ENH: port time.pxd from cython (pandas-dev#45864)

* ENH: port time.pxd from cython

* update API test

* manually convert to dict for windows compat

* mypy fixup

Author: jbrockmendel

pandas/_libs/tslibs/ctime.pyx

@@ -0,0 +1,78 @@
+"""
+Cython implementation of (parts of) the standard library time module.
+"""
+
+from cpython.exc cimport PyErr_SetFromErrno
+from libc.stdint cimport int64_t
+
+
+cdef extern from "Python.h":
+    ctypedef int64_t _PyTime_t
+    _PyTime_t _PyTime_GetSystemClock() nogil
+    double _PyTime_AsSecondsDouble(_PyTime_t t) nogil
+
+from libc.time cimport (
+    localtime as libc_localtime,
+    time_t,
+    tm,
+)
+
+
+def pytime():
+    """
+    python-exposed for testing
+    """
+    return time()
+
+
+def pylocaltime():
+    """
+    python-exposed for testing
+    """
+    lt = localtime()
+    # https://github.com/pandas-dev/pandas/pull/45864#issuecomment-1033021599
+    return {
+        "tm_year": lt.tm_year,
+        "tm_mon": lt.tm_mon,
+        "tm_mday": lt.tm_mday,
+        "tm_hour": lt.tm_hour,
+        "tm_min": lt.tm_min,
+        "tm_sec": lt.tm_sec,
+        "tm_wday": lt.tm_wday,
+        "tm_yday": lt.tm_yday,
+        "tm_isdst": lt.tm_isdst,
+    }
+
+
+cdef inline double time() nogil:
+    cdef:
+        _PyTime_t tic
+
+    tic = _PyTime_GetSystemClock()
+    return _PyTime_AsSecondsDouble(tic)
+
+
+cdef inline int _raise_from_errno() except -1 with gil:
+    PyErr_SetFromErrno(RuntimeError)
+    return <int>-1  # Let the C compiler know that this function always raises.
+
+
+cdef inline tm localtime() nogil except *:
+    """
+    Analogue to the stdlib time.localtime.  The returned struct
+    has some entries that the stdlib version does not: tm_gmtoff, tm_zone
+    """
+    cdef:
+        time_t tic = <time_t>time()
+        tm* result
+
+    result = libc_localtime(&tic)
+    if result is NULL:
+        _raise_from_errno()
+    # Fix 0-based date values (and the 1900-based year).
+    # See tmtotuple() in https://github.com/python/cpython/blob/master/Modules/timemodule.c
+    result.tm_year += 1900
+    result.tm_mon += 1
+    result.tm_wday = (result.tm_wday + 6) % 7
+    result.tm_yday += 1
+    return result[0]

pandas/tests/tslibs/test_api.py

@@ -52,5 +52,6 @@ def test_namespace():
     ]
 
     expected = set(submodules + api)
-    names = [x for x in dir(tslibs) if not x.startswith("__")]
+    # exclude "ctime" bc it is not (yet) imported outside of tests
+    names = [x for x in dir(tslibs) if not x.startswith("__") and x != "ctime"]
     assert set(names) == expected

pandas/tests/tslibs/test_ctime.py

@@ -0,0 +1,44 @@
+"""
+These tests are adapted from cython's tests
+https://github.com/cython/cython/blob/master/tests/run/time_pxd.pyx
+"""
+# TODO(cython3): use cython's cpython.time implementation
+
+
+import time
+
+# error: Module "pandas._libs.tslibs" has no attribute "ctime"
+from pandas._libs.tslibs import ctime  # type: ignore[attr-defined]
+
+
+def test_time():
+    # check that ctime.time() matches time.time() to within call-time tolerance
+    tic1 = time.time()
+    tic2 = ctime.pytime()
+    tic3 = time.time()
+
+    assert tic1 <= tic3  # sanity check
+    assert tic1 <= tic2
+    assert tic2 <= tic3
+
+
+def test_localtime():
+    ltp = time.localtime()
+    ltc = ctime.pylocaltime()
+
+    if ltp.tm_sec != ltc["tm_sec"]:
+        # If the time.localtime call is just before the end of a second and the
+        #  ctime.localtime call is just after the beginning of the next second,
+        #  re-call.  This should not occur twice in a row.
+        ltp = time.localtime()
+        ltc = ctime.pylocaltime()
+
+    assert ltp.tm_year == ltc["tm_year"] or (ltp.tm_year, ltc["tm_year"])
+    assert ltp.tm_mon == ltc["tm_mon"] or (ltp.tm_mon, ltc["tm_mon"])
+    assert ltp.tm_mday == ltc["tm_mday"] or (ltp.tm_mday, ltc["tm_mday"])
+    assert ltp.tm_hour == ltc["tm_hour"] or (ltp.tm_hour, ltc["tm_hour"])
+    assert ltp.tm_min == ltc["tm_min"] or (ltp.tm_min, ltc["tm_min"])
+    assert ltp.tm_sec == ltc["tm_sec"] or (ltp.tm_sec, ltc["tm_sec"])
+    assert ltp.tm_wday == ltc["tm_wday"] or (ltp.tm_wday, ltc["tm_wday"])
+    assert ltp.tm_yday == ltc["tm_yday"] or (ltp.tm_yday, ltc["tm_yday"])
+    assert ltp.tm_isdst == ltc["tm_isdst"] or (ltp.tm_isdst, ltc["tm_isdst"])

setup.py

@@ -210,6 +210,7 @@ class CheckSDist(sdist_class):
         "pandas/_libs/parsers.pyx",
         "pandas/_libs/tslibs/base.pyx",
         "pandas/_libs/tslibs/ccalendar.pyx",
+        "pandas/_libs/tslibs/ctime.pyx",
         "pandas/_libs/tslibs/dtypes.pyx",
         "pandas/_libs/tslibs/period.pyx",
         "pandas/_libs/tslibs/strptime.pyx",
@@ -495,6 +496,7 @@ def srcpath(name=None, suffix=".pyx", subdir="src"):
     "_libs.tslib": {"pyxfile": "_libs/tslib", "depends": tseries_depends},
     "_libs.tslibs.base": {"pyxfile": "_libs/tslibs/base"},
     "_libs.tslibs.ccalendar": {"pyxfile": "_libs/tslibs/ccalendar"},
+    "_libs.tslibs.ctime": {"pyxfile": "_libs/tslibs/ctime"},
     "_libs.tslibs.dtypes": {"pyxfile": "_libs/tslibs/dtypes"},
     "_libs.tslibs.conversion": {
         "pyxfile": "_libs/tslibs/conversion",