samples/thread/thread.cpp

   1 /////////////////////////////////////////////////////////////////////////////
   2 // Name:        thread.cpp
   3 // Purpose:     wxWidgets thread sample
   4 // Author:      Guilhem Lavaux, Vadim Zeitlin
   5 // Modified by:
   6 // Created:     06/16/98
   7 // RCS-ID:      $Id$
   8 // Copyright:   (c) 1998-2002 wxWidgets team
   9 // Licence:     wxWindows license
  10 /////////////////////////////////////////////////////////////////////////////
  11
  12 // For compilers that support precompilation, includes "wx/wx.h".
  13 #include "wx/wxprec.h"
  14
  15 #ifdef __BORLANDC__
  16     #pragma hdrstop
  17 #endif
  18
  19 #ifndef WX_PRECOMP
  20     #include "wx/wx.h"
  21 #endif
  22
  23 #if !wxUSE_THREADS
  24     #error "This sample requires thread support!"
  25 #endif // wxUSE_THREADS
  26
  27 #include "wx/thread.h"
  28 #include "wx/dynarray.h"
  29 #include "wx/numdlg.h"
  30
  31 #include "wx/progdlg.h"
  32
  33 #include "../sample.xpm"
  34
  35 // define this to use wxExecute in the exec tests, otherwise just use system
  36 #define USE_EXECUTE
  37
  38 #ifdef USE_EXECUTE
  39     #define EXEC(cmd) wxExecute((cmd), wxEXEC_SYNC)
  40 #else
  41     #define EXEC(cmd) system(cmd)
  42 #endif
  43
  44 class MyThread;
  45 WX_DEFINE_ARRAY_PTR(wxThread *, wxArrayThread);
  46
  47 // Define a new application type
  48 class MyApp : public wxApp
  49 {
  50 public:
  51     MyApp();
  52     virtual ~MyApp(){};
  53
  54     virtual bool OnInit();
  55
  56     // critical section protects access to all of the fields below
  57     wxCriticalSection m_critsect;
  58
  59     // all the threads currently alive - as soon as the thread terminates, it's
  60     // removed from the array
  61     wxArrayThread m_threads;
  62
  63     // semaphore used to wait for the threads to exit, see MyFrame::OnQuit()
  64     wxSemaphore m_semAllDone;
  65
  66     // indicates that we're shutting down and all threads should exit
  67     bool m_shuttingDown;
  68 };
  69
  70 // Create a new application object
  71 IMPLEMENT_APP(MyApp)
  72
  73 // Define a new frame type
  74 class MyFrame: public wxFrame
  75 {
  76 public:
  77     // ctor
  78     MyFrame(wxFrame *frame, const wxString& title, int x, int y, int w, int h);
  79     virtual ~MyFrame();
  80
  81     // this function is MT-safe, i.e. it can be called from worker threads
  82     // safely without any additional locking
  83     void LogThreadMessage(const wxString& text)
  84     {
  85         wxCriticalSectionLocker lock(m_csMessages);
  86         m_messages.push_back(text);
  87
  88         // as we effectively log the messages from the idle event handler,
  89         // ensure it's going to be called now that we have some messages to log
  90         wxWakeUpIdle();
  91     }
  92
  93     // accessors for MyWorkerThread (called in its context!)
