| /* |
| * A type which wraps a semaphore |
| * |
| * semaphore.c |
| * |
| * Copyright (c) 2006-2008, R Oudkerk --- see COPYING.txt |
| */ |
| |
| #include "multiprocessing.h" |
| |
| enum { RECURSIVE_MUTEX, SEMAPHORE }; |
| |
| typedef struct { |
| PyObject_HEAD |
| SEM_HANDLE handle; |
| long last_tid; |
| int count; |
| int maxvalue; |
| int kind; |
| } SemLockObject; |
| |
| #define ISMINE(o) (o->count > 0 && PyThread_get_thread_ident() == o->last_tid) |
| |
| |
| #ifdef MS_WINDOWS |
| |
| /* |
| * Windows definitions |
| */ |
| |
| #define SEM_FAILED NULL |
| |
| #define SEM_CLEAR_ERROR() SetLastError(0) |
| #define SEM_GET_LAST_ERROR() GetLastError() |
| #define SEM_CREATE(name, val, max) CreateSemaphore(NULL, val, max, NULL) |
| #define SEM_CLOSE(sem) (CloseHandle(sem) ? 0 : -1) |
| #define SEM_GETVALUE(sem, pval) _GetSemaphoreValue(sem, pval) |
| #define SEM_UNLINK(name) 0 |
| |
| static int |
| _GetSemaphoreValue(HANDLE handle, long *value) |
| { |
| long previous; |
| |
| switch (WaitForSingleObject(handle, 0)) { |
| case WAIT_OBJECT_0: |
| if (!ReleaseSemaphore(handle, 1, &previous)) |
| return MP_STANDARD_ERROR; |
| *value = previous + 1; |
| return 0; |
| case WAIT_TIMEOUT: |
| *value = 0; |
| return 0; |
| default: |
| return MP_STANDARD_ERROR; |
| } |
| } |
| |
| static PyObject * |
| semlock_acquire(SemLockObject *self, PyObject *args, PyObject *kwds) |
| { |
| int blocking = 1; |
| double timeout; |
| PyObject *timeout_obj = Py_None; |
| DWORD res, full_msecs, msecs, start, ticks; |
| |
| static char *kwlist[] = {"block", "timeout", NULL}; |
| |
| if (!PyArg_ParseTupleAndKeywords(args, kwds, "|iO", kwlist, |
| &blocking, &timeout_obj)) |
| return NULL; |
| |
| /* calculate timeout */ |
| if (!blocking) { |
| full_msecs = 0; |
| } else if (timeout_obj == Py_None) { |
| full_msecs = INFINITE; |
| } else { |
| timeout = PyFloat_AsDouble(timeout_obj); |
| if (PyErr_Occurred()) |
| return NULL; |
| timeout *= 1000.0; /* convert to millisecs */ |
| if (timeout < 0.0) { |
| timeout = 0.0; |
| } else if (timeout >= 0.5 * INFINITE) { /* 25 days */ |
| PyErr_SetString(PyExc_OverflowError, |
| "timeout is too large"); |
| return NULL; |
| } |
| full_msecs = (DWORD)(timeout + 0.5); |
| } |
| |
| /* check whether we already own the lock */ |
| if (self->kind == RECURSIVE_MUTEX && ISMINE(self)) { |
| ++self->count; |
| Py_RETURN_TRUE; |
| } |
| |
| /* check whether we can acquire without blocking */ |
| if (WaitForSingleObject(self->handle, 0) == WAIT_OBJECT_0) { |
| self->last_tid = GetCurrentThreadId(); |
| ++self->count; |
| Py_RETURN_TRUE; |
| } |
| |
| msecs = full_msecs; |
| start = GetTickCount(); |
| |
| for ( ; ; ) { |
| HANDLE handles[2] = {self->handle, sigint_event}; |
| |
| /* do the wait */ |
| Py_BEGIN_ALLOW_THREADS |
| ResetEvent(sigint_event); |
| res = WaitForMultipleObjects(2, handles, FALSE, msecs); |
| Py_END_ALLOW_THREADS |
| |
| /* handle result */ |
