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: notice that this
  79     // type can't hold a pointer under Win64
  80     typedef unsigned THREAD_RETVAL;
  81
  82     // the calling convention of the thread function entry point
  83     #define THREAD_CALLCONV __stdcall
  84 #else
  85     // the settings for CreateThread()
  86     typedef DWORD THREAD_RETVAL;
  87     #define THREAD_CALLCONV WINAPI
  88 #endif
  89
  90 static const THREAD_RETVAL THREAD_ERROR_EXIT = (THREAD_RETVAL)-1;
  91
  92 // ----------------------------------------------------------------------------
  93 // constants
  94 // ----------------------------------------------------------------------------
  95
  96 // the possible states of the thread ("=>" shows all possible transitions from
  97 // this state)
  98 enum wxThreadState
  99 {
 100     STATE_NEW,          // didn't start execution yet (=> RUNNING)
 101     STATE_RUNNING,      // thread is running (=> PAUSED, CANCELED)
 102     STATE_PAUSED,       // thread is temporarily suspended (=> RUNNING)
 103     STATE_CANCELED,     // thread should terminate a.s.a.p. (=> EXITED)
 104     STATE_EXITED        // thread is terminating
 105 };
 106
 107 // ----------------------------------------------------------------------------
 108 // this module globals
 109 // ----------------------------------------------------------------------------
 110
 111 // TLS index of the slot where we store the pointer to the current thread
 112 static DWORD gs_tlsThisThread = 0xFFFFFFFF;
 113
 114 // id of the main thread - the one which can call GUI functions without first
 115 // calling wxMutexGuiEnter()
 116 static DWORD gs_idMainThread = 0;
 117
 118 // if it's false, some secondary thread is holding the GUI lock
 119 static bool gs_bGuiOwnedByMainThread = true;
 120
 121 // critical section which controls access to all GUI functions: any secondary
 122 // thread (i.e. except the main one) must enter this crit section before doing
 123 // any GUI calls
 124 static wxCriticalSection *gs_critsectGui = NULL;
 125
 126 // critical section which protects gs_nWaitingForGui variable
 127 static wxCriticalSection *gs_critsectWaitingForGui = NULL;
 128
 129 // critical section which serializes WinThreadStart() and WaitForTerminate()
 130 // (this is a potential bottleneck, we use a single crit sect for all threads
 131 // in the system, but normally time spent inside it should be quite short)
 132 static wxCriticalSection *gs_critsectThreadDelete = NULL;
 133
 134 // number of threads waiting for GUI in wxMutexGuiEnter()
 135 static size_t gs_nWaitingForGui = 0;
 136
 137 // are we waiting for a thread termination?
 138 static bool gs_waitingForThread = false;
 139
 140 // ============================================================================
 141 // Windows implementation of thread and related classes
 142 // ============================================================================
 143
 144 // ----------------------------------------------------------------------------
 145 // wxCriticalSection
 146 // ----------------------------------------------------------------------------
 147
 148 wxCriticalSection::wxCriticalSection( wxCriticalSectionType WXUNUSED(critSecType) )
 149 {
 150     wxCOMPILE_TIME_ASSERT( sizeof(CRITICAL_SECTION) <= sizeof(wxCritSectBuffer),
 151                            wxCriticalSectionBufferTooSmall );
 152
 153     ::InitializeCriticalSection((CRITICAL_SECTION *)m_buffer);
 154 }
 155
 156 wxCriticalSection::~wxCriticalSection()
 157 {
 158     ::DeleteCriticalSection((CRITICAL_SECTION *)m_buffer);
 159 }
 160
 161 void wxCriticalSection::Enter()
 162 {
 163     ::EnterCriticalSection((CRITICAL_SECTION *)m_buffer);
 164 }
 165
 166 void wxCriticalSection::Leave()
 167 {
 168     ::LeaveCriticalSection((CRITICAL_SECTION *)m_buffer);
 169 }
 170
 171 // ----------------------------------------------------------------------------
 172 // wxMutex
 173 // ----------------------------------------------------------------------------
 174
 175 class wxMutexInternal
 176 {
 177 public:
 178     wxMutexInternal(wxMutexType mutexType);
 179     ~wxMutexInternal();
 180
 181     bool IsOk() const { return m_mutex != NULL; }
 182
 183     wxMutexError Lock() { return LockTimeout(INFINITE); }
 184     wxMutexError Lock(unsigned long ms) { return LockTimeout(ms); }
 185     wxMutexError TryLock();
 186     wxMutexError Unlock();
 187
 188 private:
 189     wxMutexError LockTimeout(DWORD milliseconds);
 190
 191     HANDLE m_mutex;
 192
 193     unsigned long m_owningThread;
 194     wxMutexType m_type;
 195
 196     wxDECLARE_NO_COPY_CLASS(wxMutexInternal);
 197 };
 198
 199 // all mutexes are recursive under Win32 so we don't use mutexType
 200 wxMutexInternal::wxMutexInternal(wxMutexType mutexType)
 201 {
 202     // create a nameless (hence intra process and always private) mutex
 203     m_mutex = ::CreateMutex
 204                 (
 205                     NULL,       // default secutiry attributes
 206                     FALSE,      // not initially locked
 207                     NULL        // no name
 208                 );
 209
 210     m_type = mutexType;
