src/newlib/winsup/cygwin/cygthread.cc - stadia-controller/gcc-arm-none-eabi - Git at Google

 /* cygthread.cc

 This software is a copyrighted work licensed under the terms of the
 Cygwin license.  Please consult the file "CYGWIN_LICENSE" for
 details. */

 #include "winsup.h"
 #include "miscfuncs.h"
 #include <stdlib.h>
 #include "sigproc.h"
 #include "cygtls.h"
 #include "ntdll.h"

 #undef CloseHandle

 static cygthread NO_COPY threads[64];
 #define NTHREADS (sizeof (threads) / sizeof (threads[0]))

 DWORD NO_COPY cygthread::main_thread_id;
 bool NO_COPY cygthread::exiting;

 void
 cygthread::callfunc (bool issimplestub)
 {
   void *pass_arg;
   if (arg == cygself)
     pass_arg = this;
   else if (!arglen)
     pass_arg = arg;
   else
     {
       if (issimplestub)
 	ev = CreateEvent (&sec_none_nih, TRUE, FALSE, NULL);
       pass_arg = alloca (arglen);
       memcpy (pass_arg, arg, arglen);
       SetEvent (ev);
     }
   if (issimplestub)
     {
       /* Wait for main thread to assign 'h' */
       while (!h)
 	yield ();
       if (ev)
 	CloseHandle (ev);
       ev = h;
     }
   /* Cygwin threads should not call ExitThread directly */
   func (pass_arg);
   /* ...so the above should always return */
 }

 /* Initial stub called by cygthread constructor. Performs initial
    per-thread initialization and loops waiting for another thread function
    to execute.  */
 DWORD WINAPI
 cygthread::stub (VOID *arg)
 {
   cygthread *info = (cygthread *) arg;
   _my_tls._ctinfo = info;
   if (info->arg == cygself)
     {
       if (info->ev)
 	{
 	  CloseHandle (info->ev);
 	  CloseHandle (info->thread_sync);
 	}
       info->ev = info->thread_sync = info->stack_ptr = NULL;
     }
   else
     {
       info->stack_ptr = &arg;
       debug_printf ("thread '%s', id %y, stack_ptr %p", info->name (), info->id, info->stack_ptr);
       if (!info->ev)
 	{
 	  info->ev = CreateEvent (&sec_none_nih, TRUE, FALSE, NULL);
 	  info->thread_sync = CreateEvent (&sec_none_nih, FALSE, FALSE, NULL);
 	}
     }

   while (1)
     {
       if (!info->__name)
 #ifdef DEBUGGING
 	system_printf ("erroneous thread activation, name is NULL prev thread name = '%s'", info->__oldname);
 #else
 	system_printf ("erroneous thread activation, name is NULL");
 #endif
       else
 	{
 	  info->callfunc (false);

 	  HANDLE notify = info->notify_detached;
 	  /* If func is NULL, the above function has set that to indicate
 	     that it doesn't want to alert anyone with a SetEvent and should
 	     just be marked as no longer inuse.  Hopefully the function knows
 	     what it is doing.  */
 	  if (!info->func)
 	    info->release (false);
 	  else
 	    {
 #ifdef DEBUGGING
 	      info->func = NULL;	// catch erroneous activation
 	      info->__oldname = info->__name;
 #endif
 	      info->__name = NULL;
 	      SetEvent (info->ev);
 	    }
 	  if (notify)
 	    SetEvent (notify);
 	}
       switch (WaitForSingleObject (info->thread_sync, INFINITE))
 	{
 	case WAIT_OBJECT_0:
 	  continue;
 	default:
 	  api_fatal ("WFSO failed, %E");
 	  break;
 	}
     }
 }

 /* Overflow stub called by cygthread constructor. Calls specified function
    and then exits the thread.  */
 DWORD WINAPI
 cygthread::simplestub (VOID *arg)
 {
   cygthread *info = (cygthread *) arg;
   _my_tls._ctinfo = info;
   info->stack_ptr = &arg;
   HANDLE notify = info->notify_detached;
   info->callfunc (true);
   if (notify)
      SetEvent (notify);
   return 0;
 }

