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[wxWidgets.git] / src / os2 / thread.cpp
index 34ad1a4f14ad02ddcb343efea7d17dbca7ea45db..94de24c7cdc4d2353d6cf4f6b4c5a488db934f68 100644 (file)
 // Name:        thread.cpp
 // Purpose:     wxThread Implementation. For Unix ports, see e.g. src/gtk
 // Author:      Original from Wolfram Gloger/Guilhem Lavaux
-// Modified by:
+// Modified by: David Webster
 // Created:     04/22/98
 // RCS-ID:      $Id$
 // Copyright:   (c) Wolfram Gloger (1996, 1997); Guilhem Lavaux (1998)
 // Licence:     wxWindows licence
 /////////////////////////////////////////////////////////////////////////////
 
-#ifdef __GNUG__
-#pragma implementation "thread.h"
-#endif
+// ----------------------------------------------------------------------------
+// headers
+// ----------------------------------------------------------------------------
+
+// For compilers that support precompilation, includes "wx.h".
+#include "wx/wxprec.h"
+
+#if wxUSE_THREADS
+
+#include <stdio.h>
 
 #include "wx/module.h"
 #include "wx/thread.h"
-#include "wx/utils.h"
 
-#if wxUSE_THREADS
+#define INCL_DOSSEMAPHORES
+#define INCL_DOSPROCESS
+#define INCL_ERRORS
+#include <os2.h>
+#include <bseerr.h>
 
-enum thread_state {
-  STATE_IDLE = 0,
-  STATE_RUNNING,
-  STATE_CANCELED,
-  STATE_EXITED
+// the possible states of the thread ("=>" shows all possible transitions from
+// this state)
+enum wxThreadState
+{
+    STATE_NEW,          // didn't start execution yet (=> RUNNING)
+    STATE_RUNNING,      // thread is running (=> PAUSED, CANCELED)
+    STATE_PAUSED,       // thread is temporarily suspended (=> RUNNING)
+    STATE_CANCELED,     // thread should terminate a.s.a.p. (=> EXITED)
+    STATE_EXITED        // thread is terminating
 };
 
-/////////////////////////////////////////////////////////////////////////////
-// Static variables
-/////////////////////////////////////////////////////////////////////////////
+// ----------------------------------------------------------------------------
+// static variables
+// ----------------------------------------------------------------------------
 
-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 ULONG                        s_ulIdMainThread = 0;
+wxMutex*                            p_wxMainMutex;
 
-/////////////////////////////////////////////////////////////////////////////
-// Windows implementation
-/////////////////////////////////////////////////////////////////////////////
+// OS2 substitute for Tls pointer the current parent thread object
+wxThread*                           m_pThread;    // pointer to the wxWindows thread object
+
+// if it's FALSE, some secondary thread is holding the GUI lock
+static bool gs_bGuiOwnedByMainThread = TRUE;
+
+// 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 *gs_pCritsectGui = NULL;
+
+// critical section which protects s_nWaitingForGui variable
+static wxCriticalSection *gs_pCritsectWaitingForGui = NULL;
+
+// number of threads waiting for GUI in wxMutexGuiEnter()
+static size_t gs_nWaitingForGui = 0;
 
-class wxMutexInternal {
+// are we waiting for a thread termination?
+static bool gs_bWaitingForThread = FALSE;
+
+// ============================================================================
+// OS/2 implementation of thread classes
+// ============================================================================
+
+// ----------------------------------------------------------------------------
+// wxMutex implementation
+// ----------------------------------------------------------------------------
+class wxMutexInternal
+{
 public:
-  // TODO: internal mutex handle
+    HMTX                            m_vMutex;
 };
 
 wxMutex::wxMutex()
 {
-    p_internal = new wxMutexInternal;
-    // TODO: create internal mutext handle
+    APIRET                          ulrc;
+
+    m_internal = new wxMutexInternal;
+    ulrc = ::DosCreateMutexSem(NULL, &m_internal->m_vMutex, 0L, FALSE);
+    if (ulrc != 0)
+    {
+        wxLogSysError(_("Can not create mutex."));
+    }
     m_locked = 0;
 }
 
