void cancel() {
      cancelled = true;
    }
Process a {@link List} of {@link IndexEntry} belonging to the same {@link IndexSegment} to populate container and
log segment buckets. The function is called in reverse chronological order. That is, newest {@link IndexSegment}
to older ones.
@param indexSegment the {@link IndexSegment} where the index entries belong to
@param predicate if not null, then only apply entries from the index segment if the predicate is true.
@param keyFinalStates a {@link Map} of key to {@link IndexFinalState}.
@throws StoreException
ambry-store/src/main/java/com/github/ambry/store/BlobStoreStats.java