Parent

Merb::Cache::AbstractStrategyStore

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.

Attributes

stores[RW]

END: interface for creating strategy stores.

Public Class Methods

[](*stores) click to toggle source
Alias for: contextualize
contextualize(*stores) click to toggle source

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
Also aliased as: []
new(config = {}) click to toggle source
# File lib/merb-cache/stores/strategy/abstract_strategy_store.rb, line 50
def initialize(config = {})
  @stores = contextualized_stores.map do |cs|
    case cs
    when Symbol
      Merb::Cache[cs]
    when Class
      cs.new(config)
    end
  end
end

Public Instance Methods

clone() click to toggle source
# 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
delete(key, parameters = {}) click to toggle source

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
delete_all!() click to toggle source

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
exists?(key, parameters = {}) click to toggle source

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
fetch(key, parameters = {}, conditions = {}, &blk) click to toggle source

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
read(key, parameters = {}) click to toggle source

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
writable?(key, parameters = {}, conditions = {}) click to toggle source

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
write(key, data = nil, parameters = {}, conditions = {}) click to toggle source

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
write_all(key, data = nil, parameters = {}, conditions = {}) click to toggle source

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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