from __future__ import absolute_import
import atexit
import binascii
import collections
import struct
from threading import Thread, Event
import weakref
from kafka.vendor import six
from kafka.errors import BufferUnderflowError
[docs]def crc32(data):
crc = binascii.crc32(data)
# py2 and py3 behave a little differently
# CRC is encoded as a signed int in kafka protocol
# so we'll convert the py3 unsigned result to signed
if six.PY3 and crc >= 2**31:
crc -= 2**32
return crc
[docs]def write_int_string(s):
if s is not None and not isinstance(s, six.binary_type):
raise TypeError('Expected "%s" to be bytes\n'
'data=%s' % (type(s), repr(s)))
if s is None:
return struct.pack('>i', -1)
else:
return struct.pack('>i%ds' % len(s), len(s), s)
[docs]def read_short_string(data, cur):
if len(data) < cur + 2:
raise BufferUnderflowError("Not enough data left")
(strlen,) = struct.unpack('>h', data[cur:cur + 2])
if strlen == -1:
return None, cur + 2
cur += 2
if len(data) < cur + strlen:
raise BufferUnderflowError("Not enough data left")
out = data[cur:cur + strlen]
return out, cur + strlen
[docs]def relative_unpack(fmt, data, cur):
size = struct.calcsize(fmt)
if len(data) < cur + size:
raise BufferUnderflowError("Not enough data left")
out = struct.unpack(fmt, data[cur:cur + size])
return out, cur + size
[docs]def group_by_topic_and_partition(tuples):
out = collections.defaultdict(dict)
for t in tuples:
assert t.topic not in out or t.partition not in out[t.topic], \
'Duplicate {0}s for {1} {2}'.format(t.__class__.__name__,
t.topic, t.partition)
out[t.topic][t.partition] = t
return out
[docs]class ReentrantTimer(object):
"""
A timer that can be restarted, unlike threading.Timer
(although this uses threading.Timer)
Arguments:
t: timer interval in milliseconds
fn: a callable to invoke
args: tuple of args to be passed to function
kwargs: keyword arguments to be passed to function
"""
def __init__(self, t, fn, *args, **kwargs):
if t <= 0:
raise ValueError('Invalid timeout value')
if not callable(fn):
raise ValueError('fn must be callable')
self.thread = None
self.t = t / 1000.0
self.fn = fn
self.args = args
self.kwargs = kwargs
self.active = None
def _timer(self, active):
# python2.6 Event.wait() always returns None
# python2.7 and greater returns the flag value (true/false)
# we want the flag value, so add an 'or' here for python2.6
# this is redundant for later python versions (FLAG OR FLAG == FLAG)
while not (active.wait(self.t) or active.is_set()):
self.fn(*self.args, **self.kwargs)
[docs] def start(self):
if self.thread is not None:
self.stop()
self.active = Event()
self.thread = Thread(target=self._timer, args=(self.active,))
self.thread.daemon = True # So the app exits when main thread exits
self.thread.start()
[docs] def stop(self):
if self.thread is None:
return
self.active.set()
self.thread.join(self.t + 1)
# noinspection PyAttributeOutsideInit
self.timer = None
self.fn = None
def __del__(self):
self.stop()
[docs]class WeakMethod(object):
"""
Callable that weakly references a method and the object it is bound to. It
is based on http://stackoverflow.com/a/24287465.
Arguments:
object_dot_method: A bound instance method (i.e. 'object.method').
"""
def __init__(self, object_dot_method):
try:
self.target = weakref.ref(object_dot_method.__self__)
except AttributeError:
self.target = weakref.ref(object_dot_method.im_self)
self._target_id = id(self.target())
try:
self.method = weakref.ref(object_dot_method.__func__)
except AttributeError:
self.method = weakref.ref(object_dot_method.im_func)
self._method_id = id(self.method())
def __call__(self, *args, **kwargs):
"""
Calls the method on target with args and kwargs.
"""
return self.method()(self.target(), *args, **kwargs)
def __hash__(self):
return hash(self.target) ^ hash(self.method)
def __eq__(self, other):
if not isinstance(other, WeakMethod):
return False
return self._target_id == other._target_id and self._method_id == other._method_id
[docs]def try_method_on_system_exit(obj, method, *args, **kwargs):
def wrapper(_obj, _meth, *args, **kwargs):
try:
getattr(_obj, _meth)(*args, **kwargs)
except (ReferenceError, AttributeError):
pass
atexit.register(wrapper, weakref.proxy(obj), method, *args, **kwargs)