Python/thread_nt.h - platform/external/python/cpython3 - Gitiles


 /* This code implemented by Dag.Gruneau@elsa.preseco.comm.se */
 /* Fast NonRecursiveMutex support by Yakov Markovitch, markovitch@iso.ru */

 #include <windows.h>
 #include <limits.h>
 #include <process.h>
 #include <Python.h>

 typedef struct NRMUTEX {
 	LONG   owned ;
 	DWORD  thread_id ;
 	HANDLE hevent ;
 } NRMUTEX, *PNRMUTEX ;

 /* dictionary to correlate thread ids with the handle needed to terminate them*/
 static PyObject *threads = NULL;

 typedef PVOID WINAPI interlocked_cmp_xchg_t(PVOID *dest, PVOID exc, PVOID comperand) ;

 /* Sorry mate, but we haven't got InterlockedCompareExchange in Win95! */
 static PVOID WINAPI interlocked_cmp_xchg(PVOID *dest, PVOID exc, PVOID comperand)
 {
 	static LONG spinlock = 0 ;
 	PVOID result ;
 	DWORD dwSleep = 0;

 	/* Acqire spinlock (yielding control to other threads if cant aquire for the moment) */
 	while(InterlockedExchange(&spinlock, 1))
 	{
 		// Using Sleep(0) can cause a priority inversion.
 		// Sleep(0) only yields the processor if there's
 		// another thread of the same priority that's
 		// ready to run.  If a high-priority thread is
 		// trying to acquire the lock, which is held by
 		// a low-priority thread, then the low-priority
 		// thread may never get scheduled and hence never
 		// free the lock.  NT attempts to avoid priority
 		// inversions by temporarily boosting the priority
 		// of low-priority runnable threads, but the problem
 		// can still occur if there's a medium-priority
 		// thread that's always runnable.  If Sleep(1) is used,
 		// then the thread unconditionally yields the CPU.  We
 		// only do this for the second and subsequent even
 		// iterations, since a millisecond is a long time to wait
 		// if the thread can be scheduled in again sooner
 		// (~100,000 instructions).
 		// Avoid priority inversion: 0, 1, 0, 1,...
 		Sleep(dwSleep);
 		dwSleep = !dwSleep;
 	}
 	result = *dest ;
 	if (result == comperand)
 		*dest = exc ;
 	/* Release spinlock */
 	spinlock = 0 ;
 	return result ;
 } ;

 static interlocked_cmp_xchg_t *ixchg ;
 BOOL InitializeNonRecursiveMutex(PNRMUTEX mutex)
 {
 	if (!ixchg)
 	{
 		/* Sorely, Win95 has no InterlockedCompareExchange API (Win98 has), so we have to use emulation */
 		HANDLE kernel = GetModuleHandle("kernel32.dll") ;
 		if (!kernel || (ixchg = (interlocked_cmp_xchg_t *)GetProcAddress(kernel, "InterlockedCompareExchange")) == NULL)
 			ixchg = interlocked_cmp_xchg ;
 	}

 	mutex->owned = -1 ;  /* No threads have entered NonRecursiveMutex */
 	mutex->thread_id = 0 ;
 	mutex->hevent = CreateEvent(NULL, FALSE, FALSE, NULL) ;
 	return mutex->hevent != NULL ;	/* TRUE if the mutex is created */
 }

 #ifdef InterlockedCompareExchange
 #undef InterlockedCompareExchange
 #endif
 #define InterlockedCompareExchange(dest,exchange,comperand) (ixchg((dest), (exchange), (comperand)))

 VOID DeleteNonRecursiveMutex(PNRMUTEX mutex)
 {
 	/* No in-use check */
 	CloseHandle(mutex->hevent) ;
 	mutex->hevent = NULL ; /* Just in case */
 }

 DWORD EnterNonRecursiveMutex(PNRMUTEX mutex, BOOL wait)
 {
 	/* Assume that the thread waits successfully */
 	DWORD ret ;

