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-rw-r--r--contrib/python/podman/libs/__init__.py96
1 files changed, 96 insertions, 0 deletions
diff --git a/contrib/python/podman/libs/__init__.py b/contrib/python/podman/libs/__init__.py
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+++ b/contrib/python/podman/libs/__init__.py
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+"""Support files for podman API implementation."""
+import datetime
+import re
+import threading
+
+__all__ = [
+ 'cached_property',
+ 'datetime_parse',
+ 'datetime_format',
+]
+
+
+class cached_property(object):
+ """cached_property() - computed once per instance, cached as attribute.
+
+ Maybe this will make a future version of python.
+ """
+
+ def __init__(self, func):
+ """Construct context manager."""
+ self.func = func
+ self.__doc__ = func.__doc__
+ self.lock = threading.RLock()
+
+ def __get__(self, instance, cls=None):
+ """Retrieve previous value, or call func()."""
+ if instance is None:
+ return self
+
+ attrname = self.func.__name__
+ try:
+ cache = instance.__dict__
+ except AttributeError: # objects with __slots__ have no __dict__
+ msg = ("No '__dict__' attribute on {}"
+ " instance to cache {} property.").format(
+ repr(type(instance).__name__), repr(attrname))
+ raise TypeError(msg) from None
+
+ with self.lock:
+ # check if another thread filled cache while we awaited lock
+ if attrname not in cache:
+ cache[attrname] = self.func(instance)
+ return cache[attrname]
+
+
+def datetime_parse(string):
+ """Convert timestamp to datetime.
+
+ Because date/time parsing in python is still pedantically stupid,
+ we rip the input string apart throwing out the stop characters etc;
+ then rebuild a string strptime() can parse. Igit!
+
+ - Python >3.7 will address colons in the UTC offset.
+ - There is no ETA on microseconds > 6 digits.
+ - And giving an offset and timezone name...
+
+ # match: 2018-05-08T14:12:53.797795191-07:00
+ # match: 2018-05-08T18:24:52.753227-07:00
+ # match: 2018-05-08 14:12:53.797795191 -0700 MST
+ # match: 2018-05-09T10:45:57.576002 (python isoformat())
+
+ Some people, when confronted with a problem, think “I know,
+ I'll use regular expressions.” Now they have two problems.
+ -- Jamie Zawinski
+ """
+ ts = re.compile(r'^(\d+)-(\d+)-(\d+)'
+ r'[ T]?(\d+):(\d+):(\d+).(\d+)'
+ r' *([-+][\d:]{4,5})? *')
+
+ x = ts.match(string)
+ if x is None:
+ raise ValueError('Unable to parse {}'.format(string))
+
+ # converting everything to int() not worth the readablity hit
+ igit_proof = '{}T{}.{}{}'.format(
+ '-'.join(x.group(1, 2, 3)),
+ ':'.join(x.group(4, 5, 6)),
+ x.group(7)[0:6],
+ x.group(8).replace(':', '') if x.group(8) else '',
+ )
+
+ format = '%Y-%m-%dT%H:%M:%S.%f'
+ if x.group(8):
+ format += '%z'
+ return datetime.datetime.strptime(igit_proof, format)
+
+
+def datetime_format(dt):
+ """Format datetime in consistent style."""
+ if isinstance(dt, str):
+ return datetime_parse(dt).isoformat()
+ elif isinstance(dt, datetime.datetime):
+ return dt.isoformat()
+ else:
+ raise ValueError('Unable to format {}. Type {} not supported.'.format(
+ dt, type(dt)))