 /* Start things going.  Called from dll_crt0_1. */
 void
 cygthread::init ()
 {
   main_thread_id = GetCurrentThreadId ();
 }

 cygthread *
 cygthread::freerange ()
 {
   cygthread *self = (cygthread *) calloc (1, sizeof (*self));
   self->is_freerange = true;
   self->inuse = 1;
   return self;
 }

 void * cygthread::operator
 new (size_t)
 {
   cygthread *info;

   /* Search the threads array for an empty slot to use */
   for (info = threads; info < threads + NTHREADS; info++)
     if (!InterlockedExchange (&info->inuse, 1))
       {
 	/* available */
 #ifdef DEBUGGING
 	if (info->__name)
 	  api_fatal ("name not NULL? %s, id %y, i %ld", info->__name, info->id, info - threads);
 #endif
 	goto out;
       }

 #ifdef DEBUGGING
   if (!getenv ("CYGWIN_FREERANGE_NOCHECK"))
     api_fatal ("overflowed cygwin thread pool");
   else
     thread_printf ("overflowed cygwin thread pool");
 #endif

   info = freerange ();	/* exhausted thread pool */

 out:
   return info;
 }

 /* This function is called via QueueUserAPC.  Apparently creating threads
    asynchronously is a huge performance win on Win64.  */
 void CALLBACK
 cygthread::async_create (ULONG_PTR arg)
 {
   cygthread *that = (cygthread *) arg;
   that->create ();
   ::SetThreadPriority (that->h, THREAD_PRIORITY_HIGHEST);
   that->zap_h ();
 }

 void
 cygthread::create ()
 {
   thread_printf ("name %s, id %y, this %p", __name, id, this);
   HANDLE htobe;
   if (h)
     {
       if (ev)
 	ResetEvent (ev);
       while (!thread_sync)
 	yield ();
       SetEvent (thread_sync);
       thread_printf ("activated name '%s', thread_sync %p for id %y", __name, thread_sync, id);
       htobe = h;
     }
   else
     {
       stack_ptr = NULL;
       htobe = CreateThread (&sec_none_nih, 0, is_freerange ? simplestub : stub,
 			    this, 0, &id);
       if (!htobe)
 	api_fatal ("CreateThread failed for %s - %p<%y>, %E", __name, h, id);
       else
 	SetThreadName (GetThreadId (htobe), __name);
       thread_printf ("created name '%s', thread %p, id %y", __name, h, id);
 #ifdef DEBUGGING
       terminated = false;
 #endif
     }

   if (arglen)
     {
       while (!ev)
 	yield ();
       WaitForSingleObject (ev, INFINITE);
       ResetEvent (ev);
     }
   h = htobe;
 }

 /* Return the symbolic name of the current thread for debugging.
  */
 const char *
 cygthread::name (DWORD tid)
 {
   const char *res = NULL;
   if (!tid)
     tid = GetCurrentThreadId ();

   if (tid == main_thread_id)
     return "main";

   for (DWORD i = 0; i < NTHREADS; i++)
     if (threads[i].id == tid)
       {
 	res = threads[i].__name ?: "exiting thread";
 	break;
       }

   if (res)
     /* ok */;
   else if (!_main_tls)
     res = "main";
   else
     {
       __small_sprintf (_my_tls.locals.unknown_thread_name, "unknown (%y)", tid);
       res = _my_tls.locals.unknown_thread_name;
     }
   return res;
 }

 cygthread::operator
 HANDLE ()
 {
   while (!ev)
     yield ();
   return ev;
 }

 void
 cygthread::release (bool nuke_h)
 {
   if (nuke_h)
     h = NULL;
 #ifdef DEBUGGING
   __oldname = __name;
   debug_printf ("released thread '%s'", __oldname);
 #endif
   __name = NULL;
   func = NULL;
   /* Must be last */
   if (!InterlockedExchange (&inuse, 0))
 #ifdef DEBUGGING
     api_fatal ("released a thread that was not inuse");
 #else
     system_printf ("released a thread that was not inuse");
 #endif
 }

