2 * Copyright (c) 2015 Cisco Systems, Inc. and others. All rights reserved.
4 * This program and the accompanying materials are made available under the
5 * terms of the Eclipse Public License v1.0 which accompanies this distribution,
6 * and is available at http://www.eclipse.org/legal/epl-v10.html
9 package org.opendaylight.controller.cluster.raft.behaviors;
11 import akka.actor.ActorRef;
12 import com.google.common.base.Preconditions;
13 import org.opendaylight.controller.cluster.raft.base.messages.FollowerInitialSyncUpStatus;
16 * The SyncStatusTracker tracks if a Follower is in sync with any given Leader or not
17 * When an update is received from the Leader and the update happens to be the first update
18 * from that Leader then the SyncStatusTracker will not mark the Follower as not in-sync till the
19 * Followers commitIndex matches the commitIndex that the Leader sent in it's very first update.
20 * Subsequently when an update is received the tracker will consider the Follower to be out of
21 * sync if it is behind by 'syncThreshold' commits.
23 public class SyncStatusTracker {
25 private static final boolean IN_SYNC = true;
26 private static final boolean NOT_IN_SYNC = false;
27 private static final boolean FORCE_STATUS_CHANGE = true;
29 private final String id;
30 private String syncedLeaderId = null;
31 private final ActorRef actor;
32 private final int syncThreshold;
33 private boolean syncStatus = false;
34 private long minimumExpectedIndex = -2L;
36 public SyncStatusTracker(ActorRef actor, String id, int syncThreshold) {
37 this.actor = Preconditions.checkNotNull(actor, "actor should not be null");
38 this.id = Preconditions.checkNotNull(id, "id should not be null");
39 Preconditions.checkArgument(syncThreshold >= 0, "syncThreshold should be greater than or equal to 0");
40 this.syncThreshold = syncThreshold;
43 public void update(String leaderId, long leaderCommit, long commitIndex){
44 leaderId = Preconditions.checkNotNull(leaderId, "leaderId should not be null");
46 if(!leaderId.equals(syncedLeaderId)){
47 minimumExpectedIndex = leaderCommit;
48 changeSyncStatus(NOT_IN_SYNC, FORCE_STATUS_CHANGE);
49 syncedLeaderId = leaderId;
53 if((leaderCommit - commitIndex) > syncThreshold){
54 changeSyncStatus(NOT_IN_SYNC);
55 } else if((leaderCommit - commitIndex) <= syncThreshold && commitIndex >= minimumExpectedIndex) {
56 changeSyncStatus(IN_SYNC);
60 private void changeSyncStatus(boolean newSyncStatus){
61 changeSyncStatus(newSyncStatus, !FORCE_STATUS_CHANGE);
64 private void changeSyncStatus(boolean newSyncStatus, boolean forceStatusChange){
65 if(syncStatus == newSyncStatus && !forceStatusChange){
68 actor.tell(new FollowerInitialSyncUpStatus(newSyncStatus, id), ActorRef.noSender());
69 syncStatus = newSyncStatus;