  94     bool Cancelled();
  95
  96 private:
  97     // event handlers
  98     void OnQuit(wxCommandEvent& event);
  99     void OnClear(wxCommandEvent& event);
 100
 101     void OnStartThread(wxCommandEvent& event);
 102     void OnStartThreads(wxCommandEvent& event);
 103     void OnStopThread(wxCommandEvent& event);
 104     void OnPauseThread(wxCommandEvent& event);
 105     void OnResumeThread(wxCommandEvent& event);
 106
 107     void OnStartWorker(wxCommandEvent& event);
 108     void OnWorkerEvent(wxCommandEvent& event);
 109     void OnUpdateWorker(wxUpdateUIEvent& event);
 110
 111     void OnExecMain(wxCommandEvent& event);
 112     void OnExecThread(wxCommandEvent& event);
 113
 114     void OnShowCPUs(wxCommandEvent& event);
 115     void OnAbout(wxCommandEvent& event);
 116
 117     void OnIdle(wxIdleEvent &event);
 118
 119     // helper function - creates a new thread (but doesn't run it)
 120     MyThread *CreateThread();
 121
 122     // update display in our status bar: called during idle handling
 123     void UpdateThreadStatus();
 124
 125     // log the messages queued by LogThreadMessage()
 126     void DoLogThreadMessages();
 127
 128
 129     // just some place to put our messages in
 130     wxTextCtrl *m_txtctrl;
 131
 132     // the array of pending messages to be displayed and the critical section
 133     // protecting it
 134     wxArrayString m_messages;
 135     wxCriticalSection m_csMessages;
 136
 137     // remember the number of running threads and total number of threads
 138     size_t m_nRunning,
 139            m_nCount;
 140
 141     // the progress dialog which we show while worker thread is running
 142     wxProgressDialog *m_dlgProgress;
 143
 144     // was the worker thread cancelled by user?
 145     bool m_cancelled;
 146
 147     // protects m_cancelled
 148     wxCriticalSection m_critsectWork;
 149
 150     DECLARE_EVENT_TABLE()
 151 };
 152
 153 // ID for the menu commands
 154 enum
 155 {
 156     THREAD_QUIT  = wxID_EXIT,
 157     THREAD_ABOUT = wxID_ABOUT,
 158     THREAD_TEXT          = 101,
 159     THREAD_CLEAR,
 160     THREAD_START_THREAD  = 201,
 161     THREAD_START_THREADS,
 162     THREAD_STOP_THREAD,
 163     THREAD_PAUSE_THREAD,
 164     THREAD_RESUME_THREAD,
 165     THREAD_START_WORKER,
 166
 167     THREAD_EXEC_MAIN,
 168     THREAD_EXEC_THREAD,
 169
 170     THREAD_SHOWCPUS,
 171
 172     WORKER_EVENT    // this one gets sent from the worker thread
 173 };
 174
 175 // ----------------------------------------------------------------------------
 176 // GUI thread
 177 // ----------------------------------------------------------------------------
 178
 179 class MyThread : public wxThread
 180 {
 181 public:
 182     MyThread(MyFrame *frame);
 183     virtual ~MyThread();
 184
 185     // thread execution starts here
 186     virtual void *Entry();
 187
 188     // write something to the text control in the main frame
 189     void WriteText(const wxString& text)
 190     {
 191         m_frame->LogThreadMessage(text);
 192     }
 193
 194 public:
 195     unsigned m_count;
 196     MyFrame *m_frame;
 197 };
 198
 199 MyThread::MyThread(MyFrame *frame)
 200         : wxThread()
 201 {
 202     m_count = 0;
 203     m_frame = frame;
 204 }
 205
 206 MyThread::~MyThread()
 207 {
 208     wxCriticalSectionLocker locker(wxGetApp().m_critsect);
 209
 210     wxArrayThread& threads = wxGetApp().m_threads;
 211     threads.Remove(this);
 212
 213     if ( threads.IsEmpty() )
 214     {
 215         // signal the main thread that there are no more threads left if it is
 216         // waiting for us
 217         if ( wxGetApp().m_shuttingDown )
 218         {
 219             wxGetApp().m_shuttingDown = false;
 220
 221             wxGetApp().m_semAllDone.Post();
 222         }
 223     }
 224 }
 225
 226 void *MyThread::Entry()
 227 {
 228     wxString text;
 229
 230     text.Printf(wxT("Thread 0x%lx started (priority = %u).\n"),
 231                 GetId(), GetPriority());
 232     WriteText(text);
 233     // wxLogMessage(text); -- test wxLog thread safeness
 234
 235     for ( m_count = 0; m_count < 10; m_count++ )
 236     {
 237         // check if the application is shutting down: in this case all threads
 238         // should stop a.s.a.p.
