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[3.6] bpo-31786: Make functions in the select module blocking when timeout is a small negative value. (GH-4003). (#4022)

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(cherry picked from commit 2c15b29aea)
This commit is contained in:
Pablo Galindo 2017-10-18 09:12:47 +01:00 • committed by Serhiy Storchaka
parent 1781480254
commit 95602b368b
7 changed files with 78 additions and 18 deletions
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13
Include/pytime.h
View file

@ -29,9 +29,20 @@ typedef enum {
_PyTime_ROUND_CEILING=1,
/* Round to nearest with ties going to nearest even integer.
For example, used to round from a Python float. */
_PyTime_ROUND_HALF_EVEN
_PyTime_ROUND_HALF_EVEN=2,
/* Round away from zero
For example, used for timeout. _PyTime_ROUND_CEILING rounds
-1e-9 to 0 milliseconds which causes bpo-31786 issue.
_PyTime_ROUND_UP rounds -1e-9 to -1 millisecond which keeps
the timeout sign as expected. select.poll(timeout) must block
for negative values." */
_PyTime_ROUND_UP=3,
/* _PyTime_ROUND_TIMEOUT (an alias for _PyTime_ROUND_UP) should be
used for timeouts. */
_PyTime_ROUND_TIMEOUT = _PyTime_ROUND_UP
} _PyTime_round_t;
/* Convert a time_t to a PyLong. */
PyAPI_FUNC(PyObject *) _PyLong_FromTime_t(
time_t sec);

22
Lib/test/test_poll.py
View file

@ -208,6 +208,28 @@ class PollTests(unittest.TestCase):
os.write(w, b'spam')
t.join()
@unittest.skipUnless(threading, 'Threading required for this test.')
@reap_threads
def test_poll_blocks_with_negative_ms(self):
for timeout_ms in [None, -1, -1.0, -0.1, -1e-100]:
# Create two file descriptors. This will be used to unlock
# the blocking call to poll.poll inside the thread
r, w = os.pipe()
pollster = select.poll()
pollster.register(r, select.POLLIN)
poll_thread = threading.Thread(target=pollster.poll, args=(timeout_ms,))
poll_thread.start()
poll_thread.join(timeout=0.1)
self.assertTrue(poll_thread.is_alive())
# Write to the pipe so pollster.poll unblocks and the thread ends.
os.write(w, b'spam')
poll_thread.join()
self.assertFalse(poll_thread.is_alive())
os.close(r)
os.close(w)
def test_main():
run_unittest(PollTests)

3
Lib/test/test_time.py
View file

@ -36,6 +36,8 @@ class _PyTime(enum.IntEnum):
ROUND_CEILING = 1
# Round to nearest with ties going to nearest even integer
ROUND_HALF_EVEN = 2
# Round away from zero
ROUND_UP = 3
# Rounding modes supported by PyTime
ROUNDING_MODES = (
@ -43,6 +45,7 @@ ROUNDING_MODES = (
(_PyTime.ROUND_FLOOR, decimal.ROUND_FLOOR),
(_PyTime.ROUND_CEILING, decimal.ROUND_CEILING),
(_PyTime.ROUND_HALF_EVEN, decimal.ROUND_HALF_EVEN),
(_PyTime.ROUND_UP, decimal.ROUND_UP),
)

3
Misc/NEWS.d/next/Core and Builtins/2017-10-15-23-44-57.bpo-31786.XwdEP4.rst Normal file
View file

@ -0,0 +1,3 @@
Fix timeout rounding in the select module to round correctly negative timeouts between -1.0 and 0.0.
The functions now block waiting for events as expected. Previously, the call was incorrectly non-blocking.
Patch by Pablo Galindo.

3
Modules/_testcapimodule.c
View file

@ -3016,7 +3016,8 @@ check_time_rounding(int round)
{
if (round != _PyTime_ROUND_FLOOR
&& round != _PyTime_ROUND_CEILING
&& round != _PyTime_ROUND_HALF_EVEN) {
&& round != _PyTime_ROUND_HALF_EVEN
&& round != _PyTime_ROUND_UP) {
PyErr_SetString(PyExc_ValueError, "invalid rounding");
return -1;
}

