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bpo-41710: Add private _PyDeadline_Get() function (GH-28674)
Add a private C API for deadlines: add _PyDeadline_Init() and _PyDeadline_Get() functions. * Add _PyTime_Add() and _PyTime_Mul() functions which compute t1+t2 and t1*t2 and clamp the result on overflow. * _PyTime_MulDiv() now uses _PyTime_Add() and _PyTime_Mul().
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11 files changed

+176
-108
lines changed

11 files changed

+176
-108
lines changed

‎Include/cpython/pytime.h‎

Lines changed: 16 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -27,6 +27,8 @@
2727
//
2828
// Some functions clamp the result in the range [_PyTime_MIN; _PyTime_MAX], so
2929
// the caller doesn't have to handle errors and doesn't need to hold the GIL.
30+
// For example, _PyTime_Add(t1, t2) computes t1+t2 and clamp the result on
31+
// overflow.
3032
//
3133
// Clocks:
3234
//
@@ -215,7 +217,12 @@ PyAPI_FUNC(int) _PyTime_AsTimespec(_PyTime_t t, struct timespec *ts);
215217
PyAPI_FUNC(void) _PyTime_AsTimespec_clamp(_PyTime_t t, struct timespec *ts);
216218
#endif
217219

220+
221+
// Compute t1 + t2. Clamp to [_PyTime_MIN; _PyTime_MAX] on overflow.
222+
PyAPI_FUNC(_PyTime_t) _PyTime_Add(_PyTime_t t1, _PyTime_t t2);
223+
218224
/* Compute ticks * mul / div.
225+
Clamp to [_PyTime_MIN; _PyTime_MAX] on overflow.
219226
The caller must ensure that ((div - 1) * mul) cannot overflow. */
220227
PyAPI_FUNC(_PyTime_t) _PyTime_MulDiv(_PyTime_t ticks,
221228
_PyTime_t mul,
@@ -299,6 +306,15 @@ PyAPI_FUNC(int) _PyTime_GetPerfCounterWithInfo(
299306
_PyTime_t *t,
300307
_Py_clock_info_t *info);
301308

309+
310+
// Create a deadline.
311+
// Pseudo code: _PyTime_GetMonotonicClock() + timeout.
312+
PyAPI_FUNC(_PyTime_t) _PyDeadline_Init(_PyTime_t timeout);
313+
314+
// Get remaining time from a deadline.
315+
// Pseudo code: deadline - _PyTime_GetMonotonicClock().
316+
PyAPI_FUNC(_PyTime_t) _PyDeadline_Get(_PyTime_t deadline);
317+
302318
#ifdef __cplusplus
303319
}
304320
#endif

‎Modules/_queuemodule.c‎

Lines changed: 18 additions & 13 deletions
Original file line numberDiff line numberDiff line change
@@ -182,7 +182,7 @@ _queue.SimpleQueue.get
182182
cls: defining_class
183183
/
184184
block: bool = True
185-
timeout: object = None
185+
timeout as timeout_obj: object = None
186186
187187
Remove and return an item from the queue.
188188
@@ -198,11 +198,11 @@ in that case).
198198