 	/* InterlockedIncrement(&mutex->owned) == 0 means that no thread currently owns the mutex */
 	if (!wait)
 	{
 		if (InterlockedCompareExchange((PVOID *)&mutex->owned, (PVOID)0, (PVOID)-1) != (PVOID)-1)
 			return WAIT_TIMEOUT ;
 		ret = WAIT_OBJECT_0 ;
 	}
 	else
 		ret = InterlockedIncrement(&mutex->owned) ?
 			/* Some thread owns the mutex, let's wait... */
 			WaitForSingleObject(mutex->hevent, INFINITE) : WAIT_OBJECT_0 ;

 	mutex->thread_id = GetCurrentThreadId() ; /* We own it */
 	return ret ;
 }

 BOOL LeaveNonRecursiveMutex(PNRMUTEX mutex)
 {
 	/* We don't own the mutex */
 	mutex->thread_id = 0 ;
 	return
 		InterlockedDecrement(&mutex->owned) < 0 ||
 		SetEvent(mutex->hevent) ; /* Other threads are waiting, wake one on them up */
 }

 PNRMUTEX AllocNonRecursiveMutex(void)
 {
 	PNRMUTEX mutex = (PNRMUTEX)malloc(sizeof(NRMUTEX)) ;
 	if (mutex && !InitializeNonRecursiveMutex(mutex))
 	{
 		free(mutex) ;
 		mutex = NULL ;
 	}
 	return mutex ;
 }

 void FreeNonRecursiveMutex(PNRMUTEX mutex)
 {
 	if (mutex)
 	{
 		DeleteNonRecursiveMutex(mutex) ;
 		free(mutex) ;
 	}
 }

 long PyThread_get_thread_ident(void);

 /*
  * Change all headers to pure ANSI as no one will use K&R style on an
  * NT
  */

 /*
  * Initialization of the C package, should not be needed.
  */
 static void PyThread__init_thread(void)
 {
 	threads = PyDict_New();
 }

 /*
  * Thread support.
  */

 typedef struct {
 	void (*func)(void*);
 	void *arg;
 	long id;
 	HANDLE done;
 } callobj;

 static int
 bootstrap(void *call)
 {
 	callobj *obj = (callobj*)call;
 	/* copy callobj since other thread might free it before we're done */
 	void (*func)(void*) = obj->func;
 	void *arg = obj->arg;

 	obj->id = PyThread_get_thread_ident();
 	ReleaseSemaphore(obj->done, 1, NULL);
 	func(arg);
 	return 0;
 }

 long PyThread_start_new_thread(void (*func)(void *), void *arg)
 {
 	unsigned long rv;
 	int success = 0;
 	callobj *obj;
 	int id;
 	PyObject *key, *val;

 	dprintf(("%ld: PyThread_start_new_thread called\n", PyThread_get_thread_ident()));
 	if (!initialized)
 		PyThread_init_thread();

 	obj = malloc(sizeof(callobj));
 	obj->func = func;
 	obj->arg = arg;
 	obj->done = CreateSemaphore(NULL, 0, 1, NULL);

 	rv = _beginthread(func, 0, obj); /* use default stack size */

 	if (rv != (unsigned long)-1) {
 		success = 1;
 		dprintf(("%ld: PyThread_start_new_thread succeeded: %p\n", PyThread_get_thread_ident(), rv));
 	}

 	/* wait for thread to initialize and retrieve id */
 	WaitForSingleObject(obj->done, 5000);  /* maybe INFINITE instead of 5000? */
 	CloseHandle((HANDLE)obj->done);
 	key = PyLong_FromLong(obj->id);
 	val = PyLong_FromLong((long)rv);
 	PyDict_SetItem(threads, key, val);
 	id = obj->id;
 	free(obj);
 	return id;
 }

 /*
  * Return the thread Id instead of an handle. The Id is said to uniquely identify the
  * thread in the system
  */
 long PyThread_get_thread_ident(void)
 {
 	if (!initialized)
 		PyThread_init_thread();

 	return GetCurrentThreadId();
 }

 static void do_PyThread_exit_thread(int no_cleanup)
 {
 	dprintf(("%ld: PyThread_exit_thread called\n", PyThread_get_thread_ident()));
 	if (!initialized)
 		if (no_cleanup)
 			_exit(0);
 		else
 			exit(0);
 	_endthread();
 }

 void PyThread_exit_thread(void)
 {
 	do_PyThread_exit_thread(0);
 }

 void PyThread__exit_thread(void)
 {
 	do_PyThread_exit_thread(1);
 }

 #ifndef NO_EXIT_PROG
 static void do_PyThread_exit_prog(int status, int no_cleanup)
 {
 	dprintf(("PyThread_exit_prog(%d) called\n", status));
 	if (!initialized)
 		if (no_cleanup)
 			_exit(status);
 		else
 			exit(status);
 }

 void PyThread_exit_prog(int status)
 {
 	do_PyThread_exit_prog(status, 0);
 }

 void PyThread__exit_prog(int status)
 {
 	do_PyThread_exit_prog(status, 1);
 }
 #endif /* NO_EXIT_PROG */

