/////////////////////////////////////////////////////////////////////////////
// Name:        src/unix/threadpsx.cpp
// Purpose:     wxThread (Posix) Implementation
// Author:      Original from Wolfram Gloger/Guilhem Lavaux
// Modified by: K. S. Sreeram (2002): POSIXified wxCondition, added wxSemaphore
// Created:     04/22/98
// Copyright:   (c) Wolfram Gloger (1996, 1997)
//                  Guilhem Lavaux (1998)
//                  Vadim Zeitlin (1999-2002)
//                  Robert Roebling (1999)
//                  K. S. Sreeram (2002)
// Licence:     wxWindows licence
/////////////////////////////////////////////////////////////////////////////

// ============================================================================
// declaration
// ============================================================================

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

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

#if wxUSE_THREADS

#include "wx/thread.h"

#ifndef WX_PRECOMP
    #include "wx/app.h"
    #include "wx/dynarray.h"
    #include "wx/intl.h"
    #include "wx/log.h"
    #include "wx/utils.h"
    #include "wx/timer.h"
    #include "wx/stopwatch.h"
    #include "wx/module.h"
#endif

#include "wx/private/safecall.h"

#include <stdio.h>
#include <unistd.h>
#include <pthread.h>
#include <errno.h>
#include <time.h>
#include <sys/time.h>           // needed for at least __QNX__
#ifdef HAVE_SCHED_H
    #include <sched.h>
#endif

#ifdef HAVE_THR_SETCONCURRENCY
    #include <thread.h>
#endif

#ifdef HAVE_ABI_FORCEDUNWIND
    #include <cxxabi.h>
#endif

#ifdef HAVE_SETPRIORITY
    #include <sys/resource.h>   // for setpriority()
#endif

// we use wxFFile under Linux in GetCPUCount()
#ifdef __LINUX__
    #include "wx/ffile.h"
    #include "wx/private/glibc.h"
    #if wxCHECK_GLIBC_VERSION(2, 12)
        #define wxHAVE_PTHREAD_SETNAME_NP
        #define wxCAN_SET_LINUX_THREAD_NAME
    #else
        #include <sys/prctl.h>

        // This is only available since Linux 2.6.9
        #ifdef PR_SET_NAME
            #define wxCAN_SET_LINUX_THREAD_NAME
        #endif
    #endif
#endif

#include <atomic>
#include <cstdlib>
#include <exception>

#define THR_ID_CAST(id)  (reinterpret_cast<void*>(id))
#define THR_ID(thr)      THR_ID_CAST((thr)->GetId())

// ----------------------------------------------------------------------------
// constants
// ----------------------------------------------------------------------------

// the possible states of the thread and transitions from them
enum wxThreadState
{
    STATE_NEW,          // didn't start execution yet (=> RUNNING)
    STATE_RUNNING,      // running (=> PAUSED or EXITED)
    STATE_PAUSED,       // suspended (=> RUNNING or EXITED)
    STATE_EXITED        // thread doesn't exist any more
};

// the exit value of a thread which has been cancelled
static const wxThread::ExitCode EXITCODE_CANCELLED = (wxThread::ExitCode)-1;

// trace mask for wxThread operations
#define TRACE_THREADS   wxT("thread")

// you can get additional debugging messages for the semaphore operations
#define TRACE_SEMA      wxT("semaphore")

// ----------------------------------------------------------------------------
// private functions
// ----------------------------------------------------------------------------

static void ScheduleThreadForDeletion();
static void DeleteThread(wxThread *This);

// ----------------------------------------------------------------------------
// private classes
// ----------------------------------------------------------------------------

// an (non owning) array of pointers to threads
WX_DEFINE_ARRAY_PTR(wxThread *, wxArrayThread);

// an entry for a thread we can wait for

// -----------------------------------------------------------------------------
// global data
// -----------------------------------------------------------------------------

// we keep the list of all threads created by the application to be able to
// terminate them on exit if there are some left - otherwise the process would
// be left in memory
static wxArrayThread gs_allThreads;

// a mutex to protect gs_allThreads
static wxMutex *gs_mutexAllThreads = nullptr;

// the id of the main thread
//
// we suppose that 0 is not a valid pthread_t value but in principle this might
// be false (e.g. if it's a selector-like value), wxThread::IsMain() would need
// to be updated in such case
wxThreadIdType wxThread::ms_idMainThread = 0;

// the key for the pointer to the associated wxThread object
static pthread_key_t gs_keySelf;

// the number of threads which are being deleted - the program won't exit
// until there are any left
static size_t gs_nThreadsBeingDeleted = 0;

// a mutex to protect gs_nThreadsBeingDeleted
static wxMutex *gs_mutexDeleteThread = nullptr;

// and a condition variable which will be signaled when all
// gs_nThreadsBeingDeleted will have been deleted
static wxCondition *gs_condAllDeleted = nullptr;

#ifndef __DARWIN__
// this mutex must be acquired before any call to a GUI function
// (it's not inside #if wxUSE_GUI because this file is compiled as part
// of wxBase)
static wxMutex *gs_mutexGui = nullptr;
#endif

// when we wait for a thread to exit, we're blocking on a condition which the
// thread signals in its SignalExit() method -- but this condition can't be a
// member of the thread itself as a detached thread may delete itself at any
// moment and accessing the condition member of the thread after this would
// result in a disaster
//
// so instead we maintain a global list of the structs below for the threads
// we're interested in waiting on

// ============================================================================
// wxMutex implementation
// ============================================================================

// ----------------------------------------------------------------------------
// wxMutexInternal
// ----------------------------------------------------------------------------

// this is a simple wrapper around pthread_mutex_t which provides error
// checking
class wxMutexInternal
{
public:
    wxMutexInternal(wxMutexType mutexType);
    ~wxMutexInternal();

    wxMutexError Lock();
    wxMutexError Lock(unsigned long ms);
    wxMutexError TryLock();
    wxMutexError Unlock();

    bool IsOk() const { return m_isOk; }

private:
    // convert the result of pthread_mutex_[timed]lock() call to wx return code
    wxMutexError HandleLockResult(int err);

private:
    pthread_mutex_t m_mutex;
    bool m_isOk;
    wxMutexType m_type;

    // This member must be atomic as it's written and read from different
    // threads. If atomic operations are not available, we won't detect mutex
    // deadlocks at wx level.
    std::atomic_ulong m_owningThread;

    // wxConditionInternal uses our m_mutex
    friend class wxConditionInternal;
};

