A Raft leader tracks the greatest replicated log index for every server in matchIndex. An entry can advance the commit index when it is stored on a majority of servers. Raft also restricts this calculation to entries from the leader's current term.
Design a RaftCommitCalculator class:
RaftCommitCalculator() creates a stateless calculator.int commitIndex(int[] matchIndex, int[] logTerms, int currentTerm) returns the greatest committable log index, or 0 if none qualifies.
Indices in matchIndex are one-based log positions. logTerms[i] is the term of log entry i + 1. A candidate N qualifies when:
Do not modify either input array.
Example 1:
Input:
Output:
Explanation: Three of five servers have index 3, which is a majority. Entry 3 belongs to term 2.
Example 2:
Input:
Output:
Explanation: A majority has replicated through index 2, but both entries through that frontier have older terms. Entry 3 is current-term but appears on only two servers.
Constraints
1 <= matchIndex.length <= 10^51 <= logTerms.length <= 10^50 <= matchIndex[i] <= logTerms.length1 <= logTerms[i] <= currentTerm <= 10^9logTerms is nondecreasing, as in a valid Raft log.- At most
100 calls are made to commitIndex.
Calculate the Raft Commit Indexmedium