 211     m_owningThread = 0;
 212
 213     if ( !m_mutex )
 214     {
 215         wxLogLastError(_T("CreateMutex()"));
 216     }
 217
 218 }
 219
 220 wxMutexInternal::~wxMutexInternal()
 221 {
 222     if ( m_mutex )
 223     {
 224         if ( !::CloseHandle(m_mutex) )
 225         {
 226             wxLogLastError(_T("CloseHandle(mutex)"));
 227         }
 228     }
 229 }
 230
 231 wxMutexError wxMutexInternal::TryLock()
 232 {
 233     const wxMutexError rc = LockTimeout(0);
 234
 235     // we have a special return code for timeout in this case
 236     return rc == wxMUTEX_TIMEOUT ? wxMUTEX_BUSY : rc;
 237 }
 238
 239 wxMutexError wxMutexInternal::LockTimeout(DWORD milliseconds)
 240 {
 241     if (m_type == wxMUTEX_DEFAULT)
 242     {
 243         // Don't allow recursive
 244         if (m_owningThread != 0)
 245         {
 246             if (m_owningThread == wxThread::GetCurrentId())
 247                 return wxMUTEX_DEAD_LOCK;
 248         }
 249     }
 250
 251     DWORD rc = ::WaitForSingleObject(m_mutex, milliseconds);
 252     switch ( rc )
 253     {
 254         case WAIT_ABANDONED:
 255             // the previous caller died without releasing the mutex, so even
 256             // though we did get it, log a message about this
 257             wxLogDebug(_T("WaitForSingleObject() returned WAIT_ABANDONED"));
 258             // fall through
 259
 260         case WAIT_OBJECT_0:
 261             // ok
 262             break;
 263
 264         case WAIT_TIMEOUT:
 265             return wxMUTEX_TIMEOUT;
 266
 267         default:
 268             wxFAIL_MSG(wxT("impossible return value in wxMutex::Lock"));
 269             // fall through
 270
 271         case WAIT_FAILED:
 272             wxLogLastError(_T("WaitForSingleObject(mutex)"));
 273             return wxMUTEX_MISC_ERROR;
 274     }
 275
 276     if (m_type == wxMUTEX_DEFAULT)
 277     {
 278         // required for checking recursiveness
 279         m_owningThread = wxThread::GetCurrentId();
 280     }
 281
 282     return wxMUTEX_NO_ERROR;
 283 }
 284
 285 wxMutexError wxMutexInternal::Unlock()
 286 {
 287     // required for checking recursiveness
 288     m_owningThread = 0;
 289
 290     if ( !::ReleaseMutex(m_mutex) )
 291     {
 292         wxLogLastError(_T("ReleaseMutex()"));
 293
 294         return wxMUTEX_MISC_ERROR;
 295     }
 296
 297     return wxMUTEX_NO_ERROR;
 298 }
 299
 300 // --------------------------------------------------------------------------
 301 // wxSemaphore
 302 // --------------------------------------------------------------------------
 303
 304 // a trivial wrapper around Win32 semaphore
 305 class wxSemaphoreInternal
 306 {
 307 public:
 308     wxSemaphoreInternal(int initialcount, int maxcount);
 309     ~wxSemaphoreInternal();
 310
 311     bool IsOk() const { return m_semaphore != NULL; }
 312
 313     wxSemaError Wait() { return WaitTimeout(INFINITE); }
 314
 315     wxSemaError TryWait()
 316     {
 317         wxSemaError rc = WaitTimeout(0);
 318         if ( rc == wxSEMA_TIMEOUT )
 319             rc = wxSEMA_BUSY;
 320
 321         return rc;
 322     }
 323
 324     wxSemaError WaitTimeout(unsigned long milliseconds);
 325
 326     wxSemaError Post();
 327
 328 private:
 329     HANDLE m_semaphore;
 330
 331     wxDECLARE_NO_COPY_CLASS(wxSemaphoreInternal);
 332 };
 333
 334 wxSemaphoreInternal::wxSemaphoreInternal(int initialcount, int maxcount)
 335 {
 336 #if !defined(_WIN32_WCE) || (_WIN32_WCE >= 300)
 337     if ( maxcount == 0 )
 338     {
 339         // make it practically infinite
 340         maxcount = INT_MAX;
 341     }
 342
 343     m_semaphore = ::CreateSemaphore
 344                     (
 345                         NULL,           // default security attributes
 346                         initialcount,
 347                         maxcount,
 348                         NULL            // no name
 349                     );
 350 #endif
 351     if ( !m_semaphore )
 352     {
 353         wxLogLastError(_T("CreateSemaphore()"));
 354     }
 355 }
 356
 357 wxSemaphoreInternal::~wxSemaphoreInternal()
 358 {
 359     if ( m_semaphore )
 360     {
 361         if ( !::CloseHandle(m_semaphore) )
 362         {
 363             wxLogLastError(_T("CloseHandle(semaphore)"));
 364         }
 365     }
 366 }
 367
 368 wxSemaError wxSemaphoreInternal::WaitTimeout(unsigned long milliseconds)
 369 {
 370     DWORD rc = ::WaitForSingleObject( m_semaphore, milliseconds );
 371
 372     switch ( rc )
 373     {
 374         case WAIT_OBJECT_0:
 375            return wxSEMA_NO_ERROR;
 376
 377         case WAIT_TIMEOUT:
 378            return wxSEMA_TIMEOUT;
 379
 380         default:
 381             wxLogLastError(_T("WaitForSingleObject(semaphore)"));
 382     }
 383
 384     return wxSEMA_MISC_ERROR;
 385 }
 386
 387 wxSemaError wxSemaphoreInternal::Post()
 388 {
 389 #if !defined(_WIN32_WCE) || (_WIN32_WCE >= 300)
 390     if ( !::ReleaseSemaphore(m_semaphore, 1, NULL /* ptr to previous count */) )
 391     {
 392         if ( GetLastError() == ERROR_TOO_MANY_POSTS )
 393         {
 394             return wxSEMA_OVERFLOW;
 395         }
