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VC++ compilation correction; doc file corrections
[wxWidgets.git] / src / msw / thread.cpp
diff --git a/src/msw/thread.cpp b/src/msw/thread.cpp
index 0832f9a2b7042b711709158923e26998bebc299a..eb0f663724caeb6d0ac08ceb1557c204a1c84545 100644 (file)
--- a/src/msw/thread.cpp
+++ b/src/msw/thread.cpp
@@ -2,396 +2,614 @@
 // Name:        thread.cpp
 // Purpose:     wxThread Implementation
 // Author:      Original from Wolfram Gloger/Guilhem Lavaux
 // Name:        thread.cpp
 // Purpose:     wxThread Implementation
 // Author:      Original from Wolfram Gloger/Guilhem Lavaux
-// Modified by:
+// Modified by: Vadim Zeitlin to make it work :-)
 // Created:     04/22/98
 // RCS-ID:      $Id$
 // Created:     04/22/98
 // RCS-ID:      $Id$
-// Copyright:   (c) Wolfram Gloger (1996, 1997); Guilhem Lavaux (1998)
+// Copyright:   (c) Wolfram Gloger (1996, 1997); Guilhem Lavaux (1998),
+//                  Vadim Zeitlin (1999)
 // Licence:     wxWindows licence
 /////////////////////////////////////////////////////////////////////////////
 
 #ifdef __GNUG__
 // Licence:     wxWindows licence
 /////////////////////////////////////////////////////////////////////////////
 
 #ifdef __GNUG__
-#pragma implementation "thread.h"
+    #pragma implementation "thread.h"
 #endif
 
 #endif
 
-// this is here to regen the precompiled header in the ide compile otherwise the
-// compiler crashes in vc5 (nfi why)
+// ----------------------------------------------------------------------------
+// headers
+// ----------------------------------------------------------------------------
+
 // For compilers that support precompilation, includes "wx.h".
 #include "wx/wxprec.h"
 
 #if defined(__BORLANDC__)
 // For compilers that support precompilation, includes "wx.h".
 #include "wx/wxprec.h"
 
 #if defined(__BORLANDC__)
-#pragma hdrstop
+    #pragma hdrstop
 #endif
 
 #ifndef WX_PRECOMP
 #endif
 
 #ifndef WX_PRECOMP
-#include "wx/wx.h"
+    #include "wx/wx.h"
 #endif
 
 #endif
 
+#if wxUSE_THREADS
+
 #include <stdio.h>
 
 #include <windows.h>
 #include <stdio.h>
 
 #include <windows.h>
+
 #include "wx/module.h"
 #include "wx/thread.h"
 
 #include "wx/module.h"
 #include "wx/thread.h"
 
-enum thread_state {
-  STATE_IDLE = 0,
-  STATE_RUNNING,
-  STATE_CANCELED,
-  STATE_EXITED
+enum thread_state
+{
+    STATE_IDLE = 0,
+    STATE_RUNNING,
+    STATE_PAUSED,
+    STATE_CANCELED,
+    STATE_EXITED
 };
 
 };
 
-/////////////////////////////////////////////////////////////////////////////
-// Static variables
-/////////////////////////////////////////////////////////////////////////////
+// ----------------------------------------------------------------------------
+// static variables
+// ----------------------------------------------------------------------------
 
 
-static HANDLE p_mainid;
-wxMutex *wxMainMutex; // controls access to all GUI functions
+// id of the main thread - the one which can call GUI functions without first
+// calling wxMutexGuiEnter()
+static DWORD s_idMainThread = 0;
 
 
-/////////////////////////////////////////////////////////////////////////////
-// Windows implementation
-/////////////////////////////////////////////////////////////////////////////
+// if it's FALSE, some secondary thread is holding the GUI lock
+static bool s_bGuiOwnedByMainThread = TRUE;
 