 wxMutex::~wxMutex()
 {
     if (m_locked > 0)
-        wxDebugMsg("wxMutex warning: freeing a locked mutex (%d locks)\n", m_locked);
-    // TODO: free internal mutext handle
+        wxLogDebug(wxT("Warning: freeing a locked mutex (%d locks)."), m_locked);
+    ::DosCloseMutexSem(m_internal->m_vMutex);
+    m_internal->m_vMutex = NULL;
 }
 
 wxMutexError wxMutex::Lock()
 {
-    // TODO
+    APIRET                          ulrc;
+
+    ulrc = ::DosRequestMutexSem(m_internal->m_vMutex, SEM_INDEFINITE_WAIT);
+
+    switch (ulrc)
+    {
+        case ERROR_TOO_MANY_SEM_REQUESTS:
+            return wxMUTEX_BUSY;
+
+        case NO_ERROR:
+            // ok
+            break;
+
+        case ERROR_INVALID_HANDLE:
+        case ERROR_INTERRUPT:
+        case ERROR_SEM_OWNER_DIED:
+            wxLogSysError(_("Couldn't acquire a mutex lock"));
+            return wxMUTEX_MISC_ERROR;
+
+        case ERROR_TIMEOUT:
+        default:
+            wxFAIL_MSG(wxT("impossible return value in wxMutex::Lock"));
+    }
     m_locked++;
     return wxMUTEX_NO_ERROR;
 }
 
 wxMutexError wxMutex::TryLock()
 {
-    // TODO
+    ULONG                           ulrc;
+
+    ulrc = ::DosRequestMutexSem(m_internal->m_vMutex, SEM_IMMEDIATE_RETURN /*0L*/);
+    if (ulrc == ERROR_TIMEOUT || ulrc == ERROR_TOO_MANY_SEM_REQUESTS)
+        return wxMUTEX_BUSY;
+
     m_locked++;
     return wxMUTEX_NO_ERROR;
 }
 
 wxMutexError wxMutex::Unlock()
 {
+    APIRET                          ulrc;
+
     if (m_locked > 0)
         m_locked--;
 
-    // TODO
+    ulrc = ::DosReleaseMutexSem(m_internal->m_vMutex);
+    if (ulrc != 0)
+    {
+        wxLogSysError(_("Couldn't release a mutex"));
+        return wxMUTEX_MISC_ERROR;
+    }
     return wxMUTEX_NO_ERROR;
 }
 
-class wxConditionInternal {
+// ----------------------------------------------------------------------------
+// wxCondition implementation
+// ----------------------------------------------------------------------------
+
+class wxConditionInternal
+{
 public:
-  // TODO: internal handle
-  int waiters;
+    inline wxConditionInternal ()
+    {
+        ::DosCreateEventSem(NULL, &m_vEvent, DC_SEM_SHARED, FALSE);
+        if (!m_vEvent)
+        {
+            wxLogSysError(_("Can not create event semaphore."));
+        }
+        m_nWaiters = 0;
+    }
+
+    inline bool Wait(
+      unsigned long                 ulTimeout
+    )
+    {
+        APIRET                      ulrc;
+
+        m_nWaiters++;
+        ulrc = ::DosWaitEventSem(m_vEvent, ulTimeout);
+        m_nWaiters--;
+        return (ulrc != ERROR_TIMEOUT);
+    }
+
+    inline ~wxConditionInternal ()
+    {
+        APIRET                      ulrc;
+
+        if (m_vEvent)
+        {
+            ulrc = ::DosCloseEventSem(m_vEvent);
+            if (!ulrc)
+            {
+                wxLogLastError("DosCloseEventSem(m_vEvent)");
+            }
+        }
+    }
+
+    HEV                             m_vEvent;
+    int                             m_nWaiters;
 };
 