#if defined(HAVE_PTHREAD_MUTEXATTR_T) && \
        wxUSE_UNIX && !defined(HAVE_PTHREAD_MUTEXATTR_SETTYPE_DECL)
// on some systems pthread_mutexattr_settype() is not in the headers (but it is
// in the library, otherwise we wouldn't compile this code at all)
extern "C" int pthread_mutexattr_settype(pthread_mutexattr_t *, int);
#endif

wxMutexInternal::wxMutexInternal(wxMutexType mutexType)
{
    m_type = mutexType;
    m_owningThread = 0;

    int err;
    switch ( mutexType )
    {
        case wxMUTEX_RECURSIVE:
            // support recursive locks like Win32, i.e. a thread can lock a
            // mutex which it had itself already locked
            //
            // unfortunately initialization of recursive mutexes is non
            // portable, so try several methods
#ifdef HAVE_PTHREAD_MUTEXATTR_T
            {
                pthread_mutexattr_t attr;
                pthread_mutexattr_init(&attr);
                pthread_mutexattr_settype(&attr, PTHREAD_MUTEX_RECURSIVE);

                err = pthread_mutex_init(&m_mutex, &attr);
            }
#elif defined(HAVE_PTHREAD_RECURSIVE_MUTEX_INITIALIZER)
            // we can use this only as initializer so we have to assign it
            // first to a temp var - assigning directly to m_mutex wouldn't
            // even compile
            {
                pthread_mutex_t mutex = PTHREAD_RECURSIVE_MUTEX_INITIALIZER_NP;
                m_mutex = mutex;
            }
#else // no recursive mutexes
            err = EINVAL;
#endif // HAVE_PTHREAD_MUTEXATTR_T/...
            break;

        default:
            wxFAIL_MSG( wxT("unknown mutex type") );
            wxFALLTHROUGH;

        case wxMUTEX_DEFAULT:
            err = pthread_mutex_init(&m_mutex, nullptr);
            break;
    }

    m_isOk = err == 0;
    if ( !m_isOk )
    {
        wxLogApiError( wxT("pthread_mutex_init()"), err);
    }
}

wxMutexInternal::~wxMutexInternal()
{
    if ( m_isOk )
    {
        int err = pthread_mutex_destroy(&m_mutex);
        if ( err != 0 )
        {
            wxLogApiError( wxT("pthread_mutex_destroy()"), err);
        }
    }
}

wxMutexError wxMutexInternal::Lock()
{
    if ( m_type == wxMUTEX_DEFAULT && m_owningThread == wxThread::GetCurrentId() )
           return wxMUTEX_DEAD_LOCK;

    return HandleLockResult(pthread_mutex_lock(&m_mutex));
}

wxMutexError wxMutexInternal::Lock(unsigned long ms)
{
#ifdef HAVE_PTHREAD_MUTEX_TIMEDLOCK
    static const long MSEC_IN_SEC   = 1000;
    static const long NSEC_IN_MSEC  = 1000000;
    static const long NSEC_IN_USEC  = 1000;
    static const long NSEC_IN_SEC   = MSEC_IN_SEC * NSEC_IN_MSEC;

    time_t seconds = ms/MSEC_IN_SEC;
    long nanoseconds = (ms % MSEC_IN_SEC) * NSEC_IN_MSEC;
    timespec ts = { 0, 0 };

    // normally we should use clock_gettime(CLOCK_REALTIME) here but this
    // function is in librt and we don't link with it currently, so use
    // gettimeofday() instead -- if it turns out that this is really too
    // imprecise, we should modify configure to check if clock_gettime() is
    // available and whether it requires -lrt and use it instead
#if 0
    if ( clock_gettime(CLOCK_REALTIME, &ts) == 0 )
    {
    }
#else
    struct timeval tv;
    if ( wxGetTimeOfDay(&tv) != -1 )
    {
        ts.tv_sec = tv.tv_sec;
        ts.tv_nsec = tv.tv_usec*NSEC_IN_USEC;
    }
#endif
    else // fall back on system timer
    {
        ts.tv_sec = time(nullptr);
    }

    ts.tv_sec += seconds;
    ts.tv_nsec += nanoseconds;
    if ( ts.tv_nsec > NSEC_IN_SEC )
    {
        ts.tv_sec += 1;
        ts.tv_nsec -= NSEC_IN_SEC;
    }

    return HandleLockResult(pthread_mutex_timedlock(&m_mutex, &ts));
#else // !HAVE_PTHREAD_MUTEX_TIMEDLOCK
    wxUnusedVar(ms);

    return wxMUTEX_MISC_ERROR;
#endif // HAVE_PTHREAD_MUTEX_TIMEDLOCK/!HAVE_PTHREAD_MUTEX_TIMEDLOCK
}

wxMutexError wxMutexInternal::HandleLockResult(int err)
{
    // wxPrintf( "err %d\n", err );

    switch ( err )
    {
        case EDEADLK:
            // only error checking mutexes return this value and so it's an
            // unexpected situation -- hence use assert, not wxLogDebug
            wxFAIL_MSG( wxT("mutex deadlock prevented") );
            return wxMUTEX_DEAD_LOCK;

        case EINVAL:
            wxLogDebug(wxT("pthread_mutex_[timed]lock(): mutex not initialized"));
            break;

        case ETIMEDOUT:
            return wxMUTEX_TIMEOUT;

        case 0:
            if (m_type == wxMUTEX_DEFAULT)
                m_owningThread = wxThread::GetCurrentId();
            return wxMUTEX_NO_ERROR;

        default:
            wxLogApiError(wxT("pthread_mutex_[timed]lock()"), err);
    }

    return wxMUTEX_MISC_ERROR;
}


wxMutexError wxMutexInternal::TryLock()
{
    int err = pthread_mutex_trylock(&m_mutex);
    switch ( err )
    {
        case EBUSY:
            // not an error: mutex is already locked, but we're prepared for
            // this
            return wxMUTEX_BUSY;

        case EINVAL:
            wxLogDebug(wxT("pthread_mutex_trylock(): mutex not initialized."));
            break;

        case 0:
            if (m_type == wxMUTEX_DEFAULT)
                m_owningThread = wxThread::GetCurrentId();
            return wxMUTEX_NO_ERROR;

        default:
            wxLogApiError(wxT("pthread_mutex_trylock()"), err);
    }

    return wxMUTEX_MISC_ERROR;
}

wxMutexError wxMutexInternal::Unlock()
{
    m_owningThread = 0;

    int err = pthread_mutex_unlock(&m_mutex);
    switch ( err )
    {
        case EPERM:
            // we don't own the mutex
            return wxMUTEX_UNLOCKED;

        case EINVAL:
            wxLogDebug(wxT("pthread_mutex_unlock(): mutex not initialized."));
            break;

        case 0:
            return wxMUTEX_NO_ERROR;

        default:
            wxLogApiError(wxT("pthread_mutex_unlock()"), err);
    }

    return wxMUTEX_MISC_ERROR;
}

// ===========================================================================
// wxCondition implementation
// ===========================================================================

// ---------------------------------------------------------------------------
// wxConditionInternal
// ---------------------------------------------------------------------------