 
-class wxMutexInternal {
+// critical section which controls access to all GUI functions: any secondary
+// thread (i.e. except the main one) must enter this crit section before doing
+// any GUI calls
+static wxCriticalSection *s_critsectGui = NULL;
+
+// critical section which protects s_nWaitingForGui variable
+static wxCriticalSection *s_critsectWaitingForGui = NULL;
+
+// number of threads waiting for GUI in wxMutexGuiEnter()
+static size_t s_nWaitingForGui = 0;
+
+// ============================================================================
+// Windows implementation of thread classes
+// ============================================================================
+
+// ----------------------------------------------------------------------------
+// wxMutex implementation
+// ----------------------------------------------------------------------------
+class wxMutexInternal
+{
 public:
 public:
-  HANDLE p_mutex;
+    HANDLE p_mutex;
 };
 
 wxMutex::wxMutex()
 {
 };
 
 wxMutex::wxMutex()
 {
-  p_internal = new wxMutexInternal;
-  p_internal->p_mutex = CreateMutex(NULL, FALSE, NULL);
-  if ( !p_internal->p_mutex )
-  {
-    wxLogSysError(_("Can not create mutex."));
-  }
+    p_internal = new wxMutexInternal;
+    p_internal->p_mutex = CreateMutex(NULL, FALSE, NULL);
+    if ( !p_internal->p_mutex )
+    {
+        wxLogSysError(_("Can not create mutex."));
+    }
 
 
-  m_locked = 0;
+    m_locked = 0;
 }
 
 wxMutex::~wxMutex()
 {
 }
 
 wxMutex::~wxMutex()
 {
-  if (m_locked > 0)
-    wxLogDebug("Warning: freeing a locked mutex (%d locks).", m_locked);
-  CloseHandle(p_internal->p_mutex);
+    if (m_locked > 0)
+        wxLogDebug("Warning: freeing a locked mutex (%d locks).", m_locked);
+    CloseHandle(p_internal->p_mutex);
 }
 
 wxMutexError wxMutex::Lock()
 {
 }
 
 wxMutexError wxMutex::Lock()
 {
-  DWORD ret;
+    DWORD ret;
 
 
-  ret = WaitForSingleObject(p_internal->p_mutex, INFINITE);
-  if (ret == WAIT_ABANDONED)
-    return wxMUTEX_BUSY;
+    ret = WaitForSingleObject(p_internal->p_mutex, INFINITE);
+    switch ( ret )
+    {
+        case WAIT_ABANDONED:
+            return wxMUTEX_BUSY;
+
+        case WAIT_OBJECT_0:
+            // ok
+            break;
 
 
-  m_locked++;
-  return wxMUTEX_NO_ERROR;
+        case WAIT_FAILED:
+            wxLogSysError(_("Couldn't acquire a mutex lock"));
+            return wxMUTEX_MISC_ERROR;
+
+        case WAIT_TIMEOUT:
+        default:
+            wxFAIL_MSG("impossible return value in wxMutex::Lock");
+    }
+
+    m_locked++;
+    return wxMUTEX_NO_ERROR;
 }
 
 wxMutexError wxMutex::TryLock()
 {
 }
 
 wxMutexError wxMutex::TryLock()
 {
-  DWORD ret;
+    DWORD ret;
 
 
-  ret = WaitForSingleObject(p_internal->p_mutex, 0);
-  if (ret == WAIT_TIMEOUT || ret == WAIT_ABANDONED)
-    return wxMUTEX_BUSY;
+    ret = WaitForSingleObject(p_internal->p_mutex, 0);
+    if (ret == WAIT_TIMEOUT || ret == WAIT_ABANDONED)
+        return wxMUTEX_BUSY;
 
 
-  m_locked++;
-  return wxMUTEX_NO_ERROR;
+    m_locked++;
+    return wxMUTEX_NO_ERROR;
 }
 
 wxMutexError wxMutex::Unlock()
 {
 }
 
 wxMutexError wxMutex::Unlock()
 {
-  if (m_locked > 0)
-    m_locked--;
+    if (m_locked > 0)
+        m_locked--;
 
 
-  BOOL ret = ReleaseMutex(p_internal->p_mutex);
-  if ( ret != 0 )
-  {
-      wxLogSysError(_("Couldn't release a mutex"));
-      return wxMUTEX_MISC_ERROR;
-  }
+    BOOL ret = ReleaseMutex(p_internal->p_mutex);
+    if ( ret == 0 )
+    {
+        wxLogSysError(_("Couldn't release a mutex"));
+        return wxMUTEX_MISC_ERROR;
+    }
 