 /*
  * Lock support. It has too be implemented as semaphores.
  * I [Dag] tried to implement it with mutex but I could find a way to
  * tell whether a thread already own the lock or not.
  */
 PyThread_type_lock PyThread_allocate_lock(void)
 {
 	PNRMUTEX aLock;

 	dprintf(("PyThread_allocate_lock called\n"));
 	if (!initialized)
 		PyThread_init_thread();

 	aLock = AllocNonRecursiveMutex() ;

 	dprintf(("%ld: PyThread_allocate_lock() -> %p\n", PyThread_get_thread_ident(), aLock));

 	return (PyThread_type_lock) aLock;
 }

 void PyThread_free_lock(PyThread_type_lock aLock)
 {
 	dprintf(("%ld: PyThread_free_lock(%p) called\n", PyThread_get_thread_ident(),aLock));

 	FreeNonRecursiveMutex(aLock) ;
 }

 /*
  * Return 1 on success if the lock was acquired
  *
  * and 0 if the lock was not acquired. This means a 0 is returned
  * if the lock has already been acquired by this thread!
  */
 int PyThread_acquire_lock(PyThread_type_lock aLock, int waitflag)
 {
 	int success ;

 	dprintf(("%ld: PyThread_acquire_lock(%p, %d) called\n", PyThread_get_thread_ident(),aLock, waitflag));

 	success = aLock && EnterNonRecursiveMutex((PNRMUTEX) aLock, (waitflag == 1 ? INFINITE : 0)) == WAIT_OBJECT_0 ;

 	dprintf(("%ld: PyThread_acquire_lock(%p, %d) -> %d\n", PyThread_get_thread_ident(),aLock, waitflag, success));

 	return success;
 }

 void PyThread_release_lock(PyThread_type_lock aLock)
 {
 	dprintf(("%ld: PyThread_release_lock(%p) called\n", PyThread_get_thread_ident(),aLock));

 	if (!(aLock && LeaveNonRecursiveMutex((PNRMUTEX) aLock)))
 		dprintf(("%ld: Could not PyThread_release_lock(%p) error: %l\n", PyThread_get_thread_ident(), aLock, GetLastError()));
 }

 /*
  * Semaphore support.
  */
 PyThread_type_sema PyThread_allocate_sema(int value)
 {
 	HANDLE aSemaphore;

 	dprintf(("%ld: PyThread_allocate_sema called\n", PyThread_get_thread_ident()));
 	if (!initialized)
 		PyThread_init_thread();

 	aSemaphore = CreateSemaphore( NULL,           /* Security attributes          */
 	                              value,          /* Initial value                */
 	                              INT_MAX,        /* Maximum value                */
 	                              NULL);          /* Name of semaphore            */

 	dprintf(("%ld: PyThread_allocate_sema() -> %p\n", PyThread_get_thread_ident(), aSemaphore));

 	return (PyThread_type_sema) aSemaphore;
 }

 void PyThread_free_sema(PyThread_type_sema aSemaphore)
 {
 	dprintf(("%ld: PyThread_free_sema(%p) called\n", PyThread_get_thread_ident(), aSemaphore));

 	CloseHandle((HANDLE) aSemaphore);
 }

 /*
   XXX must do something about waitflag
  */
 int PyThread_down_sema(PyThread_type_sema aSemaphore, int waitflag)
 {
 	DWORD waitResult;

 	dprintf(("%ld: PyThread_down_sema(%p) called\n", PyThread_get_thread_ident(), aSemaphore));

 	waitResult = WaitForSingleObject( (HANDLE) aSemaphore, INFINITE);

 	dprintf(("%ld: PyThread_down_sema(%p) return: %l\n", PyThread_get_thread_ident(), aSemaphore, waitResult));
 	return 0;
 }

 void PyThread_up_sema(PyThread_type_sema aSemaphore)
 {
 	ReleaseSemaphore(
                 (HANDLE) aSemaphore,            /* Handle of semaphore                          */
                 1,                              /* increment count by one                       */
                 NULL);                          /* not interested in previous count             */

 	dprintf(("%ld: PyThread_up_sema(%p)\n", PyThread_get_thread_ident(), aSemaphore));
 }