// this is a wrapper around pthread_cond_t associated with a wxMutex (and hence
// with a pthread_mutex_t)
class wxConditionInternal
{
public:
    wxConditionInternal(wxMutex& mutex);
    ~wxConditionInternal();

    bool IsOk() const { return m_isOk && m_mutex.IsOk(); }

    wxCondError Wait();
    wxCondError WaitTimeout(unsigned long milliseconds);

    wxCondError Signal();
    wxCondError Broadcast();

private:
    // get the POSIX mutex associated with us
    pthread_mutex_t *GetPMutex() const { return &m_mutex.m_internal->m_mutex; }

    wxMutex& m_mutex;
    pthread_cond_t m_cond;

    bool m_isOk;
};

wxConditionInternal::wxConditionInternal(wxMutex& mutex)
                   : m_mutex(mutex)
{
    int err = pthread_cond_init(&m_cond, nullptr /* default attributes */);

    m_isOk = err == 0;

    if ( !m_isOk )
    {
        wxLogApiError(wxT("pthread_cond_init()"), err);
    }
}

wxConditionInternal::~wxConditionInternal()
{
    if ( m_isOk )
    {
        int err = pthread_cond_destroy(&m_cond);
        if ( err != 0 )
        {
            wxLogApiError(wxT("pthread_cond_destroy()"), err);
        }
    }
}

wxCondError wxConditionInternal::Wait()
{
    int err = pthread_cond_wait(&m_cond, GetPMutex());
    if ( err != 0 )
    {
        wxLogApiError(wxT("pthread_cond_wait()"), err);

        return wxCOND_MISC_ERROR;
    }

    return wxCOND_NO_ERROR;
}

wxCondError wxConditionInternal::WaitTimeout(unsigned long milliseconds)
{
    const wxLongLong_t endtime = wxGetUTCTimeMillis().GetValue() + milliseconds;
    const auto div = std::div(endtime, 1000LL);

    timespec tspec;

    tspec.tv_sec = div.quot;
    tspec.tv_nsec = div.rem * 1000L * 1000L;

    int err = pthread_cond_timedwait( &m_cond, GetPMutex(), &tspec );
    switch ( err )
    {
        case ETIMEDOUT:
            return wxCOND_TIMEOUT;

        case 0:
            return wxCOND_NO_ERROR;

        default:
            wxLogApiError(wxT("pthread_cond_timedwait()"), err);
    }

    return wxCOND_MISC_ERROR;
}

wxCondError wxConditionInternal::Signal()
{
    int err = pthread_cond_signal(&m_cond);
    if ( err != 0 )
    {
        wxLogApiError(wxT("pthread_cond_signal()"), err);

        return wxCOND_MISC_ERROR;
    }

    return wxCOND_NO_ERROR;
}

wxCondError wxConditionInternal::Broadcast()
{
    int err = pthread_cond_broadcast(&m_cond);
    if ( err != 0 )
    {
        wxLogApiError(wxT("pthread_cond_broadcast()"), err);

        return wxCOND_MISC_ERROR;
    }

    return wxCOND_NO_ERROR;
}

// ===========================================================================
// wxSemaphore implementation
// ===========================================================================

// ---------------------------------------------------------------------------
// wxSemaphoreInternal
// ---------------------------------------------------------------------------

// we implement the semaphores using mutexes and conditions instead of using
// the sem_xxx() POSIX functions because they're not widely available and also
// because it's impossible to implement WaitTimeout() using them
class wxSemaphoreInternal
{
public:
    wxSemaphoreInternal(int initialcount, int maxcount);

    bool IsOk() const { return m_isOk; }

    wxSemaError Wait();
    wxSemaError TryWait();
    wxSemaError WaitTimeout(unsigned long milliseconds);

    wxSemaError Post();

private:
    wxMutex m_mutex;
    wxCondition m_cond;

    size_t m_count,
           m_maxcount;

    bool m_isOk;
};

wxSemaphoreInternal::wxSemaphoreInternal(int initialcount, int maxcount)
                   : m_cond(m_mutex)
{

    if ( (initialcount < 0 || maxcount < 0) ||
            ((maxcount > 0) && (initialcount > maxcount)) )
    {
        wxFAIL_MSG( wxT("wxSemaphore: invalid initial or maximal count") );

        m_isOk = false;
    }
    else
    {
        m_maxcount = (size_t)maxcount;
        m_count = (size_t)initialcount;
    }

    m_isOk = m_mutex.IsOk() && m_cond.IsOk();
}

wxSemaError wxSemaphoreInternal::Wait()
{
    wxMutexLocker locker(m_mutex);

    while ( m_count == 0 )
    {
        wxLogTrace(TRACE_SEMA,
                   wxT("Thread %p waiting for semaphore to become signalled"),
                   THR_ID_CAST(wxThread::GetCurrentId()));

        if ( m_cond.Wait() != wxCOND_NO_ERROR )
            return wxSEMA_MISC_ERROR;

        wxLogTrace(TRACE_SEMA,
                   wxT("Thread %p finished waiting for semaphore, count = %lu"),
                   THR_ID_CAST(wxThread::GetCurrentId()), (unsigned long)m_count);
    }

    m_count--;

    return wxSEMA_NO_ERROR;
}

wxSemaError wxSemaphoreInternal::TryWait()
{
    wxMutexLocker locker(m_mutex);

    if ( m_count == 0 )
        return wxSEMA_BUSY;

    m_count--;

    return wxSEMA_NO_ERROR;
}

wxSemaError wxSemaphoreInternal::WaitTimeout(unsigned long milliseconds)
{
    wxMutexLocker locker(m_mutex);

    wxLongLong startTime = wxGetLocalTimeMillis();

    while ( m_count == 0 )
    {
        wxLongLong elapsed = wxGetLocalTimeMillis() - startTime;
        long remainingTime = (long)milliseconds - (long)elapsed.GetLo();
        if ( remainingTime <= 0 )
        {
            // timeout
            return wxSEMA_TIMEOUT;
        }

        switch ( m_cond.WaitTimeout(remainingTime) )
        {
            case wxCOND_TIMEOUT:
                return wxSEMA_TIMEOUT;

            default:
                return wxSEMA_MISC_ERROR;

            case wxCOND_NO_ERROR:
                ;
        }
    }

    m_count--;

    return wxSEMA_NO_ERROR;
}

wxSemaError wxSemaphoreInternal::Post()
{
    wxMutexLocker locker(m_mutex);

    if ( m_maxcount > 0 && m_count == m_maxcount )
    {
        return wxSEMA_OVERFLOW;
    }

    m_count++;

    wxLogTrace(TRACE_SEMA,
               wxT("Thread %p about to signal semaphore, count = %lu"),
               THR_ID_CAST(wxThread::GetCurrentId()), (unsigned long)m_count);

    return m_cond.Signal() == wxCOND_NO_ERROR ? wxSEMA_NO_ERROR
                                              : wxSEMA_MISC_ERROR;
}

// ===========================================================================
// wxThread implementation
// ===========================================================================