 
-  return wxMUTEX_NO_ERROR;
+    return wxMUTEX_NO_ERROR;
 }
 
 }
 
-class wxConditionInternal {
+// ----------------------------------------------------------------------------
+// wxCondition implementation
+// ----------------------------------------------------------------------------
+
+class wxConditionInternal
+{
 public:
 public:
-  HANDLE event;
-  int waiters;
+    HANDLE event;
+    int waiters;
 };
 
 wxCondition::wxCondition()
 {
 };
 
 wxCondition::wxCondition()
 {
-  p_internal = new wxConditionInternal;
-  p_internal->event = CreateEvent(NULL, FALSE, FALSE, NULL);
-  if ( !p_internal->event )
-  {
-    wxLogSysError(_("Can not create event object."));
-  }
+    p_internal = new wxConditionInternal;
+    p_internal->event = CreateEvent(NULL, FALSE, FALSE, NULL);
+    if ( !p_internal->event )
+    {
+        wxLogSysError(_("Can not create event object."));
+    }
 
 
-  p_internal->waiters = 0;
+    p_internal->waiters = 0;
 }
 
 wxCondition::~wxCondition()
 {
 }
 
 wxCondition::~wxCondition()
 {
-  CloseHandle(p_internal->event);
+    CloseHandle(p_internal->event);
 }
 
 void wxCondition::Wait(wxMutex& mutex)
 {
 }
 
 void wxCondition::Wait(wxMutex& mutex)
 {
-  mutex.Unlock();
-  p_internal->waiters++;
-  WaitForSingleObject(p_internal->event, INFINITE);
-  p_internal->waiters--;
-  mutex.Lock();
+    mutex.Unlock();
+    p_internal->waiters++;
+    WaitForSingleObject(p_internal->event, INFINITE);
+    p_internal->waiters--;
+    mutex.Lock();
 }
 
 }
 
-bool wxCondition::Wait(wxMutex& mutex, unsigned long sec,
+bool wxCondition::Wait(wxMutex& mutex,
+                       unsigned long sec,
                        unsigned long nsec)
 {
                        unsigned long nsec)
 {
-  DWORD ret;
+    DWORD ret;
 
 
-  mutex.Unlock();
-  p_internal->waiters++;
-  ret = WaitForSingleObject(p_internal->event, (sec*1000)+(nsec/1000000));
-  p_internal->waiters--;
-  mutex.Lock();
+    mutex.Unlock();
+    p_internal->waiters++;
+    ret = WaitForSingleObject(p_internal->event, (sec*1000)+(nsec/1000000));
+    p_internal->waiters--;
+    mutex.Lock();
 
 
-  return (ret != WAIT_TIMEOUT);
+    return (ret != WAIT_TIMEOUT);
 }
 
 void wxCondition::Signal()
 {
 }
 
 void wxCondition::Signal()
 {
-  SetEvent(p_internal->event);
+    SetEvent(p_internal->event);
 }
 
 void wxCondition::Broadcast()
 {
 }
 
 void wxCondition::Broadcast()
 {
-  int i;
+    int i;
 
 
-  for (i=0;i<p_internal->waiters;i++)
-  {
-    if ( SetEvent(p_internal->event) == 0 )
+    for (i=0;i<p_internal->waiters;i++)
     {
     {
-        wxLogSysError(_("Couldn't change the state of event object."));
+        if ( SetEvent(p_internal->event) == 0 )
+        {
+            wxLogSysError(_("Couldn't change the state of event object."));
+        }
     }
     }
-  }
 }
 
 }
 
-class wxThreadInternal {
+// ----------------------------------------------------------------------------
+// wxCriticalSection implementation
+// ----------------------------------------------------------------------------
+
+class wxCriticalSectionInternal
+{
 public:
 public:
-  static DWORD WinThreadStart(LPVOID arg);
+    // init the critical section object
+    wxCriticalSectionInternal()
+        { ::InitializeCriticalSection(&m_data); }
+
+    // implicit cast to the associated data
+    operator CRITICAL_SECTION *() { return &m_data; }
 
