Houliang Qi created IOTDB-948:
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Summary: Use binary search when checking the follower's match
index when catchup
Key: IOTDB-948
URL: https://issues.apache.org/jira/browse/IOTDB-948
Project: Apache IoTDB
Issue Type: Improvement
Components: Core/Cluster
Reporter: Houliang Qi
Now, when the follower lags behind the leader a lot, one catchup task will be
triggered. When catchup, it will judge whether a certain log saved in the
leader's memory is consistent with the follower. If so, the leader can use logs
in its memory to catch up. If the leader cannot find a log in memory that
matches the follower, the leader needs to send snapshots.
When checking whether the leader's log match with the follower's, the current
implementation starts from the largest index of the stored log in memory, and
traverses from large to small to see whether it is consistent with the
follower. However, each traversal will send one RPC. Since the maximum number
of logs in memory is 1000, there may be 1000 times of RPC, and the time is
O(n). If it becomes a binary search, it only needs O(log(n)), and 1000 logs
only need 10 RPC communications, it'll save communication cost.
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