// the thread callback functions must have the C linkage
extern "C"
{

#ifdef wxHAVE_PTHREAD_CLEANUP
    // thread exit function
    static
    void wxPthreadCleanup(void *ptr);
#endif // wxHAVE_PTHREAD_CLEANUP

static
void *wxPthreadStart(void *ptr);

} // extern "C"

// ----------------------------------------------------------------------------
// wxThreadInternal
// ----------------------------------------------------------------------------

class wxThreadInternal
{
public:
    wxThreadInternal();
    ~wxThreadInternal();

    // thread entry function
    static void *PthreadStart(wxThread *thread);

    // thread actions
         // create the thread
    wxThreadError Create(wxThread *thread, unsigned int stackSize);
        // start the thread
    wxThreadError Run();
        // unblock the thread allowing it to run
    void SignalRun() { m_semRun.Post(); }
        // ask the thread to terminate
    void Wait();
        // go to sleep until Resume() is called
    void Pause();
        // resume the thread
    void Resume();

    // accessors
        // priority
    int GetPriority() const { return m_prio; }
    void SetPriority(int prio) { m_prio = prio; }
        // state
    wxThreadState GetState() const { return m_state; }
    void SetState(wxThreadState state)
    {
#if wxUSE_LOG_TRACE
        static const wxChar *const stateNames[] =
        {
            wxT("NEW"),
            wxT("RUNNING"),
            wxT("PAUSED"),
            wxT("EXITED"),
        };

        wxLogTrace(TRACE_THREADS, wxT("Thread %p: %s => %s."),
                   THR_ID(this), stateNames[m_state], stateNames[state]);
#endif // wxUSE_LOG_TRACE

        m_state = state;
    }
        // id
    pthread_t GetId() const { return m_threadId; }
    pthread_t *GetIdPtr() { return &m_threadId; }
        // "created" flag
    bool WasCreated() const { return m_created; }
        // "cancelled" flag
    void SetCancelFlag() { m_cancelled = true; }
    bool WasCancelled() const { return m_cancelled; }
        // exit code
    void SetExitCode(wxThread::ExitCode exitcode) { m_exitcode = exitcode; }
    wxThread::ExitCode GetExitCode() const { return m_exitcode; }

        // the pause flag
    void SetReallyPaused(bool paused) { m_isPaused = paused; }
    bool IsReallyPaused() const { return m_isPaused; }

        // tell the thread that it is a detached one
    void Detach()
    {
        wxCriticalSectionLocker lock(m_csJoinFlag);

        m_shouldBeJoined = false;
        m_isDetached = true;
    }

#ifdef wxHAVE_PTHREAD_CLEANUP
    // this is used by wxPthreadCleanup() only
    static void Cleanup(wxThread *thread);
#endif // wxHAVE_PTHREAD_CLEANUP

private:
    pthread_t     m_threadId;   // id of the thread
    wxThreadState m_state;      // see wxThreadState enum
    int           m_prio;       // in wxWidgets units: from 0 to 100

    // this flag is set when the thread was successfully created
    bool m_created;

    // this flag is set when the thread should terminate
    bool m_cancelled;

    // this flag is set when the thread is blocking on m_semSuspend
    bool m_isPaused;

    // the thread exit code - only used for joinable (!detached) threads and
    // is only valid after the thread termination
    wxThread::ExitCode m_exitcode;

    // many threads may call Wait(), but only one of them should call
    // pthread_join(), so we have to keep track of this
    wxCriticalSection m_csJoinFlag;
    bool m_shouldBeJoined;
    bool m_isDetached;

    // this semaphore is posted by Run() and the threads Entry() is not
    // called before it is done
    wxSemaphore m_semRun;

    // this one is signaled when the thread should resume after having been
    // Pause()d
    wxSemaphore m_semSuspend;
};

// ----------------------------------------------------------------------------
// thread startup and exit functions
// ----------------------------------------------------------------------------

void *wxPthreadStart(void *ptr)
{
    return wxThreadInternal::PthreadStart((wxThread *)ptr);
}

void *wxThreadInternal::PthreadStart(wxThread *thread)
{
    wxThreadInternal *pthread = thread->m_internal;

    wxLogTrace(TRACE_THREADS, wxT("Thread %p started."), THR_ID(pthread));

    // associate the thread pointer with the newly created thread so that
    // wxThread::This() will work
    int rc = pthread_setspecific(gs_keySelf, thread);
    if ( rc != 0 )
    {
        wxLogSysError(rc, _("Cannot start thread: error writing TLS."));

        return (void *)-1;
    }

    // have to declare this before pthread_cleanup_push() which defines a
    // block!
    bool dontRunAtAll;

#ifdef wxHAVE_PTHREAD_CLEANUP
    // install the cleanup handler which will be called if the thread is
    // cancelled
    pthread_cleanup_push(wxPthreadCleanup, thread);
#endif // wxHAVE_PTHREAD_CLEANUP

    // wait for the semaphore to be posted from Run()
    pthread->m_semRun.Wait();

    // test whether we should run the run at all - may be it was deleted
    // before it started to Run()?
    {
        wxCriticalSectionLocker lock(thread->m_critsect);

        dontRunAtAll = pthread->GetState() == STATE_NEW &&
                       pthread->WasCancelled();
    }

    if ( !dontRunAtAll )
    {
        // call the main entry
        wxLogTrace(TRACE_THREADS,
                   wxT("Thread %p about to enter its Entry()."),
                   THR_ID(pthread));

        // When using common C++ ABI under Linux we must always rethrow this
        // special exception used to unwind the stack when the thread was
        // cancelled, otherwise the thread library would simply terminate the
        // program, see http://udrepper.livejournal.com/21541.html
#if defined(HAVE_ABI_FORCEDUNWIND) && wxUSE_EXCEPTIONS
        #define CATCH_AND_RETHROW_FORCED_UNWIND

        std::exception_ptr threadException;
#endif

        wxSafeCall([&]()
        {
#ifdef CATCH_AND_RETHROW_FORCED_UNWIND
            try
            {
#endif // CATCH_AND_RETHROW_FORCED_UNWIND
                pthread->m_exitcode = thread->Entry();

                wxLogTrace(TRACE_THREADS,
                           wxT("Thread %p Entry() returned %lu."),
                           THR_ID(pthread), wxPtrToUInt(pthread->m_exitcode));
#ifdef CATCH_AND_RETHROW_FORCED_UNWIND
            }
            catch ( abi::__forced_unwind& )
            {
                wxCriticalSectionLocker lock(thread->m_critsect);
                pthread->SetState(STATE_EXITED);
                threadException = std::current_exception();
            }
#endif // CATCH_AND_RETHROW_FORCED_UNWIND
        });

#ifdef CATCH_AND_RETHROW_FORCED_UNWIND
        if ( threadException )
            std::rethrow_exception(threadException);
#endif // CATCH_AND_RETHROW_FORCED_UNWIND