 
-  HANDLE thread_id;
-  int state;
-  int prio, defer;
-  DWORD tid;
+    // free the associated ressources
+    ~wxCriticalSectionInternal()
+        { ::DeleteCriticalSection(&m_data); }
+
+private:
+    CRITICAL_SECTION m_data;
 };
 
 };
 
-DWORD wxThreadInternal::WinThreadStart(LPVOID arg)
+wxCriticalSection::wxCriticalSection()
+{
+    m_critsect = new wxCriticalSectionInternal;
+}
+
+wxCriticalSection::~wxCriticalSection()
+{
+    delete m_critsect;
+}
+
+void wxCriticalSection::Enter()
+{
+    ::EnterCriticalSection(*m_critsect);
+}
+
+void wxCriticalSection::Leave()
+{
+    ::LeaveCriticalSection(*m_critsect);
+}
+
+// ----------------------------------------------------------------------------
+// wxThread implementation
+// ----------------------------------------------------------------------------
+
+class wxThreadInternal
 {
 {
-  wxThread *ptr = (wxThread *)arg;
-  DWORD ret;
+public:
+    static DWORD WinThreadStart(wxThread *thread);
+
+    HANDLE       hThread;
+    thread_state state;
+    int          prio, defer;
+    DWORD        tid;
+};
 
 
-  ret = (DWORD)ptr->Entry();
-  ptr->p_internal->state = STATE_EXITED;
+DWORD wxThreadInternal::WinThreadStart(wxThread *thread)
+{
+    DWORD ret = (DWORD)thread->Entry();
+    thread->p_internal->state = STATE_EXITED;
+    thread->OnExit();
 
 
-  return ret;
+    return ret;
 }
 
 wxThreadError wxThread::Create()
 {
 }
 
 wxThreadError wxThread::Create()
 {
-  int prio = p_internal->prio;
-
-  p_internal->thread_id = CreateThread(NULL, 0,
-                   (LPTHREAD_START_ROUTINE)wxThreadInternal::WinThreadStart,
-                   (void *)this, CREATE_SUSPENDED, &p_internal->tid);
-
-  if ( p_internal->thread_id == NULL )
-  {
-    wxLogSysError(_("Can't create thread"));
-    return wxTHREAD_NO_RESOURCE;
-  }
-
-  int win_prio;
-  if (prio <= 20)
-    win_prio = THREAD_PRIORITY_LOWEST;
-  else if (prio <= 40)
-    win_prio = THREAD_PRIORITY_BELOW_NORMAL;
-  else if (prio <= 60)
-    win_prio = THREAD_PRIORITY_NORMAL;
-  else if (prio <= 80)
-    win_prio = THREAD_PRIORITY_ABOVE_NORMAL;
-  else if (prio <= 100)
-    win_prio = THREAD_PRIORITY_HIGHEST;
-  else
-  {
-    wxFAIL_MSG("invalid value of thread priority parameter");
-    win_prio = THREAD_PRIORITY_NORMAL;
-  }
-
-  SetThreadPriority(p_internal->thread_id, win_prio);
-
-  ResumeThread(p_internal->thread_id);
-  p_internal->state = STATE_RUNNING;
- 
-  return wxTHREAD_NO_ERROR;
+    p_internal->hThread = ::CreateThread
+                          (
+                            NULL,               // default security
+                            0,                  // default stack size
+                            (LPTHREAD_START_ROUTINE)
+                            wxThreadInternal::WinThreadStart, // entry point
+                            (void *)this,       // parameter
+                            CREATE_SUSPENDED,   // flags
+                            &p_internal->tid    // [out] thread id
+                          );
+
+    if ( p_internal->hThread == NULL )
+    {
+        wxLogSysError(_("Can't create thread"));
+        return wxTHREAD_NO_RESOURCE;
+    }
+
+    int win_prio, prio = p_internal->prio;
+    if (prio <= 20)
+        win_prio = THREAD_PRIORITY_LOWEST;
+    else if (prio <= 40)
+        win_prio = THREAD_PRIORITY_BELOW_NORMAL;
+    else if (prio <= 60)
+        win_prio = THREAD_PRIORITY_NORMAL;
+    else if (prio <= 80)
+        win_prio = THREAD_PRIORITY_ABOVE_NORMAL;
+    else if (prio <= 100)
+        win_prio = THREAD_PRIORITY_HIGHEST;
+    else
+    {
+        wxFAIL_MSG("invalid value of thread priority parameter");
+        win_prio = THREAD_PRIORITY_NORMAL;
+    }
+
+    if ( SetThreadPriority(p_internal->hThread, win_prio) == 0 )
+    {
+        wxLogSysError(_("Can't set thread priority"));
+    }
+
+    return Resume();
 }
 
