[Bug] Multi-level (such as star topology) geo-replication doesn't work after PIP-180 in Pulsar 3.0.0

[lhotari]

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• I searched in the issues and found nothing similar.

Read release policy

• I understand that unsupported versions don't get bug fixes. I will attempt to reproduce the issue on a supported version of Pulsar client and Pulsar broker.

Version

Since Pulsar 3.0.0 with PR #17150 changes

Minimal reproduce step

This code break multi-level replication:

pulsar/pulsar-broker/src/main/java/org/apache/pulsar/broker/service/persistent/GeoPersistentReplicator.java

Lines 135 to 141 in 44f9860

	if (msg.isReplicated()) {
	// Discard messages that were already replicated into this region
	cursor.asyncDelete(entry.getPosition(), this, entry.getPosition());
	entry.release();
	msg.recycle();
	continue;
	}

What did you expect to see?

Before Pulsar 3.0.0, it has been possible to have multi-level replication in Pulsar clusters, for example with a star topology. Star topology is useful since instead of having every cluster connected with every other cluster, it's possible to configure geo-replication in a star topology where the number of connections is significantly reduced.
I'm not sure if star topology was officially ever supported, but it has been possible to configure geo-replication successfully in that way in pulsar 2.x.

What did you see instead?

Forwarding of replicated messages is prevented with code added in #17150.

Anything else?

No response

Are you willing to submit a PR?

• I'm willing to submit a PR!

[lhotari]

It looks like multi-level 2-way replication has never been possible.

This is the code in branch-2.11:

pulsar/pulsar-broker/src/main/java/org/apache/pulsar/broker/service/persistent/PersistentReplicator.java

Lines 326 to 332 in ff3018a

	if (msg.isReplicated()) {
	// Discard messages that were already replicated into this region
	cursor.asyncDelete(entry.getPosition(), this, entry.getPosition());
	entry.release();
	msg.recycle();
	continue;
	}

Closing this issue since it's not introduced in PIP-180.