        {
            wxCriticalSectionLocker lock(thread->m_critsect);

            // change the state of the thread to "exited" so that
            // wxPthreadCleanup handler won't do anything from now (if it's
            // called before we do pthread_cleanup_pop below)
            pthread->SetState(STATE_EXITED);
        }
    }

    // NB: pthread_cleanup_push/pop() are macros and pop contains the matching
    //     '}' for the '{' in push, so they must be used in the same block!
#ifdef wxHAVE_PTHREAD_CLEANUP
    #ifdef __DECCXX
        // under Tru64 we get a warning from macro expansion
        #pragma message save
        #pragma message disable(declbutnotref)
    #endif

    // remove the cleanup handler without executing it
    pthread_cleanup_pop(FALSE);

    #ifdef __DECCXX
        #pragma message restore
    #endif
#endif // wxHAVE_PTHREAD_CLEANUP

    if ( dontRunAtAll )
    {
        // FIXME: deleting a possibly joinable thread here???
        delete thread;

        return EXITCODE_CANCELLED;
    }
    else
    {
        // terminate the thread
        thread->Exit(pthread->m_exitcode);

        wxFAIL_MSG(wxT("wxThread::Exit() can't return."));

        return nullptr;
    }
}

#ifdef wxHAVE_PTHREAD_CLEANUP

// this handler is called when the thread is cancelled
extern "C" void wxPthreadCleanup(void *ptr)
{
    wxThreadInternal::Cleanup((wxThread *)ptr);
}

void wxThreadInternal::Cleanup(wxThread *thread)
{
    if (pthread_getspecific(gs_keySelf) == nullptr)
        return;

    {
        wxCriticalSectionLocker lock(thread->m_critsect);
        if ( thread->m_internal->GetState() == STATE_EXITED )
        {
            // thread is already considered as finished.
            return;
        }
    }

    // exit the thread gracefully
    thread->Exit(EXITCODE_CANCELLED);
}

#endif // wxHAVE_PTHREAD_CLEANUP

// ----------------------------------------------------------------------------
// wxThreadInternal
// ----------------------------------------------------------------------------

wxThreadInternal::wxThreadInternal()
    : m_threadId()
{
    m_state = STATE_NEW;
    m_created = false;
    m_cancelled = false;
    m_prio = wxPRIORITY_DEFAULT;
    m_exitcode = nullptr;

    // set to true only when the thread starts waiting on m_semSuspend
    m_isPaused = false;

    // defaults for joinable threads
    m_shouldBeJoined = true;
    m_isDetached = false;
}

wxThreadInternal::~wxThreadInternal()
{
}

static bool SetThreadPriority(pthread_attr_t& attr, int prio)
{
    if ( prio == wxPRIORITY_DEFAULT )
    {
        // Don't even try to do anything, there is no need for it and it could
        // result in failures if we don't handle setting the priority correctly
        // under the current platform, see e.g. #18195.
        return true;
    }

#ifdef HAVE_THREAD_PRIORITY_FUNCTIONS
    int policy;
    if ( pthread_attr_getschedpolicy(&attr, &policy) != 0 )
    {
        wxLogError(_("Cannot retrieve thread scheduling policy."));
        return false;
    }

    // TODO: on most (all?) systems, thread priorities can't be used with
    //       SCHED_OTHER policy, so we need to check if this is the current
    //       policy and change it to something else (SCHED_FIFO or SCHED_RR?)
    //       in order to be able to actually change the priority as without
    //       doing it the code below just not going to work.

#ifdef __VMS__
   /* the pthread.h contains too many spaces. This is a work-around */
# undef sched_get_priority_max
#undef sched_get_priority_min
#define sched_get_priority_max(_pol_) \
     (_pol_ == SCHED_OTHER ? PRI_FG_MAX_NP : PRI_FIFO_MAX)
#define sched_get_priority_min(_pol_) \
     (_pol_ == SCHED_OTHER ? PRI_FG_MIN_NP : PRI_FIFO_MIN)
#endif

    int max_prio = sched_get_priority_max(policy),
        min_prio = sched_get_priority_min(policy);

    if ( min_prio == -1 || max_prio == -1 )
    {
        wxLogError(_("Cannot get priority range for scheduling policy %d."),
                   policy);
        return false;
    }

    if ( max_prio == min_prio )
    {
        // notify the programmer that this doesn't work here
        wxLogWarning(_("Thread priority setting is ignored."));
        return false;
    }

    struct sched_param sp;
    if ( pthread_attr_getschedparam(&attr, &sp) != 0 )
    {
        wxFAIL_MSG(wxT("pthread_attr_getschedparam() failed"));
        return false;
    }

    sp.sched_priority = min_prio + (prio*(max_prio - min_prio))/100;

    if ( pthread_attr_setschedparam(&attr, &sp) != 0 )
    {
        wxFAIL_MSG(wxT("pthread_attr_setschedparam(priority) failed"));
        return false;
    }

    return true;
#else // !HAVE_THREAD_PRIORITY_FUNCTIONS
    wxUnusedVar(attr);

    return false;
#endif // HAVE_THREAD_PRIORITY_FUNCTIONS
}

wxThreadError wxThreadInternal::Create(wxThread *thread, unsigned int stackSize)
{
    if ( GetState() != STATE_NEW )
    {
        // don't recreate thread
        return wxTHREAD_RUNNING;
    }

    // set up the thread attribute: such as priority and stack size
    pthread_attr_t attr;
    pthread_attr_init(&attr);

#ifdef HAVE_PTHREAD_ATTR_SETSTACKSIZE
    if (stackSize)
      pthread_attr_setstacksize(&attr, stackSize);
#else
    wxUnusedVar(stackSize);
#endif

    if ( !SetThreadPriority(attr, GetPriority()) )
    {
        // We currently ignore the failure to set the thread priority as it
        // seems better to create a thread with default priority than to
        // not create one at all.
        wxLogDebug("Failed to set thread priority to %d", GetPriority());
    }

#ifdef HAVE_PTHREAD_ATTR_SETSCOPE
    // this will make the threads created by this process really concurrent
    if ( pthread_attr_setscope(&attr, PTHREAD_SCOPE_SYSTEM) != 0 )
    {
        wxFAIL_MSG(wxT("pthread_attr_setscope(PTHREAD_SCOPE_SYSTEM) failed"));
    }
#endif // HAVE_PTHREAD_ATTR_SETSCOPE

    // VZ: assume that this one is always available (it's rather fundamental),
    //     if this function is ever missing we should try to use
    //     pthread_detach() instead (after thread creation)
    if ( thread->IsDetached() )
    {
        if ( pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_DETACHED) != 0 )
        {
            wxFAIL_MSG(wxT("pthread_attr_setdetachstate(DETACHED) failed"));
        }

        // never try to join detached threads
        Detach();
    }
    //else: threads are created joinable by default, it's ok