16
Modules/selectmodule.c
View file

@ -213,7 +213,7 @@ select_select(PyObject *self, PyObject *args)
tvp = (struct timeval *)NULL;
else {
if (_PyTime_FromSecondsObject(&timeout, timeout_obj,
_PyTime_ROUND_CEILING) < 0) {
_PyTime_ROUND_TIMEOUT) < 0) {
if (PyErr_ExceptionMatches(PyExc_TypeError)) {
PyErr_SetString(PyExc_TypeError,
"timeout must be a float or None");
@ -221,7 +221,7 @@ select_select(PyObject *self, PyObject *args)
return NULL;
}
if (_PyTime_AsTimeval(timeout, &tv, _PyTime_ROUND_CEILING) == -1)
if (_PyTime_AsTimeval(timeout, &tv, _PyTime_ROUND_TIMEOUT) == -1)
return NULL;
if (tv.tv_sec < 0) {
PyErr_SetString(PyExc_ValueError, "timeout must be non-negative");
@ -543,7 +543,7 @@ poll_poll(pollObject *self, PyObject *args)
}
else {
if (_PyTime_FromMillisecondsObject(&timeout, timeout_obj,
_PyTime_ROUND_CEILING) < 0) {
_PyTime_ROUND_TIMEOUT) < 0) {
if (PyErr_ExceptionMatches(PyExc_TypeError)) {
PyErr_SetString(PyExc_TypeError,
"timeout must be an integer or None");
@ -551,7 +551,7 @@ poll_poll(pollObject *self, PyObject *args)
return NULL;
}
ms = _PyTime_AsMilliseconds(timeout, _PyTime_ROUND_CEILING);
ms = _PyTime_AsMilliseconds(timeout, _PyTime_ROUND_TIMEOUT);
if (ms < INT_MIN || ms > INT_MAX) {
PyErr_SetString(PyExc_OverflowError, "timeout is too large");
return NULL;
@ -899,7 +899,7 @@ devpoll_poll(devpollObject *self, PyObject *args)
}
else {
if (_PyTime_FromMillisecondsObject(&timeout, timeout_obj,
_PyTime_ROUND_CEILING) < 0) {
_PyTime_ROUND_TIMEOUT) < 0) {
if (PyErr_ExceptionMatches(PyExc_TypeError)) {
PyErr_SetString(PyExc_TypeError,
"timeout must be an integer or None");
@ -907,7 +907,7 @@ devpoll_poll(devpollObject *self, PyObject *args)
return NULL;
}
ms = _PyTime_AsMilliseconds(timeout, _PyTime_ROUND_CEILING);
ms = _PyTime_AsMilliseconds(timeout, _PyTime_ROUND_TIMEOUT);
if (ms < -1 || ms > INT_MAX) {
PyErr_SetString(PyExc_OverflowError, "timeout is too large");
return NULL;
@ -1514,7 +1514,7 @@ pyepoll_poll(pyEpoll_Object *self, PyObject *args, PyObject *kwds)
/* epoll_wait() has a resolution of 1 millisecond, round towards
infinity to wait at least timeout seconds. */
if (_PyTime_FromSecondsObject(&timeout, timeout_obj,
_PyTime_ROUND_CEILING) < 0) {
_PyTime_ROUND_TIMEOUT) < 0) {
if (PyErr_ExceptionMatches(PyExc_TypeError)) {
PyErr_SetString(PyExc_TypeError,
"timeout must be an integer or None");
@ -2129,7 +2129,7 @@ kqueue_queue_control(kqueue_queue_Object *self, PyObject *args)
}
else {
if (_PyTime_FromSecondsObject(&timeout,
otimeout, _PyTime_ROUND_CEILING) < 0) {
otimeout, _PyTime_ROUND_TIMEOUT) < 0) {
PyErr_Format(PyExc_TypeError,
"timeout argument must be a number "
"or None, got %.200s",

36
Python/pytime.c
View file

@ -84,12 +84,19 @@ _PyTime_Round(double x, _PyTime_round_t round)
volatile double d;
d = x;
if (round == _PyTime_ROUND_HALF_EVEN)
if (round == _PyTime_ROUND_HALF_EVEN){
d = _PyTime_RoundHalfEven(d);
else if (round == _PyTime_ROUND_CEILING)
}
else if (round == _PyTime_ROUND_CEILING){
d = ceil(d);
else
}
else if (round == _PyTime_ROUND_FLOOR) {
d = floor(d);
}
else {
assert(round == _PyTime_ROUND_UP);
d = (d >= 0.0) ? ceil(d) : floor(d);
}
return d;
}
@ -395,16 +402,29 @@ _PyTime_Divide(const _PyTime_t t, const _PyTime_t k,
return x;
}
else if (round == _PyTime_ROUND_CEILING) {
if (t >= 0)
if (t >= 0){
return (t + k - 1) / k;
else
}
else{
return t / k;
}
}
else if (round == _PyTime_ROUND_FLOOR){
if (t >= 0) {
return t / k;
}
else{
return (t - (k - 1)) / k;
}
}
else {
if (t >= 0)
return t / k;
else
assert(round == _PyTime_ROUND_UP);
if (t >= 0) {
return (t + k - 1) / k;
}
else {
return (t - (k - 1)) / k;
}
}
}