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Patch #1643738 by Ulisses Furquim -- make the is_tripped variable 

in signalmodule.c more robust.  Includes Martin von Loewis's suggestion
to set is_tripped after .tripped.
This commit is contained in:
Guido van Rossum 2007-12-10 23:00:12 +00:00
parent 284d927625
commit 137c49ce6a
2 changed files with 27 additions and 5 deletions
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1
Misc/ACKS
View File

@ -223,6 +223,7 @@ Tadayoshi Funaba
Gyro Funch
Peter Funk
Geoff Furnish
Ulisses Furquim
Lele Gaifax
Santiago Gala
Yitzchak Gale

31
Modules/signalmodule.c
View File

@ -75,7 +75,8 @@ static struct {
PyObject *func;
} Handlers[NSIG];
static int is_tripped = 0; /* Speed up sigcheck() when none tripped */
/* Speed up sigcheck() when none tripped */
static volatile sig_atomic_t is_tripped = 0;
static PyObject *DefaultHandler;
static PyObject *IgnoreHandler;
@ -122,8 +123,10 @@ signal_handler(int sig_num)
/* See NOTES section above */
if (getpid() == main_pid) {
#endif
is_tripped++;
Handlers[sig_num].tripped = 1;
/* Set is_tripped after setting .tripped, as it gets
cleared in PyErr_CheckSignals() before .tripped. */
is_tripped = 1;
Py_AddPendingCall(checksignals_witharg, NULL);
#ifdef WITH_THREAD
}
@ -597,13 +600,31 @@ PyErr_CheckSignals(void)
if (!is_tripped)
return 0;
#ifdef WITH_THREAD
if (PyThread_get_thread_ident() != main_thread)
return 0;
#endif
/*
* The is_stripped variable is meant to speed up the calls to
* PyErr_CheckSignals (both directly or via pending calls) when no
* signal has arrived. This variable is set to 1 when a signal arrives
* and it is set to 0 here, when we know some signals arrived. This way
* we can run the registered handlers with no signals blocked.
*
* NOTE: with this approach we can have a situation where is_tripped is
* 1 but we have no more signals to handle (Handlers[i].tripped
* is 0 for every signal i). This won't do us any harm (except
* we're gonna spent some cycles for nothing). This happens when
* we receive a signal i after we zero is_tripped and before we
* check Handlers[i].tripped.
*/
is_tripped = 0;
if (!(f = (PyObject *)PyEval_GetFrame()))
f = Py_None;
for (i = 1; i < NSIG; i++) {
if (Handlers[i].tripped) {
PyObject *result = NULL;
@ -621,7 +642,7 @@ PyErr_CheckSignals(void)
Py_DECREF(result);
}
}
is_tripped = 0;
return 0;
}
@ -632,7 +653,7 @@ PyErr_CheckSignals(void)
void
PyErr_SetInterrupt(void)
{
is_tripped++;
is_tripped = 1;
Handlers[SIGINT].tripped = 1;
Py_AddPendingCall((int (*)(void *))PyErr_CheckSignals, NULL);
}