public static WALKeyImpl writeRegionEventMarker(WAL wal,
    NavigableMap<byte[], Integer> replicationScope, RegionInfo hri, RegionEventDescriptor r,
    MultiVersionConcurrencyControl mvcc, RegionReplicationSink sink) throws IOException {
    WALKeyImpl walKey = writeMarker(wal, replicationScope, hri,
      WALEdit.createRegionEventWALEdit(hri, r), mvcc, null, sink);
    if (LOG.isTraceEnabled()) {
      LOG.trace("Appended region event marker " + TextFormat.shortDebugString(r));
    }
    return walKey;
  }
Write a region open marker indicating that the region is opened. This write is for internal use
only. Not for external client consumption.
hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/wal/WALUtil.java