 239         {
 240             wxCriticalSectionLocker locker(wxGetApp().m_critsect);
 241             if ( wxGetApp().m_shuttingDown )
 242                 return NULL;
 243         }
 244
 245         // check if just this thread was asked to exit
 246         if ( TestDestroy() )
 247             break;
 248
 249         text.Printf(wxT("[%u] Thread 0x%lx here.\n"), m_count, GetId());
 250         WriteText(text);
 251
 252         // wxSleep() can't be called from non-GUI thread!
 253         wxThread::Sleep(1000);
 254     }
 255
 256     text.Printf(wxT("Thread 0x%lx finished.\n"), GetId());
 257     WriteText(text);
 258     // wxLogMessage(text); -- test wxLog thread safeness
 259
 260     return NULL;
 261 }
 262
 263 // ----------------------------------------------------------------------------
 264 // worker thread
 265 // ----------------------------------------------------------------------------
 266
 267 class MyWorkerThread : public wxThread
 268 {
 269 public:
 270     MyWorkerThread(MyFrame *frame);
 271
 272     // thread execution starts here
 273     virtual void *Entry();
 274
 275     // called when the thread exits - whether it terminates normally or is
 276     // stopped with Delete() (but not when it is Kill()ed!)
 277     virtual void OnExit();
 278
 279 public:
 280     MyFrame *m_frame;
 281     unsigned m_count;
 282 };
 283
 284 MyWorkerThread::MyWorkerThread(MyFrame *frame)
 285         : wxThread()
 286 {
 287     m_frame = frame;
 288     m_count = 0;
 289 }
 290
 291 void MyWorkerThread::OnExit()
 292 {
 293 }
 294
 295 void *MyWorkerThread::Entry()
 296 {
 297     for ( m_count = 0; !m_frame->Cancelled() && (m_count < 100); m_count++ )
 298     {
 299         // check if we were asked to exit
 300         if ( TestDestroy() )
 301             break;
 302
 303         // create any type of command event here
 304         wxCommandEvent event( wxEVT_COMMAND_MENU_SELECTED, WORKER_EVENT );
 305         event.SetInt( m_count );
 306
 307         // send in a thread-safe way
 308         wxQueueEvent( m_frame, new wxCommandEvent(event) );
 309
 310         wxMilliSleep(200);
 311     }
 312
 313     wxCommandEvent event( wxEVT_COMMAND_MENU_SELECTED, WORKER_EVENT );
 314     event.SetInt(-1); // that's all
 315     wxQueueEvent( m_frame, new wxCommandEvent(event) );
 316
 317     return NULL;
 318 }
 319
 320 // ----------------------------------------------------------------------------
 321 // a thread which simply calls wxExecute
 322 // ----------------------------------------------------------------------------
 323
 324 class MyExecThread : public wxThread
 325 {
 326 public:
 327     MyExecThread(const wxChar *command) : wxThread(wxTHREAD_JOINABLE),
 328                                           m_command(command)
 329     {
 330         Create();
 331     }
 332
 333     virtual ExitCode Entry()
 334     {
 335         return wxUIntToPtr(EXEC(m_command));
 336     }
 337
 338 private:
 339     wxString m_command;
 340 };
 341
 342 // ----------------------------------------------------------------------------
 343 // implementation
 344 // ----------------------------------------------------------------------------
 345
 346 BEGIN_EVENT_TABLE(MyFrame, wxFrame)
 347     EVT_MENU(THREAD_QUIT, MyFrame::OnQuit)
 348     EVT_MENU(THREAD_CLEAR, MyFrame::OnClear)
 349     EVT_MENU(THREAD_START_THREAD, MyFrame::OnStartThread)
 350     EVT_MENU(THREAD_START_THREADS, MyFrame::OnStartThreads)
