/////////////////////////////////////////////////////////////////////////////
-// Name: thread.cpp
+// Name: src/msw/thread.cpp
// Purpose: wxThread Implementation
// Author: Original from Wolfram Gloger/Guilhem Lavaux
// Modified by: Vadim Zeitlin to make it work :-)
// Created: 04/22/98
// RCS-ID: $Id$
-// Copyright: (c) Wolfram Gloger (1996, 1997); Guilhem Lavaux (1998),
-// Vadim Zeitlin (1999)
+// Copyright: (c) Wolfram Gloger (1996, 1997), Guilhem Lavaux (1998);
+// Vadim Zeitlin (1999-2002)
// Licence: wxWindows licence
/////////////////////////////////////////////////////////////////////////////
#if wxUSE_THREADS
#include "wx/msw/private.h"
+#include "wx/msw/missing.h"
#include "wx/module.h"
#include "wx/thread.h"
-#ifdef Yield
-# undef Yield
-#endif
-
// must have this symbol defined to get _beginthread/_endthread declarations
#ifndef _MT
#define _MT
#if defined(__VISUALC__) || \
(defined(__BORLANDC__) && (__BORLANDC__ >= 0x500)) || \
(defined(__GNUG__) && defined(__MSVCRT__)) || \
- defined(__WATCOMC__)
+ defined(__WATCOMC__) || defined(__MWERKS__)
#undef wxUSE_BEGIN_THREAD
#define wxUSE_BEGIN_THREAD
static bool gs_waitingForThread = FALSE;
// ============================================================================
-// Windows implementation of thread classes
+// Windows implementation of thread and related classes
// ============================================================================
// ----------------------------------------------------------------------------
-// wxMutex implementation
+// wxCriticalSection
+// ----------------------------------------------------------------------------
+
+wxCriticalSection::wxCriticalSection()
+{
+ wxCOMPILE_TIME_ASSERT( sizeof(CRITICAL_SECTION) <= sizeof(wxCritSectBuffer),
+ wxCriticalSectionBufferTooSmall );
+
+ ::InitializeCriticalSection((CRITICAL_SECTION *)m_buffer);
+}
+
+wxCriticalSection::~wxCriticalSection()
+{
+ ::DeleteCriticalSection((CRITICAL_SECTION *)m_buffer);
+}
+
+void wxCriticalSection::Enter()
+{
+ ::EnterCriticalSection((CRITICAL_SECTION *)m_buffer);
+}
+
+void wxCriticalSection::Leave()
+{
+ ::LeaveCriticalSection((CRITICAL_SECTION *)m_buffer);
+}
+
+// ----------------------------------------------------------------------------
+// wxMutex
// ----------------------------------------------------------------------------
class wxMutexInternal
{
public:
- wxMutexInternal()
- {
- m_mutex = ::CreateMutex(NULL, FALSE, NULL);
- if ( !m_mutex )
- {
- wxLogSysError(_("Can not create mutex"));
- }
- }
+ wxMutexInternal(wxMutexType mutexType);
+ ~wxMutexInternal();
- ~wxMutexInternal() { if ( m_mutex ) CloseHandle(m_mutex); }
+ bool IsOk() const { return m_mutex != NULL; }
+
+ wxMutexError Lock() { return LockTimeout(INFINITE); }
+ wxMutexError TryLock() { return LockTimeout(0); }
+ wxMutexError Unlock();
+
+private:
+ wxMutexError LockTimeout(DWORD milliseconds);
-public:
HANDLE m_mutex;
};
-wxMutex::wxMutex()
+// all mutexes are recursive under Win32 so we don't use mutexType
+wxMutexInternal::wxMutexInternal(wxMutexType WXUNUSED(mutexType))
{
- m_internal = new wxMutexInternal;
-
- m_locked = 0;
+ // create a nameless (hence intra process and always private) mutex
+ m_mutex = ::CreateMutex
+ (
+ NULL, // default secutiry attributes
+ FALSE, // not initially locked
+ NULL // no name
+ );
+
+ if ( !m_mutex )
+ {
+ wxLogLastError(_T("CreateMutex()"));
+ }
}
-wxMutex::~wxMutex()
+wxMutexInternal::~wxMutexInternal()
{
- if ( m_locked > 0 )
+ if ( m_mutex )
{
- wxLogDebug(_T("Warning: freeing a locked mutex (%d locks)."), m_locked);
+ if ( !::CloseHandle(m_mutex) )
+ {
+ wxLogLastError(_T("CloseHandle(mutex)"));
+ }
}
-
- delete m_internal;
}
-wxMutexError wxMutex::Lock()
+wxMutexError wxMutexInternal::LockTimeout(DWORD milliseconds)
{
