thread.cpp

Wxpython Implemented on Windows CE, Source code

// pause/resume
// -----------------------------------------------------------------------------

wxThreadError wxThread::Pause()
{
    wxCHECK_MSG( This() != this, wxTHREAD_MISC_ERROR,
                 _T("a thread can't pause itself") );

    wxCriticalSectionLocker lock(m_critsect);

    if ( m_internal->GetState() != STATE_RUNNING )
    {
        wxLogDebug( wxT("Can't pause thread which is not running.") );

        return wxTHREAD_NOT_RUNNING;
    }

    // just set a flag, the thread will be really paused only during the next
    // call to TestDestroy()
    m_internal->SetState( STATE_PAUSED );

    return wxTHREAD_NO_ERROR;
}

wxThreadError wxThread::Resume()
{
    wxCHECK_MSG( This() != this, wxTHREAD_MISC_ERROR,
                 wxT("a thread can't resume itself") );

    wxCriticalSectionLocker lock(m_critsect);

    wxThreadState state = m_internal->GetState();

    switch ( state )
    {
        case STATE_PAUSED:
            m_internal->Resume();
            return wxTHREAD_NO_ERROR;

        case STATE_EXITED:
            return wxTHREAD_NO_ERROR;

        default:
            wxLogDebug( wxT("Attempt to resume a thread which is not paused.") );

            return wxTHREAD_MISC_ERROR;
    }
}

// -----------------------------------------------------------------------------
// exiting thread
// -----------------------------------------------------------------------------

wxThread::ExitCode wxThread::Wait()
{
    wxCHECK_MSG( This() != this, (ExitCode)-1,
                 wxT("a thread can't wait for itself") );

    wxCHECK_MSG( !m_isDetached, (ExitCode)-1,
                 wxT("can't wait for detached thread") );

    m_internal->Wait();

    return m_internal->GetExitCode();
}

wxThreadError wxThread::Delete(ExitCode *rc)
{
    wxCHECK_MSG( This() != this, wxTHREAD_MISC_ERROR,
                 wxT("a thread can't delete itself") );

    bool isDetached = m_isDetached;

    m_critsect.Enter();
    wxThreadState state = m_internal->GetState();

    // ask the thread to stop
    m_internal->SetCancelFlag();

    m_critsect.Leave();

    switch ( state )
    {
        case STATE_NEW:
            // we need to wake up the thread so that PthreadStart() will
            // terminate - right now it's blocking on run semaphore in
            // PthreadStart()
            m_internal->SignalRun();

            // fall through

        case STATE_EXITED:
            // nothing to do
            break;

        case STATE_PAUSED:
            // resume the thread first
            m_internal->Resume();

            // fall through

        default:
            if ( !isDetached )
            {
                // wait until the thread stops
                m_internal->Wait();

                if ( rc )
                {
                    // return the exit code of the thread
                    *rc = m_internal->GetExitCode();
                }
            }
    }

    return wxTHREAD_NO_ERROR;
}

wxThreadError wxThread::Kill()
{
    wxCHECK_MSG( This() != this, wxTHREAD_MISC_ERROR,
                 wxT("a thread can't kill itself") );

    switch ( m_internal->GetState() )
    {
        case STATE_NEW:
        case STATE_EXITED:
            return wxTHREAD_NOT_RUNNING;

        case STATE_PAUSED:
            // resume the thread first
            Resume();

            // fall through

        default:
            OSStatus err = MPTerminateTask( m_internal->GetId() , -1 ) ;
            if (err != noErr)
            {
                wxLogError( wxT("Failed to terminate a thread.") );

                return wxTHREAD_MISC_ERROR;
            }

            if ( m_isDetached )
            {
                delete this ;
            }
            else
            {
                // this should be retrieved by Wait actually
                m_internal->SetExitCode( (void*)-1 );
            }

            return wxTHREAD_NO_ERROR;
    }
}

void wxThread::Exit( ExitCode status )
{
    wxASSERT_MSG( This() == this,
                  wxT("wxThread::Exit() can only be called in the context of the same thread") );

    // don't enter m_critsect before calling OnExit() because the user code
    // might deadlock if, for example, it signals a condition in OnExit() (a
    // common case) while the main thread calls any of functions entering
    // m_critsect on us (almost all of them do)
    OnExit();

    MPTaskID threadid = m_internal->GetId();

    if ( IsDetached() )
    {
        delete this;
    }
    else // joinable
    {
        // update the status of the joinable thread
        wxCriticalSectionLocker lock( m_critsect );
        m_internal->SetState( STATE_EXITED );
    }