 wxCondition::wxCondition()
 {
-    p_internal = new wxConditionInternal;
-    // TODO: create internal handle
-    p_internal->waiters = 0;
+    APIRET                          ulrc;
+    ULONG                           ulCount;
+
+    m_internal = new wxConditionInternal;
+    ulrc = ::DosCreateEventSem(NULL, &m_internal->m_vEvent, 0L, FALSE);
+    if (ulrc != 0)
+    {
+        wxLogSysError(_("Can not create event object."));
+    }
+    m_internal->m_nWaiters = 0;
+    // ?? just for good measure?
+    ::DosResetEventSem(m_internal->m_vEvent, &ulCount);
 }
 
 wxCondition::~wxCondition()
 {
-    // TODO: destroy internal handle
+    ::DosCloseEventSem(m_internal->m_vEvent);
+    delete m_internal;
+    m_internal = NULL;
 }
 
-void wxCondition::Wait(wxMutex& mutex)
+void wxCondition::Wait()
 {
-    mutex.Unlock();
-    p_internal->waiters++;
-    // TODO wait here
-    p_internal->waiters--;
-    mutex.Lock();
+    (void)m_internal->Wait(SEM_INDEFINITE_WAIT);
 }
 
-bool wxCondition::Wait(wxMutex& mutex, unsigned long sec,
-                       unsigned long nsec)
+bool wxCondition::Wait(
+  unsigned long                     lSec
+, unsigned long                     lNsec)
 {
-    mutex.Unlock();
-    p_internal->waiters++;
-
-    // TODO wait here
-    p_internal->waiters--;
-    mutex.Lock();
-
-    return FALSE;
+    return m_internal->Wait(lSec*1000 + lNsec/1000000);
 }
 
 void wxCondition::Signal()
 {
-    // TODO
+    ::DosPostEventSem(m_internal->m_vEvent);
 }
 
 void wxCondition::Broadcast()
 {
-    // TODO
+    int                             i;
+
+    for (i = 0; i < m_internal->m_nWaiters; i++)
+    {
+        if (::DosPostEventSem(m_internal->m_vEvent) != 0)
+        {
+            wxLogSysError(_("Couldn't change the state of event object."));
+        }
+    }
+}
+
+// ----------------------------------------------------------------------------
+// wxCriticalSection implementation
+// ----------------------------------------------------------------------------
+
+wxCriticalSection::wxCriticalSection()
+{
+}
+
+wxCriticalSection::~wxCriticalSection()
+{
+}
+
+void wxCriticalSection::Enter()
+{
+    ::DosEnterCritSec();
+}
+
+void wxCriticalSection::Leave()
+{
+    ::DosExitCritSec();
 }
 
-class wxThreadInternal {
+// ----------------------------------------------------------------------------
+// wxThread implementation
+// ----------------------------------------------------------------------------
+
+// wxThreadInternal class
+// ----------------------
+
+class wxThreadInternal
+{
 public:
-    // TODO
+    inline wxThreadInternal()
+    {
+        m_hThread = 0;
+        m_eState = STATE_NEW;
+        m_nPriority = 0;
+    }
+
+    ~wxThreadInternal()
+    {
+        Free();
+    }
+
+    void Free()
+    {
+        if (m_hThread)
+        {
+            ::DosExit(0,0);
+            m_hThread = 0;
+        }
+    }
+
+    // create a new (suspended) thread (for the given thread object)
+    bool Create(wxThread* pThread);
+
+    // suspend/resume/terminate
+    bool Suspend();
+    bool Resume();
+    inline void Cancel() { m_eState = STATE_CANCELED; }
+
+    // thread state
+    inline void SetState(wxThreadState eState) { m_eState = eState; }
+    inline wxThreadState GetState() const { return m_eState; }
+
+    // thread priority
+    void                SetPriority(unsigned int nPriority);
+    inline unsigned int GetPriority() const { return m_nPriority; }
+
+    // thread handle and id
+    inline TID GetHandle() const { return m_hThread; }
+    TID  GetId() const { return m_hThread; }
+
+    // thread function
+    static DWORD OS2ThreadStart(wxThread *thread);
+
+private:
+    // Threads in OS/2 have only an ID, so m_hThread is both it's handle and ID
+    // PM also has no real Tls mechanism to index pointers by so we'll just
+    // keep track of the wxWindows parent object here.
+    TID                             m_hThread;    // handle and ID of the thread
+    wxThreadState                   m_eState;     // state, see wxThreadState enum
+    unsigned int                    m_nPriority;  // thread priority in "wx" units
 };
 
