@Override
        public void visitLogEntryBeforeWrite(RegionInfo info, WALKey logKey, WALEdit logEdit) {
          this.appends++;
          if (this.appends % whenToRoll == 0) {
            LOG.info("Rolling after " + appends + " edits");
            // We used to do explicit call to rollWriter but changed it to a request
            // to avoid dead lock (there are less threads going on in this class than
            // in the regionserver -- regionserver does not have the issue).
            AbstractFSWALProvider.requestLogRoll(wal);
          }
        }
Verify the content of the WAL file. Verify that the file has expected number of edits.
@param wals may not be null
@return Count of edits.
hbase-diagnostics/src/main/java/org/apache/hadoop/hbase/wal/WALPerformanceEvaluation.java