cpython/Python/thread_nt.h at 3.3 · python/cpython · GitHub

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/* 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

/* options */

#ifndef _PY_USE_CV_LOCKS

#define _PY_USE_CV_LOCKS 1 /* use locks based on cond vars */

#endif

/* Now, define a non-recursive mutex using either condition variables

* and critical sections (fast) or using operating system mutexes

* (slow)

#if _PY_USE_CV_LOCKS

#include "condvar.h"

typedef struct _NRMUTEX

{

PyMUTEX_T cs;

PyCOND_T cv;

int locked;

} NRMUTEX;

typedef NRMUTEX *PNRMUTEX;

PNRMUTEX

AllocNonRecursiveMutex()

{

PNRMUTEX m = (PNRMUTEX)malloc(sizeof(NRMUTEX));

if (!m)

return NULL;

if (PyCOND_INIT(&m->cv))

goto fail;

if (PyMUTEX_INIT(&m->cs)) {

PyCOND_FINI(&m->cv);

goto fail;

}

m->locked = 0;

return m;

fail:

free(m);

return NULL;

}

VOID

FreeNonRecursiveMutex(PNRMUTEX mutex)

{

if (mutex) {

PyCOND_FINI(&mutex->cv);

PyMUTEX_FINI(&mutex->cs);

free(mutex);

}

DWORD

EnterNonRecursiveMutex(PNRMUTEX mutex, DWORD milliseconds)

{

DWORD result = WAIT_OBJECT_0;

if (PyMUTEX_LOCK(&mutex->cs))

return WAIT_FAILED;

if (milliseconds == INFINITE) {

while (mutex->locked) {

if (PyCOND_WAIT(&mutex->cv, &mutex->cs)) {

result = WAIT_FAILED;

break;

}

} else if (milliseconds != 0) {

/* wait at least until the target */

DWORD now, target = GetTickCount() + milliseconds;

while (mutex->locked) {

if (PyCOND_TIMEDWAIT(&mutex->cv, &mutex->cs, (PY_LONG_LONG)milliseconds*1000) < 0) {

result = WAIT_FAILED;

break;

}

now = GetTickCount();

if (target <= now)

break;

milliseconds = target-now;

}

if (!mutex->locked) {

mutex->locked = 1;

result = WAIT_OBJECT_0;

} else if (result == WAIT_OBJECT_0)

result = WAIT_TIMEOUT;

/* else, it is WAIT_FAILED */

PyMUTEX_UNLOCK(&mutex->cs); /* must ignore result here */

return result;

}

BOOL

LeaveNonRecursiveMutex(PNRMUTEX mutex)

{

BOOL result;

if (PyMUTEX_LOCK(&mutex->cs))

return FALSE;

mutex->locked = 0;

result = PyCOND_SIGNAL(&mutex->cv);

result &= PyMUTEX_UNLOCK(&mutex->cs);

return result;

}

#else /* if ! _PY_USE_CV_LOCKS */

/* NR-locks based on a kernel mutex */

#define PNRMUTEX HANDLE

PNRMUTEX

AllocNonRecursiveMutex()

{

return CreateSemaphore(NULL, 1, 1, NULL);

}

VOID

FreeNonRecursiveMutex(PNRMUTEX mutex)

{

/* No in-use check */

CloseHandle(mutex);

}

DWORD

EnterNonRecursiveMutex(PNRMUTEX mutex, DWORD milliseconds)

{

return WaitForSingleObject(mutex, milliseconds);

}

BOOL

LeaveNonRecursiveMutex(PNRMUTEX mutex)

{

return ReleaseSemaphore(mutex, 1, NULL);

}

#endif /* _PY_USE_CV_LOCKS */

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;

} callobj;

/* thunker to call adapt between the function type used by the system's

thread start function and the internally used one. */

#if defined(MS_WINCE)

static DWORD WINAPI

#else

static unsigned __stdcall

#endif

bootstrap(void *call)

{

callobj *obj = (callobj*)call;

void (*func)(void*) = obj->func;

void *arg = obj->arg;

HeapFree(GetProcessHeap(), 0, obj);

func(arg);

return 0;

}

long

PyThread_start_new_thread(void (*func)(void *), void *arg)

{

HANDLE hThread;

unsigned threadID;

callobj *obj;

dprintf(("%ld: PyThread_start_new_thread called\n",

PyThread_get_thread_ident()));

if (!initialized)

PyThread_init_thread();

obj = (callobj*)HeapAlloc(GetProcessHeap(), 0, sizeof(*obj));

if (!obj)

return -1;

obj->func = func;

obj->arg = arg;

