thrimpl.cpp"
1391
1392 #endif // wxUSE_THREADS