 396         else
 397         {
 398             wxLogLastError(_T("ReleaseSemaphore"));
 399             return wxSEMA_MISC_ERROR;
 400         }
 401     }
 402
 403     return wxSEMA_NO_ERROR;
 404 #else
 405     return wxSEMA_MISC_ERROR;
 406 #endif
 407 }
 408
 409 // ----------------------------------------------------------------------------
 410 // wxThread implementation
 411 // ----------------------------------------------------------------------------
 412
 413 // wxThreadInternal class
 414 // ----------------------
 415
 416 class wxThreadInternal
 417 {
 418 public:
 419     wxThreadInternal(wxThread *thread)
 420     {
 421         m_thread = thread;
 422         m_hThread = 0;
 423         m_state = STATE_NEW;
 424         m_priority = WXTHREAD_DEFAULT_PRIORITY;
 425         m_nRef = 1;
 426     }
 427
 428     ~wxThreadInternal()
 429     {
 430         Free();
 431     }
 432
 433     void Free()
 434     {
 435         if ( m_hThread )
 436         {
 437             if ( !::CloseHandle(m_hThread) )
 438             {
 439                 wxLogLastError(wxT("CloseHandle(thread)"));
 440             }
 441
 442             m_hThread = 0;
 443         }
 444     }
 445
 446     // create a new (suspended) thread (for the given thread object)
 447     bool Create(wxThread *thread, unsigned int stackSize);
 448
 449     // wait for the thread to terminate, either by itself, or by asking it
 450     // (politely, this is not Kill()!) to do it
 451     wxThreadError WaitForTerminate(wxCriticalSection& cs,
 452                                    wxThread::ExitCode *pRc,
 453                                    wxThread *threadToDelete = NULL);
 454
 455     // kill the thread unconditionally
 456     wxThreadError Kill();
 457
 458     // suspend/resume/terminate
 459     bool Suspend();
 460     bool Resume();
 461     void Cancel() { m_state = STATE_CANCELED; }
 462
 463     // thread state
 464     void SetState(wxThreadState state) { m_state = state; }
 465     wxThreadState GetState() const { return m_state; }
 466
 467     // thread priority
 468     void SetPriority(unsigned int priority);
 469     unsigned int GetPriority() const { return m_priority; }
 470
 471     // thread handle and id
 472     HANDLE GetHandle() const { return m_hThread; }
 473     DWORD  GetId() const { return m_tid; }
 474
 475     // the thread function forwarding to DoThreadStart
 476     static THREAD_RETVAL THREAD_CALLCONV WinThreadStart(void *thread);
 477
 478     // really start the thread (if it's not already dead)
 479     static THREAD_RETVAL DoThreadStart(wxThread *thread);
 480
 481     // call OnExit() on the thread
 482     static void DoThreadOnExit(wxThread *thread);
 483
 484
 485     void KeepAlive()
 486     {
 487         if ( m_thread->IsDetached() )
 488             ::InterlockedIncrement(&m_nRef);
 489     }
 490
 491     void LetDie()
 492     {
 493         if ( m_thread->IsDetached() && !::InterlockedDecrement(&m_nRef) )
 494             delete m_thread;
 495     }
 496
 497 private:
 498     // the thread we're associated with
 499     wxThread *m_thread;
 500
 501     HANDLE        m_hThread;    // handle of the thread
 502     wxThreadState m_state;      // state, see wxThreadState enum
 503     unsigned int  m_priority;   // thread priority in "wx" units
 504     DWORD         m_tid;        // thread id
 505
 506     // number of threads which need this thread to remain alive, when the count
 507     // reaches 0 we kill the owning wxThread -- and die ourselves with it
 508     LONG m_nRef;
 509
 510     wxDECLARE_NO_COPY_CLASS(wxThreadInternal);
 511 };
 512
 513 // small class which keeps a thread alive during its lifetime
 514 class wxThreadKeepAlive
 515 {
 516 public:
 517     wxThreadKeepAlive(wxThreadInternal& thrImpl) : m_thrImpl(thrImpl)
 518         { m_thrImpl.KeepAlive(); }
 519     ~wxThreadKeepAlive()
 520         { m_thrImpl.LetDie(); }
 521
 522 private:
 523     wxThreadInternal& m_thrImpl;
 524 };
 525
 526 /* static */
 527 void wxThreadInternal::DoThreadOnExit(wxThread *thread)
 528 {
 529     wxTRY
 530     {
 531         thread->OnExit();
 532     }
 533     wxCATCH_ALL( wxTheApp->OnUnhandledException(); )
 534 }
 535
 536 /* static */
 537 THREAD_RETVAL wxThreadInternal::DoThreadStart(wxThread *thread)
 538 {
 539     wxON_BLOCK_EXIT1(DoThreadOnExit, thread);
 540
 541     THREAD_RETVAL rc = THREAD_ERROR_EXIT;
 542
 543     wxTRY
 544     {
 545         // store the thread object in the TLS
 546         if ( !::TlsSetValue(gs_tlsThisThread, thread) )
 547         {
 548             wxLogSysError(_("Can not start thread: error writing TLS."));
 549
 550             return THREAD_ERROR_EXIT;
 551         }
 552
 553         rc = wxPtrToUInt(thread->Entry());
 554     }
 555     wxCATCH_ALL( wxTheApp->OnUnhandledException(); )
 556
 557     return rc;
 558 }
 559
 560 /* static */
 561 THREAD_RETVAL THREAD_CALLCONV wxThreadInternal::WinThreadStart(void *param)
 562 {
 563     THREAD_RETVAL rc = THREAD_ERROR_EXIT;
 564
 565     wxThread * const thread = (wxThread *)param;
 566
 567     // each thread has its own SEH translator so install our own a.s.a.p.