- DWORD ret;
-
- ret = WaitForSingleObject(m_internal->m_mutex, INFINITE);
- switch ( ret )
+ DWORD rc = ::WaitForSingleObject(m_mutex, milliseconds);
+ if ( rc == WAIT_ABANDONED )
{
- case WAIT_ABANDONED:
- return wxMUTEX_BUSY;
+ // the previous caller died without releasing the mutex, but now we can
+ // really lock it
+ wxLogDebug(_T("WaitForSingleObject() returned WAIT_ABANDONED"));
+
+ // use 0 timeout, normally we should always get it
+ rc = ::WaitForSingleObject(m_mutex, 0);
+ }
+ switch ( rc )
+ {
case WAIT_OBJECT_0:
// ok
break;
- case WAIT_FAILED:
- wxLogSysError(_("Couldn't acquire a mutex lock"));
- return wxMUTEX_MISC_ERROR;
-
case WAIT_TIMEOUT:
+ return wxMUTEX_BUSY;
+
+ case WAIT_ABANDONED: // checked for above
default:
wxFAIL_MSG(wxT("impossible return value in wxMutex::Lock"));
- }
+ // fall through
- m_locked++;
- return wxMUTEX_NO_ERROR;
-}
-
-wxMutexError wxMutex::TryLock()
-{
- DWORD ret;
-
- ret = WaitForSingleObject(m_internal->m_mutex, 0);
- if (ret == WAIT_TIMEOUT || ret == WAIT_ABANDONED)
- return wxMUTEX_BUSY;
+ case WAIT_FAILED:
+ wxLogLastError(_T("WaitForSingleObject(mutex)"));
+ return wxMUTEX_MISC_ERROR;
+ }
- m_locked++;
return wxMUTEX_NO_ERROR;
}
-wxMutexError wxMutex::Unlock()
+wxMutexError wxMutexInternal::Unlock()
{
- if (m_locked > 0)
- m_locked--;
-
- BOOL ret = ReleaseMutex(m_internal->m_mutex);
- if ( ret == 0 )
+ if ( !::ReleaseMutex(m_mutex) )
{
- wxLogSysError(_("Couldn't release a mutex"));
+ wxLogLastError(_("ReleaseMutex()"));
+
return wxMUTEX_MISC_ERROR;
}
return wxMUTEX_NO_ERROR;
}
-// ----------------------------------------------------------------------------
-// wxCondition implementation
-// ----------------------------------------------------------------------------
+// --------------------------------------------------------------------------
+// wxSemaphore
+// --------------------------------------------------------------------------
-class wxConditionInternal
+// a trivial wrapper around Win32 semaphore
+class wxSemaphoreInternal
{
public:
- 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."));
- }
+ wxSemaphoreInternal(int initialcount, int maxcount);
+ ~wxSemaphoreInternal();
- // nobody waits for us yet
- m_nWaiters = 0;
- }
+ bool IsOk() const { return m_semaphore != NULL; }
- 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);
+ wxSemaError Wait() { return WaitTimeout(INFINITE); }
+ wxSemaError TryWait() { return WaitTimeout(0); }
+ wxSemaError WaitTimeout(unsigned long milliseconds);
- // 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);
+ wxSemaError Post();
- ::InterlockedDecrement(&m_nWaiters);
+private:
+ HANDLE m_semaphore;
+};
- return rc != WAIT_TIMEOUT;
+wxSemaphoreInternal::wxSemaphoreInternal(int initialcount, int maxcount)
+{
+ if ( maxcount == 0 )
+ {
+ // make it practically infinite
+ maxcount = INT_MAX;
}
- void Signal()
+ m_semaphore = ::CreateSemaphore
+ (
+ NULL, // default security attributes
+ initialcount,
+ maxcount,
+ NULL // no name
+ );
+
+ if ( !m_semaphore )
{
- // 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"));
- }
+ wxLogLastError(_T("CreateSemaphore()"));
}
+}
- void Broadcast()
+wxSemaphoreInternal::~wxSemaphoreInternal()
+{
+ if ( m_semaphore )
{
- // 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++ )
+ if ( !::CloseHandle(m_semaphore) )
{
- Signal();
+ wxLogLastError(_T("CloseHandle(semaphore)"));
}
}
+}
+
+wxSemaError wxSemaphoreInternal::WaitTimeout(unsigned long milliseconds)
+{
+ DWORD rc = ::WaitForSingleObject( m_semaphore, milliseconds );
- ~wxConditionInternal()
+ switch ( rc )
{
- if ( m_hEvent )
- {
- if ( !::CloseHandle(m_hEvent) )
- {
- wxLogLastError(wxT("CloseHandle(event)"));
- }
- }
- }
+ case WAIT_OBJECT_0:
+ return wxSEMA_NO_ERROR;
-private:
- // the Win32 synchronization object corresponding to this event
- HANDLE m_hEvent;
+ case WAIT_TIMEOUT:
+ return wxSEMA_BUSY;
- // number of threads waiting for this condition
- LONG m_nWaiters;
-};
+ default:
+ wxLogLastError(_T("WaitForSingleObject(semaphore)"));
+ }
-wxCondition::wxCondition()
-{
- m_internal = new wxConditionInternal;
+ return wxSEMA_MISC_ERROR;
}
-wxCondition::~wxCondition()
+wxSemaError wxSemaphoreInternal::Post()
{
- delete m_internal;
+ if ( !::ReleaseSemaphore(m_semaphore, 1, NULL /* ptr to previous count */) )
+ {
+ wxLogLastError(_T("ReleaseSemaphore"));
+
+ return wxSEMA_MISC_ERROR;
+ }
+
+ return wxSEMA_NO_ERROR;
}
-void wxCondition::Wait()
+// --------------------------------------------------------------------------
+// wxCondition
+// --------------------------------------------------------------------------
+
+// Win32 doesn't have explicit support for the POSIX condition variables and
+// the Win32 events have quite different semantics, so we reimplement the
+// conditions from scratch using the mutexes and semaphores
+class wxConditionInternal
{
- (void)m_internal->Wait(INFINITE);
-}
+public:
+ wxConditionInternal(wxMutex& mutex);
-bool wxCondition::Wait(unsigned long sec,
- unsigned long nsec)
+ bool IsOk() const { return m_mutex.IsOk() && m_semaphore.IsOk(); }
+
+ wxCondError Wait();
+ wxCondError WaitTimeout(unsigned long milliseconds);
+
+ wxCondError Signal();
+ wxCondError Broadcast();
+
+private:
+ // the number of threads currently waiting for this condition
+ LONG m_numWaiters;
+
+ // the critical section protecting m_numWaiters
+ wxCriticalSection m_csWaiters;
+
+ wxMutex& m_mutex;
+ wxSemaphore m_semaphore;
+};
+
+wxConditionInternal::wxConditionInternal(wxMutex& mutex)
+ : m_mutex(mutex)
{
- return m_internal->Wait(sec*1000 + nsec/1000000);
+ // another thread can't access it until we return from ctor, so no need to
+ // protect access to m_numWaiters here
+ m_numWaiters = 0;
}
-void wxCondition::Signal()
+wxCondError wxConditionInternal::Wait()
{
- m_internal->Signal();
+ // increment the number of waiters
+ ::InterlockedIncrement(&m_numWaiters);
+
+ m_mutex.Unlock();
+
+ // a potential race condition can occur here
+ //
+ // after a thread increments nwaiters, and unlocks the mutex and before the
+ // semaphore.Wait() is called, if another thread can cause a signal to be
+ // generated
+ //
+ // this race condition is handled by using a semaphore and incrementing the
+ // semaphore only if 'nwaiters' is greater that zero since the semaphore,
+ // can 'remember' signals the race condition will not occur
+
+ // wait ( if necessary ) and decrement semaphore
+ wxSemaError err = m_semaphore.Wait();
+ m_mutex.Lock();
+
+ return err == wxSEMA_NO_ERROR ? wxCOND_NO_ERROR : wxCOND_MISC_ERROR;
}
-void wxCondition::Broadcast()
+wxCondError wxConditionInternal::WaitTimeout(unsigned long milliseconds)
{
- m_internal->Broadcast();
-}
+ ::InterlockedIncrement(&m_numWaiters);
-// ----------------------------------------------------------------------------
-// wxCriticalSection implementation
-// ----------------------------------------------------------------------------
+ m_mutex.Unlock();
-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
+ // a race condition can occur at this point in the code
+ //
+ // please see the comments in Wait(), for details
- ::InitializeCriticalSection((CRITICAL_SECTION *)m_buffer);
-}
+ wxSemaError err = m_semaphore.WaitTimeout(milliseconds);
-wxCriticalSection::~wxCriticalSection()
-{
- ::DeleteCriticalSection((CRITICAL_SECTION *)m_buffer);
+ if ( err == wxSEMA_BUSY )
+ {
+ // another potential race condition exists here it is caused when a
+ // 'waiting' thread timesout, and returns from WaitForSingleObject, but
+ // has not yet decremented 'nwaiters'.
