ref: a7f5ecaf636e38f407c951d0e86dcc4c4f424bd6
dir: /sys/src/cmd/python/Python/thread_nt.h/
/* This code implemented by Dag.Gruneau@elsa.preseco.comm.se */
/* Fast NonRecursiveMutex support by Yakov Markovitch, markovitch@iso.ru */
/* Eliminated some memory leaks, gsw@agere.com */
#include <windows.h>
#include <limits.h>
#ifdef HAVE_PROCESS_H
#include <process.h>
#endif
typedef struct NRMUTEX {
LONG owned ;
DWORD thread_id ;
HANDLE hevent ;
} NRMUTEX, *PNRMUTEX ;
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);
/*
* Initialization of the C package, should not be needed.
*/
static void
PyThread__init_thread(void)
{
}
/*
* 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)
{
Py_uintptr_t rv;
callobj obj;
dprintf(("%ld: PyThread_start_new_thread called\n",
PyThread_get_thread_ident()));
if (!initialized)
PyThread_init_thread();
obj.id = -1; /* guilty until proved innocent */
obj.func = func;
obj.arg = arg;
obj.done = CreateSemaphore(NULL, 0, 1, NULL);
if (obj.done == NULL)
return -1;
rv = _beginthread(bootstrap, _pythread_stacksize, &obj);
if (rv == (Py_uintptr_t)-1) {
/* I've seen errno == EAGAIN here, which means "there are
* too many threads".
*/
dprintf(("%ld: PyThread_start_new_thread failed: %p errno %d\n",
PyThread_get_thread_ident(), rv, errno));
obj.id = -1;
}
else {
dprintf(("%ld: PyThread_start_new_thread succeeded: %p\n",
PyThread_get_thread_ident(), rv));
/* wait for thread to initialize, so we can get its id */
WaitForSingleObject(obj.done, INFINITE);
assert(obj.id != -1);
}
CloseHandle((HANDLE)obj.done);
return obj.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 ? 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()));
}
/* minimum/maximum thread stack sizes supported */
#define THREAD_MIN_STACKSIZE 0x8000 /* 32kB */
#define THREAD_MAX_STACKSIZE 0x10000000 /* 256MB */
/* set the thread stack size.
* Return 0 if size is valid, -1 otherwise.
*/
static int
_pythread_nt_set_stacksize(size_t size)
{
/* set to default */
if (size == 0) {
_pythread_stacksize = 0;
return 0;
}
/* valid range? */
if (size >= THREAD_MIN_STACKSIZE && size < THREAD_MAX_STACKSIZE) {
_pythread_stacksize = size;
return 0;
}
return -1;
}
#define THREAD_SET_STACKSIZE(x) _pythread_nt_set_stacksize(x)