+ULONG wxThreadInternal::OS2ThreadStart(
+  wxThread*                         pThread
+)
+{
+    m_pThread = pThread;
+
+    DWORD                           dwRet = (DWORD)pThread->Entry();
+
+    // enter m_critsect before changing the thread state
+    pThread->m_critsect.Enter();
+
+    bool                            bWasCancelled = pThread->m_internal->GetState() == STATE_CANCELED;
+
+    pThread->m_internal->SetState(STATE_EXITED);
+    pThread->m_critsect.Leave();
+
+    pThread->OnExit();
+
+    // if the thread was cancelled (from Delete()), then it the handle is still
+    // needed there
+    if (pThread->IsDetached() && !bWasCancelled)
+    {
+        // auto delete
+        delete pThread;
+    }
+    //else: the joinable threads handle will be closed when Wait() is done
+    return dwRet;
+}
+
+void wxThreadInternal::SetPriority(
+  unsigned int                      nPriority
+)
+{
+    // translate wxWindows priority to the PM one
+    ULONG                           ulOS2_Priority;
+    ULONG                           ulrc;
+
+    m_nPriority = nPriority;
+
+    if (m_nPriority <= 20)
+        ulOS2_Priority = PRTYC_NOCHANGE;
+    else if (m_nPriority <= 40)
+        ulOS2_Priority = PRTYC_IDLETIME;
+    else if (m_nPriority <= 60)
+        ulOS2_Priority = PRTYC_REGULAR;
+    else if (m_nPriority <= 80)
+        ulOS2_Priority = PRTYC_TIMECRITICAL;
+    else if (m_nPriority <= 100)
+        ulOS2_Priority = PRTYC_FOREGROUNDSERVER;
+    else
+    {
+        wxFAIL_MSG(wxT("invalid value of thread priority parameter"));
+        ulOS2_Priority = PRTYC_REGULAR;
+    }
+    ulrc = ::DosSetPriority( PRTYS_THREAD
+                            ,ulOS2_Priority
+                            ,0
+                            ,(ULONG)m_hThread
+                           );
+    if (ulrc != 0)
+    {
+        wxLogSysError(_("Can't set thread priority"));
+    }
+}
+
+bool wxThreadInternal::Create(
+  wxThread*                         pThread
+)
+{
+    APIRET                          ulrc;
+
+    ulrc = ::DosCreateThread( &m_hThread
+                             ,(PFNTHREAD)wxThreadInternal::OS2ThreadStart
+                             ,(ULONG)pThread
+                             ,CREATE_SUSPENDED | STACK_SPARSE
+                             ,8192L
+                            );
+    if(ulrc != 0)
+    {
+        wxLogSysError(_("Can't create thread"));
+
+        return FALSE;
+    }
+    if (m_nPriority != WXTHREAD_DEFAULT_PRIORITY)
+    {
+        SetPriority(m_nPriority);
+    }
+    return(TRUE);
+}
+
+bool wxThreadInternal::Suspend()
+{
+    ULONG                           ulrc = ::DosSuspendThread(m_hThread);
+
+    if (ulrc != 0)
+    {
+        wxLogSysError(_("Can not suspend thread %lu"), m_hThread);
+        return FALSE;
+    }
+    m_eState = STATE_PAUSED;
+    return TRUE;
+}
+
+bool wxThreadInternal::Resume()
+{
+    ULONG                           ulrc = ::DosResumeThread(m_hThread);
+
+    if (ulrc != 0)
+    {
+        wxLogSysError(_("Can not suspend thread %lu"), m_hThread);
+        return FALSE;
+    }
+    m_eState = STATE_PAUSED;
+    return TRUE;
+}
+
+// static functions
+// ----------------
+
+wxThread *wxThread::This()
+{
+    wxThread*                       pThread = m_pThread;
+    return pThread;
+}
+
+bool wxThread::IsMain()
+{
+    PTIB                            ptib;
+    PPIB                            ppib;
+
+    ::DosGetInfoBlocks(&ptib, &ppib);
+
+    if (ptib->tib_ptib2->tib2_ultid == s_ulIdMainThread)
+        return TRUE;
+    return FALSE;
+}
+
+#ifdef Yield
+    #undef Yield
+#endif
+
+void wxThread::Yield()
+{
+    ::DosSleep(0);
+}
+
+void wxThread::Sleep(
+  unsigned long                     ulMilliseconds
+)
+{
+    ::DosSleep(ulMilliseconds);
+}
+
+// ctor and dtor
+// -------------
+
+wxThread::wxThread(wxThreadKind kind)
+{
+    m_internal = new wxThreadInternal();
+
+    m_isDetached = kind == wxTHREAD_DETACHED;
+}
+
+wxThread::~wxThread()
+{
+    delete m_internal;
+}
+
+// create/start thread
+// -------------------
+
 wxThreadError wxThread::Create()
 {
-    // TODO
+    if ( !m_internal->Create(this) )
+        return wxTHREAD_NO_RESOURCE;
+
     return wxTHREAD_NO_ERROR;
 }
 
