71 lines
1.7 KiB
Python
71 lines
1.7 KiB
Python
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#!/usr/bin/env python
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# -*- coding: utf-8 -*-
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"""
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Developed by niphlod@gmail.com
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License MIT/BSD/GPL
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Serves as base to implement Redis connection object and various utils
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for redis_cache, redis_session and redis_scheduler in the future
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Should-could be overriden in case redis doesn't keep up (e.g. cluster support)
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to ensure compatibility with another - similar - library
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"""
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import logging
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from threading import Lock
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import time
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from gluon import current
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logger = logging.getLogger("web2py.redis_utils")
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try:
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import redis
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from redis.exceptions import WatchError as RWatchError
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from redis.exceptions import ConnectionError as RConnectionError
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except ImportError:
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logger.error("Needs redis library to work")
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raise RuntimeError('Needs redis library to work')
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locker = Lock()
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def RConn(*args, **vars):
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"""
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Istantiates a StrictRedis connection with parameters, at the first time
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only
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"""
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locker.acquire()
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try:
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instance_name = 'redis_conn_' + current.request.application
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if not hasattr(RConn, instance_name):
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setattr(RConn, instance_name, redis.StrictRedis(*args, **vars))
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return getattr(RConn, instance_name)
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finally:
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locker.release()
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def acquire_lock(conn, lockname, identifier, ltime=10):
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while True:
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if conn.set(lockname, identifier, ex=ltime, nx=True):
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return identifier
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time.sleep(.01)
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_LUA_RELEASE_LOCK = """
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if redis.call("get", KEYS[1]) == ARGV[1]
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then
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return redis.call("del", KEYS[1])
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else
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return 0
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end
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"""
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def release_lock(instance, lockname, identifier):
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return instance._release_script(
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keys=[lockname], args=[identifier])
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def register_release_lock(conn):
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rtn = conn.register_script(_LUA_RELEASE_LOCK)
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return rtn
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