#if defined(MS_WINCE)

hThread = CreateThread(NULL,

Py_SAFE_DOWNCAST(_pythread_stacksize, Py_ssize_t, SIZE_T),

bootstrap, obj, 0, &threadID);

#else

hThread = (HANDLE)_beginthreadex(0,

Py_SAFE_DOWNCAST(_pythread_stacksize,

Py_ssize_t, unsigned int),

bootstrap, obj,

0, &threadID);

#endif

if (hThread == 0) {

#if defined(MS_WINCE)

/* Save error in variable, to prevent PyThread_get_thread_ident

from clobbering it. */

unsigned e = GetLastError();

dprintf(("%ld: PyThread_start_new_thread failed, win32 error code %u\n",

PyThread_get_thread_ident(), e));

#else

/* I've seen errno == EAGAIN here, which means "there are

* too many threads".

int e = errno;

dprintf(("%ld: PyThread_start_new_thread failed, errno %d\n",

PyThread_get_thread_ident(), e));

#endif

threadID = (unsigned)-1;

HeapFree(GetProcessHeap(), 0, obj);

}

else {

dprintf(("%ld: PyThread_start_new_thread succeeded: %p\n",

PyThread_get_thread_ident(), (void*)hThread));

CloseHandle(hThread);

}

return (long) threadID;

}

* 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();

}

void

PyThread_exit_thread(void)

{

dprintf(("%ld: PyThread_exit_thread called\n", PyThread_get_thread_ident()));

if (!initialized)

exit(0);

#if defined(MS_WINCE)

ExitThread(0);

#else

_endthreadex(0);

#endif

}

* 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!

PyLockStatus

PyThread_acquire_lock_timed(PyThread_type_lock aLock,

PY_TIMEOUT_T microseconds, int intr_flag)

{

/* Fow now, intr_flag does nothing on Windows, and lock acquires are

* uninterruptible. */

PyLockStatus success;

PY_TIMEOUT_T milliseconds;

if (microseconds >= 0) {

milliseconds = microseconds / 1000;

if (microseconds % 1000 > 0)

++milliseconds;

if ((DWORD) milliseconds != milliseconds)

Py_FatalError("Timeout too large for a DWORD, "

"please check PY_TIMEOUT_MAX");

}

else

milliseconds = INFINITE;

dprintf(("%ld: PyThread_acquire_lock_timed(%p, %lld) called\n",

PyThread_get_thread_ident(), aLock, microseconds));

if (aLock && EnterNonRecursiveMutex((PNRMUTEX)aLock,

(DWORD)milliseconds) == WAIT_OBJECT_0) {

success = PY_LOCK_ACQUIRED;

}

else {

success = PY_LOCK_FAILURE;

}

dprintf(("%ld: PyThread_acquire_lock(%p, %lld) -> %d\n",

PyThread_get_thread_ident(), aLock, microseconds, success));

return success;

}

int

PyThread_acquire_lock(PyThread_type_lock aLock, int waitflag)

{

return PyThread_acquire_lock_timed(aLock, waitflag ? -1 : 0, 0);

}

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: %ld\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)

/* use native Windows TLS functions */

#define Py_HAVE_NATIVE_TLS

#ifdef Py_HAVE_NATIVE_TLS

int

PyThread_create_key(void)

{

DWORD result= TlsAlloc();

if (result == TLS_OUT_OF_INDEXES)

return -1;

return (int)result;

}

void

PyThread_delete_key(int key)

{

TlsFree(key);

}

/* We must be careful to emulate the strange semantics implemented in thread.c,

* where the value is only set if it hasn't been set before.

int

PyThread_set_key_value(int key, void *value)

{

BOOL ok;

void *oldvalue;

assert(value != NULL);

oldvalue = TlsGetValue(key);

if (oldvalue != NULL)

/* ignore value if already set */

return 0;

ok = TlsSetValue(key, value);

if (!ok)

return -1;

return 0;

}

void *

PyThread_get_key_value(int key)

{

/* because TLS is used in the Py_END_ALLOW_THREAD macro,

* it is necessary to preserve the windows error state, because

* it is assumed to be preserved across the call to the macro.

* Ideally, the macro should be fixed, but it is simpler to

* do it here.

DWORD error = GetLastError();

void *result = TlsGetValue(key);

SetLastError(error);

return result;

}

void

PyThread_delete_key_value(int key)

{

/* NULL is used as "key missing", and it is also the default

* given by TlsGetValue() if nothing has been set yet.

TlsSetValue(key, NULL);

}

/* reinitialization of TLS is not necessary after fork when using

* the native TLS functions. And forking isn't supported on Windows either.

void

PyThread_ReInitTLS(void)

{}

#endif

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