 wxThreadError wxThread::Destroy()
 {
 }
 
 wxThreadError wxThread::Destroy()
 {
-  if (p_internal->state != STATE_RUNNING)
-    return wxTHREAD_NOT_RUNNING;
+    if ( p_internal->state != STATE_RUNNING )
+        return wxTHREAD_NOT_RUNNING;
 
 
-  if (p_internal->defer == FALSE)
-    TerminateThread(p_internal->thread_id, 0);
-  else
-    p_internal->state = STATE_CANCELED;
+    if ( p_internal->defer )
+    {
+        // soft termination: just set the flag and wait until the thread
+        // auto terminates
+        p_internal->state = STATE_CANCELED;
+    }
+    else
+    {
+        // kill the thread
+        OnExit();
+        if ( ::TerminateThread(p_internal->hThread, 0) == 0 )
+        {
+            wxLogLastError("TerminateThread");
+        }
+    }
 
 
-  return wxTHREAD_NO_ERROR;
+    return wxTHREAD_NO_ERROR;
 }
 
 wxThreadError wxThread::Pause()
 {
 }
 
 wxThreadError wxThread::Pause()
 {
-    DWORD nSuspendCount = ::SuspendThread(p_internal->thread_id);
+    DWORD nSuspendCount = ::SuspendThread(p_internal->hThread);
     if ( nSuspendCount == (DWORD)-1 )
     {
     if ( nSuspendCount == (DWORD)-1 )
     {
-        wxLogSysError(_("Can not suspend thread %x"), p_internal->thread_id);
+        wxLogSysError(_("Can not suspend thread %x"), p_internal->hThread);
 
         return wxTHREAD_MISC_ERROR;   // no idea what might provoke this error...
     }
 
 
         return wxTHREAD_MISC_ERROR;   // no idea what might provoke this error...
     }
 
+    p_internal->state = STATE_PAUSED;
+
     return wxTHREAD_NO_ERROR;
 }
 
 wxThreadError wxThread::Resume()
 {
     return wxTHREAD_NO_ERROR;
 }
 
 wxThreadError wxThread::Resume()
 {
-    DWORD nSuspendCount = ::ResumeThread(p_internal->thread_id);
+    DWORD nSuspendCount = ::ResumeThread(p_internal->hThread);
     if ( nSuspendCount == (DWORD)-1 )
     {
     if ( nSuspendCount == (DWORD)-1 )
     {
-        wxLogSysError(_("Can not resume thread %x"), p_internal->thread_id);
+        wxLogSysError(_("Can not resume thread %x"), p_internal->hThread);
 
         return wxTHREAD_MISC_ERROR;   // no idea what might provoke this error...
     }
 
 
         return wxTHREAD_MISC_ERROR;   // no idea what might provoke this error...
     }
 
+    p_internal->state = STATE_RUNNING;
+
     return wxTHREAD_NO_ERROR;
 }
 
 void wxThread::Exit(void *status)
 {
     return wxTHREAD_NO_ERROR;
 }
 
 void wxThread::Exit(void *status)
 {
-  p_internal->state = STATE_EXITED;
-  ExitThread((DWORD)status);
+    p_internal->state = STATE_EXITED;
+    ExitThread((DWORD)status);
 }
 
 void wxThread::SetPriority(int prio)
 {
 }
 
 void wxThread::SetPriority(int prio)
 {
-  p_internal->prio = prio;
+    p_internal->prio = prio;
 }
 
 int wxThread::GetPriority() const
 {
 }
 
 int wxThread::GetPriority() const
 {
-  return p_internal->prio;
+    return p_internal->prio;
 }
 
 void wxThread::DeferDestroy(bool on)
 {
 }
 
 void wxThread::DeferDestroy(bool on)
 {
-  p_internal->defer = on;
+    p_internal->defer = on;
 }
 