 351     EVT_MENU(THREAD_STOP_THREAD, MyFrame::OnStopThread)
 352     EVT_MENU(THREAD_PAUSE_THREAD, MyFrame::OnPauseThread)
 353     EVT_MENU(THREAD_RESUME_THREAD, MyFrame::OnResumeThread)
 354
 355     EVT_MENU(THREAD_EXEC_MAIN, MyFrame::OnExecMain)
 356     EVT_MENU(THREAD_EXEC_THREAD, MyFrame::OnExecThread)
 357
 358     EVT_MENU(THREAD_SHOWCPUS, MyFrame::OnShowCPUs)
 359     EVT_MENU(THREAD_ABOUT, MyFrame::OnAbout)
 360
 361     EVT_UPDATE_UI(THREAD_START_WORKER, MyFrame::OnUpdateWorker)
 362     EVT_MENU(THREAD_START_WORKER, MyFrame::OnStartWorker)
 363     EVT_MENU(WORKER_EVENT, MyFrame::OnWorkerEvent)
 364
 365     EVT_IDLE(MyFrame::OnIdle)
 366 END_EVENT_TABLE()
 367
 368 MyApp::MyApp()
 369 {
 370     m_shuttingDown = false;
 371 }
 372
 373 // `Main program' equivalent, creating windows and returning main app frame
 374 bool MyApp::OnInit()
 375 {
 376     if ( !wxApp::OnInit() )
 377         return false;
 378
 379     // uncomment this to get some debugging messages from the trace code
 380     // on the console (or just set WXTRACE env variable to include "thread")
 381     //wxLog::AddTraceMask("thread");
 382
 383     // Create the main frame window
 384     MyFrame *frame = new MyFrame((wxFrame *)NULL, _T("wxWidgets threads sample"),
 385                                  50, 50, 450, 340);
 386
 387     // Make a menubar
 388     wxMenuBar *menuBar = new wxMenuBar;
 389
 390     wxMenu *menuFile = new wxMenu;
 391     menuFile->Append(THREAD_CLEAR, _T("&Clear log\tCtrl-L"));
 392     menuFile->AppendSeparator();
 393     menuFile->Append(THREAD_QUIT, _T("E&xit\tAlt-X"));
 394     menuBar->Append(menuFile, _T("&File"));
 395
 396     wxMenu *menuThread = new wxMenu;
 397     menuThread->Append(THREAD_START_THREAD, _T("&Start a new thread\tCtrl-N"));
 398     menuThread->Append(THREAD_START_THREADS, _T("Start &many threads at once"));
 399     menuThread->Append(THREAD_STOP_THREAD, _T("S&top a running thread\tCtrl-S"));
 400     menuThread->AppendSeparator();
 401     menuThread->Append(THREAD_PAUSE_THREAD, _T("&Pause a running thread\tCtrl-P"));
 402     menuThread->Append(THREAD_RESUME_THREAD, _T("&Resume suspended thread\tCtrl-R"));
 403     menuThread->AppendSeparator();
 404     menuThread->Append(THREAD_START_WORKER, _T("Start &worker thread\tCtrl-W"));
 405     menuBar->Append(menuThread, _T("&Thread"));
 406
 407     wxMenu *menuExec = new wxMenu;
 408     menuExec->Append(THREAD_EXEC_MAIN, _T("&Launch a program from main thread\tF5"));
 409     menuExec->Append(THREAD_EXEC_THREAD, _T("L&aunch a program from a thread\tCtrl-F5"));
 410     menuBar->Append(menuExec, _T("&Execute"));
 411
 412     wxMenu *menuHelp = new wxMenu;
 413     menuHelp->Append(THREAD_SHOWCPUS, _T("&Show CPU count"));
 414     menuHelp->AppendSeparator();
 415     menuHelp->Append(THREAD_ABOUT, _T("&About..."));
 416     menuBar->Append(menuHelp, _T("&Help"));
 417
 418     frame->SetMenuBar(menuBar);
 419
 420     // Show the frame
 421     frame->Show(true);
 422
 423     SetTopWindow(frame);
 424
 425     return true;
 426 }
 427
 428 // My frame constructor
 429 MyFrame::MyFrame(wxFrame *frame, const wxString& title,
 430                  int x, int y, int w, int h)
 431        : wxFrame(frame, wxID_ANY, title, wxPoint(x, y), wxSize(w, h))
 432 {
 433     SetIcon(wxIcon(sample_xpm));
 434
 435     m_nRunning = m_nCount = 0;
 436
 437     m_dlgProgress = (wxProgressDialog *)NULL;
 438
 439 #if wxUSE_STATUSBAR
