public void debug() {
    String msg = "active size=" + getActive().getDataSize();
    msg += " allow compaction is " + (allowCompaction.get() ? "true" : "false");
    msg +=
      " inMemoryCompactionInProgress is " + (inMemoryCompactionInProgress.get() ? "true" : "false");
    LOG.debug(msg);
  }
@param cell Find the row that comes after this one. If null, we return the first.
@return Next row or null if none found.
hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/CompactingMemStore.java