// Licence: wxWindows licence
/////////////////////////////////////////////////////////////////////////////
-#ifdef __GNUG__
- #pragma implementation "thread.h"
-#endif
-
// ----------------------------------------------------------------------------
// headers
// ----------------------------------------------------------------------------
// calling wxMutexGuiEnter()
static DWORD gs_idMainThread = 0;
-// if it's FALSE, some secondary thread is holding the GUI lock
-static bool gs_bGuiOwnedByMainThread = TRUE;
+// 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
// critical section which protects gs_nWaitingForGui variable
static wxCriticalSection *gs_critsectWaitingForGui = NULL;
+// critical section which serializes WinThreadStart() and WaitForTerminate()
+// (this is a potential bottleneck, we use a single crit sect for all threads
+// in the system, but normally time spent inside it should be quite short)
+static wxCriticalSection *gs_critsectThreadDelete = NULL;
+
// 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;
+static bool gs_waitingForThread = false;
// ============================================================================
// Windows implementation of thread and related classes
m_mutex = ::CreateMutex
(
NULL, // default secutiry attributes
- FALSE, // not initially locked
+ false, // not initially locked
NULL // no name
);
wxSemaphoreInternal::wxSemaphoreInternal(int initialcount, int maxcount)
{
-#ifndef __WXWINCE__
+#if !defined(_WIN32_WCE) || (_WIN32_WCE >= 300)
if ( maxcount == 0 )
{
// make it practically infinite
wxSemaError wxSemaphoreInternal::Post()
{
-#ifndef __WXWINCE__
+#if !defined(_WIN32_WCE) || (_WIN32_WCE >= 300)
if ( !::ReleaseSemaphore(m_semaphore, 1, NULL /* ptr to previous count */) )
#endif
{
return wxSEMA_NO_ERROR;
}
-// --------------------------------------------------------------------------
-// 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
-{
-public:
- wxConditionInternal(wxMutex& mutex);
-
- 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;
-
- DECLARE_NO_COPY_CLASS(wxConditionInternal)
-};
-
-wxConditionInternal::wxConditionInternal(wxMutex& mutex)
- : m_mutex(mutex)
-{
- // another thread can't access it until we return from ctor, so no need to
- // protect access to m_numWaiters here
- m_numWaiters = 0;
-}
-
-wxCondError wxConditionInternal::Wait()
-{
- // 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;
-}
-
-wxCondError wxConditionInternal::WaitTimeout(unsigned long milliseconds)
-{
- ::InterlockedIncrement(&m_numWaiters);
-
- m_mutex.Unlock();
-
- // a race condition can occur at this point in the code
- //
- // please see the comments in Wait(), for details
-
- wxSemaError err = m_semaphore.WaitTimeout(milliseconds);
-
- 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;
-}
-
-wxCondError wxConditionInternal::Signal()
-{
- 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;
-}
-
-wxCondError wxConditionInternal::Broadcast()
-{
- 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;
-}
-
// ----------------------------------------------------------------------------
// wxThread implementation
// ----------------------------------------------------------------------------
class wxThreadInternal
{
public:
- wxThreadInternal()
+ wxThreadInternal(wxThread *thread)
{
+ m_thread = thread;
m_hThread = 0;
m_state = STATE_NEW;
m_priority = WXTHREAD_DEFAULT_PRIORITY;
+ m_nRef = 1;
}
~wxThreadInternal()
// wait for the thread to terminate, either by itself, or by asking it
// (politely, this is not Kill()!) to do it
- wxThreadError WaitForTerminate(bool shouldCancel,
- wxCriticalSection& cs,
- wxThread::ExitCode *pRc);
+ wxThreadError WaitForTerminate(wxCriticalSection& cs,
+ wxThread::ExitCode *pRc,
+ wxThread *threadToDelete = NULL);
// kill the thread unconditionally
wxThreadError Kill();
// thread function
static THREAD_RETVAL THREAD_CALLCONV WinThreadStart(void *thread);
+ void KeepAlive()
+ {
+ if ( m_thread->IsDetached() )
+ ::InterlockedIncrement(&m_nRef);
+ }
+
+ void LetDie()
+ {
+ if ( m_thread->IsDetached() && !::InterlockedDecrement(&m_nRef) )
+ delete m_thread;
+ }
+
private:
+ // the thread we're associated with
+ wxThread *m_thread;
+
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
+ // number of threads which need this thread to remain alive, when the count
+ // reaches 0 we kill the owning wxThread -- and die ourselves with it
+ LONG m_nRef;
+
DECLARE_NO_COPY_CLASS(wxThreadInternal)
};
+// small class which keeps a thread alive during its lifetime
+class wxThreadKeepAlive
+{
+public:
+ wxThreadKeepAlive(wxThreadInternal& thrImpl) : m_thrImpl(thrImpl)
+ { m_thrImpl.KeepAlive(); }
+ ~wxThreadKeepAlive()
+ { m_thrImpl.LetDie(); }
+
+private:
+ wxThreadInternal& m_thrImpl;
+};
+
+
THREAD_RETVAL THREAD_CALLCONV wxThreadInternal::WinThreadStart(void *param)
{
THREAD_RETVAL rc;
- bool wasCancelled;
+
+ wxThread * const thread = (wxThread *)param;
// first of all, check whether we hadn't been cancelled already and don't
// start the user code at all then
- wxThread *thread = (wxThread *)param;
- if ( thread->m_internal->GetState() == STATE_EXITED )
+ const bool hasExited = thread->m_internal->GetState() == STATE_EXITED;
+
+ if ( hasExited )
{
rc = (THREAD_RETVAL)-1;
- wasCancelled = TRUE;
}
else // do run thread
{
}
rc = (THREAD_RETVAL)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 )
+ // save IsDetached because thread object can be deleted by joinable
+ // threads after state is changed to STATE_EXITED.