 440     CreateStatusBar(2);
 441 #endif // wxUSE_STATUSBAR
 442
 443     m_txtctrl = new wxTextCtrl(this, wxID_ANY, _T(""), wxPoint(0, 0), wxSize(0, 0),
 444                                wxTE_MULTILINE | wxTE_READONLY);
 445
 446 }
 447
 448 MyFrame::~MyFrame()
 449 {
 450     // NB: although the OS will terminate all the threads anyhow when the main
 451     //     one exits, it's good practice to do it ourselves -- even if it's not
 452     //     completely trivial in this example
 453
 454     // tell all the threads to terminate: note that they can't terminate while
 455     // we're deleting them because they will block in their OnExit() -- this is
 456     // important as otherwise we might access invalid array elements
 457
 458     {
 459         wxCriticalSectionLocker locker(wxGetApp().m_critsect);
 460
 461         // check if we have any threads running first
 462         const wxArrayThread& threads = wxGetApp().m_threads;
 463         size_t count = threads.GetCount();
 464
 465         if ( !count )
 466             return;
 467
 468         // set the flag indicating that all threads should exit
 469         wxGetApp().m_shuttingDown = true;
 470     }
 471
 472     // now wait for them to really terminate
 473     wxGetApp().m_semAllDone.Wait();
 474 }
 475
 476 MyThread *MyFrame::CreateThread()
 477 {
 478     MyThread *thread = new MyThread(this);
 479
 480     if ( thread->Create() != wxTHREAD_NO_ERROR )
 481     {
 482         wxLogError(wxT("Can't create thread!"));
 483     }
 484
 485     wxCriticalSectionLocker enter(wxGetApp().m_critsect);
 486     wxGetApp().m_threads.Add(thread);
 487
 488     return thread;
 489 }
 490
 491 void MyFrame::OnStartThreads(wxCommandEvent& WXUNUSED(event) )
 492 {
 493     static long s_num;
 494
 495     s_num = wxGetNumberFromUser(_T("How many threads to start: "), _T(""),
 496                                 _T("wxThread sample"), s_num, 1, 10000, this);
 497     if ( s_num == -1 )
 498     {
 499         s_num = 10;
 500
 501         return;
 502     }
 503
 504     unsigned count = unsigned(s_num), n;
 505
 506     wxArrayThread threads;
 507
 508     // first create them all...
 509     for ( n = 0; n < count; n++ )
 510     {
 511         wxThread *thr = CreateThread();
 512
 513         // we want to show the effect of SetPriority(): the first thread will
 514         // have the lowest priority, the second - the highest, all the rest
 515         // the normal one
 516         if ( n == 0 )
 517             thr->SetPriority(WXTHREAD_MIN_PRIORITY);
 518         else if ( n == 1 )
 519             thr->SetPriority(WXTHREAD_MAX_PRIORITY);
 520         else
 521             thr->SetPriority(WXTHREAD_DEFAULT_PRIORITY);
 522
 523         threads.Add(thr);
 524     }
 525
 526 #if wxUSE_STATUSBAR
 527     wxString msg;
 528     msg.Printf(wxT("%d new threads created."), count);
 529     SetStatusText(msg, 1);
 530 #endif // wxUSE_STATUSBAR
 531
 532     // ...and then start them
 533     for ( n = 0; n < count; n++ )
 534     {
 535         threads[n]->Run();
 536     }
 537 }
 538
 539 void MyFrame::OnStartThread(wxCommandEvent& WXUNUSED(event) )
 540 {
 541     MyThread *thread = CreateThread();
 542
 543     if ( thread->Run() != wxTHREAD_NO_ERROR )
 544     {
 545         wxLogError(wxT("Can't start thread!"));
 546     }
 547
 548 #if wxUSE_STATUSBAR
 549     SetStatusText(_T("New thread started."), 1);
 550 #endif // wxUSE_STATUSBAR
