As described in the related bug report, unnecessary updates
to the container db during replication can impact object
object GET performance in certain circumstances.
This patch changes swift/container/replicator.py so that
calls to merge_timestamps and update_reconciler_sync
are conditional on values having actually changed.
Related-Bug: 1332025
Change-Id: If498251656500ed7a3d7ca4b109ea1079b8513c2
The normalized form of the X-Timestamp header looks like a float with a fixed
width to ensure stable string sorting - normalized timestamps look like
"1402464677.04188"
To support overwrites of existing data without modifying the original
timestamp but still maintain consistency a second internal offset
vector is append to the normalized timestamp form which compares and
sorts greater than the fixed width float format but less than a newer
timestamp. The internalized format of timestamps looks like
"1402464677.04188_0000000000000000" - the portion after the underscore
is the offset and is a formatted hexadecimal integer.
The internalized form is not exposed to clients in responses from Swift.
Normal client operations will not create a timestamp with an offset.
The Timestamp class in common.utils supports internalized and normalized
formatting of timestamps and also comparison of timestamp values. When the
offset value of a Timestamp is 0 - it's considered insignificant and need not
be represented in the string format; to support backwards compatibility during
a Swift upgrade the internalized and normalized form of a Timestamp with an
insignificant offset are identical. When a timestamp includes an offset it
will always be represented in the internalized form, but is still excluded
from the normalized form. Timestamps with an equivalent timestamp portion
(the float part) will compare and order by their offset. Timestamps with a
greater timestamp portion will always compare and order greater than a
Timestamp with a lesser timestamp regardless of it's offset. String
comparison and ordering is guaranteed for the internalized string format, and
is backwards compatible for normalized timestamps which do not include an
offset.
The reconciler currently uses a offset bump to ensure that objects can move to
the wrong storage policy and be moved back. This use-case is valid because
the content represented by the user-facing timestamp is not modified in way.
Future consumers of the offset vector of timestamps should be mindful of HTTP
semantics of If-Modified and take care to avoid deviation in the response from
the object server without an accompanying change to the user facing timestamp.
DocImpact
Implements: blueprint storage-policies
Change-Id: Id85c960b126ec919a481dc62469bf172b7fb8549
After a container database is replicated, a _post_replicate_hook will enqueue
misplaced objects for the container-reconciler into the .misplaced_objects
containers. Items to be reconciled are "batch loaded" into the reconciler
queue and the end of a container replication cycle by levering container
replication itself.
DocImpact
Implements: blueprint storage-policies
Change-Id: I3627efcdea75403586dffee46537a60add08bfda
Keep status_changed_at in container databases current with status changes that
occur as a result of container creation, deletion, or re-creation.
Merge container put/delete/created timestamps when handling replicate
responses from remote servers in addition to during the handling of the
REPLICATE request.
When storage policies are configured on a cluster send status_changed_at,
object_count and storage_policy_index as part of container replication sync
args.
Use status_changed_at during replication to determine the oldest active
container and merge storage_policy_index.
DocImpact
Implements: blueprint storage-policies
Change-Id: Ib9a0dd42c271145e641437dc04d0ebea1e11fc47
This reverts commit 7760f41c3ce436cb23b4b8425db3749a3da33d32
Change-Id: I95e57a2563784a8cd5e995cc826afeac0eadbe62
Signed-off-by: Peter Portante <peter.portante@redhat.com>
Place all the methods related to on-disk layout and / or configuration
into a new common module that can be shared by the various modules
using the same on-disk layout.
Change-Id: I27ffd4665d5115ffdde649c48a4d18e12017e6a9
Signed-off-by: Peter Portante <peter.portante@redhat.com>
Before, a really lagged cluster might not get its final report for a
deleted container database sent to its corresponding account
database. In such a case, the container database file would be
permanently deleted while still leaving the container listed in the
account database, never to be updated since the actual container
database file was gone. The only way to fix such the situation before
was to recreate and redelete the container.
Now, the container database file will not be permanently deleted
until it has sent its final report successfully to its corresponding
account database.
Change-Id: I1f42202455e7ecb0533b84ce7f45fcc7b98aeaa3
