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[wxWidgets.git] / src / msw / thread.cpp
index f6b625878f6bb422810ecd0182ee192981b38535..f76f9a4c7bb4d848d0c2aa83d4afbbdcc929dbfe 100644 (file)
 // 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:      $Id$
-// 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__
-#pragma implementation "thread.h"
+    #pragma implementation "thread.h"
 #endif
 
+// ----------------------------------------------------------------------------
+// headers
+// ----------------------------------------------------------------------------
+
+// For compilers that support precompilation, includes "wx.h".
 #include "wx/wxprec.h"
 
 #if defined(__BORLANDC__)
-#pragma hdrstop
+    #pragma hdrstop
 #endif
 
 #ifndef WX_PRECOMP
-#include "wx/wx.h"
+#    include "wx/wx.h"
 #endif
 
-#include <stdio.h>
+#if wxUSE_THREADS
+
+#include "wx/msw/private.h"
 
-#include <windows.h>
 #include "wx/module.h"
 #include "wx/thread.h"
 
-enum thread_state {
-  STATE_IDLE = 0,
-  STATE_RUNNING,
-  STATE_CANCELED,
-  STATE_EXITED
+#ifdef Yield
+#    undef Yield
+#endif
+
+// must have this symbol defined to get _beginthread/_endthread declarations
+#ifndef _MT
+    #define _MT
+#endif
+
+#if defined(__VISUALC__) || \
+    (defined(__BORLANDC__) && (__BORLANDC__ >= 0x500)) || \
+    (defined(__GNUG__) && defined(__MSVCRT__))
+
+#if defined(__BORLANDC__) && !defined(__MT__)
+// I can't set -tWM in the IDE (anyone?) so have to do this
+#define __MT__
+#endif
+
+#if defined(__BORLANDC__) && !defined(__MFC_COMPAT__)
+// Needed to know about _beginthreadex etc..
+#define __MFC_COMPAT__
+#endif
+
+    #include <process.h>
+#endif
+
+// ----------------------------------------------------------------------------
+// constants
+// ----------------------------------------------------------------------------
+
+// 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
-/////////////////////////////////////////////////////////////////////////////
+// ----------------------------------------------------------------------------
+// this module globals
+// ----------------------------------------------------------------------------
 
-static HANDLE p_mainid;
-wxMutex wxMainMutex; // controls access to all GUI functions
+// TLS index of the slot where we store the pointer to the current thread
+static DWORD gs_tlsThisThread = 0xFFFFFFFF;
 
-/////////////////////////////////////////////////////////////////////////////
-// Windows implementation
-/////////////////////////////////////////////////////////////////////////////
+// id of the main thread - the one which can call GUI functions without first
+// calling wxMutexGuiEnter()
+static DWORD gs_idMainThread = 0;
+
+// 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_critsectGui = NULL;
+
+// critical section which protects gs_nWaitingForGui variable
+static wxCriticalSection *gs_critsectWaitingForGui = NULL;
 
-class wxMutexInternal {
+// number of threads waiting for GUI in wxMutexGuiEnter()
+static size_t gs_nWaitingForGui = 0;
+
+// are we waiting for a thread termination?
+static bool gs_waitingForThread = FALSE;
+
+// ============================================================================
+// Windows implementation of thread classes
+// ============================================================================
+
+// ----------------------------------------------------------------------------
+// wxMutex implementation
+// ----------------------------------------------------------------------------
+
+class wxMutexInternal
+{
 public:
-  HANDLE p_mutex;
+    wxMutexInternal()
+    {
+        m_mutex = ::CreateMutex(NULL, FALSE, NULL);
+        if ( !m_mutex )
+        {
+            wxLogSysError(_("Can not create mutex"));
+        }
+    }
+
+    ~wxMutexInternal() { if ( m_mutex ) CloseHandle(m_mutex); }
+
+public:
+    HANDLE m_mutex;
 };
 
-wxMutex::wxMutex(void)
+wxMutex::wxMutex()
 {
-  p_internal = new wxMutexInternal;
-  p_internal->p_mutex = CreateMutex(NULL, FALSE, NULL);
-  m_locked = 0;
+    m_internal = new wxMutexInternal;
+
+    m_locked = 0;
 }
 
-wxMutex::~wxMutex(void)
+wxMutex::~wxMutex()
 {
-  CloseHandle(p_internal->p_mutex);
+    if ( m_locked > 0 )
+    {
+        wxLogDebug(_T("Warning: freeing a locked mutex (%d locks)."), m_locked);
+    }
+
+    delete m_internal;
 }
 
-wxMutexError wxMutex::Lock(void)
+wxMutexError wxMutex::Lock()
 {
-  DWORD ret;
+    DWORD ret;
+
+    ret = WaitForSingleObject(m_internal->m_mutex, INFINITE);
+    switch ( ret )
+    {
+        case WAIT_ABANDONED:
+            return wxMUTEX_BUSY;
 
-  ret = WaitForSingleObject(p_internal->p_mutex, INFINITE);
-  if (ret == WAIT_ABANDONED)
-    return MUTEX_BUSY;
+        case WAIT_OBJECT_0:
+            // ok
+            break;
 
