You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
48 lines
1.2 KiB
48 lines
1.2 KiB
6 years ago
|
import datetime
|
||
|
|
|
||
|
|
|
||
|
|
class NeverExpires(object):
|
||
|
|
def expired(self):
|
||
|
|
return False
|
||
|
|
|
||
|
|
|
||
|
|
class Timer(object):
|
||
|
|
"""
|
||
|
|
A simple timer that will indicate when an expiration time has passed.
|
||
|
|
"""
|
||
|
|
def __init__(self, expiration):
|
||
|
|
'Create a timer that expires at `expiration` (UTC datetime)'
|
||
|
|
self.expiration = expiration
|
||
|
|
|
||
|
|
@classmethod
|
||
|
|
def after(cls, elapsed):
|
||
|
|
"""
|
||
|
|
Return a timer that will expire after `elapsed` passes.
|
||
|
|
"""
|
||
|
|
return cls(datetime.datetime.utcnow() + elapsed)
|
||
|
|
|
||
|
|
def expired(self):
|
||
|
|
return datetime.datetime.utcnow() >= self.expiration
|
||
|
|
|
||
|
|
|
||
|
|
class LockTimeout(Exception):
|
||
|
|
'An exception when a lock could not be acquired before a timeout period'
|
||
|
|
|
||
|
|
|
||
|
|
class LockChecker(object):
|
||
|
|
"""
|
||
|
|
Keep track of the time and detect if a timeout has expired
|
||
|
|
"""
|
||
|
|
def __init__(self, session_id, timeout):
|
||
|
|
self.session_id = session_id
|
||
|
|
if timeout:
|
||
|
|
self.timer = Timer.after(timeout)
|
||
|
|
else:
|
||
|
|
self.timer = NeverExpires()
|
||
|
|
|
||
|
|
def expired(self):
|
||
|
|
if self.timer.expired():
|
||
|
|
raise LockTimeout(
|
||
|
|
'Timeout acquiring lock for %(session_id)s' % vars(self))
|
||
|
|
return False
|