Alistair Coles 45884c1102 Enable per policy proxy config options
This is an alternative approach to that proposed in [1]

Adds support for optional per-policy config sections
to be added in proxy-server.conf. This is highly desirable
to allow per-policy affinity options to be set for use with
duplicated EC policies [2] and composite rings [3].

Certain options found in per-policy conf sections will
override their equivalents that may be set in the
[app:proxy-server] section. Currently the options
handled that way are:

  sorting_method
  read_affinity
  write_affinity
  write_affinity_node_count

For example:

  [proxy-server:policy:0]
  sorting_method = affinity
  read_affinity = r1=100
  write_affinity = r1
  write_affinity_node_count = 1 * replicas

The corresponding attributes of the proxy-server Application
are now available from instances of an OverrideConf object
that is obtained from Application.get_policy_options(policy).

[1] Related-Change: I9104fc789ba85ab3ab5ccd34096125b482821389
[2] Related-Change: Idd155401982a2c48110c30b480966a863f6bd305
[3] Related-Change: I0d8928b55020592f8e75321d1f7678688301d797

Co-Authored-By: Kota Tsuyuzaki <tsuyuzaki.kota@lab.ntt.co.jp>
Change-Id: I3f718f425f525baa80045ba067950c752bcaaefc
2017-05-23 20:22:30 +01:00
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