626 lines
14 KiB
C
626 lines
14 KiB
C
/*
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* A type which wraps a semaphore
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*
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* semaphore.c
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*
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* Copyright (c) 2006-2008, R Oudkerk --- see COPYING.txt
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*/
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#include "multiprocessing.h"
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enum { RECURSIVE_MUTEX, SEMAPHORE };
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typedef struct {
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PyObject_HEAD
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SEM_HANDLE handle;
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long last_tid;
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int count;
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int maxvalue;
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int kind;
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} SemLockObject;
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#define ISMINE(o) (o->count > 0 && PyThread_get_thread_ident() == o->last_tid)
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#ifdef MS_WINDOWS
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/*
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* Windows definitions
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*/
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#define SEM_FAILED NULL
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#define SEM_CLEAR_ERROR() SetLastError(0)
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#define SEM_GET_LAST_ERROR() GetLastError()
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#define SEM_CREATE(name, val, max) CreateSemaphore(NULL, val, max, NULL)
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#define SEM_CLOSE(sem) (CloseHandle(sem) ? 0 : -1)
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#define SEM_GETVALUE(sem, pval) _GetSemaphoreValue(sem, pval)
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#define SEM_UNLINK(name) 0
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static int
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_GetSemaphoreValue(HANDLE handle, long *value)
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{
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long previous;
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switch (WaitForSingleObject(handle, 0)) {
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case WAIT_OBJECT_0:
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if (!ReleaseSemaphore(handle, 1, &previous))
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return MP_STANDARD_ERROR;
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*value = previous + 1;
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return 0;
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case WAIT_TIMEOUT:
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*value = 0;
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return 0;
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default:
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return MP_STANDARD_ERROR;
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}
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}
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static PyObject *
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semlock_acquire(SemLockObject *self, PyObject *args, PyObject *kwds)
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{
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int blocking = 1;
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double timeout;
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PyObject *timeout_obj = Py_None;
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DWORD res, full_msecs, msecs, start, ticks;
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static char *kwlist[] = {"block", "timeout", NULL};
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if (!PyArg_ParseTupleAndKeywords(args, kwds, "|iO", kwlist,
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&blocking, &timeout_obj))
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return NULL;
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/* calculate timeout */
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if (!blocking) {
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full_msecs = 0;
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} else if (timeout_obj == Py_None) {
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full_msecs = INFINITE;
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} else {
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timeout = PyFloat_AsDouble(timeout_obj);
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if (PyErr_Occurred())
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return NULL;
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timeout *= 1000.0; /* convert to millisecs */
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if (timeout < 0.0) {
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timeout = 0.0;
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} else if (timeout >= 0.5 * INFINITE) { /* 25 days */
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PyErr_SetString(PyExc_OverflowError,
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"timeout is too large");
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return NULL;
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}
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full_msecs = (DWORD)(timeout + 0.5);
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}
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/* check whether we already own the lock */
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if (self->kind == RECURSIVE_MUTEX && ISMINE(self)) {
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++self->count;
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Py_RETURN_TRUE;
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}
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/* check whether we can acquire without blocking */
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if (WaitForSingleObject(self->handle, 0) == WAIT_OBJECT_0) {
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self->last_tid = GetCurrentThreadId();
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++self->count;
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Py_RETURN_TRUE;
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}
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msecs = full_msecs;
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start = GetTickCount();
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for ( ; ; ) {
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HANDLE handles[2] = {self->handle, sigint_event};
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/* do the wait */
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Py_BEGIN_ALLOW_THREADS
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ResetEvent(sigint_event);
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res = WaitForMultipleObjects(2, handles, FALSE, msecs);
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Py_END_ALLOW_THREADS
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/* handle result */
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if (res != WAIT_OBJECT_0 + 1)
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break;