    MPTerminateTask( threadid, (long)status );
}

// also test whether we were paused
bool wxThread::TestDestroy()
{
    wxASSERT_MSG( This() == this,
                  wxT("wxThread::TestDestroy() can only be called in the context of the same thread") );

    m_critsect.Enter();

    if ( m_internal->GetState() == STATE_PAUSED )
    {
        m_internal->SetReallyPaused( true );

        // leave the crit section or the other threads will stop too if they attempt
        // to call any of (seemingly harmless) IsXXX() functions while we sleep
        m_critsect.Leave();

        m_internal->Pause();
    }
    else
    {
        // thread wasn't requested to pause, nothing to do
        m_critsect.Leave();
    }

    return m_internal->WasCancelled();
}

// -----------------------------------------------------------------------------
// priority setting
// -----------------------------------------------------------------------------

void wxThread::SetPriority(unsigned int prio)
{
    wxCHECK_RET( ((int)WXTHREAD_MIN_PRIORITY <= (int)prio) &&
                 ((int)prio <= (int)WXTHREAD_MAX_PRIORITY),
                 wxT("invalid thread priority") );

    wxCriticalSectionLocker lock(m_critsect);

    switch ( m_internal->GetState() )
    {
        case STATE_RUNNING:
        case STATE_PAUSED:
        case STATE_NEW:
            // thread not yet started, priority will be set when it is
            m_internal->SetPriority( prio );
            break;

        case STATE_EXITED:
        default:
            wxFAIL_MSG( wxT("impossible to set thread priority in this state") );
    }
}

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();
}

// -----------------------------------------------------------------------------
// state tests
// -----------------------------------------------------------------------------

bool wxThread::IsRunning() const
{
    wxCriticalSectionLocker lock((wxCriticalSection &)m_critsect);

    return m_internal->GetState() == STATE_RUNNING;
}

bool wxThread::IsAlive() const
{
    wxCriticalSectionLocker lock((wxCriticalSection&)m_critsect);

    switch ( m_internal->GetState() )
    {
        case STATE_RUNNING:
        case STATE_PAUSED:
            return true;

        default:
            return false;
    }
}

bool wxThread::IsPaused() const
{
    wxCriticalSectionLocker lock((wxCriticalSection&)m_critsect);

    return (m_internal->GetState() == STATE_PAUSED);
}

// ----------------------------------------------------------------------------
// Automatic initialization for thread module
// ----------------------------------------------------------------------------

class wxThreadModule : public wxModule
{
public:
    virtual bool OnInit();
    virtual void OnExit();

private:
    DECLARE_DYNAMIC_CLASS(wxThreadModule)
};

IMPLEMENT_DYNAMIC_CLASS(wxThreadModule, wxModule)

bool wxThreadModule::OnInit()
{
    bool hasThreadManager = MPLibraryIsLoaded();

    if ( !hasThreadManager )
    {
        wxLogError( wxT("MP thread support is not available on this system" ) ) ;

        return false;
    }

    // main thread's This() is NULL
    verify_noerr( MPAllocateTaskStorageIndex( &gs_tlsForWXThread ) ) ;
    verify_noerr( MPSetTaskStorageValue( gs_tlsForWXThread, 0 ) ) ;

    gs_idMainThread = wxThread::GetCurrentId();
    gs_critsectWaitingForGui = new wxCriticalSection();

    gs_critsectGui = new wxCriticalSection();
    gs_critsectGui->Enter();

    return true;
}

void wxThreadModule::OnExit()
{
    if ( gs_critsectGui )
    {
        if ( !wxGuiOwnedByMainThread() )
        {
            gs_critsectGui->Enter();
            gs_bGuiOwnedByMainThread = true;
        }

        gs_critsectGui->Leave();
        delete gs_critsectGui;
        gs_critsectGui = NULL;
    }

    delete gs_critsectWaitingForGui;
    gs_critsectWaitingForGui = NULL;
}

// ----------------------------------------------------------------------------
// GUI Serialization copied from MSW implementation
// ----------------------------------------------------------------------------

void WXDLLIMPEXP_BASE 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 WXDLLIMPEXP_BASE 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 WXDLLIMPEXP_BASE wxMutexGuiLeaveOrEnter()
{
    wxASSERT_MSG( wxThread::IsMain(),
                  wxT("only main thread may call wxMutexGuiLeaveOrEnter()!") );

    if ( !gs_critsectWaitingForGui )
        return;

    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 WXDLLIMPEXP_BASE wxGuiOwnedByMainThread()
{
    return gs_bGuiOwnedByMainThread;
}

// wake up the main thread
void WXDLLEXPORT wxWakeUpMainThread()
{
    wxMacWakeUp();
}

// ----------------------------------------------------------------------------
// include common implementation code
// ----------------------------------------------------------------------------

#include "wx/thrimpl.cpp"

#endif // wxUSE_THREADS