AbstractStore
A strategy store wraps one or more fundamental stores, acting as a middle man between caching requests.
For example, if you need to save memory on your Memcache server, you could wrap your MemcachedStore with a GzipStore. This would automatically compress the cached data when put into the cache, and decompress it on the way out. You can even wrap strategy caches with other strategy caches. If your key was comprised of sensitive information, like a SSN, you might want to encrypt the key before storage. Wrapping your GzipStore in a SHA1Store would take care of that for you.
The AbstractStore class defines 9 methods as the API:
writable?(key, parameters = {}, conditions = {}) exists?(key, parameters = {}) read(key, parameters = {}) write(key, data = nil, parameters = {}, conditions = {}) write_all(key, data = nil, parameters = {}, conditions = {}) fetch(key, parameters = {}, conditions = {}, &blk) delete(key, parameters = {}) delete_all delete_all!
AbstractStrategyStore implements all of these with the exception of delete_all. If a strategy store can guarantee that calling delete_all on it’s wrapped store(s) will only delete entries populated by the strategy store, it may define the safe version of delete_all. However, this is usually not the case, hence delete_all is not part of the public API for AbstractStrategyStore.
START: interface for creating strategy stores. This should/might change.
# File lib/merb-cache/stores/strategy/abstract_strategy_store.rb, line 36 def self.contextualize(*stores) Class.new(self) do cattr_accessor :contextualized_stores self.contextualized_stores = stores end end
# File lib/merb-cache/stores/strategy/abstract_strategy_store.rb, line 115 def clone twin = super twin.stores = self.stores.map {|s| s.clone} twin end
deletes the entry for the key & parameter from the store.
# File lib/merb-cache/stores/strategy/abstract_strategy_store.rb, line 104 def delete(key, parameters = {}) raise NotImplementedError end
deletes all entries for the key & parameters for the store. considered dangerous because strategy stores which call delete_all! on their context stores could delete other store’s entrees.
# File lib/merb-cache/stores/strategy/abstract_strategy_store.rb, line 111 def delete_all! raise NotImplementedError end
returns true/false/nil based on if data identified by the key & parameters is persisted in the store.
# File lib/merb-cache/stores/strategy/abstract_strategy_store.rb, line 99 def exists?(key, parameters = {}) raise NotImplementedError end
tries to read the data from the store. If that fails, it calls the block parameter and persists the result.
# File lib/merb-cache/stores/strategy/abstract_strategy_store.rb, line 93 def fetch(key, parameters = {}, conditions = {}, &blk) raise NotImplementedError end
gets the data from the store identified by the key & parameters. return nil if the entry does not exist.
# File lib/merb-cache/stores/strategy/abstract_strategy_store.rb, line 73 def read(key, parameters = {}) raise NotImplementedError end
determines if the store is able to persist data identified by the key & parameters with the given conditions.
# File lib/merb-cache/stores/strategy/abstract_strategy_store.rb, line 67 def writable?(key, parameters = {}, conditions = {}) raise NotImplementedError end
persists the data so that it can be retrieved by the key & parameters. returns nil if it is unable to persist the data. returns true if successful.
# File lib/merb-cache/stores/strategy/abstract_strategy_store.rb, line 80 def write(key, data = nil, parameters = {}, conditions = {}) raise NotImplementedError end
persists the data to all context stores. returns nil if none of the stores were able to persist the data. returns true if at least one write was successful.
# File lib/merb-cache/stores/strategy/abstract_strategy_store.rb, line 87 def write_all(key, data = nil, parameters = {}, conditions = {}) raise NotImplementedError end
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