-  m_locked++;
-  return MUTEX_NO_ERROR;
+        case WAIT_FAILED:
+            wxLogSysError(_("Couldn't acquire a mutex lock"));
+            return wxMUTEX_MISC_ERROR;
+
+        case WAIT_TIMEOUT:
+        default:
+            wxFAIL_MSG(wxT("impossible return value in wxMutex::Lock"));
+    }
+
+    m_locked++;
+    return wxMUTEX_NO_ERROR;
 }
 
-wxMutexError wxMutex::TryLock(void)
+wxMutexError wxMutex::TryLock()
 {
-  DWORD ret;
+    DWORD ret;
 
-  ret = WaitForSingleObject(p_internal->p_mutex, 0);
-  if (ret == WAIT_TIMEOUT || ret == WAIT_ABANDONED)
-    return MUTEX_BUSY;
+    ret = WaitForSingleObject(m_internal->m_mutex, 0);
+    if (ret == WAIT_TIMEOUT || ret == WAIT_ABANDONED)
+        return wxMUTEX_BUSY;
 
-  m_locked++;
-  return MUTEX_NO_ERROR;
+    m_locked++;
+    return wxMUTEX_NO_ERROR;
 }
 
-wxMutexError wxMutex::Unlock(void)
+wxMutexError wxMutex::Unlock()
 {
-  BOOL ret;
+    if (m_locked > 0)
+        m_locked--;
 
-  if (m_locked > 0)
-    m_locked--;
+    BOOL ret = ReleaseMutex(m_internal->m_mutex);
+    if ( ret == 0 )
+    {
+        wxLogSysError(_("Couldn't release a mutex"));
+        return wxMUTEX_MISC_ERROR;
+    }
 
-    // Why does this have 3 args? The redundant ones removed by JACS
-//  ret = ReleaseMutex(p_internal->p_mutex, 1, NULL);
-  ret = ReleaseMutex(p_internal->p_mutex);
-  return MUTEX_NO_ERROR;
+    return wxMUTEX_NO_ERROR;
 }
 
-class wxConditionInternal {
+// ----------------------------------------------------------------------------
+// wxCondition implementation
+// ----------------------------------------------------------------------------
+
+class wxConditionInternal
+{
 public:
-  HANDLE event;
-  int waiters;
+    wxConditionInternal()
+    {
+        m_hEvent = ::CreateEvent(
+                                 NULL,   // default secutiry
+                                 FALSE,  // not manual reset
+                                 FALSE,  // nonsignaled initially
+                                 NULL    // nameless event
+                                );
+        if ( !m_hEvent )
+        {
+            wxLogSysError(_("Can not create event object."));
+        }
+
+        // nobody waits for us yet
+        m_nWaiters = 0;
+    }
+
+    bool Wait(DWORD timeout)
+    {
+        // as m_nWaiters variable is accessed from multiple waiting threads
+        // (and possibly from the broadcasting thread), we need to change its
+        // value atomically
+        ::InterlockedIncrement(&m_nWaiters);
+
+        // FIXME this should be MsgWaitForMultipleObjects() as we want to keep
+        //       processing Windows messages while waiting (or don't we?)
+        DWORD rc = ::WaitForSingleObject(m_hEvent, timeout);
+
+        ::InterlockedDecrement(&m_nWaiters);
+
+        return rc != WAIT_TIMEOUT;
+    }
+
+    void Signal()
+    {
+        // set the event to signaled: if a thread is already waiting on it, it
+        // will be woken up, otherwise the event will remain in the signaled
+        // state until someone waits on it. In any case, the system will return
+        // it to a non signalled state afterwards. If multiple threads are
+        // waiting, only one will be woken up.
+        if ( !::SetEvent(m_hEvent) )
+        {
+            wxLogLastError(wxT("SetEvent"));
+        }
+    }
+
+    void Broadcast()
+    {
+        // we need to save the original value as m_nWaiters is goign to be
+        // decreased by the signalled thread resulting in the loop being
+        // executed less times than needed
+        LONG nWaiters = m_nWaiters;
+
+        // this works because all these threads are already waiting and so each
+        // SetEvent() inside Signal() is really a PulseEvent() because the
+        // event state is immediately returned to non-signaled
+        for ( LONG n = 0; n < nWaiters; n++ )
+        {
+            Signal();
+        }
+    }
+
+    ~wxConditionInternal()
+    {
+        if ( m_hEvent )
+        {
+            if ( !::CloseHandle(m_hEvent) )
+            {
+                wxLogLastError(wxT("CloseHandle(event)"));
+            }
+        }
+    }
+
+private:
+    // the Win32 synchronization object corresponding to this event
+    HANDLE m_hEvent;
+
+    // number of threads waiting for this condition
+    LONG m_nWaiters;
 };
 
-wxCondition::wxCondition(void)
+wxCondition::wxCondition()
 {
-  p_internal = new wxConditionInternal;
-  p_internal->event = CreateEvent(NULL, FALSE, FALSE, NULL);
-  p_internal->waiters = 0;
+    m_internal = new wxConditionInternal;
 }
 