| if (res != WAIT_OBJECT_0 + 1) |
| break; |
| |
| /* got SIGINT so give signal handler a chance to run */ |
| Sleep(1); |
| |
| /* if this is main thread let KeyboardInterrupt be raised */ |
| if (PyErr_CheckSignals()) |
| return NULL; |
| |
| /* recalculate timeout */ |
| if (msecs != INFINITE) { |
| ticks = GetTickCount(); |
| if ((DWORD)(ticks - start) >= full_msecs) |
| Py_RETURN_FALSE; |
| msecs = full_msecs - (ticks - start); |
| } |
| } |
| |
| /* handle result */ |
| switch (res) { |
| case WAIT_TIMEOUT: |
| Py_RETURN_FALSE; |
| case WAIT_OBJECT_0: |
| self->last_tid = GetCurrentThreadId(); |
| ++self->count; |
| Py_RETURN_TRUE; |
| case WAIT_FAILED: |
| return PyErr_SetFromWindowsErr(0); |
| default: |
| PyErr_Format(PyExc_RuntimeError, "WaitForSingleObject() or " |
| "WaitForMultipleObjects() gave unrecognized " |
| "value %d", res); |
| return NULL; |
| } |
| } |
| |
| static PyObject * |
| semlock_release(SemLockObject *self, PyObject *args) |
| { |
| if (self->kind == RECURSIVE_MUTEX) { |
| if (!ISMINE(self)) { |
| PyErr_SetString(PyExc_AssertionError, "attempt to " |
| "release recursive lock not owned " |
| "by thread"); |
| return NULL; |
| } |
| if (self->count > 1) { |
| --self->count; |
| Py_RETURN_NONE; |
| } |
| assert(self->count == 1); |
| } |
| |
| if (!ReleaseSemaphore(self->handle, 1, NULL)) { |
| if (GetLastError() == ERROR_TOO_MANY_POSTS) { |
| PyErr_SetString(PyExc_ValueError, "semaphore or lock " |
| "released too many times"); |
| return NULL; |
| } else { |
| return PyErr_SetFromWindowsErr(0); |
| } |
| } |
| |
| --self->count; |
| Py_RETURN_NONE; |
| } |
| |
| #else /* !MS_WINDOWS */ |
| |
| /* |
| * Unix definitions |
| */ |
| |
| #define SEM_CLEAR_ERROR() |
| #define SEM_GET_LAST_ERROR() 0 |
| #define SEM_CREATE(name, val, max) sem_open(name, O_CREAT | O_EXCL, 0600, val) |
| #define SEM_CLOSE(sem) sem_close(sem) |
| #define SEM_GETVALUE(sem, pval) sem_getvalue(sem, pval) |
| #define SEM_UNLINK(name) sem_unlink(name) |
| |
| /* OS X 10.4 defines SEM_FAILED as -1 instead of (sem_t *)-1; this gives |
| compiler warnings, and (potentially) undefined behaviour. */ |
| #ifdef __APPLE__ |
| # undef SEM_FAILED |
| # define SEM_FAILED ((sem_t *)-1) |
| #endif |
| |
| #ifndef HAVE_SEM_UNLINK |
| # define sem_unlink(name) 0 |
| #endif |
| |
| #ifndef HAVE_SEM_TIMEDWAIT |
| # define sem_timedwait(sem,deadline) sem_timedwait_save(sem,deadline,_save) |
| |
| int |
| sem_timedwait_save(sem_t *sem, struct timespec *deadline, PyThreadState *_save) |
| { |
| int res; |
| unsigned long delay, difference; |
| struct timeval now, tvdeadline, tvdelay; |
| |
| errno = 0; |
| tvdeadline.tv_sec = deadline->tv_sec; |
| tvdeadline.tv_usec = deadline->tv_nsec / 1000; |
| |
| for (delay = 0 ; ; delay += 1000) { |
| /* poll */ |
| if (sem_trywait(sem) == 0) |
| return 0; |
| else if (errno != EAGAIN) |
| return MP_STANDARD_ERROR; |
| |
| /* get current time */ |
