Tushar Gohad ed54066288 Add support for policy types, 'erasure_coding' policy
This patch extends the StoragePolicy class for non-replication storage
policies, the first one being "erasure coding".

Changes:

 - Add 'policy_type' support to BaseStoragePolicy class
 - Disallow direct instantiation of BaseStoragePolicy class

 - Subclass BaseStoragePolicy

   - "StoragePolicy":
     . Replication policy, default
     . policy_type = 'replication'

   - "ECStoragePolicy":
     . Erasure Coding policy
     . policy_type = 'erasure_coding'
     . Private member variables
       ec_type (EC backend),
       ec_num_data_fragments (number of fragments original
         data split into after erasure coding operation),
       ec_num_parity_fragments (number of parity fragments
       generated during erasure coding)
     . Private methods
       EC specific attributes and ring validator methods.

 - Swift will use PyECLib, a Python Erasure Coding library, for
   erasure coding operations. PyECLib is already an approved
   OpenStack core requirement.
   (https://bitbucket.org/kmgreen2/pyeclib/)

 - Add test cases for
   - 'policy_type' StoragePolicy member
   - policy_type == 'erasure_coding'

DocImpact

Co-Authored-By: Alistair Coles <alistair.coles@hp.com>
Co-Authored-By: Thiago da Silva <thiago@redhat.com>
Co-Authored-By: Clay Gerrard <clay.gerrard@gmail.com>
Co-Authored-By: Paul Luse <paul.e.luse@intel.com>
Co-Authored-By: Samuel Merritt <sam@swiftstack.com>
Co-Authored-By: Christian Schwede <christian.schwede@enovance.com>
Co-Authored-By: Yuan Zhou <yuan.zhou@intel.com>
Change-Id: Ie0e09796e3ec45d3e656fb7540d0e5a5709b8386
Implements: blueprint ec-proxy-work
2015-04-13 22:57:42 -07:00
..
2015-03-24 11:07:56 +01:00