 }
 
-void wxThread::TestDestroy()
+bool wxThread::TestDestroy()
 {
 {
-  if (p_internal->state == STATE_CANCELED)
-    ExitThread(0);
+    return p_internal->state == STATE_CANCELED;
 }
 
 void *wxThread::Join()
 {
 }
 
 void *wxThread::Join()
 {
-  DWORD exit_code;
+    DWORD exit_code;
 
 
-  if (p_internal->state == STATE_IDLE)
-    return NULL;
+    if (p_internal->state == STATE_IDLE)
+        return NULL;
 
 
-  if (wxThread::IsMain())
-    wxMainMutex->Unlock();
-  WaitForSingleObject(p_internal->thread_id, INFINITE);
-  if (wxThread::IsMain())
-    wxMainMutex->Lock();
+    // FIXME this dead locks... wxThread class design must be changed
+#if 0
+    WaitForSingleObject(p_internal->hThread, INFINITE);
+#else
+    ::TerminateThread(p_internal->hThread, 0);
+#endif // 0
 
 
-  GetExitCodeThread(p_internal->thread_id, &exit_code);
-  CloseHandle(p_internal->thread_id);
+    GetExitCodeThread(p_internal->hThread, &exit_code);
+    CloseHandle(p_internal->hThread);
 
 
-  p_internal->state = STATE_IDLE;
+    p_internal->state = STATE_IDLE;
 
 
-  return (void *)exit_code;
+    return (void *)exit_code;
 }
 
 unsigned long wxThread::GetID() const
 {
 }
 
 unsigned long wxThread::GetID() const
 {
-  return (unsigned long)p_internal->tid;
+    return (unsigned long)p_internal->tid;
 }
 
 bool wxThread::IsRunning() const
 {
 }
 
 bool wxThread::IsRunning() const
 {
-  return (p_internal->state == STATE_RUNNING);
+    return (p_internal->state == STATE_RUNNING);
 }
 
 bool wxThread::IsAlive() const
 {
 }
 
 bool wxThread::IsAlive() const
 {
-  return (p_internal->state == STATE_RUNNING);
+    return (p_internal->state == STATE_RUNNING);
 }
 
 bool wxThread::IsMain()
 {
 }
 
 bool wxThread::IsMain()
 {
-  return (GetCurrentThread() == p_mainid);
+    return ::GetCurrentThreadId() == s_idMainThread;
 }
 
 wxThread::wxThread()
 {
 }
 
 wxThread::wxThread()
 {
-  p_internal = new wxThreadInternal();
+    p_internal = new wxThreadInternal();
 
 
-  p_internal->defer = FALSE;
-  p_internal->prio  = WXTHREAD_DEFAULT_PRIORITY;
-  p_internal->state = STATE_IDLE;
+    p_internal->defer = FALSE;
+    p_internal->prio  = WXTHREAD_DEFAULT_PRIORITY;
+    p_internal->state = STATE_IDLE;
 }
 
 wxThread::~wxThread()
 {
 }
 
 wxThread::~wxThread()
 {
-  Destroy();
-  Join();
-  delete p_internal;
+    Destroy();
+    Join();
+    delete p_internal;
 }
 
 }
 
-// The default callback just joins the thread and throws away the result.
 void wxThread::OnExit()
 {
 void wxThread::OnExit()
 {
-  Join();
 }
 
 }
 
-// Automatic initialization
-class wxThreadModule : public wxModule {
-  DECLARE_DYNAMIC_CLASS(wxThreadModule)
+// ----------------------------------------------------------------------------
+// Automatic initialization for thread module
+// ----------------------------------------------------------------------------
+
+class wxThreadModule : public wxModule
+{
 public:
 public:
-  virtual bool OnInit() {
-    wxMainMutex = new wxMutex();
-    p_mainid = GetCurrentThread();
-    wxMainMutex->Lock();
-    return TRUE;
-  }
+    virtual bool OnInit();
+    virtual void OnExit();
 
 
-  // Global cleanup
-  virtual void OnExit() {
-    wxMainMutex->Unlock();
-    delete wxMainMutex;
-  }
+private:
+    DECLARE_DYNAMIC_CLASS(wxThreadModule)
 };
 
