niphlod
12acdb51d7
This is a refactor of everything web2py uses with redis. Specifically: - a refactored redis_cache.py that fixes #958, allowing a "fail gracefully" behaviour in case redis is not available - a refactored redis_session.py that blocks less with with_lock=True (although still not optimal) - a new (and NEEDED) redis_utils.py that serves as the base for everything else, allowing an RConn object that you can freely use as a redis.StrictRedis connection, and that you can override in case you're using a different library (or that web2py will use in case redis-py won't be the de-facto standard around) - a newly - and much anticipated - redis_scheduler.py. It's a slip-in replacement for the standard scheduler that uses redis for workers coordination. Feel free to dig in the code and improve it. For redis_cache and redis_session changes are BREAKING. It means that users will need to change the import locations and tune a bit the code. Now every module depends on an gluon.contrib.redis_utils.RConn object (or similar) that in turns is very similar to a redis.StrictRedis one. The redis instance is EXTERNAL to the modules themselves (no more "host, port, db, password" parameters in RedisCache or RedisSession) See the relevant docstrings for usage examples
71 lines
1.8 KiB
Python
71 lines
1.8 KiB
Python
#!/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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import thread
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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 = thread.allocate_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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