+ bool isDetached = thread->IsDetached();
+
+ if ( !hasExited )
{
- // auto delete
- delete thread;
+ // enter m_critsect before changing the thread state
+ wxCriticalSectionLocker lock(thread->m_critsect);
+ thread->m_internal->SetState(STATE_EXITED);
}
- //else: the joinable threads handle will be closed when Wait() is done
+
+ // the thread may delete itself now if it wants, we don't need it any more
+ if ( isDetached )
+ thread->m_internal->LetDie();
return rc;
}
{
m_priority = priority;
- // translate wxWindows priority to the Windows one
+ // translate wxWidgets priority to the Windows one
int win_priority;
if (m_priority <= 20)
win_priority = THREAD_PRIORITY_LOWEST;
{
wxLogSysError(_("Can't create thread"));
- return FALSE;
+ return false;
}
if ( m_priority != WXTHREAD_DEFAULT_PRIORITY )
SetPriority(m_priority);
}
- return TRUE;
+ return true;
}
wxThreadError wxThreadInternal::Kill()
}
wxThreadError
-wxThreadInternal::WaitForTerminate(bool shouldCancel,
- wxCriticalSection& cs,
- wxThread::ExitCode *pRc)
+wxThreadInternal::WaitForTerminate(wxCriticalSection& cs,
+ wxThread::ExitCode *pRc,
+ wxThread *threadToDelete)
{
- wxThread::ExitCode rc = 0;
+ // prevent the thread C++ object from disappearing as long as we are using
+ // it here
+ wxThreadKeepAlive keepAlive(*this);
+
- // Delete() is always safe to call, so consider all possible states
+ // we may either wait passively for the thread to terminate (when called
+ // from Wait()) or ask it to terminate (when called from Delete())
+ bool shouldDelete = threadToDelete != NULL;
+
+ wxThread::ExitCode rc = 0;
- // 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,
- isRunning = FALSE;
+ // we might need to resume the thread if it's currently stopped
+ bool shouldResume = false;
- // check if the thread already started to run
+ // as Delete() (which calls us) is always safe to call we need to consider
+ // all possible states
{
wxCriticalSectionLocker lock(cs);
if ( m_state == STATE_NEW )
{
- if ( shouldCancel )
+ if ( shouldDelete )
{
- // WinThreadStart() will see it and terminate immediately, no need
- // to cancel the thread - but we still need to resume it to let it
- // run
+ // 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_state = STATE_EXITED;
- Resume(); // it knows about STATE_EXITED special case
-
- shouldCancel = FALSE;
+ // we must call Resume() as the thread hasn't been initially
+ // resumed yet (and as Resume() it knows about STATE_EXITED
+ // special case, it won't touch it and WinThreadStart() will
+ // just exit immediately)
+ shouldResume = true;
+ shouldDelete = false;
}
-
- isRunning = TRUE;
-
- // shouldResume is correctly set to FALSE here
+ //else: shouldResume is correctly set to false here, wait until
+ // someone else runs the thread and it finishes
}
- else
+ else // running, paused, cancelled or even exited
{
shouldResume = m_state == STATE_PAUSED;
}
if ( shouldResume )
Resume();
- // does is still run?
- if ( isRunning || m_state == STATE_RUNNING )
+ // ask the thread to terminate
+ if ( shouldDelete )
+ {
+ wxCriticalSectionLocker lock(cs);
+
+ Cancel();
+ }
+
+
+ // now wait for thread to finish
+ if ( wxThread::IsMain() )
+ {
+ // set flag for wxIsWaitingForThread()
+ gs_waitingForThread = true;
+ }
+
+ // 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
+ // (note that even in console applications we might have to process
+ // messages if we use wxExecute() or timers or ...)
