dombizita opened a new pull request, #10570:
URL: https://github.com/apache/ozone/pull/10570
## What changes were proposed in this pull request?
Datanodes act in a client server relationship between themselves for
replication. In general the replication process is quite simple - commands are
sent to a datanode hosting a container replica (the replication client), and it
is told to push/upload the data to another node (the replication server).
Incompatible changes in this area can be handled in a similar way to write
requests.
SCM knows the apparent version of all Datanodes since their last heartbeat.
The last known apparent version of the target/server Datanode can be included
in the replicate command sent by SCM to the source/client Datanode. It is
always the job of the newer component to handle compatibility, whether it
involves software or apparent version. If the source/client Datanode is newer
in software or apparent version, it must "downgrade" its request to the lowest
common apparent version supported by the server indicated by the SCM command. A
newer target/server Datanode will not make incompatible changes to existing
APIs, so old client Datanodes will continue to work.
Changes in this patch:
- Added peerApparentVersion field to ReplicateContainerCommandProto.
- SCM (ReplicationManager): When sending a replicate command, SCM looks up
the peer datanode's last known apparent version (from heartbeat reports) and
sets it on the command. For push replication the peer is the target DN; for
pull replication it is the minimum apparent version across all source DNs.
- Datanode (ReplicateContainerCommandHandler): Upon receiving the command,
the datanode computes min(own apparent version, peer apparent version) and
stores it as lowestCommonApparentVersion on the ReplicationTask.
- ReplicationTask: Exposes getLowestCommonApparentVersion() for
replicators to use when gating version-dependent protocol features in the
future.
Used Claude Opus 4.6.
## What is the link to the Apache JIRA
https://issues.apache.org/jira/browse/HDDS-15417
## How was this patch tested?
Green CI on my fork:
https://github.com/dombizita/ozone/actions/runs/27760621062
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