-wxThreadError wxThread::Destroy()
+wxThreadError wxThread::Run()
 {
-    // TODO
-    return wxTHREAD_NO_ERROR;
+    wxCriticalSectionLocker         lock((wxCriticalSection &)m_critsect);
+
+    if ( m_internal->GetState() != STATE_NEW )
+    {
+        // actually, it may be almost any state at all, not only STATE_RUNNING
+        return wxTHREAD_RUNNING;
+    }
+    return Resume();
 }
 
+// suspend/resume thread
+// ---------------------
+
 wxThreadError wxThread::Pause()
 {
-    // TODO
-    return wxTHREAD_NO_ERROR;
+    wxCriticalSectionLocker         lock((wxCriticalSection &)m_critsect);
+
+    return m_internal->Suspend() ? wxTHREAD_NO_ERROR : wxTHREAD_MISC_ERROR;
 }
 
 wxThreadError wxThread::Resume()
 {
-    // TODO
-    return wxTHREAD_NO_ERROR;
+    wxCriticalSectionLocker         lock((wxCriticalSection &)m_critsect);
+
+    return m_internal->Resume() ? wxTHREAD_NO_ERROR : wxTHREAD_MISC_ERROR;
 }
 
-void wxThread::Exit(void *status)
+// stopping thread
+// ---------------
+
+wxThread::ExitCode wxThread::Wait()
 {
-    // TODO
+    // although under Windows we can wait for any thread, it's an error to
+    // wait for a detached one in wxWin API
+    wxCHECK_MSG( !IsDetached(), (ExitCode)-1,
+                 _T("can't wait for detached thread") );
+    ExitCode rc = (ExitCode)-1;
+    (void)Delete(&rc);
+    m_internal->Free();
+    return(rc);
 }
 