| if (gettimeofday(&now, NULL) < 0) |
| return MP_STANDARD_ERROR; |
| |
| /* check for timeout */ |
| if (tvdeadline.tv_sec < now.tv_sec || |
| (tvdeadline.tv_sec == now.tv_sec && |
| tvdeadline.tv_usec <= now.tv_usec)) { |
| errno = ETIMEDOUT; |
| return MP_STANDARD_ERROR; |
| } |
| |
| /* calculate how much time is left */ |
| difference = (tvdeadline.tv_sec - now.tv_sec) * 1000000 + |
| (tvdeadline.tv_usec - now.tv_usec); |
| |
| /* check delay not too long -- maximum is 20 msecs */ |
| if (delay > 20000) |
| delay = 20000; |
| if (delay > difference) |
| delay = difference; |
| |
| /* sleep */ |
| tvdelay.tv_sec = delay / 1000000; |
| tvdelay.tv_usec = delay % 1000000; |
| if (select(0, NULL, NULL, NULL, &tvdelay) < 0) |
| return MP_STANDARD_ERROR; |
| |
| /* check for signals */ |
| Py_BLOCK_THREADS |
| res = PyErr_CheckSignals(); |
| Py_UNBLOCK_THREADS |
| |
| if (res) { |
| errno = EINTR; |
| return MP_EXCEPTION_HAS_BEEN_SET; |
| } |
| } |
| } |
| |
| #endif /* !HAVE_SEM_TIMEDWAIT */ |
| |
| static PyObject * |
| semlock_acquire(SemLockObject *self, PyObject *args, PyObject *kwds) |
| { |
| int blocking = 1, res; |
| double timeout; |
| PyObject *timeout_obj = Py_None; |
| struct timespec deadline = {0}; |
| struct timeval now; |
| long sec, nsec; |
| |
| static char *kwlist[] = {"block", "timeout", NULL}; |
| |
| if (!PyArg_ParseTupleAndKeywords(args, kwds, "|iO", kwlist, |
| &blocking, &timeout_obj)) |
| return NULL; |
| |
| if (self->kind == RECURSIVE_MUTEX && ISMINE(self)) { |
| ++self->count; |
| Py_RETURN_TRUE; |
| } |
| |
| if (timeout_obj != Py_None) { |
| timeout = PyFloat_AsDouble(timeout_obj); |
| if (PyErr_Occurred()) |
| return NULL; |
| if (timeout < 0.0) |
| timeout = 0.0; |
| |
| if (gettimeofday(&now, NULL) < 0) { |
| PyErr_SetFromErrno(PyExc_OSError); |
| return NULL; |
| } |
| sec = (long) timeout; |
| nsec = (long) (1e9 * (timeout - sec) + 0.5); |
| deadline.tv_sec = now.tv_sec + sec; |
| deadline.tv_nsec = now.tv_usec * 1000 + nsec; |
| deadline.tv_sec += (deadline.tv_nsec / 1000000000); |
| deadline.tv_nsec %= 1000000000; |
| } |
| |
| do { |
| Py_BEGIN_ALLOW_THREADS |
| if (blocking && timeout_obj == Py_None) |
| res = sem_wait(self->handle); |
| else if (!blocking) |
| res = sem_trywait(self->handle); |
| else |
| res = sem_timedwait(self->handle, &deadline); |
| Py_END_ALLOW_THREADS |
| if (res == MP_EXCEPTION_HAS_BEEN_SET) |
| break; |
| } while (res < 0 && errno == EINTR && !PyErr_CheckSignals()); |
| |
| if (res < 0) { |
| if (errno == EAGAIN || errno == ETIMEDOUT) |
| Py_RETURN_FALSE; |
| else if (errno == EINTR) |
| return NULL; |
| else |
| return PyErr_SetFromErrno(PyExc_OSError); |
| } |
| |
| ++self->count; |
| self->last_tid = PyThread_get_thread_ident(); |
| |
| Py_RETURN_TRUE; |
| } |
| |
| static PyObject * |
| semlock_release(SemLockObject *self, PyObject *args) |
| { |
| if (self->kind == RECURSIVE_MUTEX) { |
| if (!ISMINE(self)) { |
