Zmq Questions about Block Rollback #16372

hello, I'd like to ask ZMQ whether block monitoring for bitcoin will process rollback blocks into queues for example： I found that ZMQ hashblock listener did not listen for the correct hash of the rollback block. Original Chain： 590482 -->590483 --->590484 Normal occurrence block rollback chain:590482 -->590483(roll) --->590484(roll)-->590485--->(......) ZMQ is not acquired the 590483(r) 590484(r) blockhash ,but the blockhash of 590485 is acquired. the old 590483 590484 is acquired Does Bitcoin ZMQ not support this?

Is this for fixed indexed or block check point?

Is this for fixed indexed or block check point?

yes,this is block index, imply put, the rollback block will not be retrieved via ZMQ

I could be missing something but looking at CChainState::ActivateBestChain you can see that NotifyBlockTip is only called for the tip of the reorg. Maybe you should "walk backwards" from that new tip until you find an already known block?

After all this behavior is expected and documented in https://github.com/bitcoin/bitcoin/blob/master/doc/zmq.md#remarks, quoting:

Note that when the block chain tip changes, a reorganisation may occur and just the tip will be notified. It is up to the subscriber to retrieve the chain from the last known block to the new tip.

You can close this.

FYI #16404.