-wxCondition::~wxCondition(void)
+wxCondition::~wxCondition()
 {
-  CloseHandle(p_internal->event);
+    delete m_internal;
 }
 
-void wxCondition::Wait(wxMutex& mutex)
+void wxCondition::Wait()
 {
-  mutex.Unlock();
-  p_internal->waiters++;
-  WaitForSingleObject(p_internal->event, INFINITE);
-  p_internal->waiters--;
-  mutex.Lock();
+    (void)m_internal->Wait(INFINITE);
 }
 
-bool wxCondition::Wait(wxMutex& mutex, unsigned long sec,
+bool wxCondition::Wait(unsigned long sec,
                        unsigned long nsec)
 {
-  DWORD ret;
+    return m_internal->Wait(sec*1000 + nsec/1000000);
+}
+
+void wxCondition::Signal()
+{
+    m_internal->Signal();
+}
+
+void wxCondition::Broadcast()
+{
+    m_internal->Broadcast();
+}
 
-  mutex.Unlock();
-  p_internal->waiters++;
-  ret = WaitForSingleObject(p_internal->event, (sec*1000)+(nsec/1000000));
-  p_internal->waiters--;
-  mutex.Lock();
+// ----------------------------------------------------------------------------
+// wxCriticalSection implementation
+// ----------------------------------------------------------------------------
 
-  return (ret != WAIT_TIMEOUT);
+wxCriticalSection::wxCriticalSection()
+{
+#ifdef __WXDEBUG__
+    // Done this way to stop warnings during compilation about statement
+    // always being false
+        int csSize = sizeof(CRITICAL_SECTION);
+        int bSize  = sizeof(m_buffer);
+    wxASSERT_MSG( csSize <= bSize,
+                  _T("must increase buffer size in wx/thread.h") );
+#endif
+
+    ::InitializeCriticalSection((CRITICAL_SECTION *)m_buffer);
 }
 
-void wxCondition::Signal(void)
+wxCriticalSection::~wxCriticalSection()
 {
-  SetEvent(p_internal->event);
+    ::DeleteCriticalSection((CRITICAL_SECTION *)m_buffer);
 }
 
-void wxCondition::Broadcast(void)
+void wxCriticalSection::Enter()
 {
-  int i;
+    ::EnterCriticalSection((CRITICAL_SECTION *)m_buffer);
+}
 
-  for (i=0;i<p_internal->waiters;i++)
-    SetEvent(p_internal->event);
+void wxCriticalSection::Leave()
+{
+    ::LeaveCriticalSection((CRITICAL_SECTION *)m_buffer);
 }
 
-class wxThreadInternal {
-public:
-  static DWORD WinThreadStart(LPVOID arg);
+// ----------------------------------------------------------------------------
+// wxThread implementation
+// ----------------------------------------------------------------------------
 
-  HANDLE thread_id;
-  int state;
-  int prio, defer;
-  DWORD tid;
+// wxThreadInternal class
+// ----------------------
+
+class wxThreadInternal
+{
+public:
+    wxThreadInternal()
+    {
+        m_hThread = 0;
+        m_state = STATE_NEW;
+        m_priority = WXTHREAD_DEFAULT_PRIORITY;
+    }
+
+    ~wxThreadInternal()
+    {
+        Free();
+    }
+
+    void Free()
+    {
+        if ( m_hThread )
+        {
+            if ( !::CloseHandle(m_hThread) )
+            {
+                wxLogLastError(wxT("CloseHandle(thread)"));
+            }
+
+            m_hThread = 0;
+        }
+    }
+
+    // create a new (suspended) thread (for the given thread object)
+    bool Create(wxThread *thread);
+
+    // suspend/resume/terminate
+    bool Suspend();
+    bool Resume();
+    void Cancel() { m_state = STATE_CANCELED; }
+
+    // thread state
+    void SetState(wxThreadState state) { m_state = state; }
+    wxThreadState GetState() const { return m_state; }
+
+    // thread priority
+    void SetPriority(unsigned int priority);
+    unsigned int GetPriority() const { return m_priority; }
+
+    // thread handle and id
+    HANDLE GetHandle() const { return m_hThread; }
+    DWORD  GetId() const { return m_tid; }
+
+    // thread function
+    static DWORD WinThreadStart(wxThread *thread);
+
+private:
+    HANDLE        m_hThread;    // handle of the thread
+    wxThreadState m_state;      // state, see wxThreadState enum
+    unsigned int  m_priority;   // thread priority in "wx" units
+    DWORD         m_tid;        // thread id
 };
 