| PyErr_SetString(PyExc_AssertionError, "attempt to " |
| "release recursive lock not owned " |
| "by thread"); |
| return NULL; |
| } |
| if (self->count > 1) { |
| --self->count; |
| Py_RETURN_NONE; |
| } |
| assert(self->count == 1); |
| } else { |
| #ifdef HAVE_BROKEN_SEM_GETVALUE |
| /* We will only check properly the maxvalue == 1 case */ |
| if (self->maxvalue == 1) { |
| /* make sure that already locked */ |
| if (sem_trywait(self->handle) < 0) { |
| if (errno != EAGAIN) { |
| PyErr_SetFromErrno(PyExc_OSError); |
| return NULL; |
| } |
| /* it is already locked as expected */ |
| } else { |
| /* it was not locked so undo wait and raise */ |
| if (sem_post(self->handle) < 0) { |
| PyErr_SetFromErrno(PyExc_OSError); |
| return NULL; |
| } |
| PyErr_SetString(PyExc_ValueError, "semaphore " |
| "or lock released too many " |
| "times"); |
| return NULL; |
| } |
| } |
| #else |
| int sval; |
| |
| /* This check is not an absolute guarantee that the semaphore |
| does not rise above maxvalue. */ |
| if (sem_getvalue(self->handle, &sval) < 0) { |
| return PyErr_SetFromErrno(PyExc_OSError); |
| } else if (sval >= self->maxvalue) { |
| PyErr_SetString(PyExc_ValueError, "semaphore or lock " |
| "released too many times"); |
| return NULL; |
| } |
| #endif |
| } |
| |
| if (sem_post(self->handle) < 0) |
| return PyErr_SetFromErrno(PyExc_OSError); |
| |
| --self->count; |
| Py_RETURN_NONE; |
| } |
| |
| #endif /* !MS_WINDOWS */ |
| |
| /* |
| * All platforms |
| */ |
| |
| static PyObject * |
| newsemlockobject(PyTypeObject *type, SEM_HANDLE handle, int kind, int maxvalue) |
| { |
| SemLockObject *self; |
| |
| self = PyObject_New(SemLockObject, type); |
| if (!self) |
| return NULL; |
| self->handle = handle; |
| self->kind = kind; |
| self->count = 0; |
| self->last_tid = 0; |
| self->maxvalue = maxvalue; |
| return (PyObject*)self; |
| } |
| |
| static PyObject * |
| semlock_new(PyTypeObject *type, PyObject *args, PyObject *kwds) |
| { |
| char buffer[256]; |
| SEM_HANDLE handle = SEM_FAILED; |
| int kind, maxvalue, value; |
| PyObject *result; |
| static char *kwlist[] = {"kind", "value", "maxvalue", NULL}; |
| int try = 0; |
| |
| if (!PyArg_ParseTupleAndKeywords(args, kwds, "iii", kwlist, |
| &kind, &value, &maxvalue)) |
| return NULL; |
| |
| if (kind != RECURSIVE_MUTEX && kind != SEMAPHORE) { |
| PyErr_SetString(PyExc_ValueError, "unrecognized kind"); |
| return NULL; |
| } |
| |
| /* Create a semaphore with a unique name. The bytes returned by |
| * _PyOS_URandom() are treated as unsigned long to ensure that the filename |
| * is valid (no special characters). */ |
| do { |
| unsigned long suffix; |
| _PyOS_URandom((char *)&suffix, sizeof(suffix)); |
| PyOS_snprintf(buffer, sizeof(buffer), "/mp%ld-%lu", (long)getpid(), |
| suffix); |
| SEM_CLEAR_ERROR(); |
| handle = SEM_CREATE(buffer, value, maxvalue); |
| } while ((handle == SEM_FAILED) && (errno == EEXIST) && (++try < 100)); |