 568     DisableAutomaticSETranslator();
 569
 570     // first of all, check whether we hadn't been cancelled already and don't
 571     // start the user code at all then
 572     const bool hasExited = thread->m_internal->GetState() == STATE_EXITED;
 573
 574     // run the thread function itself inside a SEH try/except block
 575     wxSEH_TRY
 576     {
 577         if ( hasExited )
 578             DoThreadOnExit(thread);
 579         else
 580             rc = DoThreadStart(thread);
 581     }
 582     wxSEH_HANDLE(THREAD_ERROR_EXIT)
 583
 584
 585     // save IsDetached because thread object can be deleted by joinable
 586     // threads after state is changed to STATE_EXITED.
 587     const bool isDetached = thread->IsDetached();
 588     if ( !hasExited )
 589     {
 590         // enter m_critsect before changing the thread state
 591         //
 592         // NB: can't use wxCriticalSectionLocker here as we use SEH and it's
 593         //     incompatible with C++ object dtors
 594         thread->m_critsect.Enter();
 595         thread->m_internal->SetState(STATE_EXITED);
 596         thread->m_critsect.Leave();
 597     }
 598
 599     // the thread may delete itself now if it wants, we don't need it any more
 600     if ( isDetached )
 601         thread->m_internal->LetDie();
 602
 603     return rc;
 604 }
 605
 606 void wxThreadInternal::SetPriority(unsigned int priority)
 607 {
 608     m_priority = priority;
 609
 610     // translate wxWidgets priority to the Windows one
 611     int win_priority;
 612     if (m_priority <= 20)
 613         win_priority = THREAD_PRIORITY_LOWEST;
 614     else if (m_priority <= 40)
 615         win_priority = THREAD_PRIORITY_BELOW_NORMAL;
 616     else if (m_priority <= 60)
 617         win_priority = THREAD_PRIORITY_NORMAL;
 618     else if (m_priority <= 80)
 619         win_priority = THREAD_PRIORITY_ABOVE_NORMAL;
 620     else if (m_priority <= 100)
 621         win_priority = THREAD_PRIORITY_HIGHEST;
 622     else
 623     {
 624         wxFAIL_MSG(wxT("invalid value of thread priority parameter"));
 625         win_priority = THREAD_PRIORITY_NORMAL;
 626     }
 627
 628     if ( !::SetThreadPriority(m_hThread, win_priority) )
 629     {
 630         wxLogSysError(_("Can't set thread priority"));
 631     }
 632 }
 633
 634 bool wxThreadInternal::Create(wxThread *thread, unsigned int stackSize)
 635 {
 636     wxASSERT_MSG( m_state == STATE_NEW && !m_hThread,
 637                     _T("Create()ing thread twice?") );
 638
 639     // for compilers which have it, we should use C RTL function for thread
 640     // creation instead of Win32 API one because otherwise we will have memory
 641     // leaks if the thread uses C RTL (and most threads do)
 642 #ifdef wxUSE_BEGIN_THREAD
 643
 644     // Watcom is reported to not like 0 stack size (which means "use default"
 645     // for the other compilers and is also the default value for stackSize)
 646 #ifdef __WATCOMC__
 647     if ( !stackSize )
 648         stackSize = 10240;
 649 #endif // __WATCOMC__
 650
 651     m_hThread = (HANDLE)_beginthreadex
 652                         (
 653                           NULL,                             // default security
 654                           stackSize,
 655                           wxThreadInternal::WinThreadStart, // entry point
 656                           thread,
 657                           CREATE_SUSPENDED,
 658                           (unsigned int *)&m_tid
 659                         );
 660 #else // compiler doesn't have _beginthreadex
 661     m_hThread = ::CreateThread
 662                   (
 663                     NULL,                               // default security
 664                     stackSize,                          // stack size
 665                     wxThreadInternal::WinThreadStart,   // thread entry point
 666                     (LPVOID)thread,                     // parameter
 667                     CREATE_SUSPENDED,                   // flags
 668                     &m_tid                              // [out] thread id
 669                   );
 670 #endif // _beginthreadex/CreateThread
 671
 672     if ( m_hThread == NULL )
 673     {
 674         wxLogSysError(_("Can't create thread"));
 675
 676         return false;
 677     }
 678
 679     if ( m_priority != WXTHREAD_DEFAULT_PRIORITY )
 680     {
 681         SetPriority(m_priority);
 682     }
 683
 684     return true;
 685 }
 686
 687 wxThreadError wxThreadInternal::Kill()
 688 {
 689     if ( !::TerminateThread(m_hThread, THREAD_ERROR_EXIT) )
 690     {
 691         wxLogSysError(_("Couldn't terminate thread"));
 692
 693         return wxTHREAD_MISC_ERROR;
 694     }
 695
 696     Free();
 697
 698     return wxTHREAD_NO_ERROR;
 699 }
 700
 701 wxThreadError
 702 wxThreadInternal::WaitForTerminate(wxCriticalSection& cs,
 703                                    wxThread::ExitCode *pRc,
 704                                    wxThread *threadToDelete)
 705 {
 706     // prevent the thread C++ object from disappearing as long as we are using
 707     // it here
 708     wxThreadKeepAlive keepAlive(*this);
 709
 710
 711     // we may either wait passively for the thread to terminate (when called
 712     // from Wait()) or ask it to terminate (when called from Delete())
 713     bool shouldDelete = threadToDelete != NULL;
 714
 715     DWORD rc = 0;
 716
 717     // we might need to resume the thread if it's currently stopped
 718     bool shouldResume = false;
 719
 720     // as Delete() (which calls us) is always safe to call we need to consider
 721     // all possible states
 722     {
 723         wxCriticalSectionLocker lock(cs);
 724
 725         if ( m_state == STATE_NEW )
 726         {
 727             if ( shouldDelete )
 728             {
 729                 // WinThreadStart() will see it and terminate immediately, no
 730                 // need to cancel the thread -- but we still need to resume it
 731                 // to let it run
 732                 m_state = STATE_EXITED;
 733
 734                 // we must call Resume() as the thread hasn't been initially
 735                 // resumed yet (and as Resume() it knows about STATE_EXITED