 IMPLEMENT_DYNAMIC_CLASS(wxThreadModule, wxModule)
 
 };
 
 IMPLEMENT_DYNAMIC_CLASS(wxThreadModule, wxModule)
 
+bool wxThreadModule::OnInit()
+{
+    s_critsectWaitingForGui = new wxCriticalSection();
+
+    s_critsectGui = new wxCriticalSection();
+    s_critsectGui->Enter();
+
+    s_idMainThread = ::GetCurrentThreadId();
+
+    return TRUE;
+}
+
+void wxThreadModule::OnExit()
+{
+    if ( s_critsectGui )
+    {
+        s_critsectGui->Leave();
+        delete s_critsectGui;
+        s_critsectGui = NULL;
+    }
+
+    wxDELETE(s_critsectWaitingForGui);
+}
+
+// ----------------------------------------------------------------------------
+// under Windows, these functions are implemented usign a critical section and
+// not a mutex, so the names are a bit confusing
+// ----------------------------------------------------------------------------
+
 void WXDLLEXPORT wxMutexGuiEnter()
 {
 void WXDLLEXPORT wxMutexGuiEnter()
 {
-  wxFAIL_MSG("not implemented");
+    // this would dead lock everything...
+    wxASSERT_MSG( !wxThread::IsMain(),
+                  "main thread doesn't want to block in wxMutexGuiEnter()!" );
+
+    // the order in which we enter the critical sections here is crucial!!
+
+    // set the flag telling to the main thread that we want to do some GUI
+    {
+        wxCriticalSectionLocker enter(*s_critsectWaitingForGui);
+
+        s_nWaitingForGui++;
+    }
+
+    wxWakeUpMainThread();
+
+    // now we may block here because the main thread will soon let us in
+    // (during the next iteration of OnIdle())
+    s_critsectGui->Enter();
 }
 
 void WXDLLEXPORT wxMutexGuiLeave()
 {
 }
 
 void WXDLLEXPORT wxMutexGuiLeave()
 {
-  wxFAIL_MSG("not implemented");
+    wxCriticalSectionLocker enter(*s_critsectWaitingForGui);
+
+    if ( wxThread::IsMain() )
+    {
+        s_bGuiOwnedByMainThread = FALSE;
+    }
+    else
+    {
+        // decrement the number of waiters now
+        wxASSERT_MSG( s_nWaitingForGui > 0,
+                      "calling wxMutexGuiLeave() without entering it first?" );
+
+        s_nWaitingForGui--;
+
+        wxWakeUpMainThread();
+    }
+
+    s_critsectGui->Leave();
+}
+
+void WXDLLEXPORT wxMutexGuiLeaveOrEnter()
+{
+    wxASSERT_MSG( wxThread::IsMain(),
+                  "only main thread may call wxMutexGuiLeaveOrEnter()!" );
+
+    wxCriticalSectionLocker enter(*s_critsectWaitingForGui);
+
+    if ( s_nWaitingForGui == 0 )
+    {
+        // no threads are waiting for GUI - so we may acquire the lock without
+        // any danger (but only if we don't already have it)
+        if ( !wxGuiOwnedByMainThread() )
+        {
+            s_critsectGui->Enter();
+
+            s_bGuiOwnedByMainThread = TRUE;
+        }
+        //else: already have it, nothing to do
+    }
+    else
+    {
+        // some threads are waiting, release the GUI lock if we have it
+        if ( wxGuiOwnedByMainThread() )
+        {
+            wxMutexGuiLeave();
+        }
+        //else: some other worker thread is doing GUI
+    }
+}
+
+bool WXDLLEXPORT wxGuiOwnedByMainThread()
+{
+    return s_bGuiOwnedByMainThread;
 }
 }
+
+// wake up the main thread if it's in ::GetMessage()
+void WXDLLEXPORT wxWakeUpMainThread()
+{
+    // sending any message would do - hopefully WM_NULL is harmless enough
+    if ( !::PostThreadMessage(s_idMainThread, WM_NULL, 0, 0) )
+    {
+        // should never happen
+        wxLogLastError("PostThreadMessage(WM_NULL)");
+    }
+}
+
+#endif // wxUSE_THREADS
wxWidgets (Impactor)