 551 }
 552
 553 void MyFrame::OnStopThread(wxCommandEvent& WXUNUSED(event) )
 554 {
 555     wxCriticalSectionLocker enter(wxGetApp().m_critsect);
 556
 557     // stop the last thread
 558     if ( wxGetApp().m_threads.IsEmpty() )
 559     {
 560         wxLogError(wxT("No thread to stop!"));
 561     }
 562     else
 563     {
 564         wxGetApp().m_threads.Last()->Delete();
 565
 566 #if wxUSE_STATUSBAR
 567         SetStatusText(_T("Last thread stopped."), 1);
 568 #endif // wxUSE_STATUSBAR
 569     }
 570 }
 571
 572 void MyFrame::OnResumeThread(wxCommandEvent& WXUNUSED(event) )
 573 {
 574     wxCriticalSectionLocker enter(wxGetApp().m_critsect);
 575
 576     // resume first suspended thread
 577     size_t n = 0, count = wxGetApp().m_threads.Count();
 578     while ( n < count && !wxGetApp().m_threads[n]->IsPaused() )
 579         n++;
 580
 581     if ( n == count )
 582     {
 583         wxLogError(wxT("No thread to resume!"));
 584     }
 585     else
 586     {
 587         wxGetApp().m_threads[n]->Resume();
 588
 589 #if wxUSE_STATUSBAR
 590         SetStatusText(_T("Thread resumed."), 1);
 591 #endif // wxUSE_STATUSBAR
 592     }
 593 }
 594
 595 void MyFrame::OnPauseThread(wxCommandEvent& WXUNUSED(event) )
 596 {
 597     wxCriticalSectionLocker enter(wxGetApp().m_critsect);
 598
 599     // pause last running thread
 600     int n = wxGetApp().m_threads.Count() - 1;
 601     while ( n >= 0 && !wxGetApp().m_threads[n]->IsRunning() )
 602         n--;
 603
 604     if ( n < 0 )
 605     {
 606         wxLogError(wxT("No thread to pause!"));
 607     }
 608     else
 609     {
 610         wxGetApp().m_threads[n]->Pause();
 611
 612 #if wxUSE_STATUSBAR
 613         SetStatusText(_T("Thread paused."), 1);
 614 #endif // wxUSE_STATUSBAR
 615     }
 616 }
 617
 618 void MyFrame::OnIdle(wxIdleEvent& event)
 619 {
 620     DoLogThreadMessages();
 621
 622     UpdateThreadStatus();
 623
 624     event.Skip();
 625 }
 626
 627 void MyFrame::DoLogThreadMessages()
 628 {
 629     wxCriticalSectionLocker lock(m_csMessages);
 630
 631     const size_t count = m_messages.size();
 632     for ( size_t n = 0; n < count; n++ )
 633     {
 634         m_txtctrl->AppendText(m_messages[n]);
 635     }
 636
 637     m_messages.clear();
 638 }
 639
 640 void MyFrame::UpdateThreadStatus()
 641 {
 642     wxCriticalSectionLocker enter(wxGetApp().m_critsect);
 643
 644     // update the counts of running/total threads
 645     size_t nRunning = 0,
 646            nCount = wxGetApp().m_threads.Count();
 647     for ( size_t n = 0; n < nCount; n++ )
 648     {
 649         if ( wxGetApp().m_threads[n]->IsRunning() )
 650             nRunning++;
 651     }
 652
 653     if ( nCount != m_nCount || nRunning != m_nRunning )
 654     {
 655         m_nRunning = nRunning;
 656         m_nCount = nCount;
 657
 658         wxLogStatus(this, wxT("%u threads total, %u running."), unsigned(nCount), unsigned(nRunning));
 659     }
 660     //else: avoid flicker - don't print anything
 661 }
 662
 663 void MyFrame::OnQuit(wxCommandEvent& WXUNUSED(event) )
 664 {
 665     Close(true);
 666 }
 667
 668 void MyFrame::OnExecMain(wxCommandEvent& WXUNUSED(event))
 669 {
 670     wxLogMessage(wxT("The exit code from the main program is %ld"),
 671                  EXEC(_T("/bin/echo \"main program\"")));
 672 }
 673
 674 void MyFrame::OnExecThread(wxCommandEvent& WXUNUSED(event))
 675 {
 676     MyExecThread thread(wxT("/bin/echo \"child thread\""));