 736                 // special case, it won't touch it and WinThreadStart() will
 737                 // just exit immediately)
 738                 shouldResume = true;
 739                 shouldDelete = false;
 740             }
 741             //else: shouldResume is correctly set to false here, wait until
 742             //      someone else runs the thread and it finishes
 743         }
 744         else // running, paused, cancelled or even exited
 745         {
 746             shouldResume = m_state == STATE_PAUSED;
 747         }
 748     }
 749
 750     // resume the thread if it is paused
 751     if ( shouldResume )
 752         Resume();
 753
 754     // ask the thread to terminate
 755     if ( shouldDelete )
 756     {
 757         wxCriticalSectionLocker lock(cs);
 758
 759         Cancel();
 760     }
 761
 762
 763     // now wait for thread to finish
 764     if ( wxThread::IsMain() )
 765     {
 766         // set flag for wxIsWaitingForThread()
 767         gs_waitingForThread = true;
 768     }
 769
 770     // we can't just wait for the thread to terminate because it might be
 771     // calling some GUI functions and so it will never terminate before we
 772     // process the Windows messages that result from these functions
 773     // (note that even in console applications we might have to process
 774     // messages if we use wxExecute() or timers or ...)
 775     DWORD result wxDUMMY_INITIALIZE(0);
 776     do
 777     {
 778         if ( wxThread::IsMain() )
 779         {
 780             // give the thread we're waiting for chance to do the GUI call
 781             // it might be in
 782             if ( (gs_nWaitingForGui > 0) && wxGuiOwnedByMainThread() )
 783             {
 784                 wxMutexGuiLeave();
 785             }
 786         }
 787
 788         wxAppTraits *traits = wxTheApp ? wxTheApp->GetTraits() : NULL;
 789         if ( traits )
 790         {
 791             result = traits->WaitForThread(m_hThread);
 792         }
 793         else // can't wait for the thread
 794         {
 795             // so kill it below
 796             result = 0xFFFFFFFF;
 797         }
 798
 799         switch ( result )
 800         {
 801             case 0xFFFFFFFF:
 802                 // error
 803                 wxLogSysError(_("Can not wait for thread termination"));
 804                 Kill();
 805                 return wxTHREAD_KILLED;
 806
 807             case WAIT_OBJECT_0:
 808                 // thread we're waiting for terminated
 809                 break;
 810
 811             case WAIT_OBJECT_0 + 1:
 812                 // new message arrived, process it -- but only if we're the
 813                 // main thread as we don't support processing messages in
 814                 // the other ones
 815                 //
 816                 // NB: we still must include QS_ALLINPUT even when waiting
 817                 //     in a secondary thread because if it had created some
 818                 //     window somehow (possible not even using wxWidgets)
 819                 //     the system might dead lock then
 820                 if ( wxThread::IsMain() )
 821                 {
 822                     if ( traits && !traits->DoMessageFromThreadWait() )
 823                     {
 824                         // WM_QUIT received: kill the thread
 825                         Kill();
 826
 827                         return wxTHREAD_KILLED;
 828                     }
 829                 }
 830                 break;
 831
 832             default:
 833                 wxFAIL_MSG(wxT("unexpected result of MsgWaitForMultipleObject"));
 834         }
 835     } while ( result != WAIT_OBJECT_0 );
 836
 837     if ( wxThread::IsMain() )
 838     {
 839         gs_waitingForThread = false;
 840     }
 841
 842
 843     // although the thread might be already in the EXITED state it might not
 844     // have terminated yet and so we are not sure that it has actually
 845     // terminated if the "if" above hadn't been taken
 846     for ( ;; )
 847     {
 848         if ( !::GetExitCodeThread(m_hThread, &rc) )
 849         {
 850             wxLogLastError(wxT("GetExitCodeThread"));
 851
 852             rc = THREAD_ERROR_EXIT;
 853
 854             break;
 855         }
 856
 857         if ( rc != STILL_ACTIVE )
 858             break;
 859
 860         // give the other thread some time to terminate, otherwise we may be
 861         // starving it
 862         ::Sleep(1);
 863     }
 864
 865     if ( pRc )
 866         *pRc = wxUIntToPtr(rc);
 867
 868     // we don't need the thread handle any more in any case
 869     Free();
 870
 871
 872     return rc == THREAD_ERROR_EXIT ? wxTHREAD_MISC_ERROR : wxTHREAD_NO_ERROR;
 873 }
 874
 875 bool wxThreadInternal::Suspend()
 876 {
 877     DWORD nSuspendCount = ::SuspendThread(m_hThread);
 878     if ( nSuspendCount == (DWORD)-1 )
 879     {
 880         wxLogSysError(_("Can not suspend thread %x"), m_hThread);
 881
 882         return false;
 883     }
 884
 885     m_state = STATE_PAUSED;
 886
 887     return true;
 888 }
 889
 890 bool wxThreadInternal::Resume()
 891 {
 892     DWORD nSuspendCount = ::ResumeThread(m_hThread);
 893     if ( nSuspendCount == (DWORD)-1 )
 894     {
 895         wxLogSysError(_("Can not resume thread %x"), m_hThread);
 896
 897         return false;
 898     }
 899
 900     // don't change the state from STATE_EXITED because it's special and means
 901     // we are going to terminate without running any user code - if we did it,
 902     // the code in WaitForTerminate() wouldn't work
 903     if ( m_state != STATE_EXITED )
 904     {
 905         m_state = STATE_RUNNING;
 906     }
 907
 908     return true;
 909 }
 910
 911 // static functions
 912 // ----------------
 913
 914 wxThread *wxThread::This()
 915 {
 916     wxThread *thread = (wxThread *)::TlsGetValue(gs_tlsThisThread);
 917
 918     // be careful, 0 may be a valid return value as well
 919     if ( !thread && (::GetLastError() != NO_ERROR) )
 920     {
 921         wxLogSysError(_("Couldn't get the current thread pointer"));
 922
 923         // return NULL...