	/* This code implemented by Dag.Gruneau@elsa.preseco.comm.se */
	/* Fast NonRecursiveMutex support by Yakov Markovitch, markovitch@iso.ru */

	#include <windows.h>
	#include <limits.h>
	#include <process.h>
	#include <Python.h>

	typedef struct NRMUTEX {
	LONG owned ;
	DWORD thread_id ;
	HANDLE hevent ;
	} NRMUTEX, *PNRMUTEX ;

	/* dictionary to correlate thread ids with the handle needed to terminate them*/
	static PyObject *threads = NULL;

	typedef PVOID WINAPI interlocked_cmp_xchg_t(PVOID *dest, PVOID exc, PVOID comperand) ;

	/* Sorry mate, but we haven't got InterlockedCompareExchange in Win95! */
	static PVOID WINAPI interlocked_cmp_xchg(PVOID *dest, PVOID exc, PVOID comperand)
	{
	static LONG spinlock = 0 ;
	PVOID result ;
	DWORD dwSleep = 0;

	/* Acqire spinlock (yielding control to other threads if cant aquire for the moment) */
	while(InterlockedExchange(&spinlock, 1))
	{
	// Using Sleep(0) can cause a priority inversion.
	// Sleep(0) only yields the processor if there's
	// another thread of the same priority that's
	// ready to run. If a high-priority thread is
	// trying to acquire the lock, which is held by
	// a low-priority thread, then the low-priority
	// thread may never get scheduled and hence never
	// free the lock. NT attempts to avoid priority
	// inversions by temporarily boosting the priority
	// of low-priority runnable threads, but the problem
	// can still occur if there's a medium-priority
	// thread that's always runnable. If Sleep(1) is used,
	// then the thread unconditionally yields the CPU. We
	// only do this for the second and subsequent even
	// iterations, since a millisecond is a long time to wait
	// if the thread can be scheduled in again sooner
	// (~100,000 instructions).
	// Avoid priority inversion: 0, 1, 0, 1,...
	Sleep(dwSleep);
	dwSleep = !dwSleep;
	}
	result = *dest ;
	if (result == comperand)
	*dest = exc ;
	/* Release spinlock */
	spinlock = 0 ;
	return result ;
	} ;

	static interlocked_cmp_xchg_t *ixchg ;
	BOOL InitializeNonRecursiveMutex(PNRMUTEX mutex)
	{
	if (!ixchg)
	{
	/* Sorely, Win95 has no InterlockedCompareExchange API (Win98 has), so we have to use emulation */
	HANDLE kernel = GetModuleHandle("kernel32.dll") ;
	if (!kernel \|\| (ixchg = (interlocked_cmp_xchg_t *)GetProcAddress(kernel, "InterlockedCompareExchange")) == NULL)
	ixchg = interlocked_cmp_xchg ;
	}

	mutex->owned = -1 ; /* No threads have entered NonRecursiveMutex */
	mutex->thread_id = 0 ;
	mutex->hevent = CreateEvent(NULL, FALSE, FALSE, NULL) ;
	return mutex->hevent != NULL ; /* TRUE if the mutex is created */
	}

	#ifdef InterlockedCompareExchange
	#undef InterlockedCompareExchange
	#endif
	#define InterlockedCompareExchange(dest,exchange,comperand) (ixchg((dest), (exchange), (comperand)))

	VOID DeleteNonRecursiveMutex(PNRMUTEX mutex)
	{
	/* No in-use check */
	CloseHandle(mutex->hevent) ;
	mutex->hevent = NULL ; /* Just in case */
	}

	DWORD EnterNonRecursiveMutex(PNRMUTEX mutex, BOOL wait)
	{
	/* Assume that the thread waits successfully */
	DWORD ret ;

