private long getColFamilyCutoffTime(ColumnFamilyDescriptor colDesc) {
    if (colDesc.getTimeToLive() == HConstants.FOREVER) {
      return -1;
    }
    return EnvironmentEdgeManager.currentTime() - (colDesc.getTimeToLive() * 1000L);
  }
This request helps determine if a region has to be compacted based on table's TTL.
hbase-server/src/main/java/org/apache/hadoop/hbase/util/compaction/MajorCompactionTTLRequest.java