Redis Support
redis_support is a small library which provides simple support for common actions for the Redis key-value store. It is not an object-relational mapper, does not attempt to comprehensively solve all of your storage problems, and does not make julienne fries.
Redis Addition
Provides a connection to redis which is the same across all classes which use RedisSupport as a mixin. This connection can be set by calling, for example:
RedisSupport.redis = "localhost:6379"
Key Support
Redis provides a global keyspace. Most projects specify their keys using namespaces delimited by colons (:), with variables mixed in at particular points. For example:
users:1:email
redis_support
, when used as a mixin, will provide a simple method to
declare that namespace and access it later.
class User
include RedisSupport
redis_key :email, "users:USER_ID:email"
attr_accessor :id
def email
redis.get Keys.email( self.id )
end
end
Helpful exceptions are raised if you try to declare the same namespace twice - RedisSupport keeps track of all the key definitions your app wants to use.
Locking Support
There is also a simple locking mechanism based on SETNX. Locking is usually unnecessary since Redis operations are atomic and Redis' MULTI/EXEC/DISCARD gives you the ability to make multiple operations atomic. But sometimes it's useful - a contrived example - major_operation will block for up to 30 seconds if another process attempts to run it at the same time:
class User
include RedisSupport
redis_key :email, "users:USER_ID:email"
attr_accessor :id
def major_operation
redis_lock Keys.email( self.id ) do
# do my expensive stuff
end
end
end
Issues
- When RedisSupport.redis is called but not yet set, there is a stack-level too deep error though it should just return nil.