	/* InterlockedIncrement(&mutex->owned) == 0 means that no thread currently owns the mutex */
	if (!wait)
	{
	if (InterlockedCompareExchange((PVOID *)&mutex->owned, (PVOID)0, (PVOID)-1) != (PVOID)-1)
	return WAIT_TIMEOUT ;
	ret = WAIT_OBJECT_0 ;
	}
	else
	ret = InterlockedIncrement(&mutex->owned) ?
	/* Some thread owns the mutex, let's wait... */
	WaitForSingleObject(mutex->hevent, INFINITE) : WAIT_OBJECT_0 ;

	mutex->thread_id = GetCurrentThreadId() ; /* We own it */
	return ret ;
	}

	BOOL LeaveNonRecursiveMutex(PNRMUTEX mutex)
	{
	/* We don't own the mutex */
	mutex->thread_id = 0 ;
	return
	InterlockedDecrement(&mutex->owned) < 0 \|\|
	SetEvent(mutex->hevent) ; /* Other threads are waiting, wake one on them up */
	}

	PNRMUTEX AllocNonRecursiveMutex(void)
	{
	PNRMUTEX mutex = (PNRMUTEX)malloc(sizeof(NRMUTEX)) ;
	if (mutex && !InitializeNonRecursiveMutex(mutex))
	{
	free(mutex) ;
	mutex = NULL ;
	}
	return mutex ;
	}

	void FreeNonRecursiveMutex(PNRMUTEX mutex)
	{
	if (mutex)
	{
	DeleteNonRecursiveMutex(mutex) ;
	free(mutex) ;
	}
	}

	long PyThread_get_thread_ident(void);

	/*
	* Change all headers to pure ANSI as no one will use K&R style on an
	* NT
	*/

	/*
	* Initialization of the C package, should not be needed.
	*/
	static void PyThread__init_thread(void)
	{
	threads = PyDict_New();
	}

	/*
	* Thread support.
	*/

	typedef struct {
	void (func)(void);
	void *arg;
	long id;
	HANDLE done;
	} callobj;

	static int
	bootstrap(void *call)
	{
	callobj obj = (callobj)call;
	/* copy callobj since other thread might free it before we're done */
	void (func)(void) = obj->func;
	void *arg = obj->arg;

	obj->id = PyThread_get_thread_ident();
	ReleaseSemaphore(obj->done, 1, NULL);
	func(arg);
	return 0;
	}

	long PyThread_start_new_thread(void (func)(void ), void *arg)
	{
	unsigned long rv;
	int success = 0;
	callobj *obj;
	int id;
	PyObject key, val;

	dprintf(("%ld: PyThread_start_new_thread called\n", PyThread_get_thread_ident()));
	if (!initialized)
	PyThread_init_thread();

	obj = malloc(sizeof(callobj));
	obj->func = func;
	obj->arg = arg;
	obj->done = CreateSemaphore(NULL, 0, 1, NULL);

	rv = _beginthread(func, 0, obj); /* use default stack size */

	if (rv != (unsigned long)-1) {
	success = 1;
	dprintf(("%ld: PyThread_start_new_thread succeeded: %p\n", PyThread_get_thread_ident(), rv));
	}

	/* wait for thread to initialize and retrieve id */
	WaitForSingleObject(obj->done, 5000); /* maybe INFINITE instead of 5000? */
	CloseHandle((HANDLE)obj->done);
	key = PyLong_FromLong(obj->id);
	val = PyLong_FromLong((long)rv);
	PyDict_SetItem(threads, key, val);
	id = obj->id;
	free(obj);
	return id;
	}

	/*
	* Return the thread Id instead of an handle. The Id is said to uniquely identify the
	* thread in the system
	*/
	long PyThread_get_thread_ident(void)
	{
	if (!initialized)
	PyThread_init_thread();

	return GetCurrentThreadId();
	}

	static void do_PyThread_exit_thread(int no_cleanup)
	{
	dprintf(("%ld: PyThread_exit_thread called\n", PyThread_get_thread_ident()));
	if (!initialized)
	if (no_cleanup)
	_exit(0);
	else
	exit(0);
	_endthread();
	}

	void PyThread_exit_thread(void)
	{
	do_PyThread_exit_thread(0);
	}

	void PyThread__exit_thread(void)
	{
	do_PyThread_exit_thread(1);
	}

	#ifndef NO_EXIT_PROG
	static void do_PyThread_exit_prog(int status, int no_cleanup)
	{
	dprintf(("PyThread_exit_prog(%d) called\n", status));
	if (!initialized)
	if (no_cleanup)
	_exit(status);
	else
	exit(status);
	}

	void PyThread_exit_prog(int status)
	{
	do_PyThread_exit_prog(status, 0);
	}

	void PyThread__exit_prog(int status)
	{
	do_PyThread_exit_prog(status, 1);
	}
	#endif /* NO_EXIT_PROG */