-DWORD wxThreadInternal::WinThreadStart(LPVOID arg)
+DWORD wxThreadInternal::WinThreadStart(wxThread *thread)
+{
+    DWORD rc;
+    bool wasCancelled;
+
+    // first of all, check whether we hadn't been cancelled already and don't
+    // start the user code at all then
+    if ( thread->m_internal->GetState() == STATE_EXITED )
+    {
+        rc = (DWORD)-1;
+        wasCancelled = TRUE;
+    }
+    else // do run thread
+    {
+        // store the thread object in the TLS
+        if ( !::TlsSetValue(gs_tlsThisThread, thread) )
+        {
+            wxLogSysError(_("Can not start thread: error writing TLS."));
+
+            return (DWORD)-1;
+        }
+
+        rc = (DWORD)thread->Entry();
+
+        // enter m_critsect before changing the thread state
+        thread->m_critsect.Enter();
+        wasCancelled = thread->m_internal->GetState() == STATE_CANCELED;
+        thread->m_internal->SetState(STATE_EXITED);
+        thread->m_critsect.Leave();
+    }
+
+    thread->OnExit();
+
+    // if the thread was cancelled (from Delete()), then its handle is still
+    // needed there
+    if ( thread->IsDetached() && !wasCancelled )
+    {
+        // auto delete
+        delete thread;
+    }
+    //else: the joinable threads handle will be closed when Wait() is done
+
+    return rc;
+}
+
+void wxThreadInternal::SetPriority(unsigned int priority)
 {
-  wxThread *ptr = (wxThread *)arg;
-  DWORD ret;
+    m_priority = priority;
+
+    // translate wxWindows priority to the Windows one
+    int win_priority;
+    if (m_priority <= 20)
+        win_priority = THREAD_PRIORITY_LOWEST;
+    else if (m_priority <= 40)
+        win_priority = THREAD_PRIORITY_BELOW_NORMAL;
+    else if (m_priority <= 60)
+        win_priority = THREAD_PRIORITY_NORMAL;
+    else if (m_priority <= 80)
+        win_priority = THREAD_PRIORITY_ABOVE_NORMAL;
+    else if (m_priority <= 100)
+        win_priority = THREAD_PRIORITY_HIGHEST;
+    else
+    {
+        wxFAIL_MSG(wxT("invalid value of thread priority parameter"));
+        win_priority = THREAD_PRIORITY_NORMAL;
+    }
+
+    if ( !::SetThreadPriority(m_hThread, win_priority) )
+    {
+        wxLogSysError(_("Can't set thread priority"));
+    }
+}
 
-  ret = (DWORD)ptr->Entry();
-  ptr->p_internal->state = STATE_EXITED;
+bool wxThreadInternal::Create(wxThread *thread)
+{
+    // for compilers which have it, we should use C RTL function for thread
+    // creation instead of Win32 API one because otherwise we will have memory
+    // leaks if the thread uses C RTL (and most threads do)
+#if defined(__VISUALC__) || \
+    (defined(__BORLANDC__) && (__BORLANDC__ >= 0x500)) || \
+    (defined(__GNUG__) && defined(__MSVCRT__))
+    typedef unsigned (__stdcall *RtlThreadStart)(void *);
+
+    m_hThread = (HANDLE)_beginthreadex(NULL, 0,
+                                       (RtlThreadStart)
+                                       wxThreadInternal::WinThreadStart,
+                                       thread, CREATE_SUSPENDED,
+                                       (unsigned int *)&m_tid);
+#else // compiler doesn't have _beginthreadex
+    m_hThread = ::CreateThread
+                  (
+                    NULL,                               // default security
+                    0,                                  // default stack size
+                    (LPTHREAD_START_ROUTINE)            // thread entry point
+                    wxThreadInternal::WinThreadStart,   //
+                    (LPVOID)thread,                     // parameter
+                    CREATE_SUSPENDED,                   // flags
+                    &m_tid                              // [out] thread id
+                  );
+#endif // _beginthreadex/CreateThread
+
+    if ( m_hThread == NULL )
+    {
+        wxLogSysError(_("Can't create thread"));
+
+        return FALSE;
+    }
+
+    if ( m_priority != WXTHREAD_DEFAULT_PRIORITY )
+    {
+        SetPriority(m_priority);
+    }
 
-  return ret;
+    return TRUE;
 }
 
-wxThreadError wxThread::Create(void)
+bool wxThreadInternal::Suspend()
 {
-  int win_prio, prio = p_internal->prio;
+    DWORD nSuspendCount = ::SuspendThread(m_hThread);
+    if ( nSuspendCount == (DWORD)-1 )
+    {
+        wxLogSysError(_("Can not suspend thread %x"), m_hThread);
 
-  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) {
-    printf("Error = %d\n", GetLastError());
-    return THREAD_NO_RESOURCE;
-  }
+        return FALSE;
+    }
 
-  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;
+    m_state = STATE_PAUSED;
 
-  SetThreadPriority(p_internal->thread_id, win_prio);
+    return TRUE;
+}
 
-  ResumeThread(p_internal->thread_id);
-  p_internal->state = STATE_RUNNING;
-  return THREAD_NO_ERROR;
+bool wxThreadInternal::Resume()
+{
+    DWORD nSuspendCount = ::ResumeThread(m_hThread);
+    if ( nSuspendCount == (DWORD)-1 )
+    {
+        wxLogSysError(_("Can not resume thread %x"), m_hThread);
+
+        return FALSE;
+    }
+
+    // don't change the state from STATE_EXITED because it's special and means
+    // we are going to terminate without running any user code - if we did it,
+    // the codei n Delete() wouldn't work
+    if ( m_state != STATE_EXITED )
+    {
+        m_state = STATE_RUNNING;
+    }
+
+    return TRUE;
 }
 