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/* got SIGINT so give signal handler a chance to run */
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Sleep(1);
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/* if this is main thread let KeyboardInterrupt be raised */
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if (PyErr_CheckSignals())
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return NULL;
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/* recalculate timeout */
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if (msecs != INFINITE) {
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ticks = GetTickCount();
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if ((DWORD)(ticks - start) >= full_msecs)
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Py_RETURN_FALSE;
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msecs = full_msecs - (ticks - start);
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}
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}
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/* handle result */
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switch (res) {
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case WAIT_TIMEOUT:
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Py_RETURN_FALSE;
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case WAIT_OBJECT_0:
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self->last_tid = GetCurrentThreadId();
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++self->count;
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Py_RETURN_TRUE;
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case WAIT_FAILED:
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return PyErr_SetFromWindowsErr(0);
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default:
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PyErr_Format(PyExc_RuntimeError, "WaitForSingleObject() or "
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"WaitForMultipleObjects() gave unrecognized "
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"value %d", res);
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return NULL;
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}
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}
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static PyObject *
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semlock_release(SemLockObject *self, PyObject *args)
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{
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if (self->kind == RECURSIVE_MUTEX) {
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if (!ISMINE(self)) {
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PyErr_SetString(PyExc_AssertionError, "attempt to "
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"release recursive lock not owned "
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"by thread");
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return NULL;
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}
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if (self->count > 1) {
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--self->count;
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Py_RETURN_NONE;
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}
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assert(self->count == 1);
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}
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if (!ReleaseSemaphore(self->handle, 1, NULL)) {
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if (GetLastError() == ERROR_TOO_MANY_POSTS) {
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PyErr_SetString(PyExc_ValueError, "semaphore or lock "
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"released too many times");
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return NULL;
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} else {
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return PyErr_SetFromWindowsErr(0);
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}
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}
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--self->count;
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Py_RETURN_NONE;
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}
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#else /* !MS_WINDOWS */
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/*
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* Unix definitions
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*/
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#define SEM_CLEAR_ERROR()
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#define SEM_GET_LAST_ERROR() 0
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#define SEM_CREATE(name, val, max) sem_open(name, O_CREAT | O_EXCL, 0600, val)
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#define SEM_CLOSE(sem) sem_close(sem)
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#define SEM_GETVALUE(sem, pval) sem_getvalue(sem, pval)
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#define SEM_UNLINK(name) sem_unlink(name)
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#ifndef HAVE_SEM_UNLINK
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# define sem_unlink(name) 0
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#endif
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#ifndef HAVE_SEM_TIMEDWAIT
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# define sem_timedwait(sem,deadline) sem_timedwait_save(sem,deadline,_save)
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int
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sem_timedwait_save(sem_t *sem, struct timespec *deadline, PyThreadState *_save)
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{
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int res;
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unsigned long delay, difference;
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struct timeval now, tvdeadline, tvdelay;
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errno = 0;
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tvdeadline.tv_sec = deadline->tv_sec;
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tvdeadline.tv_usec = deadline->tv_nsec / 1000;
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for (delay = 0 ; ; delay += 1000) {
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/* poll */
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if (sem_trywait(sem) == 0)
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return 0;
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else if (errno != EAGAIN)
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return MP_STANDARD_ERROR;
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/* get current time */
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if (gettimeofday(&now, NULL) < 0)
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return MP_STANDARD_ERROR;
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/* check for timeout */
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if (tvdeadline.tv_sec < now.tv_sec ||
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(tvdeadline.tv_sec == now.tv_sec &&
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tvdeadline.tv_usec <= now.tv_usec)) {
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errno = ETIMEDOUT;
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return MP_STANDARD_ERROR;
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}
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/* calculate how much time is left */
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difference = (tvdeadline.tv_sec - now.tv_sec) * 1000000 +