199199
static PyObject *
200200
_queue_SimpleQueue_get_impl(simplequeueobject *self, PyTypeObject *cls,
201-
int block, PyObject *timeout)
202-
/*[clinic end generated code: output=1969aefa7db63666 input=5fc4d56b9a54757e]*/
201+
int block, PyObject *timeout_obj)
202+
/*[clinic end generated code: output=5c2cca914cd1e55b input=5b4047bfbc645ec1]*/
203203
{
204204
_PyTime_t endtime = 0;
205-
_PyTime_t timeout_val;
205+
_PyTime_t timeout;
206206
PyObject *item;
207207
PyLockStatus r;
208208
PY_TIMEOUT_T microseconds;
@@ -211,24 +211,25 @@ _queue_SimpleQueue_get_impl(simplequeueobject *self, PyTypeObject *cls,
211211
/* Non-blocking */
212212
microseconds = 0;
213213
}
214-
else if (timeout != Py_None) {
214+
else if (timeout_obj != Py_None) {
215215
/* With timeout */
216-
if (_PyTime_FromSecondsObject(&timeout_val,
217-
timeout, _PyTime_ROUND_CEILING) < 0)
216+
if (_PyTime_FromSecondsObject(&timeout,
217+
timeout_obj, _PyTime_ROUND_CEILING) < 0) {
218218
return NULL;
219-
if (timeout_val < 0) {
219+
}
220+
if (timeout < 0) {
220221
PyErr_SetString(PyExc_ValueError,
221222
"'timeout' must be a non-negative number");
222223
return NULL;
223224
}
224-
microseconds = _PyTime_AsMicroseconds(timeout_val,
225+
microseconds = _PyTime_AsMicroseconds(timeout,
225226
_PyTime_ROUND_CEILING);
226227
if (microseconds > PY_TIMEOUT_MAX) {
227228
PyErr_SetString(PyExc_OverflowError,
228229
"timeout value is too large");
229230
return NULL;
230231
}
231-
endtime = _PyTime_GetMonotonicClock() + timeout_val;
232+
endtime = _PyDeadline_Init(timeout);
232233
}
233234
else {
234235
/* Infinitely blocking */
@@ -247,6 +248,7 @@ _queue_SimpleQueue_get_impl(simplequeueobject *self, PyTypeObject *cls,
247248
r = PyThread_acquire_lock_timed(self->lock, microseconds, 1);
248249
Py_END_ALLOW_THREADS
249250
}
251+
250252
if (r == PY_LOCK_INTR && Py_MakePendingCalls() < 0) {
251253
return NULL;
252254
}
@@ -258,12 +260,15 @@ _queue_SimpleQueue_get_impl(simplequeueobject *self, PyTypeObject *cls,
258260
return NULL;
259261
}
260262
self->locked = 1;
263+
261264
/* Adjust timeout for next iteration (if any) */
262-
if (endtime > 0) {
263-
timeout_val = endtime - _PyTime_GetMonotonicClock();
264-
microseconds = _PyTime_AsMicroseconds(timeout_val, _PyTime_ROUND_CEILING);
265+
if (microseconds > 0) {
266+
timeout = _PyDeadline_Get(endtime);
267+
microseconds = _PyTime_AsMicroseconds(timeout,
268+
_PyTime_ROUND_CEILING);
265269
}
266270
}
271+
267272
/* BEGIN GIL-protected critical section */
268273
assert(self->lst_pos < PyList_GET_SIZE(self->lst));
269274
item = simplequeue_pop_item(self);

‎Modules/_ssl.c‎

Lines changed: 20 additions & 14 deletions
Original file line numberDiff line numberDiff line change
@@ -949,8 +949,9 @@ _ssl__SSLSocket_do_handshake_impl(PySSLSocket *self)
949949

950950
timeout = GET_SOCKET_TIMEOUT(sock);
951951
has_timeout = (timeout > 0);
952-
if (has_timeout)
953-
deadline = _PyTime_GetMonotonicClock() + timeout;
952+
if (has_timeout) {
953+
deadline = _PyDeadline_Init(timeout);
954+
}
954955

955956
/* Actually negotiate SSL connection */
956957
/* XXX If SSL_do_handshake() returns 0, it's also a failure. */
@@ -965,7 +966,7 @@ _ssl__SSLSocket_do_handshake_impl(PySSLSocket *self)
965966
goto error;
966967

967968
if (has_timeout)
968-
timeout = deadline - _PyTime_GetMonotonicClock();
969+
timeout = _PyDeadline_Get(deadline);
969970

970971
if (err.ssl == SSL_ERROR_WANT_READ) {
971972
sockstate = PySSL_select(sock, 0, timeout);
@@ -2326,8 +2327,9 @@ _ssl__SSLSocket_write_impl(PySSLSocket *self, Py_buffer *b)
23262327

23272328
timeout = GET_SOCKET_TIMEOUT(sock);
23282329
has_timeout = (timeout > 0);
2329-
if (has_timeout)
2330-
deadline = _PyTime_GetMonotonicClock() + timeout;
2330+
if (has_timeout) {
2331+
deadline = _PyDeadline_Init(timeout);
2332+
}
23312333

23322334
sockstate = PySSL_select(sock, 1, timeout);
23332335
if (sockstate == SOCKET_HAS_TIMED_OUT) {
@@ -2354,8 +2356,9 @@ _ssl__SSLSocket_write_impl(PySSLSocket *self, Py_buffer *b)
23542356
if (PyErr_CheckSignals())
23552357
goto error;
23562358

