public synchronized int clear(RegionVersionVector rvv,
        Map<DiskEntry, VersionHolder> pendingKrfTags) {
      if (rvv == null) {
        if (pendingKrfTags != null) {
          pendingKrfTags.clear();
        }
        return clear();
      } else {
        // Clearing the list is handled in AbstractRegionMap.clear for RVV
        // based clears, because it removes each entry.
        // It needs to be handled there because the entry is synched at that
        // point
        return 0;
      }
    }
returns the number of entries cleared
geode-core/src/main/java/org/apache/geode/internal/cache/Oplog.java