-wxThreadError wxThread::Destroy()
+// static functions
+// ----------------
+
+wxThread *wxThread::This()
 {
-  if (p_internal->state != STATE_RUNNING)
-    return THREAD_NOT_RUNNING;
+    wxThread *thread = (wxThread *)::TlsGetValue(gs_tlsThisThread);
+
+    // be careful, 0 may be a valid return value as well
+    if ( !thread && (::GetLastError() != NO_ERROR) )
+    {
+        wxLogSysError(_("Couldn't get the current thread pointer"));
 
-  if (p_internal->defer == FALSE)
-    TerminateThread(p_internal->thread_id, 0);
-  else
-    p_internal->state = STATE_CANCELED;
+        // return NULL...
+    }
 
-  return THREAD_NO_ERROR;
+    return thread;
 }
 
-void wxThread::Exit(void *status)
+bool wxThread::IsMain()
 {
-  p_internal->state = STATE_EXITED;
-  ExitThread((DWORD)status);
+    return ::GetCurrentThreadId() == gs_idMainThread;
 }
 
-void wxThread::SetPriority(int prio)
+#ifdef Yield
+#undef Yield
+#endif
+
+void wxThread::Yield()
 {
-  p_internal->prio = prio;
+    // 0 argument to Sleep() is special and means to just give away the rest of
+    // our timeslice
+    ::Sleep(0);
 }
 
-int wxThread::GetPriority(void)
+void wxThread::Sleep(unsigned long milliseconds)
 {
-  return p_internal->prio;
+    ::Sleep(milliseconds);
 }
 
-void wxThread::DeferDestroy(bool on)
+int wxThread::GetCPUCount()
 {
-  p_internal->defer = on;
+    SYSTEM_INFO si;
+    GetSystemInfo(&si);
+
+    return si.dwNumberOfProcessors;
 }
 
-void wxThread::TestDestroy()
+bool wxThread::SetConcurrency(size_t level)
 {
-  if (p_internal->state == STATE_CANCELED)
-    ExitThread(0);
+    wxASSERT_MSG( IsMain(), _T("should only be called from the main thread") );
+
+    // ok only for the default one
+    if ( level == 0 )
+        return 0;
+
+    // get system affinity mask first
+    HANDLE hProcess = ::GetCurrentProcess();
+    DWORD dwProcMask, dwSysMask;
+    if ( ::GetProcessAffinityMask(hProcess, &dwProcMask, &dwSysMask) == 0 )
+    {
+        wxLogLastError(_T("GetProcessAffinityMask"));
+
+        return FALSE;
+    }
+
+    // how many CPUs have we got?
+    if ( dwSysMask == 1 )
+    {
+        // don't bother with all this complicated stuff - on a single
+        // processor system it doesn't make much sense anyhow
+        return level == 1;
+    }
+
+    // calculate the process mask: it's a bit vector with one bit per
+    // processor; we want to schedule the process to run on first level
+    // CPUs
+    DWORD bit = 1;
+    while ( bit )
+    {
+        if ( dwSysMask & bit )
+        {
+            // ok, we can set this bit
+            dwProcMask |= bit;
+
+            // another process added
+            if ( !--level )
+            {
+                // and that's enough
+                break;
+            }
+        }
+
+        // next bit
+        bit <<= 1;
+    }
+
+    // could we set all bits?
+    if ( level != 0 )
+    {
+        wxLogDebug(_T("bad level %u in wxThread::SetConcurrency()"), level);
+
+        return FALSE;
+    }
+
+    // set it: we can't link to SetProcessAffinityMask() because it doesn't
+    // exist in Win9x, use RT binding instead
+
+    typedef BOOL (*SETPROCESSAFFINITYMASK)(HANDLE, DWORD);
+
+    // can use static var because we're always in the main thread here
+    static SETPROCESSAFFINITYMASK pfnSetProcessAffinityMask = NULL;
+
+    if ( !pfnSetProcessAffinityMask )
+    {
+        HMODULE hModKernel = ::LoadLibrary(_T("kernel32"));
+        if ( hModKernel )
+        {
+            pfnSetProcessAffinityMask = (SETPROCESSAFFINITYMASK)
+                ::GetProcAddress(hModKernel, "SetProcessAffinityMask");
+        }
+
+        // we've discovered a MT version of Win9x!
+        wxASSERT_MSG( pfnSetProcessAffinityMask,
+                      _T("this system has several CPUs but no SetProcessAffinityMask function?") );
+    }
+
+    if ( !pfnSetProcessAffinityMask )
+    {
+        // msg given above - do it only once
+        return FALSE;
+    }
+
+    if ( pfnSetProcessAffinityMask(hProcess, dwProcMask) == 0 )
+    {
+        wxLogLastError(_T("SetProcessAffinityMask"));
+
+        return FALSE;
+    }
+
+    return TRUE;
 }
 
-void *wxThread::Join()
+// ctor and dtor
+// -------------
+
+wxThread::wxThread(wxThreadKind kind)
 {
-  DWORD exit_code;
+    m_internal = new wxThreadInternal();
+
+    m_isDetached = kind == wxTHREAD_DETACHED;
+}
 