-void wxThread::SetPriority(int prio)
+wxThreadError wxThread::Delete(ExitCode *pRc)
 {
-    // TODO
+    ExitCode rc = 0;
+
+    // Delete() is always safe to call, so consider all possible states
+    if (IsPaused())
+        Resume();
+
+    TID                             hThread = m_internal->GetHandle();
+
+    if (IsRunning())
+    {
+        if (IsMain())
+        {
+            // set flag for wxIsWaitingForThread()
+            gs_bWaitingForThread = TRUE;
+
+#if wxUSE_GUI
+            wxBeginBusyCursor();
+#endif // wxUSE_GUI
+        }
+
+        // ask the thread to terminate
+        {
+            wxCriticalSectionLocker lock(m_critsect);
+            m_internal->Cancel();
+        }
+
+#if wxUSE_GUI
+        // need a way to finish GUI processing before killing the thread
+        // until then we just exit
+
+        if ((gs_nWaitingForGui > 0) && wxGuiOwnedByMainThread())
+        {
+            wxMutexGuiLeave();
+        }
+#else // !wxUSE_GUI
+
+        // can't wait for yourself to end under OS/2 so just quit
+
+#endif // wxUSE_GUI/!wxUSE_GUI
+
+        if ( IsMain() )
+        {
+            gs_bWaitingForThread = FALSE;
+
+#if wxUSE_GUI
+            wxEndBusyCursor();
+#endif // wxUSE_GUI
+        }
+    }
+
+    ::DosExit(0, 0);
+    // probably won't get this far, but
+    if (IsDetached())
+    {
+        delete this;
+    }
+
+    if ( pRc )
+        *pRc = rc;
+
+    return rc == (ExitCode)-1 ? wxTHREAD_MISC_ERROR : wxTHREAD_NO_ERROR;
 }
 
-int wxThread::GetPriority() const
+wxThreadError wxThread::Kill()
 {
-    // TODO
-    return 0;
+    if (!IsRunning())
+        return wxTHREAD_NOT_RUNNING;
+
+    ::DosKillThread(m_internal->GetHandle());
+    m_internal->Free();
+    if (IsDetached())
+    {
+        delete this;
+    }
+    return wxTHREAD_NO_ERROR;
 }
 
-void wxThread::DeferDestroy(bool on)
+void wxThread::Exit(
+  ExitCode                          pStatus
+)
 {
-    // TODO
+    m_internal->Free();
+    delete this;
+    ::DosExit(EXIT_THREAD, ULONG(pStatus));
+    wxFAIL_MSG(wxT("Couldn't return from DosExit()!"));
 }
 
-void wxThread::TestDestroy()
+void wxThread::SetPriority(
+  unsigned int                      nPrio
+)
 {
-    // TODO
+    wxCriticalSectionLocker         lock((wxCriticalSection &)m_critsect);
+
+    m_internal->SetPriority(nPrio);
 }
 
-void *wxThread::Join()
+unsigned int wxThread::GetPriority() const
 {
-    // TODO
-    return (void*) NULL;
+    wxCriticalSectionLocker         lock((wxCriticalSection &)m_critsect);
+
+    return m_internal->GetPriority();
 }
 
-unsigned long wxThread::GetID() const
+unsigned long wxThread::GetId() const
 {
-    // TODO
-    return 0;
+    wxCriticalSectionLocker lock((wxCriticalSection &)m_critsect); // const_cast
+
+    return (unsigned long)m_internal->GetId();
 }
 
-/*
-wxThread *wxThread::GetThreadFromID(unsigned long id)
+bool wxThread::IsRunning() const
 {
-    // TODO
-    return NULL;
+    wxCriticalSectionLocker         lock((wxCriticalSection &)m_critsect);
+
+    return(m_internal->GetState() == STATE_RUNNING);
 }
-*/
 
 bool wxThread::IsAlive() const
 {
-    // TODO
-    return FALSE;
+    wxCriticalSectionLocker         lock((wxCriticalSection &)m_critsect);
+
+    return (m_internal->GetState() == STATE_RUNNING) ||
+           (m_internal->GetState() == STATE_PAUSED);
 }
 
-bool wxThread::IsRunning() const
+bool wxThread::IsPaused() const
 {
-    // TODO
-    return FALSE;
+    wxCriticalSectionLocker         lock((wxCriticalSection &)m_critsect);
+
+    return (m_internal->GetState() == STATE_PAUSED);
 }
 
-bool wxThread::IsMain()
+bool wxThread::TestDestroy()
 {
-    // TODO
-    return FALSE;
+    wxCriticalSectionLocker         lock((wxCriticalSection &)m_critsect);
+
+    return m_internal->GetState() == STATE_CANCELED;
 }
 
