How to use

determineMergeLeader

method

in

org.jgroups.protocols.pbcast.Merger

/**
 * Invoked upon receiving a MERGE event from the MERGE layer. Starts the merge protocol.
 * See description of protocol in DESIGN.
 * @param views A List of <em>different</em> views detected by the merge protocol, keyed by sender
 */
public void merge(Map<Address, View> views) {
  if(views == null || views.isEmpty()) {
    log.warn("the views passed with the MERGE event were empty (or null); ignoring MERGE event");
    return;
  }
  if(View.sameViews(views.values())) {
    log.debug("MERGE event is ignored because of identical views: %s", Util.printListWithDelimiter(views.values(), ", "));
    return;
  }
  if(isMergeInProgress()) {
    log.trace("%s: merge is already running (merge_id=%s)", gms.local_addr, merge_id);
    return;
  }
  Address merge_leader=determineMergeLeader(views);
  if(merge_leader == null)
    return;
  if(merge_leader.equals(gms.local_addr)) {
    log.debug("%s: I will be the merge leader. Starting the merge task. Views: %s", gms.local_addr, views);
    merge_task.start(views);
  }
  else
    log.trace("%s: I'm not the merge leader, waiting for merge leader (%s) to start merge", gms.local_addr, merge_leader);
}

/**
 * Invoked upon receiving a MERGE event from the MERGE layer. Starts the merge protocol.
 * See description of protocol in DESIGN.
 * @param views A List of <em>different</em> views detected by the merge protocol, keyed by sender
 */
public void merge(Map<Address, View> views) {
  if(views == null || views.isEmpty()) {
    log.warn("the views passed with the MERGE event were empty (or null); ignoring MERGE event");
    return;
  }
  if(View.sameViews(views.values())) {
    log.debug("MERGE event is ignored because of identical views: %s", Util.printListWithDelimiter(views.values(), ", "));
    return;
  }
  if(isMergeInProgress()) {
    log.trace("%s: merge is already running (merge_id=%s)", gms.local_addr, merge_id);
    return;
  }
  Address merge_leader=determineMergeLeader(views);
  if(merge_leader == null)
    return;
  if(merge_leader.equals(gms.local_addr)) {
    log.debug("%s: I will be the merge leader. Starting the merge task. Views: %s", gms.local_addr, views);
    merge_task.start(views);
  }
  else
    log.trace("%s: I'm not the merge leader, waiting for merge leader (%s) to start merge", gms.local_addr, merge_leader);
}