+ DWORD result wxDUMMY_INITIALIZE(0);
+ do
{
if ( wxThread::IsMain() )
{
- // set flag for wxIsWaitingForThread()
- gs_waitingForThread = TRUE;
+ // give the thread we're waiting for chance to do the GUI call
+ // it might be in
+ if ( (gs_nWaitingForGui > 0) && wxGuiOwnedByMainThread() )
+ {
+ wxMutexGuiLeave();
+ }
}
- // ask the thread to terminate
- if ( shouldCancel )
- {
- wxCriticalSectionLocker lock(cs);
+#if !defined(QS_ALLPOSTMESSAGE)
+#define QS_ALLPOSTMESSAGE 0
+#endif
- Cancel();
- }
+ result = ::MsgWaitForMultipleObjects
+ (
+ 1, // number of objects to wait for
+ &m_hThread, // the objects
+ false, // don't wait for all objects
+ INFINITE, // no timeout
+ QS_ALLINPUT|QS_ALLPOSTMESSAGE // return as soon as there are any events
+ );
- // 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
- // (note that even in console applications we might have to process
- // messages if we use wxExecute() or timers or ...)
- DWORD result = 0; // suppress warnings from broken compilers
- do
+ switch ( result )
{
- if ( wxThread::IsMain() )
- {
- // give the thread we're waiting for chance to do the GUI call
- // it might be in
- if ( (gs_nWaitingForGui > 0) && wxGuiOwnedByMainThread() )
+ 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 -- but only if we're the
+ // main thread as we don't support processing messages in
+ // the other ones
+ //
+ // NB: we still must include QS_ALLINPUT even when waiting
+ // in a secondary thread because if it had created some
+ // window somehow (possible not even using wxWidgets)
+ // the system might dead lock then
+ if ( wxThread::IsMain() )
{
- wxMutexGuiLeave();
- }
- }
+ // it looks that sometimes WAIT_OBJECT_0 + 1 is
+ // returned but there are no messages in the thread
+ // queue -- prevent DoMessageFromThreadWait() from
+ // blocking inside ::GetMessage() forever in this case
+ ::PostMessage(NULL, WM_NULL, 0, 0);
- result = ::MsgWaitForMultipleObjects
- (
- 1, // number of objects to wait for
- &m_hThread, // the objects
- FALSE, // don't wait for all objects
- INFINITE, // no timeout
- QS_ALLINPUT | // return as soon as there are any events
- QS_ALLPOSTMESSAGE
- );
-
- 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
+ wxAppTraits *traits = wxTheApp ? wxTheApp->GetTraits()
+ : NULL;
+
+ if ( traits && !traits->DoMessageFromThreadWait() )
{
- // it looks that sometimes WAIT_OBJECT_0 + 1 is
- // returned but there are no messages in the thread
- // queue -- prevent DoMessageFromThreadWait() from
- // blocking inside ::GetMessage() forever in this case
- ::PostMessage(NULL, WM_NULL, 0, 0);
-
- wxAppTraits *traits = wxTheApp ? wxTheApp->GetTraits()
- : NULL;
-
- if ( traits && !traits->DoMessageFromThreadWait() )
- {
- // WM_QUIT received: kill the thread
- Kill();
-
- return wxTHREAD_KILLED;
- }
- }
- break;
+ // WM_QUIT received: kill the thread
+ Kill();
- default:
- wxFAIL_MSG(wxT("unexpected result of MsgWaitForMultipleObject"));
- }
- } while ( result != WAIT_OBJECT_0 );
+ return wxTHREAD_KILLED;
+ }
+ }
+ break;
- if ( wxThread::IsMain() )
- {
- gs_waitingForThread = FALSE;
+ default:
+ wxFAIL_MSG(wxT("unexpected result of MsgWaitForMultipleObject"));
}
+ } while ( result != WAIT_OBJECT_0 );
+
+ if ( wxThread::IsMain() )
+ {
+ gs_waitingForThread = false;
}
+
// 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
+ for ( ;; )
{
if ( !::GetExitCodeThread(m_hThread, (LPDWORD)&rc) )
{
wxLogLastError(wxT("GetExitCodeThread"));
rc = (wxThread::ExitCode)-1;
+
+ break;
}
- } while ( (DWORD)rc == STILL_ACTIVE );
+
+ if ( (DWORD)rc != STILL_ACTIVE )
+ break;
+
+ // give the other thread some time to terminate, otherwise we may be
+ // starving it
+ ::Sleep(1);
+ }
if ( pRc )
*pRc = rc;
+ // we don't need the thread handle any more in any case
+ Free();
+
+
return rc == (wxThread::ExitCode)-1 ? wxTHREAD_MISC_ERROR
: wxTHREAD_NO_ERROR;
}
{
wxLogSysError(_("Can not suspend thread %x"), m_hThread);
