Comment 12 for bug 1031954

Reviewed: https://review.openstack.org/10846
Committed: http://github.com/openstack/swift/commit/f8ce43a21891ae2cc00d0770895b556eea9c7845
Submitter: Jenkins
Branch: master

commit f8ce43a21891ae2cc00d0770895b556eea9c7845
Author: Darrell Bishop <email address hidden>
Date: Sun Aug 5 00:51:49 2012 -0700

    Use custom encoding for RingData, not pickle.

    Serialize RingData in a versioned, custom format which is a combination
    of a JSON-encoded header and .tostring() dumps of the
    replica2part2dev_id arrays. This format deserializes hundreds of times
    faster than rings serialized with Python 2.7's pickle (a significant
    performance regression for ring loading between Python 2.6 and Python
    2.7). Fixes bug 1031954.

    swift.common.ring.ring.RingData is now responsible for serialization and
    deserialization of its data via a new load() class method and save()
    object method. The new implementation is backward-compatible; if a ring
    does not begin with a new-style magic string, it is assumed to be an
    old-style pickle-dumped ring and is handled as before. So new Swift
    code can read old rings, but old Swift code will not be able to read
    newly-serialized rings. THIS SHOULD BE MENTIONED PROMINENTLY IN THE
    RELEASE NOTES.

    I didn't want to bite of more than necessary, so I didn't mess with
    builder file serialization.

    Change-Id: I799b9a4c894d54fb16592443904ac055b2638e2d