 /* Forcibly terminate a thread. */
 bool
 cygthread::terminate_thread ()
 {
   bool terminated = true;
   debug_printf ("thread '%s', id %y, inuse %d, stack_ptr %p", __name, id, inuse, stack_ptr);
   while (inuse && !stack_ptr)
     yield ();

   if (!inuse)
     goto force_notterminated;

   TerminateThread (h, 0);
   WaitForSingleObject (h, INFINITE);
   CloseHandle (h);

   if (!inuse || exiting)
     goto force_notterminated;

   if (ev && !(terminated = !IsEventSignalled (ev)))
     ResetEvent (ev);

   if (is_freerange)
     free (this);
   else
     {
 #ifdef DEBUGGING
       terminated = true;
 #endif
       release (true);
     }

   goto out;

 force_notterminated:
   terminated = false;
 out:
   return terminated;
 }

 /* Detach the cygthread from the current thread.  Note that the
    theory is that cygthreads are only associated with one thread.
    So, there should be never be multiple threads doing waits
    on the same cygthread. */
 bool
 cygthread::detach (HANDLE sigwait)
 {
   bool signalled = false;
   bool thread_was_reset = false;
   if (!inuse)
     system_printf ("called detach but inuse %d, thread %y?", inuse, id);
   else
     {
       DWORD res;

       if (!sigwait)
 	/* If the caller specified a special handle for notification, wait for that.
 	   This assumes that the thread in question is auto releasing. */
 	res = WaitForSingleObject (*this, INFINITE);
       else
 	{
 	  /* Lower our priority and give priority to the read thread */
 	  HANDLE hth = GetCurrentThread ();
 	  LONG prio = GetThreadPriority (hth);
 	  ::SetThreadPriority (hth, THREAD_PRIORITY_BELOW_NORMAL);

 	  HANDLE w4[2];
 	  unsigned n = 2;
 	  DWORD howlong = INFINITE;
 	  w4[0] = sigwait;
 	  wait_signal_arrived here (w4[1]);
 	  /* For a description of the below loop see the end of this file */
 	  for (int i = 0; i < 2; i++)
 	    switch (res = WaitForMultipleObjects (n, w4, FALSE, howlong))
 	      {
 	      case WAIT_OBJECT_0:
 		if (n == 1)
 		  howlong = 50;
 		break;
 	      case WAIT_OBJECT_0 + 1:
 		n = 1;
 		if (i--)
 		  howlong = 50;
 		break;
 	      case WAIT_TIMEOUT:
 		break;
 	      default:
 		if (!exiting)
 		  {
 		    system_printf ("WFMO failed waiting for cygthread '%s', %E", __name);
 		    for (unsigned j = 0; j < n; j++)
 		      switch (WaitForSingleObject (w4[j], 0))
 			{
 			case WAIT_OBJECT_0:
 			case WAIT_TIMEOUT:
 			  break;
 			default:
 			  system_printf ("%s handle %p is bad", (j ? "signal_arrived" : "semaphore"), w4[j]);
 			  break;
 			}
 		    api_fatal ("exiting on fatal error");
 		  }
 		break;
 	      }
 	  /* WAIT_OBJECT_0 means that the thread successfully read something,
 	     so wait for the cygthread to "terminate". */
 	  if (res == WAIT_OBJECT_0)
 	    WaitForSingleObject (*this, INFINITE);
 	  else
 	    {
 	      /* Thread didn't terminate on its own, so maybe we have to
 		 do it. */
 	      signalled = terminate_thread ();
 	      /* Possibly the thread completed *just* before it was
 		 terminated.  Detect this. If this happened then the
 		 read was not terminated on a signal. */
 	      if (WaitForSingleObject (sigwait, 0) == WAIT_OBJECT_0)
 		signalled = false;
 	      if (signalled)
 		set_sig_errno (EINTR);
 	      thread_was_reset = true;
 	    }
 	  ::SetThreadPriority (hth, prio);
 	}

