thread.cpp

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/////////////////////////////////////////////////////////////////////////////
// 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: thread.cpp,v 1.95 2005/07/01 13:38:58 ABX Exp $
// Copyright:   (c) Wolfram Gloger (1996, 1997), Guilhem Lavaux (1998);
//                  Vadim Zeitlin (1999-2002)
// Licence:     wxWindows licence
/////////////////////////////////////////////////////////////////////////////

#if defined(__GNUG__) && !defined(NO_GCC_PRAGMA)
    #pragma implementation "thread.h"
#endif

// ----------------------------------------------------------------------------
// headers
// ----------------------------------------------------------------------------

// For compilers that support precompilation, includes "wx.h".
#include "wx/wxprec.h"

#if defined(__BORLANDC__)
    #pragma hdrstop
#endif

#ifndef WX_PRECOMP
    #include "wx/intl.h"
    #include "wx/app.h"
#endif

#if wxUSE_THREADS

#include "wx/apptrait.h"

#include "wx/msw/private.h"
#include "wx/msw/missing.h"

#include "wx/module.h"
#include "wx/thread.h"

// must have this symbol defined to get _beginthread/_endthread declarations
#ifndef _MT
    #define _MT
#endif

#if defined(__BORLANDC__)
    #if !defined(__MT__)
        // I can't set -tWM in the IDE (anyone?) so have to do this
        #define __MT__
    #endif

    #if !defined(__MFC_COMPAT__)
        // Needed to know about _beginthreadex etc..
        #define __MFC_COMPAT__
    #endif
#endif // BC++

// define wxUSE_BEGIN_THREAD if the compiler has _beginthreadex() function
// which should be used instead of Win32 ::CreateThread() if possible
#if defined(__VISUALC__) || \
    (defined(__BORLANDC__) && (__BORLANDC__ >= 0x500)) || \
    (defined(__GNUG__) && defined(__MSVCRT__)) || \
    defined(__WATCOMC__) || defined(__MWERKS__)

#ifndef __WXWINCE__
    #undef wxUSE_BEGIN_THREAD
    #define wxUSE_BEGIN_THREAD
#endif

#endif

#ifdef wxUSE_BEGIN_THREAD
    // this is where _beginthreadex() is declared
    #include <process.h>

    // the return type of the thread function entry point
    typedef unsigned THREAD_RETVAL;

    // the calling convention of the thread function entry point
    #define THREAD_CALLCONV __stdcall
#else
    // the settings for CreateThread()
    typedef DWORD THREAD_RETVAL;
    #define THREAD_CALLCONV WINAPI
#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
};

// ----------------------------------------------------------------------------
// this module globals
// ----------------------------------------------------------------------------

// TLS index of the slot where we store the pointer to the current thread
static DWORD gs_tlsThisThread = 0xFFFFFFFF;

// 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;

// 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;

// ============================================================================
// Windows implementation of thread and related classes
// ============================================================================

// ----------------------------------------------------------------------------
// 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(wxMutexType mutexType);
    ~wxMutexInternal();

    bool IsOk() const { return m_mutex != NULL; }

    wxMutexError Lock() { return LockTimeout(INFINITE); }
    wxMutexError TryLock() { return LockTimeout(0); }
    wxMutexError Unlock();

private:
    wxMutexError LockTimeout(DWORD milliseconds);

    HANDLE m_mutex;

    DECLARE_NO_COPY_CLASS(wxMutexInternal)
};

// all mutexes are recursive under Win32 so we don't use mutexType
wxMutexInternal::wxMutexInternal(wxMutexType WXUNUSED(mutexType))
{
    // 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()"));
    }
}

wxMutexInternal::~wxMutexInternal()
{
    if ( m_mutex )
    {
        if ( !::CloseHandle(m_mutex) )
        {
            wxLogLastError(_T("CloseHandle(mutex)"));
        }
    }
}

wxMutexError wxMutexInternal::LockTimeout(DWORD milliseconds)
{
    DWORD rc = ::WaitForSingleObject(m_mutex, milliseconds);
    if ( rc == WAIT_ABANDONED )
    {
        // 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_TIMEOUT:
            return wxMUTEX_BUSY;

