/**
* 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
*/
public void merge(Map<Address, View> views) {
if (isMergeInProgress()) {
if (log.isTraceEnabled())
log.trace(gms.local_addr + ": merge is already running (merge_id=" + merge_id + ")");
return;
}
// we need the merge *coordinators* not merge participants because not everyone can lead a merge
// !
Collection<Address> coords = Util.determineMergeCoords(views);
Collection<Address> merge_participants = Util.determineMergeParticipants(views);
Membership tmp =
new Membership(coords); // establish a deterministic order, so that coords can elect leader
tmp.sort();
Address merge_leader = tmp.elementAt(0);
if (log.isDebugEnabled()) log.debug("determining merge leader from " + merge_participants);
if (merge_leader.equals(gms.local_addr)) {
if (log.isDebugEnabled())
log.debug(
"I ("
+ gms.local_addr
+ ") will be the leader. Starting the merge task for "
+ merge_participants);
merge_task.start(views);
} else {
if (log.isDebugEnabled())
log.debug(
"I ("
+ gms.local_addr
+ ") am not the merge leader, "
+ "waiting for merge leader ("
+ merge_leader
+ ") to initiate merge");
}
}
public static void testDetermineMergeParticipantsAndMergeCoords4() {
Address a = Util.createRandomAddress(),
b = Util.createRandomAddress(),
c = Util.createRandomAddress(),
d = Util.createRandomAddress();
org.jgroups.util.UUID.add(a, "A");
org.jgroups.util.UUID.add(b, "B");
org.jgroups.util.UUID.add(c, "C");
org.jgroups.util.UUID.add(d, "D");
View v1 = View.create(a, 1, a, b);
View v2 = View.create(c, 1, c, d);
Map<Address, View> map = new HashMap<>();
map.put(a, v1);
map.put(b, v1);
map.put(d, v2);
StringBuilder sb = new StringBuilder("map:\n");
for (Map.Entry<Address, View> entry : map.entrySet())
sb.append(entry.getKey() + ": " + entry.getValue() + "\n");
System.out.println(sb);
Collection<Address> merge_participants = Util.determineMergeParticipants(map);
System.out.println("merge_participants = " + merge_participants);
assert merge_participants.size() == 3;
assert merge_participants.contains(a)
&& merge_participants.contains(c)
&& merge_participants.contains(d);
Collection<Address> merge_coords = Util.determineMergeCoords(map);
System.out.println("merge_coords = " + merge_coords);
assert merge_coords.size() == 2;
assert merge_coords.contains(a) && merge_coords.contains(c);
}
/**
* @param views Guaranteed to be non-null and to have >= 2 members, or else this thread would
* not be started
*/
public synchronized void start(Map<Address, View> views) {
if (thread == null || thread.isAlive()) {
this.coords.clear();
// now remove all members which don't have us in their view, so RPCs won't block (e.g.
// FLUSH)
// https://jira.jboss.org/browse/JGRP-1061
sanitizeViews(views);
// Add all different coordinators of the views into the hashmap and sets their members:
Collection<Address> coordinators = Util.determineMergeCoords(views);
for (Address coord : coordinators) {
View view = views.get(coord);
if (view != null) this.coords.put(coord, new ArrayList<Address>(view.getMembers()));
}
// For the merge participants which are not coordinator, we simply add them, and the
// associated
// membership list consists only of themselves
Collection<Address> merge_participants = Util.determineMergeParticipants(views);
merge_participants.removeAll(coordinators);
for (Address merge_participant : merge_participants) {
Collection<Address> tmp = new ArrayList<Address>();
tmp.add(merge_participant);
coords.putIfAbsent(merge_participant, tmp);
}
thread = gms.getThreadFactory().newThread(this, "MergeTask");
thread.setDaemon(true);
thread.start();
}
}