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"""
kombu.utils
===========
Internal utilities.
:copyright: (c) 2009 - 2012 by Ask Solem.
:license: BSD, see LICENSE for more details.
"""
from __future__ import absolute_import
import sys
from contextlib import contextmanager
from time import sleep
from uuid import UUID, uuid4 as _uuid4, _uuid_generate_random
from .encoding import safe_repr as _safe_repr
try:
import ctypes
except:
ctypes = None # noqa
__all__ = ['EqualityDict', 'say', 'uuid', 'kwdict', 'maybe_list',
'fxrange', 'fxrangemax', 'retry_over_time',
'emergency_dump_state', 'cached_property',
'reprkwargs', 'reprcall', 'nested']
def eqhash(o):
try:
return o.__eqhash__()
except AttributeError:
return hash(o)
class EqualityDict(dict):
def __getitem__(self, key):
h = eqhash(key)
if h not in self:
return self.__missing__(key)
return dict.__getitem__(self, h)
def __setitem__(self, key, value):
return dict.__setitem__(self, eqhash(key), value)
def __delitem__(self, key):
return dict.__delitem__(self, eqhash(key))
def say(m, *s):
sys.stderr.write(str(m) % s + '\n')
def uuid4():
# Workaround for http://bugs.python.org/issue4607
if ctypes and _uuid_generate_random: # pragma: no cover
buffer = ctypes.create_string_buffer(16)
_uuid_generate_random(buffer)
return UUID(bytes=buffer.raw)
return _uuid4()
def uuid():
"""Generate a unique id, having - hopefully - a very small chance of
collision.
For now this is provided by :func:`uuid.uuid4`.
"""
return str(uuid4())
gen_unique_id = uuid
if sys.version_info >= (2, 6, 5):
def kwdict(kwargs):
return kwargs
else:
def kwdict(kwargs): # pragma: no cover # noqa
"""Make sure keyword arguments are not in Unicode.
This should be fixed in newer Python versions,
see: http://bugs.python.org/issue4978.
"""
return dict((key.encode('utf-8'), value)
for key, value in kwargs.items())
def maybe_list(v):
if v is None:
return []
if hasattr(v, '__iter__'):
return v
return [v]
def fxrange(start=1.0, stop=None, step=1.0, repeatlast=False):
cur = start * 1.0
while 1:
if not stop or cur <= stop:
yield cur
cur += step
else:
if not repeatlast:
break
yield cur - step
def fxrangemax(start=1.0, stop=None, step=1.0, max=100.0):
sum_, cur = 0, start * 1.0
while 1:
if sum_ >= max:
break
yield cur
if stop:
cur = min(cur + step, stop)
else:
cur += step
sum_ += cur
def retry_over_time(fun, catch, args=[], kwargs={}, errback=None,
max_retries=None, interval_start=2, interval_step=2, interval_max=30,
callback=None):
"""Retry the function over and over until max retries is exceeded.
For each retry we sleep a for a while before we try again, this interval
is increased for every retry until the max seconds is reached.
:param fun: The function to try
:param catch: Exceptions to catch, can be either tuple or a single
exception class.
:keyword args: Positional arguments passed on to the function.
:keyword kwargs: Keyword arguments passed on to the function.
:keyword errback: Callback for when an exception in ``catch`` is raised.
The callback must take two arguments: ``exc`` and ``interval``, where
``exc`` is the exception instance, and ``interval`` is the time in
seconds to sleep next..
:keyword max_retries: Maximum number of retries before we give up.
If this is not set, we will retry forever.
:keyword interval_start: How long (in seconds) we start sleeping between
retries.
:keyword interval_step: By how much the interval is increased for each
retry.
:keyword interval_max: Maximum number of seconds to sleep between retries.
"""
retries = 0
interval_range = fxrange(interval_start,
interval_max + interval_start,
interval_step, repeatlast=True)
for retries, interval in enumerate(interval_range): # for infinity
try:
return fun(*args, **kwargs)
except catch, exc:
if max_retries is not None and retries > max_retries:
raise
if callback:
callback()
if errback:
errback(exc, interval)
for i in fxrange(stop=interval or 1.0):
if i and callback:
callback()
sleep(i)
def emergency_dump_state(state, open_file=open, dump=None):
from pprint import pformat
from tempfile import mktemp
if dump is None:
import pickle
dump = pickle.dump
persist = mktemp()
say('EMERGENCY DUMP STATE TO FILE -> %s <-' % persist)
fh = open_file(persist, 'w')
try:
try:
dump(state, fh, protocol=0)
except Exception, exc:
say('Cannot pickle state: %r. Fallback to pformat.' % (exc, ))
fh.write(pformat(state))
finally:
fh.flush()
fh.close()
return persist
class cached_property(object):
"""Property descriptor that caches the return value
of the get function.
*Examples*
.. code-block:: python
@cached_property
def connection(self):
return Connection()
@connection.setter # Prepares stored value
def connection(self, value):
if value is None:
raise TypeError('Connection must be a connection')
return value
@connection.deleter
def connection(self, value):
# Additional action to do at del(self.attr)
if value is not None:
print('Connection %r deleted' % (value, ))
"""
def __init__(self, fget=None, fset=None, fdel=None, doc=None):
self.__get = fget
self.__set = fset
self.__del = fdel
self.__doc__ = doc or fget.__doc__
self.__name__ = fget.__name__
self.__module__ = fget.__module__
def __get__(self, obj, type=None):
if obj is None:
return self
try:
return obj.__dict__[self.__name__]
except KeyError:
value = obj.__dict__[self.__name__] = self.__get(obj)
return value
def __set__(self, obj, value):
if obj is None:
return self
if self.__set is not None:
value = self.__set(obj, value)
obj.__dict__[self.__name__] = value
def __delete__(self, obj):
if obj is None:
return self
try:
value = obj.__dict__.pop(self.__name__)
except KeyError:
pass
else:
if self.__del is not None:
self.__del(obj, value)
def setter(self, fset):
return self.__class__(self.__get, fset, self.__del)
def deleter(self, fdel):
return self.__class__(self.__get, self.__set, fdel)
def reprkwargs(kwargs, sep=', ', fmt='%s=%s'):
return sep.join(fmt % (k, _safe_repr(v)) for k, v in kwargs.iteritems())
def reprcall(name, args=(), kwargs={}, sep=', '):
return '%s(%s%s%s)' % (name, sep.join(map(_safe_repr, args or ())),
(args and kwargs) and sep or '',
reprkwargs(kwargs, sep))
@contextmanager
def nested(*managers): # pragma: no cover
"""Combine multiple context managers into a single nested
context manager."""
exits = []
vars = []
exc = (None, None, None)
try:
try:
for mgr in managers:
exit = mgr.__exit__
enter = mgr.__enter__
vars.append(enter())
exits.append(exit)
yield vars
except:
exc = sys.exc_info()
finally:
while exits:
exit = exits.pop()
try:
if exit(*exc):
exc = (None, None, None)
except:
exc = sys.exc_info()
if exc != (None, None, None):
# Don't rely on sys.exc_info() still containing
# the right information. Another exception may
# have been raised and caught by an exit method
raise exc[0], exc[1], exc[2]
finally:
del(exc)
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