Previously, ssync would not sync nor cleanup non-durable data
fragments on handoffs. When the reconstructor is syncing objects from
a handoff node (a 'revert' reconstructor job) it may be useful, and is
not harmful, to also send non-durable fragments if the receiver has
older or no fragment data.
Several changes are made to enable this. On the sending side:
- For handoff (revert) jobs, the reconstructor instantiates
SsyncSender with a new 'include_non_durable' option.
- If configured with the include_non_durable option, the SsyncSender
calls the diskfile yield_hashes function with options that allow
non-durable fragments to be yielded.
- The diskfile yield_hashes function is enhanced to include a
'durable' flag in the data structure yielded for each object.
- The SsyncSender includes the 'durable' flag in the metadata sent
during the missing_check exchange with the receiver.
- If the receiver requests the non-durable object, the SsyncSender
includes a new 'X-Backend-No-Commit' header when sending the PUT
subrequest for the object.
- The SsyncSender includes the non-durable object in the collection
of synced objects returned to the reconstructor so that the
non-durable fragment is removed from the handoff node.
On the receiving side:
- The object server includes a new 'X-Backend-Accept-No-Commit'
header in its response to SSYNC requests. This indicates to the
sender that the receiver has been upgraded to understand the
'X-Backend-No-Commit' header.
- The SsyncReceiver is enhanced to consider non-durable data when
determining if the sender's data is wanted or not.
- The object server PUT method is enhanced to check for and
'X-Backend-No-Commit' header before committing a diskfile.
If a handoff sender has both a durable and newer non-durable fragment
for the same object and frag-index, only the newer non-durable
fragment will be synced and removed on the first reconstructor
pass. The durable fragment will be synced and removed on the next
reconstructor pass.
Change-Id: I1d47b865e0a621f35d323bbed472a6cfd2a5971b
Closes-Bug: 1778002
1dceafa7d5