public void postWALRoll(Path oldPath, Path newPath) throws IOException {
    execOperation(coprocEnvironments.isEmpty() ? null : new WALObserverOperation() {
      @Override
      protected void call(WALObserver observer) throws IOException {
        observer.postWALRoll(this, oldPath, newPath);
      }
    });
  }
Called after rolling the current WAL
@param oldPath the path of the wal that we replaced
@param newPath the path of the wal we have created and now is the current
hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/wal/WALCoprocessorHost.java