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(tvdeadline.tv_usec - now.tv_usec);
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/* check delay not too long -- maximum is 20 msecs */
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if (delay > 20000)
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delay = 20000;
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if (delay > difference)
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delay = difference;
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/* sleep */
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tvdelay.tv_sec = delay / 1000000;
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tvdelay.tv_usec = delay % 1000000;
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if (select(0, NULL, NULL, NULL, &tvdelay) < 0)
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return MP_STANDARD_ERROR;
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/* check for signals */
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Py_BLOCK_THREADS
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res = PyErr_CheckSignals();
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Py_UNBLOCK_THREADS
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if (res) {
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errno = EINTR;
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return MP_EXCEPTION_HAS_BEEN_SET;
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}
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}
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}
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#endif /* !HAVE_SEM_TIMEDWAIT */
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static PyObject *
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semlock_acquire(SemLockObject *self, PyObject *args, PyObject *kwds)
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{
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int blocking = 1, res;
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double timeout;
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PyObject *timeout_obj = Py_None;
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struct timespec deadline = {0};
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struct timeval now;
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long sec, nsec;
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static char *kwlist[] = {"block", "timeout", NULL};
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if (!PyArg_ParseTupleAndKeywords(args, kwds, "|iO", kwlist,
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&blocking, &timeout_obj))
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return NULL;
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if (self->kind == RECURSIVE_MUTEX && ISMINE(self)) {
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++self->count;
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Py_RETURN_TRUE;
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}
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if (timeout_obj != Py_None) {
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timeout = PyFloat_AsDouble(timeout_obj);
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if (PyErr_Occurred())
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return NULL;
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if (timeout < 0.0)
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timeout = 0.0;
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if (gettimeofday(&now, NULL) < 0) {
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PyErr_SetFromErrno(PyExc_OSError);
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return NULL;
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}
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sec = (long) timeout;
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nsec = (long) (1e9 * (timeout - sec) + 0.5);
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deadline.tv_sec = now.tv_sec + sec;
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deadline.tv_nsec = now.tv_usec * 1000 + nsec;
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deadline.tv_sec += (deadline.tv_nsec / 1000000000);
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deadline.tv_nsec %= 1000000000;
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}
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do {
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Py_BEGIN_ALLOW_THREADS
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if (blocking && timeout_obj == Py_None)
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res = sem_wait(self->handle);
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else if (!blocking)
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res = sem_trywait(self->handle);
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else
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res = sem_timedwait(self->handle, &deadline);
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Py_END_ALLOW_THREADS
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if (res == MP_EXCEPTION_HAS_BEEN_SET)
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break;
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} while (res < 0 && errno == EINTR && !PyErr_CheckSignals());
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if (res < 0) {
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if (errno == EAGAIN || errno == ETIMEDOUT)
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Py_RETURN_FALSE;
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else if (errno == EINTR)
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return NULL;
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else
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return PyErr_SetFromErrno(PyExc_OSError);
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}
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++self->count;
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self->last_tid = PyThread_get_thread_ident();
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Py_RETURN_TRUE;
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}
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static PyObject *
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semlock_release(SemLockObject *self, PyObject *args)
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{
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if (self->kind == RECURSIVE_MUTEX) {
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if (!ISMINE(self)) {
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PyErr_SetString(PyExc_AssertionError, "attempt to "
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"release recursive lock not owned "
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"by thread");
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return NULL;
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}
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if (self->count > 1) {
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--self->count;
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Py_RETURN_NONE;
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}
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assert(self->count == 1);
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} else {
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#ifdef HAVE_BROKEN_SEM_GETVALUE
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/* We will only check properly the maxvalue == 1 case */
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if (self->maxvalue == 1) {