+ //
+ // at this point if another thread calls signal() then the semaphore
+ // will be incremented, but the waiting thread will miss it.
+ //
+ // to handle this particular case, the waiting thread calls
+ // WaitForSingleObject again with a timeout of 0, after locking
+ // 'nwaiters_mutex'. this call does not block because of the zero
+ // timeout, but will allow the waiting thread to catch the missed
+ // signals.
+ wxCriticalSectionLocker lock(m_csWaiters);
+
+ err = m_semaphore.WaitTimeout(0);
+
+ if ( err != wxSEMA_NO_ERROR )
+ {
+ m_numWaiters--;
+ }
+ }
+
+ m_mutex.Lock();
+
+ return err == wxSEMA_NO_ERROR ? wxCOND_NO_ERROR : wxCOND_MISC_ERROR;
}
-void wxCriticalSection::Enter()
+wxCondError wxConditionInternal::Signal()
{
- ::EnterCriticalSection((CRITICAL_SECTION *)m_buffer);
+ wxCriticalSectionLocker lock(m_csWaiters);
+
+ if ( m_numWaiters > 0 )
+ {
+ // increment the semaphore by 1
+ if ( m_semaphore.Post() != wxSEMA_NO_ERROR )
+ return wxCOND_MISC_ERROR;
+
+ m_numWaiters--;
+ }
+
+ return wxCOND_NO_ERROR;
}
-void wxCriticalSection::Leave()
+wxCondError wxConditionInternal::Broadcast()
{
- ::LeaveCriticalSection((CRITICAL_SECTION *)m_buffer);
+ wxCriticalSectionLocker lock(m_csWaiters);
+
+ while ( m_numWaiters > 0 )
+ {
+ if ( m_semaphore.Post() != wxSEMA_NO_ERROR )
+ return wxCOND_MISC_ERROR;
+
+ m_numWaiters--;
+ }
+
+ return wxCOND_NO_ERROR;
}
// ----------------------------------------------------------------------------
{
// set flag for wxIsWaitingForThread()
gs_waitingForThread = TRUE;
-
-#if wxUSE_GUI
- wxBeginBusyCursor();
-#endif // wxUSE_GUI
}
// ask the thread to terminate
// 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;
+ DWORD result = 0; // suppress warnings from broken compilers
do
{
+ if ( IsMain() )
+ {
+ // give the thread we're waiting for chance to do the GUI call
+ // it might be in
+ if ( (gs_nWaitingForGui > 0) && wxGuiOwnedByMainThread() )
+ {
+ wxMutexGuiLeave();
+ }
+ }
+
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
+ QS_ALLINPUT | // return as soon as there are any events
+ QS_ALLPOSTMESSAGE
);
switch ( result )
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:
if ( IsMain() )
{
gs_waitingForThread = FALSE;
-
-#if wxUSE_GUI
- wxEndBusyCursor();
-#endif // wxUSE_GUI
}
}
- if ( !::GetExitCodeThread(hThread, (LPDWORD)&rc) )
+ // although the thread might be already in the EXITED state it might not
+ // have terminated yet and so we are not sure that it has actually
+ // terminated if the "if" above hadn't been taken
+ do
{
- wxLogLastError(wxT("GetExitCodeThread"));
+ if ( !::GetExitCodeThread(hThread, (LPDWORD)&rc) )
+ {
+ wxLogLastError(wxT("GetExitCodeThread"));
- rc = (ExitCode)-1;
- }
+ rc = (ExitCode)-1;
+ }
+ } while ( (DWORD)rc == STILL_ACTIVE );
if ( IsDetached() )
{
delete this;
}
- wxASSERT_MSG( (DWORD)rc != STILL_ACTIVE,
- wxT("thread must be already terminated.") );
-
if ( pRc )
*pRc = rc;
return gs_waitingForThread;
}
+// ----------------------------------------------------------------------------
+// include common implementation code
+// ----------------------------------------------------------------------------
+
+#include "wx/thrimpl.cpp"
+
#endif // wxUSE_THREADS
-// vi:sts=4:sw=4:et
projects / wxWidgets.git / blobdiff