       thread_printf ("%s returns %d, id %y", sigwait ? "WFMO" : "WFSO",
 		     res, id);

       if (thread_was_reset)
 	/* already handled */;
       else if (is_freerange)
 	{
 	  CloseHandle (h);
 	  free (this);
 	}
       else
 	{
 	  ResetEvent (*this);
 	  /* Mark the thread as available by setting inuse to zero */
 	  InterlockedExchange (&inuse, 0);
 	}
     }
   return signalled;
 }

 void
 cygthread::terminate ()
 {
   exiting = 1;
 }

 /* The below is an explanation of synchronization loop in cygthread::detach.
    The intent is that the loop will always try hard to wait for both
    synchronization events from the reader thread but will exit with
    res == WAIT_TIMEOUT if a signal occurred and the reader thread is
    still blocked.

     case 0 - no signal

     i == 0 (howlong == INFINITE)
 	W0 activated
 	howlong not set because n != 1
 	just loop

     i == 1 (howlong == INFINITE)
 	W0 activated
 	howlong not set because n != 1
 	just loop (to exit loop) - no signal

     i == 2 (howlong == INFINITE)
 	exit loop

     case 1 - signal before thread initialized

     i == 0 (howlong == INFINITE)
 	WO + 1 activated
 	n set to 1
 	howlong untouched because i-- == 0
 	loop

     i == 0 (howlong == INFINITE)
 	W0 must be activated
 	howlong set to 50 because n == 1

     i == 1 (howlong == 50)
 	W0 activated
 	loop (to exit loop) - no signal

 	WAIT_TIMEOUT activated
 	signal potentially detected
 	loop (to exit loop)

     i == 2 (howlong == 50)
 	exit loop

     case 2 - signal after thread initialized

     i == 0 (howlong == INFINITE)
 	W0 activated
 	howlong not set because n != 1
 	loop

     i == 1 (howlong == INFINITE)
 	W0 + 1 activated
 	n set to 1
 	howlong set to 50 because i-- != 0
 	loop

     i == 1 (howlong == 50)
 	W0 activated
 	loop (to exit loop) - no signal

 	WAIT_TIMEOUT activated
 	loop (to exit loop) - signal

     i == 2 (howlong == 50)
 	exit loop
 */
	/* cygthread.cc

	This software is a copyrighted work licensed under the terms of the
	Cygwin license. Please consult the file "CYGWIN_LICENSE" for
	details. */

	#include "winsup.h"
	#include "miscfuncs.h"
	#include <stdlib.h>
	#include "sigproc.h"
	#include "cygtls.h"
	#include "ntdll.h"

	#undef CloseHandle

	static cygthread NO_COPY threads[64];
	#define NTHREADS (sizeof (threads) / sizeof (threads[0]))

	DWORD NO_COPY cygthread::main_thread_id;
	bool NO_COPY cygthread::exiting;

	void
	cygthread::callfunc (bool issimplestub)
	{
	void *pass_arg;
	if (arg == cygself)
	pass_arg = this;
	else if (!arglen)
	pass_arg = arg;
	else
	{
	if (issimplestub)
	ev = CreateEvent (&sec_none_nih, TRUE, FALSE, NULL);
	pass_arg = alloca (arglen);
	memcpy (pass_arg, arg, arglen);
	SetEvent (ev);
	}
	if (issimplestub)
	{
	/* Wait for main thread to assign 'h' */
	while (!h)
	yield ();
	if (ev)
	CloseHandle (ev);
	ev = h;
	}
	/* Cygwin threads should not call ExitThread directly */
	func (pass_arg);
	/* ...so the above should always return */
	}