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/* make sure that already locked */
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if (sem_trywait(self->handle) < 0) {
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if (errno != EAGAIN) {
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PyErr_SetFromErrno(PyExc_OSError);
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return NULL;
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}
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/* it is already locked as expected */
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} else {
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/* it was not locked so undo wait and raise */
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if (sem_post(self->handle) < 0) {
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PyErr_SetFromErrno(PyExc_OSError);
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return NULL;
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}
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PyErr_SetString(PyExc_ValueError, "semaphore "
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"or lock released too many "
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"times");
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return NULL;
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}
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}
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#else
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int sval;
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/* This check is not an absolute guarantee that the semaphore
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does not rise above maxvalue. */
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if (sem_getvalue(self->handle, &sval) < 0) {
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return PyErr_SetFromErrno(PyExc_OSError);
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} else if (sval >= self->maxvalue) {
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PyErr_SetString(PyExc_ValueError, "semaphore or lock "
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"released too many times");
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return NULL;
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}
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#endif
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}
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if (sem_post(self->handle) < 0)
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return PyErr_SetFromErrno(PyExc_OSError);
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--self->count;
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Py_RETURN_NONE;
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}
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#endif /* !MS_WINDOWS */
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/*
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* All platforms
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*/
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static PyObject *
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newsemlockobject(PyTypeObject *type, SEM_HANDLE handle, int kind, int maxvalue)
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{
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SemLockObject *self;
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self = PyObject_New(SemLockObject, type);
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if (!self)
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return NULL;
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self->handle = handle;
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self->kind = kind;
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self->count = 0;
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self->last_tid = 0;
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self->maxvalue = maxvalue;
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return (PyObject*)self;
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}
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static PyObject *
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semlock_new(PyTypeObject *type, PyObject *args, PyObject *kwds)
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{
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char buffer[256];
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SEM_HANDLE handle = SEM_FAILED;
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int kind, maxvalue, value;
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PyObject *result;
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static char *kwlist[] = {"kind", "value", "maxvalue", NULL};
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static int counter = 0;
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if (!PyArg_ParseTupleAndKeywords(args, kwds, "iii", kwlist,
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&kind, &value, &maxvalue))
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return NULL;
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if (kind != RECURSIVE_MUTEX && kind != SEMAPHORE) {
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PyErr_SetString(PyExc_ValueError, "unrecognized kind");
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return NULL;
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}
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PyOS_snprintf(buffer, sizeof(buffer), "/mp%d-%d", getpid(), counter++);
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SEM_CLEAR_ERROR();
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handle = SEM_CREATE(buffer, value, maxvalue);
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/* On Windows we should fail if GetLastError()==ERROR_ALREADY_EXISTS */
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if (handle == SEM_FAILED || SEM_GET_LAST_ERROR() != 0)
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goto failure;
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if (SEM_UNLINK(buffer) < 0)
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goto failure;
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result = newsemlockobject(type, handle, kind, maxvalue);
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if (!result)
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goto failure;
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return result;
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failure:
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if (handle != SEM_FAILED)
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SEM_CLOSE(handle);
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mp_SetError(NULL, MP_STANDARD_ERROR);
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return NULL;
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}
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static PyObject *
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semlock_rebuild(PyTypeObject *type, PyObject *args)
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{
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SEM_HANDLE handle;
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int kind, maxvalue;
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if (!PyArg_ParseTuple(args, F_SEM_HANDLE "ii",
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&handle, &kind, &maxvalue))
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return NULL;
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return newsemlockobject(type, handle, kind, maxvalue);
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}
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static void
