mirror of https://github.com/evilhero/mylar
48 lines
1.2 KiB
Python
48 lines
1.2 KiB
Python
import datetime
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class NeverExpires(object):
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def expired(self):
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return False
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class Timer(object):
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"""
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A simple timer that will indicate when an expiration time has passed.
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"""
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def __init__(self, expiration):
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"Create a timer that expires at `expiration` (UTC datetime)"
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self.expiration = expiration
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@classmethod
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def after(cls, elapsed):
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"""
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Return a timer that will expire after `elapsed` passes.
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"""
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return cls(datetime.datetime.utcnow() + elapsed)
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def expired(self):
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return datetime.datetime.utcnow() >= self.expiration
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class LockTimeout(Exception):
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"An exception when a lock could not be acquired before a timeout period"
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class LockChecker(object):
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"""
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Keep track of the time and detect if a timeout has expired
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"""
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def __init__(self, session_id, timeout):
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self.session_id = session_id
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if timeout:
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self.timer = Timer.after(timeout)
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else:
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self.timer = NeverExpires()
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def expired(self):
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if self.timer.expired():
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raise LockTimeout(
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"Timeout acquiring lock for %(session_id)s" % vars(self))
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return False
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