 924     }
 925
 926     return thread;
 927 }
 928
 929 bool wxThread::IsMain()
 930 {
 931     return ::GetCurrentThreadId() == gs_idMainThread || gs_idMainThread == 0;
 932 }
 933
 934 void wxThread::Yield()
 935 {
 936     // 0 argument to Sleep() is special and means to just give away the rest of
 937     // our timeslice
 938     ::Sleep(0);
 939 }
 940
 941 int wxThread::GetCPUCount()
 942 {
 943     SYSTEM_INFO si;
 944     GetSystemInfo(&si);
 945
 946     return si.dwNumberOfProcessors;
 947 }
 948
 949 unsigned long wxThread::GetCurrentId()
 950 {
 951     return (unsigned long)::GetCurrentThreadId();
 952 }
 953
 954 bool wxThread::SetConcurrency(size_t WXUNUSED_IN_WINCE(level))
 955 {
 956 #ifdef __WXWINCE__
 957     return false;
 958 #else
 959     wxASSERT_MSG( IsMain(), _T("should only be called from the main thread") );
 960
 961     // ok only for the default one
 962     if ( level == 0 )
 963         return 0;
 964
 965     // get system affinity mask first
 966     HANDLE hProcess = ::GetCurrentProcess();
 967     DWORD_PTR dwProcMask, dwSysMask;
 968     if ( ::GetProcessAffinityMask(hProcess, &dwProcMask, &dwSysMask) == 0 )
 969     {
 970         wxLogLastError(_T("GetProcessAffinityMask"));
 971
 972         return false;
 973     }
 974
 975     // how many CPUs have we got?
 976     if ( dwSysMask == 1 )
 977     {
 978         // don't bother with all this complicated stuff - on a single
 979         // processor system it doesn't make much sense anyhow
 980         return level == 1;
 981     }
 982
 983     // calculate the process mask: it's a bit vector with one bit per
 984     // processor; we want to schedule the process to run on first level
 985     // CPUs
 986     DWORD bit = 1;
 987     while ( bit )
 988     {
 989         if ( dwSysMask & bit )
 990         {
 991             // ok, we can set this bit
 992             dwProcMask |= bit;
 993
 994             // another process added
 995             if ( --level == 0 )
 996             {
 997                 // and that's enough
 998                 break;
 999             }
1000         }
1001
1002         // next bit
1003         bit <<= 1;
1004     }
1005
1006     // could we set all bits?
1007     if ( level != 0 )
1008     {
1009         wxLogDebug(_T("bad level %u in wxThread::SetConcurrency()"), level);
1010
1011         return false;
1012     }
1013
1014     // set it: we can't link to SetProcessAffinityMask() because it doesn't
1015     // exist in Win9x, use RT binding instead
1016
1017     typedef BOOL (WINAPI *SETPROCESSAFFINITYMASK)(HANDLE, DWORD_PTR);
1018
1019     // can use static var because we're always in the main thread here
1020     static SETPROCESSAFFINITYMASK pfnSetProcessAffinityMask = NULL;
1021
1022     if ( !pfnSetProcessAffinityMask )
1023     {
1024         HMODULE hModKernel = ::LoadLibrary(_T("kernel32"));
1025         if ( hModKernel )
1026         {
1027             pfnSetProcessAffinityMask = (SETPROCESSAFFINITYMASK)
1028                 ::GetProcAddress(hModKernel, "SetProcessAffinityMask");
1029         }
1030
1031         // we've discovered a MT version of Win9x!