- return FALSE;
+ return false;
}
m_state = STATE_PAUSED;
- return TRUE;
+ return true;
}
bool wxThreadInternal::Resume()
{
wxLogSysError(_("Can not resume thread %x"), m_hThread);
- return FALSE;
+ 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
+ // the code in WaitForTerminate() wouldn't work
if ( m_state != STATE_EXITED )
{
m_state = STATE_RUNNING;
}
- return TRUE;
+ return true;
}
// static functions
bool wxThread::IsMain()
{
- return ::GetCurrentThreadId() == gs_idMainThread;
+ return ::GetCurrentThreadId() == gs_idMainThread || gs_idMainThread == 0;
}
-#ifdef Yield
-#undef Yield
-#endif
-
void wxThread::Yield()
{
// 0 argument to Sleep() is special and means to just give away the rest of
return (unsigned long)::GetCurrentThreadId();
}
-bool wxThread::SetConcurrency(size_t level)
+bool wxThread::SetConcurrency(size_t WXUNUSED_IN_WINCE(level))
{
-#ifndef __WXWINCE__
+#ifdef __WXWINCE__
+ return false;
+#else
wxASSERT_MSG( IsMain(), _T("should only be called from the main thread") );
// ok only for the default one
// get system affinity mask first
HANDLE hProcess = ::GetCurrentProcess();
- DWORD dwProcMask, dwSysMask;
+ DWORD_PTR dwProcMask, dwSysMask;
if ( ::GetProcessAffinityMask(hProcess, &dwProcMask, &dwSysMask) == 0 )
{
wxLogLastError(_T("GetProcessAffinityMask"));
- return FALSE;
+ return false;
}
// how many CPUs have we got?
{
wxLogDebug(_T("bad level %u in wxThread::SetConcurrency()"), level);
- return FALSE;
+ return false;
}
// set it: we can't link to SetProcessAffinityMask() because it doesn't
if ( !pfnSetProcessAffinityMask )
{
// msg given above - do it only once
- return FALSE;
+ return false;
}
if ( pfnSetProcessAffinityMask(hProcess, dwProcMask) == 0 )
{
wxLogLastError(_T("SetProcessAffinityMask"));
- return FALSE;
+ return false;
}
-#endif
- return TRUE;
+
+ return true;
+#endif // __WXWINCE__/!__WXWINCE__
}
// ctor and dtor
wxThread::wxThread(wxThreadKind kind)
{
- m_internal = new wxThreadInternal();
+ m_internal = new wxThreadInternal(this);
m_isDetached = kind == wxTHREAD_DETACHED;
}
ExitCode rc = (ExitCode)-1;
- (void)m_internal->WaitForTerminate(false, m_critsect, &rc);
-
- m_internal->Free();
-
- wxCriticalSectionLocker lock(m_critsect);
- m_internal->SetState(STATE_EXITED);
+ (void)m_internal->WaitForTerminate(m_critsect, &rc);
return rc;
}
wxThreadError wxThread::Delete(ExitCode *pRc)
{
- wxThreadError rc = m_internal->WaitForTerminate(true, m_critsect, pRc);
-
- if ( IsDetached() )
- {
- delete this;
- }
- else // joinable
- {
- // update the status of the joinable thread
- wxCriticalSectionLocker lock(m_critsect);
- m_internal->SetState(STATE_EXITED);
- }
-
- return rc;
+ return m_internal->WaitForTerminate(m_critsect, pRc, this);
}
wxThreadError wxThread::Kill()
// words, this should never happen
wxLogSysError(_("Thread module initialization failed: impossible to allocate index in thread local storage"));
- return FALSE;
+ return false;
}
// main thread doesn't have associated wxThread object, so store 0 in the
wxLogSysError(_("Thread module initialization failed: can not store value in thread local storage"));
- return FALSE;
+ return false;
}
gs_critsectWaitingForGui = new wxCriticalSection();
gs_critsectGui = new wxCriticalSection();
gs_critsectGui->Enter();
+ gs_critsectThreadDelete = new wxCriticalSection;
+
// no error return for GetCurrentThreadId()
gs_idMainThread = ::GetCurrentThreadId();
- return TRUE;
+ return true;
}
void wxThreadModule::OnExit()
wxLogLastError(wxT("TlsFree failed."));
}
+ delete gs_critsectThreadDelete;
+ gs_critsectThreadDelete = NULL;
+
if ( gs_critsectGui )
{
gs_critsectGui->Leave();
if ( wxThread::IsMain() )
{
- gs_bGuiOwnedByMainThread = FALSE;
+ gs_bGuiOwnedByMainThread = false;
}
else
{
{
gs_critsectGui->Enter();
- gs_bGuiOwnedByMainThread = TRUE;
+ gs_bGuiOwnedByMainThread = true;
}
//else: already have it, nothing to do
}
projects / wxWidgets.git / blobdiff