 677     thread.Run();
 678
 679     wxLogMessage(wxT("The exit code from a child thread is %ld"),
 680                  (long)wxPtrToUInt(thread.Wait()));
 681 }
 682
 683 void MyFrame::OnShowCPUs(wxCommandEvent& WXUNUSED(event))
 684 {
 685     wxString msg;
 686
 687     int nCPUs = wxThread::GetCPUCount();
 688     switch ( nCPUs )
 689     {
 690         case -1:
 691             msg = _T("Unknown number of CPUs");
 692             break;
 693
 694         case 0:
 695             msg = _T("WARNING: you're running without any CPUs!");
 696             break;
 697
 698         case 1:
 699             msg = _T("This system only has one CPU.");
 700             break;
 701
 702         default:
 703             msg.Printf(wxT("This system has %d CPUs"), nCPUs);
 704     }
 705
 706     wxLogMessage(msg);
 707 }
 708
 709 void MyFrame::OnAbout(wxCommandEvent& WXUNUSED(event) )
 710 {
 711     wxMessageDialog dialog(this,
 712                            _T("wxWidgets multithreaded application sample\n")
 713                            _T("(c) 1998 Julian Smart, Guilhem Lavaux\n")
 714                            _T("(c) 1999 Vadim Zeitlin\n")
 715                            _T("(c) 2000 Robert Roebling"),
 716                            _T("About wxThread sample"),
 717                            wxOK | wxICON_INFORMATION);
 718
 719     dialog.ShowModal();
 720 }
 721
 722 void MyFrame::OnClear(wxCommandEvent& WXUNUSED(event))
 723 {
 724     m_txtctrl->Clear();
 725 }
 726
 727 void MyFrame::OnUpdateWorker(wxUpdateUIEvent& event)
 728 {
 729     event.Enable( m_dlgProgress == NULL );
 730 }
 731
 732 void MyFrame::OnStartWorker(wxCommandEvent& WXUNUSED(event))
 733 {
 734     MyWorkerThread *thread = new MyWorkerThread(this);
 735
 736     if ( thread->Create() != wxTHREAD_NO_ERROR )
 737     {
 738         wxLogError(wxT("Can't create thread!"));
 739         return;
 740     }
 741
 742     m_dlgProgress = new wxProgressDialog
 743                         (
 744                          _T("Progress dialog"),
 745                          _T("Wait until the thread terminates or press [Cancel]"),
 746                          100,
 747                          this,
 748                          wxPD_CAN_ABORT |
 749                          wxPD_APP_MODAL |
 750                          wxPD_ELAPSED_TIME |
 751                          wxPD_ESTIMATED_TIME |
 752                          wxPD_REMAINING_TIME
 753                         );
 754
 755     // thread is not running yet, no need for crit sect
 756     m_cancelled = false;
 757
 758     thread->Run();
 759 }
 760
 761 void MyFrame::OnWorkerEvent(wxCommandEvent& event)
 762 {
 763     int n = event.GetInt();
 764     if ( n == -1 )
 765     {
 766         m_dlgProgress->Destroy();
 767         m_dlgProgress = (wxProgressDialog *)NULL;
 768
 769         // the dialog is aborted because the event came from another thread, so
 770         // we may need to wake up the main event loop for the dialog to be
 771         // really closed
 772         wxWakeUpIdle();
 773     }
 774     else
 775     {
 776         if ( !m_dlgProgress->Update(n) )
 777         {
 778             wxCriticalSectionLocker lock(m_critsectWork);
 779
 780             m_cancelled = true;
 781         }
 782     }
 783 }
 784
 785 bool MyFrame::Cancelled()
 786 {
 787     wxCriticalSectionLocker lock(m_critsectWork);
 788
 789     return m_cancelled;
 790 }