datetimetz_astimezone(): Speed optimizations -- although I'd rather
find a more elegant algorithm (OTOH, the hairy new implementation allows
user-written tzinfo classes to be elegant, so it's a big win even if
astimezone() remains hairy).
Darn! I've only got 10 minutes left to get falling-down drunk! I suppose
I'll have to smoke crack instead now.
diff --git a/Modules/datetimemodule.c b/Modules/datetimemodule.c
index 40f4773..fb1f9e1 100644
--- a/Modules/datetimemodule.c
+++ b/Modules/datetimemodule.c
@@ -4753,7 +4753,7 @@
PyObject *result;
PyObject *temp;
- int myoff, otoff, newoff;
+ int selfoff, resoff, tempoff, total_added_to_result;
int none;
PyObject *tzinfo;
@@ -4776,21 +4776,23 @@
/* Get the offsets. If either object turns out to be naive, again
* there's no conversion of date or time fields.
*/
- myoff = call_utcoffset(self->tzinfo, (PyObject *)self, &none);
- if (myoff == -1 && PyErr_Occurred())
+ selfoff = call_utcoffset(self->tzinfo, (PyObject *)self, &none);
+ if (selfoff == -1 && PyErr_Occurred())
goto Fail;
if (none)
return result;
- otoff = call_utcoffset(tzinfo, result, &none);
- if (otoff == -1 && PyErr_Occurred())
+ resoff = call_utcoffset(tzinfo, result, &none);
+ if (resoff == -1 && PyErr_Occurred())
goto Fail;
if (none)
return result;
- /* Add otoff-myoff to result. */
- mm += otoff - myoff;
- if (normalize_datetime(&y, &m, &d, &hh, &mm, &ss, &us) < 0)
+ /* Add resoff-selfoff to result. */
+ total_added_to_result = resoff - selfoff;
+ mm += total_added_to_result;
+ if ((mm < 0 || mm >= 60) &&
+ normalize_datetime(&y, &m, &d, &hh, &mm, &ss, &us) < 0)
goto Fail;
temp = new_datetimetz(y, m, d, hh, mm, ss, us, tzinfo);
if (temp == NULL)
@@ -4805,16 +4807,19 @@
* Unfortunately, we can be in trouble even if we didn't cross a
* DST boundary, if we landed on one of the DST "problem hours".
*/
- newoff = call_utcoffset(tzinfo, result, &none);
- if (newoff == -1 && PyErr_Occurred())
+ tempoff = call_utcoffset(tzinfo, result, &none);
+ if (tempoff == -1 && PyErr_Occurred())
goto Fail;
if (none)
goto Inconsistent;
- if (newoff != otoff) {
+ if (tempoff != resoff) {
/* We did cross a boundary. Try to correct. */
- mm += newoff - otoff;
- if (normalize_datetime(&y, &m, &d, &hh, &mm, &ss, &us) < 0)
+ const int delta = tempoff - resoff;
+ total_added_to_result += delta;
+ mm += delta;
+ if ((mm < 0 || mm >= 60) &&
+ normalize_datetime(&y, &m, &d, &hh, &mm, &ss, &us) < 0)
goto Fail;
temp = new_datetimetz(y, m, d, hh, mm, ss, us, tzinfo);
if (temp == NULL)
@@ -4822,8 +4827,8 @@
Py_DECREF(result);
result = temp;
- otoff = call_utcoffset(tzinfo, result, &none);
- if (otoff == -1 && PyErr_Occurred())
+ resoff = call_utcoffset(tzinfo, result, &none);
+ if (resoff == -1 && PyErr_Occurred())
goto Fail;
if (none)
goto Inconsistent;
@@ -4834,13 +4839,13 @@
* sense on the local clock. So force that.
*/
hh -= 1;
- if (normalize_datetime(&y, &m, &d, &hh, &mm, &ss, &us) < 0)
+ if (hh < 0 && normalize_datetime(&y, &m, &d, &hh, &mm, &ss, &us) < 0)
goto Fail;
temp = new_datetimetz(y, m, d, hh, mm, ss, us, tzinfo);
if (temp == NULL)
goto Fail;
- newoff = call_utcoffset(tzinfo, temp, &none);
- if (newoff == -1 && PyErr_Occurred()) {
+ tempoff = call_utcoffset(tzinfo, temp, &none);
+ if (tempoff == -1 && PyErr_Occurred()) {
Py_DECREF(temp);
goto Fail;
}
@@ -4849,11 +4854,11 @@
goto Inconsistent;
}
/* Are temp and result really the same time? temp == result iff
- * temp - newoff == result - otoff, iff
- * (result - HOUR) - newoff = result - otoff, iff
- * otoff - newoff == HOUR
+ * temp - tempoff == result - resoff, iff
+ * (result - HOUR) - tempoff = result - resoff, iff
+ * resoff - tempoff == HOUR
*/
- if (otoff - newoff == 60) {
+ if (resoff - tempoff == 60) {
/* use the local time that makes sense */
Py_DECREF(result);
return temp;
@@ -4861,18 +4866,19 @@
Py_DECREF(temp);
/* There's still a problem with the unspellable (in local time)
- * hour after DST ends.
+ * hour after DST ends. If self and result map to the same UTC time
+ * time, we're OK, else the hour is unrepresentable in the tzinfo
+ * zone. The result's local time now is
+ * self + total_added_to_result, so self == result iff
+ * self - selfoff == result - resoff, iff
+ * self - selfoff == (self + total_added_to_result) - resoff, iff
+ * - selfoff == total_added_to_result - resoff, iff
+ * total_added_to_result == resoff - selfoff
*/
- temp = datetime_richcompare((PyDateTime_DateTime *)self,
- result, Py_EQ);
- if (temp == NULL)
- goto Fail;
- if (temp == Py_True) {
- Py_DECREF(temp);
+ if (total_added_to_result == resoff - selfoff)
return result;
- }
- Py_DECREF(temp);
- /* Else there's no way to spell self in zone other.tz. */
+
+ /* Else there's no way to spell self in zone tzinfo. */
PyErr_SetString(PyExc_ValueError, "astimezone(): the source "
"datetimetz can't be expressed in the target "
"timezone's local time");