2357-
if (has_timeout)
2358-
timeout = deadline - _PyTime_GetMonotonicClock();
2359+
if (has_timeout) {
2360+
timeout = _PyDeadline_Get(deadline);
2361+
}
23592362

23602363
if (err.ssl == SSL_ERROR_WANT_READ) {
23612364
sockstate = PySSL_select(sock, 0, timeout);
@@ -2494,7 +2497,7 @@ _ssl__SSLSocket_read_impl(PySSLSocket *self, Py_ssize_t len,
24942497
timeout = GET_SOCKET_TIMEOUT(sock);
24952498
has_timeout = (timeout > 0);
24962499
if (has_timeout)
2497-
deadline = _PyTime_GetMonotonicClock() + timeout;
2500+
deadline = _PyDeadline_Init(timeout);
24982501

24992502
do {
25002503
PySSL_BEGIN_ALLOW_THREADS
@@ -2506,8 +2509,9 @@ _ssl__SSLSocket_read_impl(PySSLSocket *self, Py_ssize_t len,
25062509
if (PyErr_CheckSignals())
25072510
goto error;
25082511

2509-
if (has_timeout)
2510-
timeout = deadline - _PyTime_GetMonotonicClock();
2512+
if (has_timeout) {
2513+
timeout = _PyDeadline_Get(deadline);
2514+
}
25112515

25122516
if (err.ssl == SSL_ERROR_WANT_READ) {
25132517
sockstate = PySSL_select(sock, 0, timeout);
@@ -2592,8 +2596,9 @@ _ssl__SSLSocket_shutdown_impl(PySSLSocket *self)
25922596

25932597
timeout = GET_SOCKET_TIMEOUT(sock);
25942598
has_timeout = (timeout > 0);
2595-
if (has_timeout)
2596-
deadline = _PyTime_GetMonotonicClock() + timeout;
2599+
if (has_timeout) {
2600+
deadline = _PyDeadline_Init(timeout);
2601+
}
25972602

25982603
while (1) {
25992604
PySSL_BEGIN_ALLOW_THREADS
@@ -2626,8 +2631,9 @@ _ssl__SSLSocket_shutdown_impl(PySSLSocket *self)
26262631
continue;
26272632
}
26282633

2629-
if (has_timeout)
2630-
timeout = deadline - _PyTime_GetMonotonicClock();
2634+
if (has_timeout) {
2635+
timeout = _PyDeadline_Get(deadline);
2636+
}
26312637

26322638
/* Possibly retry shutdown until timeout or failure */
26332639
if (err.ssl == SSL_ERROR_WANT_READ)

‎Modules/_threadmodule.c‎

Lines changed: 3 additions & 4 deletions
Original file line numberDiff line numberDiff line change
@@ -84,13 +84,12 @@ lock_dealloc(lockobject *self)
8484
static PyLockStatus
8585
acquire_timed(PyThread_type_lock lock, _PyTime_t timeout)
8686
{
87-
PyLockStatus r;
8887
_PyTime_t endtime = 0;
89-
9088
if (timeout > 0) {
91-
endtime = _PyTime_GetMonotonicClock() + timeout;
89+
endtime = _PyDeadline_Init(timeout);
9290
}
9391

92+
PyLockStatus r;
9493
do {
9594
_PyTime_t microseconds;
9695
microseconds = _PyTime_AsMicroseconds(timeout, _PyTime_ROUND_CEILING);
@@ -114,7 +113,7 @@ acquire_timed(PyThread_type_lock lock, _PyTime_t timeout)
114113
/* If we're using a timeout, recompute the timeout after processing
115114
* signals, since those can take time. */
116115
if (timeout > 0) {
117-
timeout = endtime - _PyTime_GetMonotonicClock();
116+
timeout = _PyDeadline_Get(endtime);
118117

119118
/* Check for negative values, since those mean block forever.
120119
*/

‎Modules/clinic/_queuemodule.c.h‎

Lines changed: 5 additions & 5 deletions
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‎Modules/selectmodule.c‎

Lines changed: 16 additions & 13 deletions
Original file line numberDiff line numberDiff line change
@@ -318,8 +318,9 @@ select_select_impl(PyObject *module, PyObject *rlist, PyObject *wlist,
318318
if (omax > max) max = omax;
319319
if (emax > max) max = emax;
320320