1032         wxASSERT_MSG( pfnSetProcessAffinityMask,
1033                       _T("this system has several CPUs but no SetProcessAffinityMask function?") );
1034     }
1035
1036     if ( !pfnSetProcessAffinityMask )
1037     {
1038         // msg given above - do it only once
1039         return false;
1040     }
1041
1042     if ( pfnSetProcessAffinityMask(hProcess, dwProcMask) == 0 )
1043     {
1044         wxLogLastError(_T("SetProcessAffinityMask"));
1045
1046         return false;
1047     }
1048
1049     return true;
1050 #endif // __WXWINCE__/!__WXWINCE__
1051 }
1052
1053 // ctor and dtor
1054 // -------------
1055
1056 wxThread::wxThread(wxThreadKind kind)
1057 {
1058     m_internal = new wxThreadInternal(this);
1059
1060     m_isDetached = kind == wxTHREAD_DETACHED;
1061 }
1062
1063 wxThread::~wxThread()
1064 {
1065     delete m_internal;
1066 }
1067
1068 // create/start thread
1069 // -------------------
1070
1071 wxThreadError wxThread::Create(unsigned int stackSize)
1072 {
1073     wxCriticalSectionLocker lock(m_critsect);
1074
1075     if ( !m_internal->Create(this, stackSize) )
1076         return wxTHREAD_NO_RESOURCE;
1077
1078     return wxTHREAD_NO_ERROR;
1079 }
1080
1081 wxThreadError wxThread::Run()
1082 {
1083     wxCriticalSectionLocker lock(m_critsect);
1084
1085     if ( m_internal->GetState() != STATE_NEW )
1086     {
1087         // actually, it may be almost any state at all, not only STATE_RUNNING
1088         return wxTHREAD_RUNNING;
1089     }
1090
1091     // the thread has just been created and is still suspended - let it run
1092     return Resume();
1093 }
1094
1095 // suspend/resume thread
1096 // ---------------------
1097
1098 wxThreadError wxThread::Pause()
1099 {
1100     wxCriticalSectionLocker lock(m_critsect);
1101
1102     return m_internal->Suspend() ? wxTHREAD_NO_ERROR : wxTHREAD_MISC_ERROR;
1103 }
1104
1105 wxThreadError wxThread::Resume()
1106 {
1107     wxCriticalSectionLocker lock(m_critsect);
1108
1109     return m_internal->Resume() ? wxTHREAD_NO_ERROR : wxTHREAD_MISC_ERROR;
1110 }
1111
1112 // stopping thread
1113 // ---------------
1114
1115 wxThread::ExitCode wxThread::Wait()
1116 {
1117     ExitCode rc = wxUIntToPtr(THREAD_ERROR_EXIT);
1118
1119     // although under Windows we can wait for any thread, it's an error to
1120     // wait for a detached one in wxWin API
1121     wxCHECK_MSG( !IsDetached(), rc,
1122                  _T("wxThread::Wait(): can't wait for detached thread") );
1123
1124     (void)m_internal->WaitForTerminate(m_critsect, &rc);
1125
1126     return rc;
1127 }
1128
1129 wxThreadError wxThread::Delete(ExitCode *pRc)
1130 {
1131     return m_internal->WaitForTerminate(m_critsect, pRc, this);
1132 }
1133
1134 wxThreadError wxThread::Kill()
1135 {
1136     if ( !IsRunning() )
1137         return wxTHREAD_NOT_RUNNING;
1138
1139     wxThreadError rc = m_internal->Kill();
1140
1141     if ( IsDetached() )
1142     {
1143         delete this;
1144     }
1145     else // joinable
1146     {
1147         // update the status of the joinable thread
1148         wxCriticalSectionLocker lock(m_critsect);
1149         m_internal->SetState(STATE_EXITED);
1150     }
1151
1152     return rc;
1153 }
1154
1155 void wxThread::Exit(ExitCode status)
1156 {
1157     m_internal->Free();
1158
1159     if ( IsDetached() )
1160     {
1161         delete this;
1162     }
1163     else // joinable
1164     {
1165         // update the status of the joinable thread
1166         wxCriticalSectionLocker lock(m_critsect);
1167         m_internal->SetState(STATE_EXITED);
1168     }
1169
1170 #ifdef wxUSE_BEGIN_THREAD
1171     _endthreadex(wxPtrToUInt(status));
1172 #else // !VC++
1173     ::ExitThread((DWORD)status);
1174 #endif // VC++/!VC++
1175
1176     wxFAIL_MSG(wxT("Couldn't return from ExitThread()!"));
1177 }
1178
1179 // priority setting
1180 // ----------------
1181
1182 void wxThread::SetPriority(unsigned int prio)
1183 {
1184     wxCriticalSectionLocker lock(m_critsect);
1185
1186     m_internal->SetPriority(prio);
1187 }
1188
1189 unsigned int wxThread::GetPriority() const
1190 {
1191     wxCriticalSectionLocker lock((wxCriticalSection &)m_critsect); // const_cast
1192
1193     return m_internal->GetPriority();
1194 }
1195
1196 unsigned long wxThread::GetId() const
1197 {
1198     wxCriticalSectionLocker lock((wxCriticalSection &)m_critsect); // const_cast
1199
1200     return (unsigned long)m_internal->GetId();
1201 }
1202
1203 bool wxThread::IsRunning() const
1204 {
1205     wxCriticalSectionLocker lock((wxCriticalSection &)m_critsect); // const_cast
1206
1207     return m_internal->GetState() == STATE_RUNNING;
1208 }
1209
1210 bool wxThread::IsAlive() const
1211 {
1212     wxCriticalSectionLocker lock((wxCriticalSection &)m_critsect); // const_cast
1213
1214     return (m_internal->GetState() == STATE_RUNNING) ||
1215            (m_internal->GetState() == STATE_PAUSED);
1216 }
1217
1218 bool wxThread::IsPaused() const
1219 {
1220     wxCriticalSectionLocker lock((wxCriticalSection &)m_critsect); // const_cast
1221
1222     return m_internal->GetState() == STATE_PAUSED;
1223 }
1224
1225 bool wxThread::TestDestroy()
1226 {
1227     wxCriticalSectionLocker lock((wxCriticalSection &)m_critsect); // const_cast
1228
1229     return m_internal->GetState() == STATE_CANCELED;
1230 }
1231
1232 // ----------------------------------------------------------------------------
1233 // Automatic initialization for thread module
1234 // ----------------------------------------------------------------------------
1235
1236 class wxThreadModule : public wxModule
1237 {
1238 public:
