public void logCompositeOrcCb(int lastChunkTaken, int lastChunkRemaining, DiskRange cc) {
    if (log == null) return;
    int offset = this.offset;
    if (offset + 5 > log.length) return;
    log[offset] = makeIntPair(COMPOSITE_ORC_CB, lastChunkTaken);
    log[offset + 1] = lastChunkRemaining;
    logRange(cc, offset + 2);
    this.offset += 5;
  }
Single threaded IO trace.
Note: this can be made MTT merely by using an AtomicInteger, and storing a thread ID.
ql/src/java/org/apache/hadoop/hive/ql/io/orc/encoded/IoTrace.java