	/* Initial stub called by cygthread constructor. Performs initial
	per-thread initialization and loops waiting for another thread function
	to execute. */
	DWORD WINAPI
	cygthread::stub (VOID *arg)
	{
	cygthread info = (cygthread ) arg;
	_my_tls._ctinfo = info;
	if (info->arg == cygself)
	{
	if (info->ev)
	{
	CloseHandle (info->ev);
	CloseHandle (info->thread_sync);
	}
	info->ev = info->thread_sync = info->stack_ptr = NULL;
	}
	else
	{
	info->stack_ptr = &arg;
	debug_printf ("thread '%s', id %y, stack_ptr %p", info->name (), info->id, info->stack_ptr);
	if (!info->ev)
	{
	info->ev = CreateEvent (&sec_none_nih, TRUE, FALSE, NULL);
	info->thread_sync = CreateEvent (&sec_none_nih, FALSE, FALSE, NULL);
	}
	}

	while (1)
	{
	if (!info->__name)
	#ifdef DEBUGGING
	system_printf ("erroneous thread activation, name is NULL prev thread name = '%s'", info->__oldname);
	#else
	system_printf ("erroneous thread activation, name is NULL");
	#endif
	else
	{
	info->callfunc (false);

	HANDLE notify = info->notify_detached;
	/* If func is NULL, the above function has set that to indicate
	that it doesn't want to alert anyone with a SetEvent and should
	just be marked as no longer inuse. Hopefully the function knows
	what it is doing. */
	if (!info->func)
	info->release (false);
	else
	{
	#ifdef DEBUGGING
	info->func = NULL; // catch erroneous activation
	info->__oldname = info->__name;
	#endif
	info->__name = NULL;
	SetEvent (info->ev);
	}
	if (notify)
	SetEvent (notify);
	}
	switch (WaitForSingleObject (info->thread_sync, INFINITE))
	{
	case WAIT_OBJECT_0:
	continue;
	default:
	api_fatal ("WFSO failed, %E");
	break;
	}
	}
	}

	/* Overflow stub called by cygthread constructor. Calls specified function
	and then exits the thread. */
	DWORD WINAPI
	cygthread::simplestub (VOID *arg)
	{
	cygthread info = (cygthread ) arg;
	_my_tls._ctinfo = info;
	info->stack_ptr = &arg;
	HANDLE notify = info->notify_detached;
	info->callfunc (true);
	if (notify)
	SetEvent (notify);
	return 0;
	}

	/* Start things going. Called from dll_crt0_1. */
	void
	cygthread::init ()
	{
	main_thread_id = GetCurrentThreadId ();
	}

	cygthread *
	cygthread::freerange ()
	{
	cygthread self = (cygthread ) calloc (1, sizeof (*self));
	self->is_freerange = true;
	self->inuse = 1;
	return self;
	}

	void * cygthread::operator
	new (size_t)
	{
	cygthread *info;

	/* Search the threads array for an empty slot to use */
	for (info = threads; info < threads + NTHREADS; info++)
	if (!InterlockedExchange (&info->inuse, 1))
	{
	/* available */
	#ifdef DEBUGGING
	if (info->__name)
	api_fatal ("name not NULL? %s, id %y, i %ld", info->__name, info->id, info - threads);
	#endif
	goto out;
	}

	#ifdef DEBUGGING
	if (!getenv ("CYGWIN_FREERANGE_NOCHECK"))
	api_fatal ("overflowed cygwin thread pool");
	else
	thread_printf ("overflowed cygwin thread pool");
	#endif

	info = freerange (); /* exhausted thread pool */

	out:
	return info;
	}

	/* This function is called via QueueUserAPC. Apparently creating threads
	asynchronously is a huge performance win on Win64. */
	void CALLBACK
	cygthread::async_create (ULONG_PTR arg)
	{
	cygthread that = (cygthread ) arg;
	that->create ();
	::SetThreadPriority (that->h, THREAD_PRIORITY_HIGHEST);
	that->zap_h ();
	}

