NAME

Jifty::CAS::Store::Nested - A layered CAS store

DESCRIPTION

This is a layered backend for Jifty::CAS, which provides a way to combine multiple CAS backends. Writes are passed through to every layer, whereas reads stop on the first layer which contains the data. This allows a fast in-memory store to be layered on top of a durable file store, for instance.

Configuration requires providing two or more CAS classes:

    framework:
      CAS:
        Default:
          Class: Jifty::CAS::Store::Nested
          Parts:
            - Class: Jifty::CAS::Store::Memory
            - Class: Jifty::CAS::Store::LocalFile
              Path: %var/cas%

METHODS

BUILD

Constructs the sub-parts and stores them.

_store DOMAIN NAME BLOB

Stores the BLOB (a Jifty::CAS::Blob) in all parts, starting at the bottom. Returns the key on success or undef on failure.

key DOMAIN NAME

Returns the most recent key for the given pair of DOMAIN and NAME, or undef if none such exists.

retrieve DOMAIN KEY

Returns a Jifty::CAS::Blob for the given pair of DOMAIN and KEY, or undef if none such exists.

durable

If any of the parts are durable, the entire nested CAS backend is durable.