-  if (p_internal->state == STATE_IDLE)
-    return NULL;
+wxThread::~wxThread()
+{
+    delete m_internal;
+}
 
-  if (wxThread::IsMain())
-    wxMainMutex.Unlock();
-  WaitForSingleObject(p_internal->thread_id, INFINITE);
-  if (wxThread::IsMain())
-    wxMainMutex.Lock();
+// create/start thread
+// -------------------
 
-  GetExitCodeThread(p_internal->thread_id, &exit_code);
-  CloseHandle(p_internal->thread_id);
+wxThreadError wxThread::Create()
+{
+    wxCriticalSectionLocker lock(m_critsect);
 
-  p_internal->state = STATE_IDLE;
+    if ( !m_internal->Create(this) )
+        return wxTHREAD_NO_RESOURCE;
 
-  return (void *)exit_code;
+    return wxTHREAD_NO_ERROR;
 }
 
-unsigned long wxThread::GetID()
+wxThreadError wxThread::Run()
 {
-  return (unsigned long)p_internal->tid;
+    wxCriticalSectionLocker lock(m_critsect);
+
+    if ( m_internal->GetState() != STATE_NEW )
+    {
+        // actually, it may be almost any state at all, not only STATE_RUNNING
+        return wxTHREAD_RUNNING;
+    }
+
+    // the thread has just been created and is still suspended - let it run
+    return Resume();
 }
 
-bool wxThread::IsMain()
+// suspend/resume thread
+// ---------------------
+
+wxThreadError wxThread::Pause()
 {
-  return (GetCurrentThread() == p_mainid);
+    wxCriticalSectionLocker lock(m_critsect);
+
+    return m_internal->Suspend() ? wxTHREAD_NO_ERROR : wxTHREAD_MISC_ERROR;
 }
 
-wxThread::wxThread()
+wxThreadError wxThread::Resume()
 {
-  p_internal = new wxThreadInternal();
+    wxCriticalSectionLocker lock(m_critsect);
 
-  p_internal->defer = FALSE;
-  p_internal->prio  = WXTHREAD_DEFAULT_PRIORITY;
-  p_internal->state = STATE_IDLE;
+    return m_internal->Resume() ? wxTHREAD_NO_ERROR : wxTHREAD_MISC_ERROR;
 }
 