	/*
	* Lock support. It has too be implemented as semaphores.
	* I [Dag] tried to implement it with mutex but I could find a way to
	* tell whether a thread already own the lock or not.
	*/
	PyThread_type_lock PyThread_allocate_lock(void)
	{
	PNRMUTEX aLock;

	dprintf(("PyThread_allocate_lock called\n"));
	if (!initialized)
	PyThread_init_thread();

	aLock = AllocNonRecursiveMutex() ;

	dprintf(("%ld: PyThread_allocate_lock() -> %p\n", PyThread_get_thread_ident(), aLock));

	return (PyThread_type_lock) aLock;
	}

	void PyThread_free_lock(PyThread_type_lock aLock)
	{
	dprintf(("%ld: PyThread_free_lock(%p) called\n", PyThread_get_thread_ident(),aLock));

	FreeNonRecursiveMutex(aLock) ;
	}

	/*
	* Return 1 on success if the lock was acquired
	*
	* and 0 if the lock was not acquired. This means a 0 is returned
	* if the lock has already been acquired by this thread!
	*/
	int PyThread_acquire_lock(PyThread_type_lock aLock, int waitflag)
	{
	int success ;

	dprintf(("%ld: PyThread_acquire_lock(%p, %d) called\n", PyThread_get_thread_ident(),aLock, waitflag));

	success = aLock && EnterNonRecursiveMutex((PNRMUTEX) aLock, (waitflag == 1 ? INFINITE : 0)) == WAIT_OBJECT_0 ;

	dprintf(("%ld: PyThread_acquire_lock(%p, %d) -> %d\n", PyThread_get_thread_ident(),aLock, waitflag, success));

	return success;
	}

	void PyThread_release_lock(PyThread_type_lock aLock)
	{
	dprintf(("%ld: PyThread_release_lock(%p) called\n", PyThread_get_thread_ident(),aLock));

	if (!(aLock && LeaveNonRecursiveMutex((PNRMUTEX) aLock)))
	dprintf(("%ld: Could not PyThread_release_lock(%p) error: %l\n", PyThread_get_thread_ident(), aLock, GetLastError()));
	}

	/*
	* Semaphore support.
	*/
	PyThread_type_sema PyThread_allocate_sema(int value)
	{
	HANDLE aSemaphore;

	dprintf(("%ld: PyThread_allocate_sema called\n", PyThread_get_thread_ident()));
	if (!initialized)
	PyThread_init_thread();

	aSemaphore = CreateSemaphore( NULL, /* Security attributes */
	value, /* Initial value */
	INT_MAX, /* Maximum value */
	NULL); /* Name of semaphore */

	dprintf(("%ld: PyThread_allocate_sema() -> %p\n", PyThread_get_thread_ident(), aSemaphore));

	return (PyThread_type_sema) aSemaphore;
	}

	void PyThread_free_sema(PyThread_type_sema aSemaphore)
	{
	dprintf(("%ld: PyThread_free_sema(%p) called\n", PyThread_get_thread_ident(), aSemaphore));

	CloseHandle((HANDLE) aSemaphore);
	}

	/*
	XXX must do something about waitflag
	*/
	int PyThread_down_sema(PyThread_type_sema aSemaphore, int waitflag)
	{
	DWORD waitResult;

	dprintf(("%ld: PyThread_down_sema(%p) called\n", PyThread_get_thread_ident(), aSemaphore));

	waitResult = WaitForSingleObject( (HANDLE) aSemaphore, INFINITE);

	dprintf(("%ld: PyThread_down_sema(%p) return: %l\n", PyThread_get_thread_ident(), aSemaphore, waitResult));
	return 0;
	}

	void PyThread_up_sema(PyThread_type_sema aSemaphore)
	{
	ReleaseSemaphore(
	(HANDLE) aSemaphore, /* Handle of semaphore */
	1, /* increment count by one */
	NULL); /* not interested in previous count */

	dprintf(("%ld: PyThread_up_sema(%p)\n", PyThread_get_thread_ident(), aSemaphore));
	}