321-
if (tvp)
322-
deadline = _PyTime_GetMonotonicClock() + timeout;
321+
if (tvp) {
322+
deadline = _PyDeadline_Init(timeout);
323+
}
323324

324325
do {
325326
Py_BEGIN_ALLOW_THREADS
@@ -335,7 +336,7 @@ select_select_impl(PyObject *module, PyObject *rlist, PyObject *wlist,
335336
goto finally;
336337

337338
if (tvp) {
338-
timeout = deadline - _PyTime_GetMonotonicClock();
339+
timeout = _PyDeadline_Get(deadline);
339340
if (timeout < 0) {
340341
/* bpo-35310: lists were unmodified -- clear them explicitly */
341342
FD_ZERO(&ifdset);
@@ -599,7 +600,7 @@ select_poll_poll_impl(pollObject *self, PyObject *timeout_obj)
599600
}
600601

601602
if (timeout >= 0) {
602-
deadline = _PyTime_GetMonotonicClock() + timeout;
603+
deadline = _PyDeadline_Init(timeout);
603604
}
604605
}
605606

@@ -646,7 +647,7 @@ select_poll_poll_impl(pollObject *self, PyObject *timeout_obj)
646647
}
647648

648649
if (timeout >= 0) {
649-
timeout = deadline - _PyTime_GetMonotonicClock();
650+
timeout = _PyDeadline_Get(deadline);
650651
if (timeout < 0) {
651652
poll_result = 0;
652653
break;
@@ -938,8 +939,9 @@ select_devpoll_poll_impl(devpollObject *self, PyObject *timeout_obj)
938939
dvp.dp_nfds = self->max_n_fds;
939940
dvp.dp_timeout = (int)ms;
940941

941-
if (timeout >= 0)
942-
deadline = _PyTime_GetMonotonicClock() + timeout;
942+
if (timeout >= 0) {
943+
deadline = _PyDeadline_Init(timeout);
944+
}
943945

944946
do {
945947
/* call devpoll() */
@@ -956,7 +958,7 @@ select_devpoll_poll_impl(devpollObject *self, PyObject *timeout_obj)
956958
return NULL;
957959

958960
if (timeout >= 0) {
959-
timeout = deadline - _PyTime_GetMonotonicClock();
961+
timeout = _PyDeadline_Get(deadline);
960962
if (timeout < 0) {
961963
poll_result = 0;
962964
break;
@@ -1550,7 +1552,7 @@ select_epoll_poll_impl(pyEpoll_Object *self, PyObject *timeout_obj,
15501552
}
15511553

15521554
if (timeout >= 0) {
1553-
deadline = _PyTime_GetMonotonicClock() + timeout;
1555+
deadline = _PyDeadline_Init(timeout);
15541556
}
15551557
}
15561558

@@ -1584,7 +1586,7 @@ select_epoll_poll_impl(pyEpoll_Object *self, PyObject *timeout_obj,
15841586
goto error;
15851587

15861588
if (timeout >= 0) {
1587-
timeout = deadline - _PyTime_GetMonotonicClock();
1589+
timeout = _PyDeadline_Get(deadline);
15881590
if (timeout < 0) {
15891591
nfds = 0;
15901592
break;
@@ -2172,8 +2174,9 @@ select_kqueue_control_impl(kqueue_queue_Object *self, PyObject *changelist,
21722174
}
21732175
}
21742176

2175-
if (ptimeoutspec)
2176-
deadline = _PyTime_GetMonotonicClock() + timeout;
2177+
if (ptimeoutspec) {
2178+
deadline = _PyDeadline_Init(timeout);
2179+
}
21772180

21782181
do {
21792182
Py_BEGIN_ALLOW_THREADS
@@ -2190,7 +2193,7 @@ select_kqueue_control_impl(kqueue_queue_Object *self, PyObject *changelist,
21902193
goto error;
21912194

21922195
if (ptimeoutspec) {
2193-
timeout = deadline - _PyTime_GetMonotonicClock();
2196+
timeout = _PyDeadline_Get(deadline);
21942197
if (timeout < 0) {
21952198
gotevents = 0;
21962199
break;

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