        case WAIT_ABANDONED:        // checked for above
        default:
            wxFAIL_MSG(wxT("impossible return value in wxMutex::Lock"));
            // fall through

        case WAIT_FAILED:
            wxLogLastError(_T("WaitForSingleObject(mutex)"));
            return wxMUTEX_MISC_ERROR;
    }

    return wxMUTEX_NO_ERROR;
}

wxMutexError wxMutexInternal::Unlock()
{
    if ( !::ReleaseMutex(m_mutex) )
    {
        wxLogLastError(_T("ReleaseMutex()"));

        return wxMUTEX_MISC_ERROR;
    }

    return wxMUTEX_NO_ERROR;
}

// --------------------------------------------------------------------------
// wxSemaphore
// --------------------------------------------------------------------------

// a trivial wrapper around Win32 semaphore
class wxSemaphoreInternal
{
public:
    wxSemaphoreInternal(int initialcount, int maxcount);
    ~wxSemaphoreInternal();

    bool IsOk() const { return m_semaphore != NULL; }

    wxSemaError Wait() { return WaitTimeout(INFINITE); }

    wxSemaError TryWait()
    {
        wxSemaError rc = WaitTimeout(0);
        if ( rc == wxSEMA_TIMEOUT )
            rc = wxSEMA_BUSY;

        return rc;
    }

    wxSemaError WaitTimeout(unsigned long milliseconds);

    wxSemaError Post();

private:
    HANDLE m_semaphore;

    DECLARE_NO_COPY_CLASS(wxSemaphoreInternal)
};

wxSemaphoreInternal::wxSemaphoreInternal(int initialcount, int maxcount)
{
#if !defined(_WIN32_WCE) || (_WIN32_WCE >= 300)
    if ( maxcount == 0 )
    {
        // make it practically infinite
        maxcount = INT_MAX;
    }

    m_semaphore = ::CreateSemaphore
                    (
                        NULL,           // default security attributes
                        initialcount,
                        maxcount,
                        NULL            // no name
                    );
#endif
    if ( !m_semaphore )
    {
        wxLogLastError(_T("CreateSemaphore()"));
    }
}

wxSemaphoreInternal::~wxSemaphoreInternal()
{
    if ( m_semaphore )
    {
        if ( !::CloseHandle(m_semaphore) )
        {
            wxLogLastError(_T("CloseHandle(semaphore)"));
        }
    }
}

wxSemaError wxSemaphoreInternal::WaitTimeout(unsigned long milliseconds)
{
    DWORD rc = ::WaitForSingleObject( m_semaphore, milliseconds );

    switch ( rc )
    {
        case WAIT_OBJECT_0:
           return wxSEMA_NO_ERROR;

        case WAIT_TIMEOUT:
           return wxSEMA_TIMEOUT;

        default:
            wxLogLastError(_T("WaitForSingleObject(semaphore)"));
    }

    return wxSEMA_MISC_ERROR;
}

wxSemaError wxSemaphoreInternal::Post()
{
#if !defined(_WIN32_WCE) || (_WIN32_WCE >= 300)
    if ( !::ReleaseSemaphore(m_semaphore, 1, NULL /* ptr to previous count */) )
#endif
    {
        wxLogLastError(_T("ReleaseSemaphore"));

        return wxSEMA_MISC_ERROR;
    }

    return wxSEMA_NO_ERROR;
}

// ----------------------------------------------------------------------------
// wxThread implementation
// ----------------------------------------------------------------------------

// wxThreadInternal class
// ----------------------

class wxThreadInternal
{
public:
    wxThreadInternal(wxThread *thread)
    {
        m_thread = thread;
        m_hThread = 0;
        m_state = STATE_NEW;
        m_priority = WXTHREAD_DEFAULT_PRIORITY;
        m_nRef = 1;
    }

    ~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, unsigned int stackSize);

    // wait for the thread to terminate, either by itself, or by asking it
    // (politely, this is not Kill()!) to do it
    wxThreadError WaitForTerminate(wxCriticalSection& cs,
                                   wxThread::ExitCode *pRc,
                                   wxThread *threadToDelete = NULL);

    // kill the thread unconditionally
    wxThreadError Kill();

    // 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 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;