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semlock_dealloc(SemLockObject* self)
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{
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if (self->handle != SEM_FAILED)
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SEM_CLOSE(self->handle);
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PyObject_Del(self);
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}
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static PyObject *
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semlock_count(SemLockObject *self)
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{
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return PyInt_FromLong((long)self->count);
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}
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static PyObject *
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semlock_ismine(SemLockObject *self)
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{
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/* only makes sense for a lock */
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return PyBool_FromLong(ISMINE(self));
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}
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static PyObject *
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semlock_getvalue(SemLockObject *self)
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{
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#ifdef HAVE_BROKEN_SEM_GETVALUE
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PyErr_SetNone(PyExc_NotImplementedError);
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return NULL;
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#else
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int sval;
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if (SEM_GETVALUE(self->handle, &sval) < 0)
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return mp_SetError(NULL, MP_STANDARD_ERROR);
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/* some posix implementations use negative numbers to indicate
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the number of waiting threads */
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if (sval < 0)
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sval = 0;
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return PyInt_FromLong((long)sval);
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#endif
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}
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static PyObject *
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semlock_iszero(SemLockObject *self)
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{
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#ifdef HAVE_BROKEN_SEM_GETVALUE
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if (sem_trywait(self->handle) < 0) {
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if (errno == EAGAIN)
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Py_RETURN_TRUE;
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return mp_SetError(NULL, MP_STANDARD_ERROR);
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} else {
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if (sem_post(self->handle) < 0)
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return mp_SetError(NULL, MP_STANDARD_ERROR);
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Py_RETURN_FALSE;
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}
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#else
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int sval;
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if (SEM_GETVALUE(self->handle, &sval) < 0)
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return mp_SetError(NULL, MP_STANDARD_ERROR);
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return PyBool_FromLong((long)sval == 0);
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#endif
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}
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static PyObject *
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semlock_afterfork(SemLockObject *self)
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{
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self->count = 0;
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Py_RETURN_NONE;
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}
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/*
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* Semaphore methods
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*/
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static PyMethodDef semlock_methods[] = {
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{"acquire", (PyCFunction)semlock_acquire, METH_VARARGS | METH_KEYWORDS,
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"acquire the semaphore/lock"},
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{"release", (PyCFunction)semlock_release, METH_NOARGS,
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"release the semaphore/lock"},
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{"__enter__", (PyCFunction)semlock_acquire, METH_VARARGS | METH_KEYWORDS,
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"enter the semaphore/lock"},
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{"__exit__", (PyCFunction)semlock_release, METH_VARARGS,
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"exit the semaphore/lock"},
|
|
{"_count", (PyCFunction)semlock_count, METH_NOARGS,
|
|
"num of `acquire()`s minus num of `release()`s for this process"},
|
|
{"_is_mine", (PyCFunction)semlock_ismine, METH_NOARGS,
|
|
"whether the lock is owned by this thread"},
|
|
{"_get_value", (PyCFunction)semlock_getvalue, METH_NOARGS,
|
|
"get the value of the semaphore"},
|
|
{"_is_zero", (PyCFunction)semlock_iszero, METH_NOARGS,
|
|
"returns whether semaphore has value zero"},
|
|
{"_rebuild", (PyCFunction)semlock_rebuild, METH_VARARGS | METH_CLASS,
|
|
""},
|
|
{"_after_fork", (PyCFunction)semlock_afterfork, METH_NOARGS,
|
|
"rezero the net acquisition count after fork()"},
|
|
{NULL}
|
|
};
|
|
|
|
/*
|
|
* Member table
|
|
*/
|
|
|
|
static PyMemberDef semlock_members[] = {
|
|
{"handle", T_SEM_HANDLE, offsetof(SemLockObject, handle), READONLY,
|
|
""},
|
|
{"kind", T_INT, offsetof(SemLockObject, kind), READONLY,
|
|
""},
|
|
{"maxvalue", T_INT, offsetof(SemLockObject, maxvalue), READONLY,
|
|
""},
|
|
{NULL}
|
|
};
|
|
|
|
/*
|
|
* Semaphore type
|
|
*/
|
|
|
|
PyTypeObject SemLockType = {
|
|
PyVarObject_HEAD_INIT(NULL, 0)
|
|
/* tp_name */ "_multiprocessing.SemLock",
|
|
/* tp_basicsize */ sizeof(SemLockObject),
|
|
/* tp_itemsize */ 0,
|
|
/* tp_dealloc */ (destructor)semlock_dealloc,
|
|
/* tp_print */ 0,
|
|
/* tp_getattr */ 0,
|
|
/* tp_setattr */ 0,
|
|
/* tp_compare */ 0,
|
|
/* tp_repr */ 0,
|
|
/* tp_as_number */ 0,
|
|
/* tp_as_sequence */ 0,
|
|
/* tp_as_mapping */ 0,
|
|
/* tp_hash */ 0,
|
|
/* tp_call */ 0,
|
|
/* tp_str */ 0,
|
|
/* tp_getattro */ 0,
|
|
/* tp_setattro */ 0,
|
|
/* tp_as_buffer */ 0,
|
|
/* tp_flags */ Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE,
|
|
/* tp_doc */ "Semaphore/Mutex type",
|
|
/* tp_traverse */ 0,
|
|
/* tp_clear */ 0,
|
|
/* tp_richcompare */ 0,
|
|
/* tp_weaklistoffset */ 0,
|
|
/* tp_iter */ 0,
|
|
/* tp_iternext */ 0,
|
|
/* tp_methods */ semlock_methods,
|
|
/* tp_members */ semlock_members,
|
|
/* tp_getset */ 0,
|
|
/* tp_base */ 0,
|
|
/* tp_dict */ 0,
|
|
/* tp_descr_get */ 0,
|
|
/* tp_descr_set */ 0,
|
|
/* tp_dictoffset */ 0,
|
|
/* tp_init */ 0,
|
|
/* tp_alloc */ 0,
|
|
/* tp_new */ semlock_new,
|
|
};
|