fix race condition in updateCommittedIndex using CAS

[dxasu]

What this PR does

Fix a potential race condition in updateCommittedIndex callback by using Compare-And-Swap (CAS) instead of check-then-act pattern.

Why this change is needed

The previous implementation had a race condition:

// Before (race condition)
cci := s.getCommittedIndex()  // Step 1: read
if ci > cci {                  // Step 2: compare
    s.setCommittedIndex(ci)    // Step 3: write
}

In concurrent scenarios, this could cause the committed index to regress

Using CAS ensures atomic compare-and-swap:

// After (race-free)
cci := s.getCommittedIndex()
for ci > cci && !s.committedIndex.CompareAndSwap(cci, ci) {
cci = s.getCommittedIndex()
}
ensure the index only increases monotonically.

Signed-off-by: baycore [email protected]

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[serathius]

There is only one writer for committed Index, so there is no race condition at present. Atomic is used to serve reads for Status request. Might be still good to fix to prevent regressions in the future.