	void
	cygthread::create ()
	{
	thread_printf ("name %s, id %y, this %p", __name, id, this);
	HANDLE htobe;
	if (h)
	{
	if (ev)
	ResetEvent (ev);
	while (!thread_sync)
	yield ();
	SetEvent (thread_sync);
	thread_printf ("activated name '%s', thread_sync %p for id %y", __name, thread_sync, id);
	htobe = h;
	}
	else
	{
	stack_ptr = NULL;
	htobe = CreateThread (&sec_none_nih, 0, is_freerange ? simplestub : stub,
	this, 0, &id);
	if (!htobe)
	api_fatal ("CreateThread failed for %s - %p<%y>, %E", __name, h, id);
	else
	SetThreadName (GetThreadId (htobe), __name);
	thread_printf ("created name '%s', thread %p, id %y", __name, h, id);
	#ifdef DEBUGGING
	terminated = false;
	#endif
	}

	if (arglen)
	{
	while (!ev)
	yield ();
	WaitForSingleObject (ev, INFINITE);
	ResetEvent (ev);
	}
	h = htobe;
	}

	/* Return the symbolic name of the current thread for debugging.
	*/
	const char *
	cygthread::name (DWORD tid)
	{
	const char *res = NULL;
	if (!tid)
	tid = GetCurrentThreadId ();

	if (tid == main_thread_id)
	return "main";

	for (DWORD i = 0; i < NTHREADS; i++)
	if (threads[i].id == tid)
	{
	res = threads[i].__name ?: "exiting thread";
	break;
	}

	if (res)
	/* ok */;
	else if (!_main_tls)
	res = "main";
	else
	{
	__small_sprintf (_my_tls.locals.unknown_thread_name, "unknown (%y)", tid);
	res = _my_tls.locals.unknown_thread_name;
	}
	return res;
	}

	cygthread::operator
	HANDLE ()
	{
	while (!ev)
	yield ();
	return ev;
	}

	void
	cygthread::release (bool nuke_h)
	{
	if (nuke_h)
	h = NULL;
	#ifdef DEBUGGING
	__oldname = __name;
	debug_printf ("released thread '%s'", __oldname);
	#endif
	__name = NULL;
	func = NULL;
	/* Must be last */
	if (!InterlockedExchange (&inuse, 0))
	#ifdef DEBUGGING
	api_fatal ("released a thread that was not inuse");
	#else
	system_printf ("released a thread that was not inuse");
	#endif
	}

	/* Forcibly terminate a thread. */
	bool
	cygthread::terminate_thread ()
	{
	bool terminated = true;
	debug_printf ("thread '%s', id %y, inuse %d, stack_ptr %p", __name, id, inuse, stack_ptr);
	while (inuse && !stack_ptr)
	yield ();

	if (!inuse)
	goto force_notterminated;

	TerminateThread (h, 0);
	WaitForSingleObject (h, INFINITE);
	CloseHandle (h);

	if (!inuse \|\| exiting)
	goto force_notterminated;

	if (ev && !(terminated = !IsEventSignalled (ev)))
	ResetEvent (ev);

	if (is_freerange)
	free (this);
	else
	{
	#ifdef DEBUGGING
	terminated = true;
	#endif
	release (true);
	}

	goto out;

	force_notterminated:
	terminated = false;
	out:
	return terminated;
	}

	/* Detach the cygthread from the current thread. Note that the
	theory is that cygthreads are only associated with one thread.
	So, there should be never be multiple threads doing waits
	on the same cygthread. */
	bool
	cygthread::detach (HANDLE sigwait)
	{
	bool signalled = false;
	bool thread_was_reset = false;
	if (!inuse)
	system_printf ("called detach but inuse %d, thread %y?", inuse, id);
	else
	{
	DWORD res;

	if (!sigwait)
	/* If the caller specified a special handle for notification, wait for that.
	This assumes that the thread in question is auto releasing. */
	res = WaitForSingleObject (*this, INFINITE);
	else
	{
	/* Lower our priority and give priority to the read thread */
	HANDLE hth = GetCurrentThread ();
	LONG prio = GetThreadPriority (hth);
	::SetThreadPriority (hth, THREAD_PRIORITY_BELOW_NORMAL);