    // create the new OS thread object
    int rc = pthread_create
             (
                GetIdPtr(),
                &attr,
                wxPthreadStart,
                (void *)thread
             );

    if ( pthread_attr_destroy(&attr) != 0 )
    {
        wxFAIL_MSG(wxT("pthread_attr_destroy() failed"));
    }

    if ( rc != 0 )
    {
        SetState(STATE_EXITED);

        return wxTHREAD_NO_RESOURCE;
    }

    m_created = true;
    return wxTHREAD_NO_ERROR;
}

wxThreadError wxThreadInternal::Run()
{
    wxCHECK_MSG( GetState() == STATE_NEW, wxTHREAD_RUNNING,
                 wxT("thread may only be started once after Create()") );

    SetState(STATE_RUNNING);

    // wake up threads waiting for our start
    SignalRun();

    return wxTHREAD_NO_ERROR;
}

void wxThreadInternal::Wait()
{
    wxCHECK_RET( !m_isDetached, wxT("can't wait for a detached thread") );

    // if the thread we're waiting for is waiting for the GUI mutex, we will
    // deadlock so make sure we release it temporarily
    if ( wxThread::IsMain() )
    {
#ifdef __DARWIN__
        // give the thread we're waiting for chance to do the GUI call
        // it might be in, we don't do this conditionally as the to be waited on
        // thread might have to acquire the mutex later but before terminating
        if ( wxGuiOwnedByMainThread() )
            wxMutexGuiLeave();
#else
        wxMutexGuiLeave();
#endif
    }

    wxLogTrace(TRACE_THREADS,
               wxT("Starting to wait for thread %p to exit."),
               THR_ID(this));

    // to avoid memory leaks we should call pthread_join(), but it must only be
    // done once so use a critical section to serialize the code below
    {
        wxCriticalSectionLocker lock(m_csJoinFlag);

        if ( m_shouldBeJoined )
        {
            // FIXME shouldn't we set cancellation type to DISABLED here? If
            //       we're cancelled inside pthread_join(), things will almost
            //       certainly break - but if we disable the cancellation, we
            //       might deadlock
            if ( pthread_join(GetId(), &m_exitcode) != 0 )
            {
                // this is a serious problem, so use wxLogError and not
                // wxLogDebug: it is possible to bring the system to its knees
                // by creating too many threads and not joining them quite
                // easily
                wxLogError(_("Failed to join a thread, potential memory leak detected - please restart the program"));
            }

            m_shouldBeJoined = false;
        }
    }

#ifndef __DARWIN__
    // reacquire GUI mutex
    if ( wxThread::IsMain() )
        wxMutexGuiEnter();
#endif
}

void wxThreadInternal::Pause()
{
    // the state is set from the thread which pauses us first, this function
    // is called later so the state should have been already set
    wxCHECK_RET( m_state == STATE_PAUSED,
                 wxT("thread must first be paused with wxThread::Pause().") );

   wxLogTrace(TRACE_THREADS,
              wxT("Thread %p goes to sleep."), THR_ID(this));

    // wait until the semaphore is Post()ed from Resume()
    m_semSuspend.Wait();
}

void wxThreadInternal::Resume()
{
    wxCHECK_RET( m_state == STATE_PAUSED,
                 wxT("can't resume thread which is not suspended.") );

    // the thread might be not actually paused yet - if there were no call to
    // TestDestroy() since the last call to Pause() for example
    if ( IsReallyPaused() )
    {
       wxLogTrace(TRACE_THREADS,
                  wxT("Waking up thread %p"), THR_ID(this));

        // wake up Pause()
        m_semSuspend.Post();

        // reset the flag
        SetReallyPaused(false);
    }
    else
    {
        wxLogTrace(TRACE_THREADS,
                   wxT("Thread %p is not yet really paused"), THR_ID(this));
    }

    SetState(STATE_RUNNING);
}

// -----------------------------------------------------------------------------
// wxThread static functions
// -----------------------------------------------------------------------------

wxThread *wxThread::This()
{
    return (wxThread *)pthread_getspecific(gs_keySelf);
}

void wxThread::Yield()
{
#ifdef HAVE_SCHED_YIELD
    sched_yield();
#endif
}

int wxThread::GetCPUCount()
{
#if defined(_SC_NPROCESSORS_ONLN)
    // this works for Solaris and Linux 2.6
    int rc = sysconf(_SC_NPROCESSORS_ONLN);
    if ( rc != -1 )
    {
        return rc;
    }
#elif defined(__LINUX__) && wxUSE_FFILE
    // read from proc (can't use wxTextFile here because it's a special file:
    // it has 0 size but still can be read from)
    wxLogNull nolog;

    wxFFile file(wxT("/proc/cpuinfo"));
    if ( file.IsOpened() )
    {
        // slurp the whole file
        wxString s;
        if ( file.ReadAll(&s) )
        {
            // (ab)use Replace() to find the number of "processor: num" strings
            size_t count = s.Replace(wxT("processor\t:"), wxT(""));
            if ( count > 0 )
            {
                return count;
            }

            wxLogDebug(wxT("failed to parse /proc/cpuinfo"));
        }
        else
        {
            wxLogDebug(wxT("failed to read /proc/cpuinfo"));
        }
    }
#endif // different ways to get number of CPUs

    // unknown
    return -1;
}

wxThreadIdType wxThread::GetCurrentId()
{
    return (wxThreadIdType)pthread_self();
}


bool wxThread::SetConcurrency(size_t level)
{
#ifdef HAVE_PTHREAD_SETCONCURRENCY
    int rc = pthread_setconcurrency( level );
#elif defined(HAVE_THR_SETCONCURRENCY)
    int rc = thr_setconcurrency(level);
#else // !HAVE_THR_SETCONCURRENCY
    // ok only for the default value
    int rc = level == 0 ? 0 : -1;
#endif // HAVE_THR_SETCONCURRENCY/!HAVE_THR_SETCONCURRENCY

    if ( rc != 0 )
    {
        wxLogSysError(rc, _("Failed to set thread concurrency level to %lu"),
                      static_cast<unsigned long>(level));
        return false;
    }

    return true;
}

// -----------------------------------------------------------------------------
// creating thread
// -----------------------------------------------------------------------------

wxThread::wxThread(wxThreadKind kind)
{
    // add this thread to the global list of all threads
    {
        wxMutexLocker lock(*gs_mutexAllThreads);

        gs_allThreads.Add(this);
    }

    m_internal = new wxThreadInternal();

    m_isDetached = kind == wxTHREAD_DETACHED;
}

wxThreadError wxThread::Create(unsigned int stackSize)
{
    wxCriticalSectionLocker lock(m_critsect);

    return m_internal->Create(this, stackSize);
}

wxThreadError wxThread::Run()
{
    wxCriticalSectionLocker lock(m_critsect);

