source: python/trunk/Python/thread_nt.h@ 281

/* 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 ;


BOOL
InitializeNonRecursiveMutex(PNRMUTEX mutex)
{
        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 */
}

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(&mutex->owned, 0, -1) != -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,
                          Py_SAFE_DOWNCAST(_pythread_stacksize,
                                           Py_ssize_t, int),
                          &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(), (void*)rv, errno));
                obj.id = -1;
        }
        else {
                dprintf(("%ld: PyThread_start_new_thread succeeded: %p\n",
                         PyThread_get_thread_ident(), (void*)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: %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)