Comment 7 for bug 1467677

Reviewed: https://review.openstack.org/201055
Committed: https://git.openstack.org/cgit/openstack/swift/commit/?id=99d052772a9585e0befdfd292fd03aefde77180a
Submitter: Jenkins
Branch: master

commit 99d052772a9585e0befdfd292fd03aefde77180a
Author: Kota Tsuyuzaki <email address hidden>
Date: Mon Jul 13 01:12:43 2015 -0700

    Fix 499 client disconnected on COPY EC object

    Currently, a COPY request for an EC object might go to fail as 499 Client
    disconnected because of the difference between destination request content
    length and actual transferred bytes.

    That is because the conditional response status and content length for
    an EC object range GET is handled at calling the response instance on
    proxy server. Therefore the calling response instance (resp()) will change
    the conditional status from 200 (HTTP_OK) to 206 (PartialContent) and will
    change the content length for the range GET.

    In EC case, sometimes Swift needs whole stored contents to decode a segment.
    It will make 200 HTTP OK response from object-server and proxy-server
    will unfortunately set whole content length to the destination content
    length and it makes the bug 1467677.

    This patch introduces a new method "fix_conditional_response" for
    swift.common.swob.Response that calling _response_iter() and cached the
    iter in the Response instance. By calling it, Swift can set correct condtional
    response any time after setting whole content_length to the response
    instance like EC case.

    Change-Id: If85826243f955d2f03c6ad395215c73daab509b1
    Closes-Bug: #1467677