    // Create the thread if it wasn't created yet with an explicit
    // Create() call:
    if ( !m_internal->WasCreated() )
    {
        wxThreadError rv = m_internal->Create(this, 0);
        if ( rv != wxTHREAD_NO_ERROR )
            return rv;
    }

    return m_internal->Run();
}

// -----------------------------------------------------------------------------
// misc accessors
// -----------------------------------------------------------------------------

void wxThread::SetPriority(unsigned int prio)
{
    // Don't compare with wxPRIORITY_MIN as long as it is 0, as the comparison
    // would be always true.
    static_assert( wxPRIORITY_MIN == 0, "update the check below" );
    wxCHECK_RET( /* wxPRIORITY_MIN <= prio && */ prio <= wxPRIORITY_MAX,
                 wxT("invalid thread priority") );

    wxCriticalSectionLocker lock(m_critsect);

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

        case STATE_RUNNING:
        case STATE_PAUSED:
            {
#ifdef HAVE_THREAD_PRIORITY_FUNCTIONS
                // We map our priority values to pthreads scheduling params as
                // follows:
                //      0..20  to SCHED_IDLE
                //     21..40  to SCHED_BATCH
                //     41..60  to SCHED_OTHER
                //     61..80  to SCHED_RR
                //     81..100 to SCHED_FIFO
                //
                // For the last two, we can also use the additional priority
                // parameter which must be in 1..99 range under Linux (TODO:
                // what should be used for the other systems?).
                struct sched_param sparam = { };

                // The only scheduling policy guaranteed to be supported
                // everywhere is this one.
                int policy = SCHED_OTHER;
#ifdef SCHED_IDLE
                if ( prio <= 20 )
                    policy = SCHED_IDLE;
#endif
#ifdef SCHED_BATCH
                if ( 20 < prio && prio <= 40 )
                    policy = SCHED_BATCH;
#endif
#ifdef SCHED_RR
                if ( 60 < prio && prio <= 80 )
                    policy = SCHED_RR;
#endif
#ifdef SCHED_FIFO
                if ( 80 < prio )
                    policy = SCHED_FIFO;
#endif

                // This test is not redundant as it takes care of the systems
                // where neither SCHED_RR nor SCHED_FIFO are defined.
                if ( prio > 60 && policy != SCHED_OTHER )
                {
                    // There is no good way to map our 20 possible priorities
                    // (61..80 or 81..100) to the 99 pthread priorities, so we
                    // do the best that we can and ensure that the extremes of
                    // our range are mapped to the pthread extremes and all the
                    // rest fall in between.

                    // This gets us to 1..96 range.
                    sparam.sched_priority = ((prio - 61) % 20)*5 + 1;

                    // And we artificially increase our highest priority to the
                    // highest pthread one.
                    if ( sparam.sched_priority == 96 )
                        sparam.sched_priority = 99;
                }

                if ( pthread_setschedparam(m_internal->GetId(),
                                           policy, &sparam) != 0 )
                {
                    wxLogError(_("Failed to set thread priority %d."), prio);
                }
#endif // HAVE_THREAD_PRIORITY_FUNCTIONS
            }
            break;

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

unsigned int wxThread::GetPriority() const
{
    wxCriticalSectionLocker lock(m_critsect);

    return m_internal->GetPriority();
}

wxThreadIdType wxThread::GetId() const
{
    return (wxThreadIdType) m_internal->GetId();
}

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

wxThreadError wxThread::Pause()
{
    wxCHECK_MSG( This() != this, wxTHREAD_MISC_ERROR,
                 wxT("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:
            wxLogTrace(TRACE_THREADS, wxT("Thread %p suspended, resuming."),
                       THR_ID(this));

            m_internal->Resume();

            return wxTHREAD_NO_ERROR;

        case STATE_EXITED:
            wxLogTrace(TRACE_THREADS, wxT("Thread %p exited, won't resume."),
                       THR_ID(this));
            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(wxThreadWait WXUNUSED(waitMode))
{
    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, wxThreadWait WXUNUSED(waitMode))
{
    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();

    // Normally we should never call out while holding the lock (on m_critsect
    // in this case), but we can't do it later because as soon as we unlock it,
    // this object may be destroyed as the thread executing its Entry() may
    // call TestDestroy() and decide to exit at any moment, so we have to do it
    // now and hope that OnDelete() doesn't do anything stupid (or, preferably,
    // anything at all).
    OnDelete();

    // If it's currently paused, we need to resume it first.
    if ( state == STATE_PAUSED )
        m_internal->Resume();

    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();

            wxFALLTHROUGH;

        case STATE_EXITED:
            // nothing to do
            break;

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

                if ( rc )
                {
                    // return the exit code of the thread
                    *rc = m_internal->GetExitCode();
                }
            }
            //else: can't wait for detached threads
    }

    if (state == STATE_NEW)
        return wxTHREAD_MISC_ERROR;
            // for coherency with the MSW implementation, signal the user that
            // Delete() was called on a thread which didn't start to run yet.

    return wxTHREAD_NO_ERROR;
}

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

    OnKill();

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

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

            wxFALLTHROUGH;

        default:
#ifdef HAVE_PTHREAD_CANCEL
            if ( pthread_cancel(m_internal->GetId()) != 0 )
#endif // HAVE_PTHREAD_CANCEL
            {
                wxLogError(_("Failed to terminate a thread."));

                return wxTHREAD_MISC_ERROR;
            }

#ifdef HAVE_PTHREAD_CANCEL
            if ( m_isDetached )
            {
                // if we use cleanup function, this will be done from
                // wxPthreadCleanup()
#ifndef wxHAVE_PTHREAD_CLEANUP
                ScheduleThreadForDeletion();

                // don't call OnExit() here, it can only be called in the
                // threads context and we're in the context of another thread

                DeleteThread(this);
#endif // wxHAVE_PTHREAD_CLEANUP
            }
            else
            {
                m_internal->SetExitCode(EXITCODE_CANCELLED);
            }

            return wxTHREAD_NO_ERROR;
#endif // HAVE_PTHREAD_CANCEL
    }
}

bool wxThread::SetName(const wxString &name)
{
    wxCHECK_MSG(this == This(), false,
        "SetName() must be called from inside the thread to be named");

    return SetNameForCurrent(name);
}

/* static */
bool wxThread::SetNameForCurrent(const wxString &name)
{
    // the API is nearly the same on different *nix, but not quite:

#if defined(__DARWIN__)
    pthread_setname_np(name.utf8_str());
    return true;
#elif defined(__LINUX__) && defined(wxCAN_SET_LINUX_THREAD_NAME)
    // Linux doesn't allow names longer than 15 bytes.
    char truncatedName[16] = { 0 };
    strncpy(truncatedName, name.utf8_str(), 15);