-wxThread::wxThread()
+// ----------------------------------------------------------------------------
+// Automatic initialization for thread module
+// ----------------------------------------------------------------------------
+
+class wxThreadModule : public wxModule
 {
-    p_internal = new wxThreadInternal();
+public:
+    virtual bool OnInit();
+    virtual void OnExit();
+
+private:
+    DECLARE_DYNAMIC_CLASS(wxThreadModule)
+};
+
+IMPLEMENT_DYNAMIC_CLASS(wxThreadModule, wxModule)
 
-    // TODO
+bool wxThreadModule::OnInit()
+{
+    gs_pCritsectWaitingForGui = new wxCriticalSection();
+
+    gs_pCritsectGui = new wxCriticalSection();
+    gs_pCritsectGui->Enter();
+
+    PTIB                            ptib;
+    PPIB                            ppib;
+
+    ::DosGetInfoBlocks(&ptib, &ppib);
+
+    s_ulIdMainThread = ptib->tib_ptib2->tib2_ultid;
+    return TRUE;
 }
 
-wxThread::~wxThread()
+void wxThreadModule::OnExit()
+{
+    if (gs_pCritsectGui)
+    {
+        gs_pCritsectGui->Leave();
+#if (!(defined(__VISAGECPP__) && (__IBMCPP__ < 400 || __IBMC__ < 400 )))
+        delete gs_pCritsectGui;
+#endif
+        gs_pCritsectGui = NULL;
+    }
+
+#if (!(defined(__VISAGECPP__) && (__IBMCPP__ < 400 || __IBMC__ < 400 )))
+    wxDELETE(gs_pCritsectWaitingForGui);
+#endif
+}
+
+// ----------------------------------------------------------------------------
+// Helper functions
+// ----------------------------------------------------------------------------
+
+// Does nothing under OS/2 [for now]
+void WXDLLEXPORT wxWakeUpMainThread()
 {
-    Destroy();
-    Join();
-    delete p_internal;
 }
 
-// The default callback just joins the thread and throws away the result.
-void wxThread::OnExit()
+void WXDLLEXPORT wxMutexGuiLeave()
 {
-    Join();
+    wxCriticalSectionLocker enter(*gs_pCritsectWaitingForGui);
+
+    if ( wxThread::IsMain() )
+    {
+        gs_bGuiOwnedByMainThread = FALSE;
+    }
+    else
+    {
+        // decrement the number of waiters now
+        wxASSERT_MSG(gs_nWaitingForGui > 0,
+                      wxT("calling wxMutexGuiLeave() without entering it first?") );
+
+        gs_nWaitingForGui--;
+
+        wxWakeUpMainThread();
+    }
+
+    gs_pCritsectGui->Leave();
 }
 
-// Automatic initialization
-class wxThreadModule : public wxModule {
-  DECLARE_DYNAMIC_CLASS(wxThreadModule)
-public:
-  virtual bool OnInit() {
-    /* TODO p_mainid = GetCurrentThread(); */
-    wxMainMutex = new wxMutex();
-    wxMainMutex->Lock();
-    return TRUE;
-  }
+void WXDLLEXPORT wxMutexGuiLeaveOrEnter()
+{
+    wxASSERT_MSG( wxThread::IsMain(),
+                  wxT("only main thread may call wxMutexGuiLeaveOrEnter()!") );
+
+    wxCriticalSectionLocker enter(*gs_pCritsectWaitingForGui);
+
+    if (gs_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())
+        {
+            gs_pCritsectGui->Enter();
+
+            gs_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
+    }
+}
 
-  // Global cleanup
-  virtual void OnExit() {
-    wxMainMutex->Unlock();
-    delete wxMainMutex;
-  }
-};
+bool WXDLLEXPORT wxGuiOwnedByMainThread()
+{
+    return gs_bGuiOwnedByMainThread;
+}
 
-IMPLEMENT_DYNAMIC_CLASS(wxThreadModule, wxModule)
+bool WXDLLEXPORT wxIsWaitingForThread()
+{
+    return gs_bWaitingForThread;
+}
 
 #endif
   // wxUSE_THREADS