long appendEntry(WAL.Entry entry) {
      internify(entry);
      entryBuffer.add(entry);
      // TODO linkedlist entry
      // entry size plus WALKey pointers
      long incrHeap = entry.getEdit().heapSize() + ClassSize.align(2 * ClassSize.REFERENCE);
      heapInBuffer += incrHeap;
      return incrHeap;
    }
A buffer of some number of edits for a given region. This accumulates edits and also provides a
memory optimization in order to share a single byte array instance for the table and region
name. Also tracks memory usage of the accumulated edits.
hbase-server/src/main/java/org/apache/hadoop/hbase/wal/EntryBuffers.java