    #ifdef wxHAVE_PTHREAD_SETNAME_NP
        return pthread_setname_np(pthread_self(), truncatedName) == 0;
    #else
        return prctl(PR_SET_NAME, (unsigned long)(void*)truncatedName, 0, 0, 0);
    #endif
#else
    wxUnusedVar(name);
    wxLogDebug("No implementation for wxThread::SetName() on this OS.");
    return false;
#endif
    // TODO: #elif defined(__FREEBSD__) || defined(__OPENBSD__)
    // TODO: These two BSDs would need #include <pthread_np.h>
    // and the function call would be:
    // pthread_set_name_np(pthread_self(), name.utf8_str());
}

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

    if ( m_isDetached )
    {
        // from the moment we call OnExit(), the main program may terminate at
        // any moment, so mark this thread as being already in process of being
        // deleted or wxThreadModule::OnExit() will try to delete it again
        ScheduleThreadForDeletion();
    }

    // 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)
    wxSafeCall([this]()
    {
        OnExit();
    });

    // delete C++ thread object if this is a detached thread - user is
    // responsible for doing this for joinable ones
    if ( m_isDetached )
    {
        // FIXME I'm feeling bad about it - what if another thread function is
        //       called (in another thread context) now? It will try to access
        //       half destroyed object which will probably result in something
        //       very bad - but we can't protect this by a crit section unless
        //       we make it a global object, but this would mean that we can
        //       only call one thread function at a time :-(
        DeleteThread(this);
        pthread_setspecific(gs_keySelf, nullptr);
    }
    else
    {
        m_critsect.Enter();
        m_internal->SetState(STATE_EXITED);
        m_critsect.Leave();
    }

    // terminate the thread (pthread_exit() never returns)
    pthread_exit(status);

    wxFAIL_MSG(wxT("pthread_exit() failed"));
}

// 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();

    const bool wasCancelled = m_internal->WasCancelled();

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

        // leave the crit section or the other threads will stop too if they
        // try 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 wasCancelled;
}

wxThread::~wxThread()
{
    m_critsect.Enter();

    // check that the thread either exited or couldn't be created
    if ( m_internal->GetState() != STATE_EXITED &&
         m_internal->GetState() != STATE_NEW )
    {
        wxLogDebug(wxT("The thread %p is being destroyed although it is still running! The application may crash."),
                   THR_ID(this));
    }

    m_critsect.Leave();

    delete m_internal;

    // remove this thread from the global array
    {
        wxMutexLocker lock(*gs_mutexAllThreads);

        gs_allThreads.Remove(this);
    }
}

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

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

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

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

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

        default:
            return false;
    }
}

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

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

//--------------------------------------------------------------------
// wxThreadModule
//--------------------------------------------------------------------

#ifdef __DARWIN__
void wxOSXThreadModuleOnInit();
void wxOSXThreadModuleOnExit();
#endif

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

private:
    wxDECLARE_DYNAMIC_CLASS(wxThreadModule);
};

wxIMPLEMENT_DYNAMIC_CLASS(wxThreadModule, wxModule);

bool wxThreadModule::OnInit()
{
    int rc = pthread_key_create(&gs_keySelf, nullptr /* dtor function */);
    if ( rc != 0 )
    {
        wxLogSysError(rc, _("Thread module initialization failed: failed to create thread key"));

        return false;
    }

    wxThread::ms_idMainThread = wxThread::GetCurrentId();

    gs_mutexAllThreads = new wxMutex();

#ifdef __DARWIN__
    wxOSXThreadModuleOnInit();
#else
    gs_mutexGui = new wxMutex();
    gs_mutexGui->Lock();
#endif

    gs_mutexDeleteThread = new wxMutex();
    gs_condAllDeleted = new wxCondition(*gs_mutexDeleteThread);

    return true;
}

void wxThreadModule::OnExit()
{
    wxASSERT_MSG( wxThread::IsMain(), wxT("only main thread can be here") );

    {
        wxMutexLocker lock( *gs_mutexDeleteThread );
        // are there any threads left which are being deleted right now?
        size_t nThreadsBeingDeleted;
        nThreadsBeingDeleted = gs_nThreadsBeingDeleted;

        if ( nThreadsBeingDeleted > 0 )
        {
            wxLogTrace(TRACE_THREADS,
                       wxT("Waiting for %lu threads to disappear"),
                       (unsigned long)nThreadsBeingDeleted);

            // have to wait until all of them disappear
            gs_condAllDeleted->Wait();
        }
    }

    size_t count;

    {
        wxMutexLocker lock(*gs_mutexAllThreads);

        // terminate any threads left
        count = gs_allThreads.GetCount();
        if ( count != 0u )
        {
            wxLogDebug(wxT("%lu threads were not terminated by the application."),
                       (unsigned long)count);
        }
    } // unlock mutex before deleting the threads as they lock it in their dtor

    for ( size_t n = 0u; n < count; n++ )
    {
        // Delete calls the destructor which removes the current entry. We
        // should only delete the first one each time.
        gs_allThreads[0]->Delete();
    }

    delete gs_mutexAllThreads;

#ifdef __DARWIN__
    wxOSXThreadModuleOnExit();
#else
    // destroy GUI mutex
    gs_mutexGui->Unlock();
    delete gs_mutexGui;
#endif

    // and free TLD slot
    (void)pthread_key_delete(gs_keySelf);

    delete gs_condAllDeleted;
    delete gs_mutexDeleteThread;
}

// ----------------------------------------------------------------------------
// global functions
// ----------------------------------------------------------------------------

static void ScheduleThreadForDeletion()
{
    wxMutexLocker lock( *gs_mutexDeleteThread );

    gs_nThreadsBeingDeleted++;

    wxLogTrace(TRACE_THREADS, wxT("%lu thread%s waiting to be deleted"),
               (unsigned long)gs_nThreadsBeingDeleted,
               gs_nThreadsBeingDeleted == 1 ? wxT("") : wxT("s"));
}

static void DeleteThread(wxThread *This)
{
    wxLogTrace(TRACE_THREADS, wxT("Thread %p auto deletes."), THR_ID(This));

    delete This;

    // only lock gs_mutexDeleteThread after deleting the thread to avoid
    // calling out into user code with it locked as this may result in
    // deadlocks if the thread dtor deletes another thread (see #11501)
    wxMutexLocker locker( *gs_mutexDeleteThread );

    wxCHECK_RET( gs_nThreadsBeingDeleted > 0,
                 wxT("no threads scheduled for deletion, yet we delete one?") );

    wxLogTrace(TRACE_THREADS, wxT("%lu threads remain scheduled for deletion."),
               (unsigned long)gs_nThreadsBeingDeleted - 1);

    if ( !--gs_nThreadsBeingDeleted )
    {
        // no more threads left, signal it
        gs_condAllDeleted->Signal();
    }
}

#ifndef __DARWIN__

void wxMutexGuiEnterImpl()
{
    gs_mutexGui->Lock();
}

void wxMutexGuiLeaveImpl()
{
    gs_mutexGui->Unlock();
}

#endif

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

#include "wx/thrimpl.cpp"

#endif // wxUSE_THREADS