-wxThread::~wxThread()
+// stopping thread
+// ---------------
+
+wxThread::ExitCode wxThread::Wait()
+{
+    // 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;
+}
+
+wxThreadError wxThread::Delete(ExitCode *pRc)
+{
+    ExitCode rc = 0;
+
+    // Delete() is always safe to call, so consider all possible states
+
+    // we might need to resume the thread, but we might also not need to cancel
+    // it if it doesn't run yet
+    bool shouldResume = FALSE,
+         shouldCancel = TRUE,
+         isRunning = FALSE;
+
+    // check if the thread already started to run
+    {
+        wxCriticalSectionLocker lock(m_critsect);
+
+        if ( m_internal->GetState() == STATE_NEW )
+        {
+            // WinThreadStart() will see it and terminate immediately, no need
+            // to cancel the thread - but we still need to resume it to let it
+            // run
+            m_internal->SetState(STATE_EXITED);
+
+            Resume();   // it knows about STATE_EXITED special case
+
+            shouldCancel = FALSE;
+            isRunning = TRUE;
+
+            // shouldResume is correctly set to FALSE here
+        }
+        else
+        {
+            shouldResume = IsPaused();
+        }
+    }
+
+    // resume the thread if it is paused
+    if ( shouldResume )
+        Resume();
+
+    HANDLE hThread = m_internal->GetHandle();
+
+    // does is still run?
+    if ( isRunning || IsRunning() )
+    {
+        if ( IsMain() )
+        {
+            // set flag for wxIsWaitingForThread()
+            gs_waitingForThread = TRUE;
+
+#if wxUSE_GUI
+            wxBeginBusyCursor();
+#endif // wxUSE_GUI
+        }
+
+        // ask the thread to terminate
+        if ( shouldCancel )
+        {
+            wxCriticalSectionLocker lock(m_critsect);
+
+            m_internal->Cancel();
+        }
+
+#if wxUSE_GUI
+        // we can't just wait for the thread to terminate because it might be
+        // calling some GUI functions and so it will never terminate before we
+        // process the Windows messages that result from these functions
+        DWORD result;
+        do
+        {
+            result = ::MsgWaitForMultipleObjects
+                     (
+                       1,              // number of objects to wait for
+                       &hThread,       // the objects
+                       FALSE,          // don't wait for all objects
+                       INFINITE,       // no timeout
+                       QS_ALLEVENTS    // return as soon as there are any events
+                     );
+
+            switch ( result )
+            {
+                case 0xFFFFFFFF:
+                    // error
+                    wxLogSysError(_("Can not wait for thread termination"));
+                    Kill();
+                    return wxTHREAD_KILLED;
+
+                case WAIT_OBJECT_0:
+                    // thread we're waiting for terminated
+                    break;
+
+                case WAIT_OBJECT_0 + 1:
+                    // new message arrived, process it
+                    if ( !wxTheApp->DoMessage() )
+                    {
+                        // WM_QUIT received: kill the thread
+                        Kill();
+
+                        return wxTHREAD_KILLED;
+                    }
+
+                    if ( IsMain() )
+                    {
+                        // give the thread we're waiting for chance to exit
+                        // from the GUI call it might have been in
+                        if ( (gs_nWaitingForGui > 0) && wxGuiOwnedByMainThread() )
+                        {
+                            wxMutexGuiLeave();
+                        }
+                    }
+
+                    break;
+
+                default:
+                    wxFAIL_MSG(wxT("unexpected result of MsgWaitForMultipleObject"));
+            }
+        } while ( result != WAIT_OBJECT_0 );
+#else // !wxUSE_GUI
+        // simply wait for the thread to terminate
+        //
+        // OTOH, even console apps create windows (in wxExecute, for WinSock
+        // &c), so may be use MsgWaitForMultipleObject() too here?
+        if ( WaitForSingleObject(hThread, INFINITE) != WAIT_OBJECT_0 )
+        {
+            wxFAIL_MSG(wxT("unexpected result of WaitForSingleObject"));
+        }
+#endif // wxUSE_GUI/!wxUSE_GUI
+
+        if ( IsMain() )
+        {
+            gs_waitingForThread = FALSE;
+
+#if wxUSE_GUI
+            wxEndBusyCursor();
+#endif // wxUSE_GUI
+        }
+    }
+
+    if ( !::GetExitCodeThread(hThread, (LPDWORD)&rc) )
+    {
+        wxLogLastError(wxT("GetExitCodeThread"));
+
+        rc = (ExitCode)-1;
+    }
+
+    if ( IsDetached() )
+    {
+        // if the thread exits normally, this is done in WinThreadStart, but in
+        // this case it would have been too early because
+        // MsgWaitForMultipleObject() would fail if the thread handle was
+        // closed while we were waiting on it, so we must do it here
+        delete this;
+    }
+
+    wxASSERT_MSG( (DWORD)rc != STILL_ACTIVE,
+                  wxT("thread must be already terminated.") );
+
+    if ( pRc )
+        *pRc = rc;
+
+    return rc == (ExitCode)-1 ? wxTHREAD_MISC_ERROR : wxTHREAD_NO_ERROR;
+}
+
+wxThreadError wxThread::Kill()
+{
+    if ( !IsRunning() )
+        return wxTHREAD_NOT_RUNNING;
+
+    if ( !::TerminateThread(m_internal->GetHandle(), (DWORD)-1) )
+    {
+        wxLogSysError(_("Couldn't terminate thread"));
+
+        return wxTHREAD_MISC_ERROR;
+    }
+
+    m_internal->Free();
+
+    if ( IsDetached() )
+    {
+        delete this;
+    }
+
+    return wxTHREAD_NO_ERROR;
+}
+
+void wxThread::Exit(ExitCode status)
+{
+    m_internal->Free();
+
+    if ( IsDetached() )
+    {
+        delete this;
+    }
+
+#if defined(__VISUALC__) || \
+    (defined(__BORLANDC__) && (__BORLANDC__ >= 0x500)) || \
+    (defined(__GNUG__) && defined(__MSVCRT__))
+    _endthreadex((unsigned)status);
+#else // !VC++
+    ::ExitThread((DWORD)status);
+#endif // VC++/!VC++
+
+    wxFAIL_MSG(wxT("Couldn't return from ExitThread()!"));
+}
+
+// priority setting
+// ----------------
+
+void wxThread::SetPriority(unsigned int prio)
+{
+    wxCriticalSectionLocker lock(m_critsect);
+
+    m_internal->SetPriority(prio);
+}
+
+unsigned int wxThread::GetPriority() const
+{
+    wxCriticalSectionLocker lock((wxCriticalSection &)m_critsect); // const_cast
+
+    return m_internal->GetPriority();
+}
+
+unsigned long wxThread::GetId() const
+{
+    wxCriticalSectionLocker lock((wxCriticalSection &)m_critsect); // const_cast
+
+    return (unsigned long)m_internal->GetId();
+}
+
+bool wxThread::IsRunning() const
+{
+    wxCriticalSectionLocker lock((wxCriticalSection &)m_critsect); // const_cast
+
+    return m_internal->GetState() == STATE_RUNNING;
+}
+
+bool wxThread::IsAlive() const
 {
-  Destroy();
-  Join();
-  delete p_internal;
+    wxCriticalSectionLocker lock((wxCriticalSection &)m_critsect); // const_cast
+
+    return (m_internal->GetState() == STATE_RUNNING) ||
+           (m_internal->GetState() == STATE_PAUSED);
 }
 
-// The default callback just joins the thread and throws away the result.
-void wxThread::OnExit()
+bool wxThread::IsPaused() const
 {
-  Join();
+    wxCriticalSectionLocker lock((wxCriticalSection &)m_critsect); // const_cast
+
+    return m_internal->GetState() == STATE_PAUSED;
 }
 
