NameNodeRpcServer#getEditsFromTxid currently decides which transactions are able to be served, i.e. which transactions are durable, using the following logic:
This assumes that the NameNode serving this request is the current writer/active NameNode, which may not be true in the ObserverNode situation. Since selectInputStreams now has a onlyDurableTxns flag, which, if enabled, will only return durable/committed transactions, we can instead leverage this to provide the same functionality. We should utilize this to avoid consistency issues when serving this request from the ObserverNode.