1239     virtual bool OnInit();
1240     virtual void OnExit();
1241
1242 private:
1243     DECLARE_DYNAMIC_CLASS(wxThreadModule)
1244 };
1245
1246 IMPLEMENT_DYNAMIC_CLASS(wxThreadModule, wxModule)
1247
1248 bool wxThreadModule::OnInit()
1249 {
1250     // allocate TLS index for storing the pointer to the current thread
1251     gs_tlsThisThread = ::TlsAlloc();
1252     if ( gs_tlsThisThread == 0xFFFFFFFF )
1253     {
1254         // in normal circumstances it will only happen if all other
1255         // TLS_MINIMUM_AVAILABLE (>= 64) indices are already taken - in other
1256         // words, this should never happen
1257         wxLogSysError(_("Thread module initialization failed: impossible to allocate index in thread local storage"));
1258
1259         return false;
1260     }
1261
1262     // main thread doesn't have associated wxThread object, so store 0 in the
1263     // TLS instead
1264     if ( !::TlsSetValue(gs_tlsThisThread, (LPVOID)0) )
1265     {
1266         ::TlsFree(gs_tlsThisThread);
1267         gs_tlsThisThread = 0xFFFFFFFF;
1268
1269         wxLogSysError(_("Thread module initialization failed: can not store value in thread local storage"));
1270
1271         return false;
1272     }
1273
1274     gs_critsectWaitingForGui = new wxCriticalSection();
1275
1276     gs_critsectGui = new wxCriticalSection();
1277     gs_critsectGui->Enter();
1278
1279     gs_critsectThreadDelete = new wxCriticalSection;
1280
1281     // no error return for GetCurrentThreadId()
1282     gs_idMainThread = ::GetCurrentThreadId();
1283
1284     return true;
1285 }
1286
1287 void wxThreadModule::OnExit()
1288 {
1289     if ( !::TlsFree(gs_tlsThisThread) )
1290     {
1291         wxLogLastError(wxT("TlsFree failed."));
1292     }
1293
1294     delete gs_critsectThreadDelete;
1295     gs_critsectThreadDelete = NULL;
1296
1297     if ( gs_critsectGui )
1298     {
1299         gs_critsectGui->Leave();
1300         delete gs_critsectGui;
1301         gs_critsectGui = NULL;
1302     }
1303
1304     delete gs_critsectWaitingForGui;
1305     gs_critsectWaitingForGui = NULL;
1306 }
1307
1308 // ----------------------------------------------------------------------------
1309 // under Windows, these functions are implemented using a critical section and
1310 // not a mutex, so the names are a bit confusing
1311 // ----------------------------------------------------------------------------
1312
1313 void wxMutexGuiEnterImpl()
1314 {
1315     // this would dead lock everything...
1316     wxASSERT_MSG( !wxThread::IsMain(),
1317                   wxT("main thread doesn't want to block in wxMutexGuiEnter()!") );
1318
1319     // the order in which we enter the critical sections here is crucial!!
1320
1321     // set the flag telling to the main thread that we want to do some GUI
1322     {
1323         wxCriticalSectionLocker enter(*gs_critsectWaitingForGui);
1324
1325         gs_nWaitingForGui++;
1326     }
1327
1328     wxWakeUpMainThread();
1329
1330     // now we may block here because the main thread will soon let us in
1331     // (during the next iteration of OnIdle())
1332     gs_critsectGui->Enter();
1333 }
1334
1335 void wxMutexGuiLeaveImpl()
1336 {
1337     wxCriticalSectionLocker enter(*gs_critsectWaitingForGui);
1338
1339     if ( wxThread::IsMain() )
1340     {
1341         gs_bGuiOwnedByMainThread = false;
1342     }
1343     else
1344     {
1345         // decrement the number of threads waiting for GUI access now
1346         wxASSERT_MSG( gs_nWaitingForGui > 0,
1347                       wxT("calling wxMutexGuiLeave() without entering it first?") );
1348
1349         gs_nWaitingForGui--;
1350
1351         wxWakeUpMainThread();
1352     }
1353
1354     gs_critsectGui->Leave();
1355 }
1356
1357 void WXDLLIMPEXP_BASE wxMutexGuiLeaveOrEnter()
1358 {
1359     wxASSERT_MSG( wxThread::IsMain(),
1360                   wxT("only main thread may call wxMutexGuiLeaveOrEnter()!") );
1361
1362     wxCriticalSectionLocker enter(*gs_critsectWaitingForGui);
1363
1364     if ( gs_nWaitingForGui == 0 )
1365     {
1366         // no threads are waiting for GUI - so we may acquire the lock without
1367         // any danger (but only if we don't already have it)
1368         if ( !wxGuiOwnedByMainThread() )
1369         {
1370             gs_critsectGui->Enter();
1371
1372             gs_bGuiOwnedByMainThread = true;
1373         }
1374         //else: already have it, nothing to do
1375     }
1376     else
1377     {
1378         // some threads are waiting, release the GUI lock if we have it
1379         if ( wxGuiOwnedByMainThread() )
1380         {
1381             wxMutexGuiLeave();
1382         }
1383         //else: some other worker thread is doing GUI
1384     }
1385 }
1386
1387 bool WXDLLIMPEXP_BASE wxGuiOwnedByMainThread()
1388 {
1389     return gs_bGuiOwnedByMainThread;
1390 }
1391
1392 // wake up the main thread if it's in ::GetMessage()
1393 void WXDLLIMPEXP_BASE wxWakeUpMainThread()
1394 {
1395     // sending any message would do - hopefully WM_NULL is harmless enough
1396     if ( !::PostThreadMessage(gs_idMainThread, WM_NULL, 0, 0) )
1397     {
1398         // should never happen
1399         wxLogLastError(wxT("PostThreadMessage(WM_NULL)"));
1400     }
1401 }
1402
1403 bool WXDLLIMPEXP_BASE wxIsWaitingForThread()
1404 {
1405     return gs_waitingForThread;
1406 }
1407
1408 // ----------------------------------------------------------------------------
1409 // include common implementation code
1410 // ----------------------------------------------------------------------------
1411
1412 #include "wx/thrimpl.cpp"
1413
1414 #endif // wxUSE_THREADS