	HANDLE w4[2];
	unsigned n = 2;
	DWORD howlong = INFINITE;
	w4[0] = sigwait;
	wait_signal_arrived here (w4[1]);
	/* For a description of the below loop see the end of this file */
	for (int i = 0; i < 2; i++)
	switch (res = WaitForMultipleObjects (n, w4, FALSE, howlong))
	{
	case WAIT_OBJECT_0:
	if (n == 1)
	howlong = 50;
	break;
	case WAIT_OBJECT_0 + 1:
	n = 1;
	if (i--)
	howlong = 50;
	break;
	case WAIT_TIMEOUT:
	break;
	default:
	if (!exiting)
	{
	system_printf ("WFMO failed waiting for cygthread '%s', %E", __name);
	for (unsigned j = 0; j < n; j++)
	switch (WaitForSingleObject (w4[j], 0))
	{
	case WAIT_OBJECT_0:
	case WAIT_TIMEOUT:
	break;
	default:
	system_printf ("%s handle %p is bad", (j ? "signal_arrived" : "semaphore"), w4[j]);
	break;
	}
	api_fatal ("exiting on fatal error");
	}
	break;
	}
	/* WAIT_OBJECT_0 means that the thread successfully read something,
	so wait for the cygthread to "terminate". */
	if (res == WAIT_OBJECT_0)
	WaitForSingleObject (*this, INFINITE);
	else
	{
	/* Thread didn't terminate on its own, so maybe we have to
	do it. */
	signalled = terminate_thread ();
	/* Possibly the thread completed just before it was
	terminated. Detect this. If this happened then the
	read was not terminated on a signal. */
	if (WaitForSingleObject (sigwait, 0) == WAIT_OBJECT_0)
	signalled = false;
	if (signalled)
	set_sig_errno (EINTR);
	thread_was_reset = true;
	}
	::SetThreadPriority (hth, prio);
	}

	thread_printf ("%s returns %d, id %y", sigwait ? "WFMO" : "WFSO",
	res, id);

	if (thread_was_reset)
	/* already handled */;
	else if (is_freerange)
	{
	CloseHandle (h);
	free (this);
	}
	else
	{
	ResetEvent (*this);
	/* Mark the thread as available by setting inuse to zero */
	InterlockedExchange (&inuse, 0);
	}
	}
	return signalled;
	}

	void
	cygthread::terminate ()
	{
	exiting = 1;
	}

	/* The below is an explanation of synchronization loop in cygthread::detach.
	The intent is that the loop will always try hard to wait for both
	synchronization events from the reader thread but will exit with
	res == WAIT_TIMEOUT if a signal occurred and the reader thread is
	still blocked.

	case 0 - no signal

	i == 0 (howlong == INFINITE)
	W0 activated
	howlong not set because n != 1
	just loop

	i == 1 (howlong == INFINITE)
	W0 activated
	howlong not set because n != 1
	just loop (to exit loop) - no signal

	i == 2 (howlong == INFINITE)
	exit loop

	case 1 - signal before thread initialized

	i == 0 (howlong == INFINITE)
	WO + 1 activated
	n set to 1
	howlong untouched because i-- == 0
	loop

	i == 0 (howlong == INFINITE)
	W0 must be activated
	howlong set to 50 because n == 1

	i == 1 (howlong == 50)
	W0 activated
	loop (to exit loop) - no signal

	WAIT_TIMEOUT activated
	signal potentially detected
	loop (to exit loop)

	i == 2 (howlong == 50)
	exit loop

	case 2 - signal after thread initialized

	i == 0 (howlong == INFINITE)
	W0 activated
	howlong not set because n != 1
	loop

	i == 1 (howlong == INFINITE)
	W0 + 1 activated
	n set to 1
	howlong set to 50 because i-- != 0
	loop

	i == 1 (howlong == 50)
	W0 activated
	loop (to exit loop) - no signal

	WAIT_TIMEOUT activated
	loop (to exit loop) - signal

	i == 2 (howlong == 50)
	exit loop
	*/