| |
| /* On Windows we should fail if GetLastError()==ERROR_ALREADY_EXISTS */ |
| if (handle == SEM_FAILED || SEM_GET_LAST_ERROR() != 0) |
| goto failure; |
| |
| if (SEM_UNLINK(buffer) < 0) |
| goto failure; |
| |
| result = newsemlockobject(type, handle, kind, maxvalue); |
| if (!result) |
| goto failure; |
| |
| return result; |
| |
| failure: |
| if (handle != SEM_FAILED) |
| SEM_CLOSE(handle); |
| mp_SetError(NULL, MP_STANDARD_ERROR); |
| return NULL; |
| } |
| |
| static PyObject * |
| semlock_rebuild(PyTypeObject *type, PyObject *args) |
| { |
| SEM_HANDLE handle; |
| int kind, maxvalue; |
| |
| if (!PyArg_ParseTuple(args, F_SEM_HANDLE "ii", |
| &handle, &kind, &maxvalue)) |
| return NULL; |
| |
| return newsemlockobject(type, handle, kind, maxvalue); |
| } |
| |
| static void |
| semlock_dealloc(SemLockObject* self) |
| { |
| if (self->handle != SEM_FAILED) |
| SEM_CLOSE(self->handle); |
| PyObject_Del(self); |
| } |
| |
| static PyObject * |
| semlock_count(SemLockObject *self) |
| { |
| return PyInt_FromLong((long)self->count); |
| } |
| |
| static PyObject * |
| semlock_ismine(SemLockObject *self) |
| { |
| /* only makes sense for a lock */ |
| return PyBool_FromLong(ISMINE(self)); |
| } |
| |
| static PyObject * |
| semlock_getvalue(SemLockObject *self) |
| { |
| #ifdef HAVE_BROKEN_SEM_GETVALUE |
| PyErr_SetNone(PyExc_NotImplementedError); |
| return NULL; |
| #else |
| int sval; |
| if (SEM_GETVALUE(self->handle, &sval) < 0) |
| return mp_SetError(NULL, MP_STANDARD_ERROR); |
| /* some posix implementations use negative numbers to indicate |
| the number of waiting threads */ |
| if (sval < 0) |
| sval = 0; |
| return PyInt_FromLong((long)sval); |
| #endif |
| } |
| |
| static PyObject * |
| semlock_iszero(SemLockObject *self) |
| { |
| #ifdef HAVE_BROKEN_SEM_GETVALUE |
| if (sem_trywait(self->handle) < 0) { |
| if (errno == EAGAIN) |
| Py_RETURN_TRUE; |
| return mp_SetError(NULL, MP_STANDARD_ERROR); |
| } else { |
| if (sem_post(self->handle) < 0) |
| return mp_SetError(NULL, MP_STANDARD_ERROR); |
| Py_RETURN_FALSE; |
| } |
| #else |
| int sval; |
| if (SEM_GETVALUE(self->handle, &sval) < 0) |
| return mp_SetError(NULL, MP_STANDARD_ERROR); |
| return PyBool_FromLong((long)sval == 0); |
| #endif |
| } |
| |
| static PyObject * |
| semlock_afterfork(SemLockObject *self) |
| { |
| self->count = 0; |
| Py_RETURN_NONE; |
| } |
| |
| /* |
| * Semaphore methods |
| */ |
| |
| static PyMethodDef semlock_methods[] = { |
| {"acquire", (PyCFunction)semlock_acquire, METH_VARARGS | METH_KEYWORDS, |
| "acquire the semaphore/lock"}, |
| {"release", (PyCFunction)semlock_release, METH_NOARGS, |
| "release the semaphore/lock"}, |
| {"__enter__", (PyCFunction)semlock_acquire, METH_VARARGS | METH_KEYWORDS, |
| "enter the semaphore/lock"}, |
| {"__exit__", (PyCFunction)semlock_release, METH_VARARGS, |
| "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, |
| }; |
