# -*- coding: utf-8 -*-
"""
proxy.py
~~~~~~~~
⚡⚡⚡ Fast, Lightweight, Pluggable, TLS interception capable proxy server focused on
Network monitoring, controls & Application development, testing, debugging.
:copyright: (c) 2013-present by Abhinav Singh and contributors.
:license: BSD, see LICENSE for more details.
"""
import time
import threading
from queue import Empty
from typing import Any, Deque
from collections import deque
[docs]class cached_property: # pragma: no cover
"""Decorator for read-only properties evaluated only once within TTL period.
It can be used to create a cached property like this::
import random
# the class containing the property must be a new-style class
class MyClass:
# create property whose value is cached for ten minutes
@cached_property(ttl=600)
def randint(self):
# will only be evaluated every 10 min. at maximum.
return random.randint(0, 100)
The value is cached in the '_cached_properties' attribute of the object instance that
has the property getter method wrapped by this decorator. The '_cached_properties'
attribute value is a dictionary which has a key for every property of the
object which is wrapped by this decorator. Each entry in the cache is
created only when the property is accessed for the first time and is a
two-element tuple with the last computed property value and the last time
it was updated in seconds since the epoch.
The default time-to-live (TTL) is 0 seconds i.e. cached value will never expire.
To expire a cached property value manually just do::
del instance._cached_properties[<property name>]
Adopted from https://wiki.python.org/moin/PythonDecoratorLibrary#Cached_Properties
© 2011 Christopher Arndt, MIT License.
NOTE: We need this function only because Python in-built are only available
for 3.8+. Hence, we must get rid of this function once proxy.py no longer
support version older than 3.8.
.. spelling::
backports
getter
Arndt
del
"""
def __init__(self, ttl: float = 0):
self.ttl = ttl
def __call__(self, fget: Any, doc: Any = None) -> 'cached_property':
self.fget = fget
self.__doc__ = doc or fget.__doc__
self.__name__ = fget.__name__
self.__module__ = fget.__module__
return self
def __get__(self, inst: Any, owner: Any) -> Any:
now = time.time()
try:
value, last_update = inst._cached_properties[self.__name__]
if self.ttl > 0 and now - last_update > self.ttl: # noqa: WPS333
raise AttributeError
except (KeyError, AttributeError):
value = self.fget(inst)
try:
cache = inst._cached_properties
except AttributeError:
cache, inst._cached_properties = {}, {}
finally:
cache[self.__name__] = (value, now) # pylint: disable=E0601
return value
[docs]class NonBlockingQueue:
'''Simple, unbounded, non-blocking FIFO queue.
Supports only a single consumer.
NOTE: This is available in Python since 3.7 as SimpleQueue.
Here because proxy.py still supports 3.6
'''
def __init__(self) -> None:
self._queue: Deque[Any] = deque()
self._count: threading.Semaphore = threading.Semaphore(0)
[docs] def put(self, item: Any) -> None:
'''Put the item on the queue.'''
self._queue.append(item)
self._count.release()
[docs] def get(self) -> Any:
'''Remove and return an item from the queue.'''
if not self._count.acquire(False, None):
raise Empty
return self._queue.popleft()
[docs] def empty(self) -> bool:
'''Return True if the queue is empty, False otherwise (not reliable!).'''
return len(self._queue) == 0 # pragma: no cover
[docs] def qsize(self) -> int:
'''Return the approximate size of the queue (not reliable!).'''
return len(self._queue) # pragma: no cover