Jian Zhang

HDFS-17545. [ARR] router async rpc client.

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### Description of PR please see: https://issues.apache.org/jira/browse/HDFS-17545 ### How was this patch tested? ### For code changes: - [x] Does the title or this PR starts with the corresponding JIRA...

HDFS-17552. [ARR] IPC client uses CompletableFuture to support asynchronous operations.

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### Description of PR please see: https://issues.apache.org/jira/browse/HDFS-17552 NOTE: This is a sub-pull request (PR) related to HDFS-17531(Asynchronous router RPC). For more details or context, please refer to the main issue...

HDFS-17438. RBF: The newest STANDBY and UNAVAILABLE nn should be the lowest priority.

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### Description of PR seeAlso: https://issues.apache.org/jira/browse/HDFS-17438 At present, when the status of all namenodes in an ns in the router is the same, the namenode which is the newest reported...

HDFS-17476. fix: False positive "Observer Node is too far behind" due to long overflow.

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### Description of PR seeAlse : https://issues.apache.org/jira/browse/HDFS-17476 In the code GlobalStateIdContext#receiveRequestState(), if clientStateId is a small negative number, clientStateId-serverStateId may be greater than （ESTIMATED_TRANSACTIONS_PER_SECOND due to overflow * TimeUnit.MILLISECONDS.toSeconds(clientWaitTime) *...