-// Automatic initialization
-class wxThreadModule : public wxModule {
-  DECLARE_DYNAMIC_CLASS(wxThreadModule)
+bool wxThread::TestDestroy()
+{
+    wxCriticalSectionLocker lock((wxCriticalSection &)m_critsect); // const_cast
+
+    return m_internal->GetState() == STATE_CANCELED;
+}
+
+// ----------------------------------------------------------------------------
+// Automatic initialization for thread module
+// ----------------------------------------------------------------------------
+
+class wxThreadModule : public wxModule
+{
 public:
-  virtual bool OnInit(void) {
-    p_mainid = GetCurrentThread();
-    wxMainMutex.Lock();
-    return TRUE;
-  }
+    virtual bool OnInit();
+    virtual void OnExit();
 
-  // Global cleanup
-  virtual void OnExit(void) {
-    wxMainMutex.Unlock();
-  }
+private:
+    DECLARE_DYNAMIC_CLASS(wxThreadModule)
 };
 
 IMPLEMENT_DYNAMIC_CLASS(wxThreadModule, wxModule)
 
+bool wxThreadModule::OnInit()
+{
+    // allocate TLS index for storing the pointer to the current thread
+    gs_tlsThisThread = ::TlsAlloc();
+    if ( gs_tlsThisThread == 0xFFFFFFFF )
+    {
+        // in normal circumstances it will only happen if all other
+        // TLS_MINIMUM_AVAILABLE (>= 64) indices are already taken - in other
+        // words, this should never happen
+        wxLogSysError(_("Thread module initialization failed: impossible to allocate index in thread local storage"));
+
+        return FALSE;
+    }
+
+    // main thread doesn't have associated wxThread object, so store 0 in the
+    // TLS instead
+    if ( !::TlsSetValue(gs_tlsThisThread, (LPVOID)0) )
+    {
+        ::TlsFree(gs_tlsThisThread);
+        gs_tlsThisThread = 0xFFFFFFFF;
+
+        wxLogSysError(_("Thread module initialization failed: can not store value in thread local storage"));
+
+        return FALSE;
+    }
+
+    gs_critsectWaitingForGui = new wxCriticalSection();
+
+    gs_critsectGui = new wxCriticalSection();
+    gs_critsectGui->Enter();
+
+    // no error return for GetCurrentThreadId()
+    gs_idMainThread = ::GetCurrentThreadId();
+
+    return TRUE;
+}
+
+void wxThreadModule::OnExit()
+{
+    if ( !::TlsFree(gs_tlsThisThread) )
+    {
+        wxLogLastError(wxT("TlsFree failed."));
+    }
+
+    if ( gs_critsectGui )
+    {
+        gs_critsectGui->Leave();
+        delete gs_critsectGui;
+        gs_critsectGui = NULL;
+    }
+
+    delete gs_critsectWaitingForGui;
+    gs_critsectWaitingForGui = NULL;
+}
+
+// ----------------------------------------------------------------------------
+// under Windows, these functions are implemented using a critical section and
+// not a mutex, so the names are a bit confusing
+// ----------------------------------------------------------------------------
+
+void WXDLLEXPORT wxMutexGuiEnter()
+{
+    // this would dead lock everything...
+    wxASSERT_MSG( !wxThread::IsMain(),
+                  wxT("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(*gs_critsectWaitingForGui);
+
+        gs_nWaitingForGui++;
+    }
+
+    wxWakeUpMainThread();
+
+    // now we may block here because the main thread will soon let us in
+    // (during the next iteration of OnIdle())
+    gs_critsectGui->Enter();
+}
+
+void WXDLLEXPORT wxMutexGuiLeave()
+{
+    wxCriticalSectionLocker enter(*gs_critsectWaitingForGui);
+
+    if ( wxThread::IsMain() )
+    {
+        gs_bGuiOwnedByMainThread = FALSE;
+    }
+    else
+    {
+        // decrement the number of threads waiting for GUI access now
+        wxASSERT_MSG( gs_nWaitingForGui > 0,
+                      wxT("calling wxMutexGuiLeave() without entering it first?") );
+
+        gs_nWaitingForGui--;
+
+        wxWakeUpMainThread();
+    }
+
+    gs_critsectGui->Leave();
+}
+
+void WXDLLEXPORT wxMutexGuiLeaveOrEnter()
+{
+    wxASSERT_MSG( wxThread::IsMain(),
+                  wxT("only main thread may call wxMutexGuiLeaveOrEnter()!") );
+
+    wxCriticalSectionLocker enter(*gs_critsectWaitingForGui);
+
+    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_critsectGui->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
+    }
+}
+
+bool WXDLLEXPORT wxGuiOwnedByMainThread()
+{
+    return gs_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(gs_idMainThread, WM_NULL, 0, 0) )
+    {
+        // should never happen
+        wxLogLastError(wxT("PostThreadMessage(WM_NULL)"));
+    }
+}
+
+bool WXDLLEXPORT wxIsWaitingForThread()
+{
+    return gs_waitingForThread;
+}
+
+#endif // wxUSE_THREADS