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Patch #1583 by Adam Olsen.

Browse source 
This adds signal.set_wakeup_fd(fd) which sets a file descriptor to
which a zero byte will be written whenever a C exception handler runs.

I added a simple C API as well, PySignal_SetWakeupFd(fd).
This commit is contained in:
Guido van Rossum 2007-12-19 19:41:06 +00:00
parent 80016c9555
commit 02de8979cc
5 changed files with 127 additions and 2 deletions
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53
Modules/signalmodule.c
View file

@ -12,6 +12,8 @@
#include <signal.h>
#include <sys/stat.h>
#ifndef SIG_ERR
#define SIG_ERR ((PyOS_sighandler_t)(-1))
#endif
@ -75,6 +77,8 @@ static struct {
PyObject *func;
} Handlers[NSIG];
static sig_atomic_t wakeup_fd = -1;
/* Speed up sigcheck() when none tripped */
static volatile sig_atomic_t is_tripped = 0;
@ -128,6 +132,8 @@ signal_handler(int sig_num)
cleared in PyErr_CheckSignals() before .tripped. */
is_tripped = 1;
Py_AddPendingCall(checksignals_witharg, NULL);
if (wakeup_fd != -1)
write(wakeup_fd, "\0", 1);
#ifdef WITH_THREAD
}
#endif
@ -267,6 +273,50 @@ None -- if an unknown handler is in effect\n\
anything else -- the callable Python object used as a handler");
static PyObject *
signal_set_wakeup_fd(PyObject *self, PyObject *args)
{
struct stat buf;
int fd, old_fd;
if (!PyArg_ParseTuple(args, "i:set_wakeup_fd", &fd))
return NULL;
#ifdef WITH_THREAD
if (PyThread_get_thread_ident() != main_thread) {
PyErr_SetString(PyExc_ValueError,
"set_wakeup_fd only works in main thread");
return NULL;
}
#endif
if (fd != -1 && fstat(fd, &buf) != 0) {
PyErr_SetString(PyExc_ValueError, "invalid fd");
return NULL;
}
old_fd = wakeup_fd;
wakeup_fd = fd;
return PyLong_FromLong(old_fd);
}
PyDoc_STRVAR(set_wakeup_fd_doc,
"set_wakeup_fd(fd) -> fd\n\
\n\
Sets the fd to be written to (with '\\0') when a signal\n\
comes in. A library can use this to wakeup select or poll.\n\
The previous fd is returned.\n\
\n\
The fd must be non-blocking.");
/* C API for the same, without all the error checking */
int
PySignal_SetWakeupFd(int fd)
{
int old_fd = wakeup_fd;
if (fd < 0)
fd = -1;
wakeup_fd = fd;
return old_fd;
}
/* List of functions defined in the module */
static PyMethodDef signal_methods[] = {
#ifdef HAVE_ALARM
@ -274,11 +324,12 @@ static PyMethodDef signal_methods[] = {
#endif
{"signal", signal_signal, METH_VARARGS, signal_doc},
{"getsignal", signal_getsignal, METH_VARARGS, getsignal_doc},
{"set_wakeup_fd", signal_set_wakeup_fd, METH_VARARGS, set_wakeup_fd_doc},
#ifdef HAVE_PAUSE
{"pause", (PyCFunction)signal_pause,
METH_NOARGS,pause_doc},
#endif
{"default_int_handler", signal_default_int_handler,
{"default_int_handler", signal_default_int_handler,
METH_VARARGS, default_int_handler_doc},
{NULL, NULL} /* sentinel */
};