BUG-8618: refactor SyncStatusTracker state

[controller.git] / opendaylight / md-sal / sal-akka-raft / src / main / java / org / opendaylight / controller / cluster / raft / behaviors / SyncStatusTracker.java

diff --git a/opendaylight/md-sal/sal-akka-raft/src/main/java/org/opendaylight/controller/cluster/raft/behaviors/SyncStatusTracker.java b/opendaylight/md-sal/sal-akka-raft/src/main/java/org/opendaylight/controller/cluster/raft/behaviors/SyncStatusTracker.java
index 85622a5908bf34074079201a5129618da8f867e8..08c90e32e308cecdc8391c9feff2cbc9ac21422a 100644 (file)
--- a/opendaylight/md-sal/sal-akka-raft/src/main/java/org/opendaylight/controller/cluster/raft/behaviors/SyncStatusTracker.java
+++ b/opendaylight/md-sal/sal-akka-raft/src/main/java/org/opendaylight/controller/cluster/raft/behaviors/SyncStatusTracker.java
@@ -11,6 +11,8 @@ package org.opendaylight.controller.cluster.raft.behaviors;
 import akka.actor.ActorRef;
 import com.google.common.base.Preconditions;
 import org.opendaylight.controller.cluster.raft.base.messages.FollowerInitialSyncUpStatus;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 
 /**
  * The SyncStatusTracker tracks if a Follower is in sync with any given Leader or not
@@ -21,51 +23,63 @@ import org.opendaylight.controller.cluster.raft.base.messages.FollowerInitialSyn
  * sync if it is behind by 'syncThreshold' commits.
  */
 public class SyncStatusTracker {
+    private static final class LeaderInfo {
+        final long minimumCommitIndex;
+        final String leaderId;
+
+        LeaderInfo(final String leaderId, final long minimumCommitIndex) {
+            this.leaderId = Preconditions.checkNotNull(leaderId);
+            this.minimumCommitIndex = minimumCommitIndex;
+        }
+    }
+
+    private static final Logger LOG = LoggerFactory.getLogger(SyncStatusTracker.class);
 
     private static final boolean IN_SYNC = true;
     private static final boolean NOT_IN_SYNC = false;
-    private static final boolean FORCE_STATUS_CHANGE = true;
 
     private final String id;
-    private String syncedLeaderId = null;
     private final ActorRef actor;
     private final int syncThreshold;
-    private boolean syncStatus = false;
-    private long minimumExpectedIndex = -2L;
 
-    public SyncStatusTracker(ActorRef actor, String id, int syncThreshold) {
+    private LeaderInfo syncTarget;
+    private boolean syncStatus;
+
+    public SyncStatusTracker(final ActorRef actor, final String id, final int syncThreshold) {
         this.actor = Preconditions.checkNotNull(actor, "actor should not be null");
         this.id = Preconditions.checkNotNull(id, "id should not be null");
         Preconditions.checkArgument(syncThreshold >= 0, "syncThreshold should be greater than or equal to 0");
         this.syncThreshold = syncThreshold;
     }
 
-    public void update(String leaderId, long leaderCommit, long commitIndex){
-        leaderId = Preconditions.checkNotNull(leaderId, "leaderId should not be null");
+    public void update(final String leaderId, final long leaderCommit, final long commitIndex) {
+        Preconditions.checkNotNull(leaderId, "leaderId should not be null");
 
-        if(!leaderId.equals(syncedLeaderId)){
-            minimumExpectedIndex = leaderCommit;
-            changeSyncStatus(NOT_IN_SYNC, FORCE_STATUS_CHANGE);
-            syncedLeaderId = leaderId;
+        if (syncTarget == null || !leaderId.equals(syncTarget.leaderId)) {
+            LOG.debug("Last sync leader does not match current leader {}, need to catch up to {}",
+                leaderId, leaderCommit);
+            changeSyncStatus(NOT_IN_SYNC, true);
+            syncTarget = new LeaderInfo(leaderId, leaderCommit);
             return;
         }
 
-        if((leaderCommit - commitIndex) > syncThreshold){
-            changeSyncStatus(NOT_IN_SYNC);
-        } else if((leaderCommit - commitIndex) <= syncThreshold && commitIndex >= minimumExpectedIndex) {
-            changeSyncStatus(IN_SYNC);
+        final long lag = leaderCommit - commitIndex;
+        if (lag > syncThreshold) {
+            LOG.debug("Lagging {} entries behind leader {}", lag, leaderId);
+            changeSyncStatus(NOT_IN_SYNC, false);
+        } else if (commitIndex >= syncTarget.minimumCommitIndex) {
+            LOG.debug("Lagging {} entries behind leader and reached {} (of expected {})", lag, leaderId, commitIndex,
+                syncTarget.minimumCommitIndex);
+            changeSyncStatus(IN_SYNC, false);
         }
     }
 
-    private void changeSyncStatus(boolean newSyncStatus){
-        changeSyncStatus(newSyncStatus, !FORCE_STATUS_CHANGE);
-    }
-
-    private void changeSyncStatus(boolean newSyncStatus, boolean forceStatusChange){
-        if(syncStatus == newSyncStatus && !forceStatusChange){
-            return;
+    private void changeSyncStatus(final boolean newSyncStatus, final boolean forceStatusChange) {
+        if (forceStatusChange || newSyncStatus != syncStatus) {
+            actor.tell(new FollowerInitialSyncUpStatus(newSyncStatus, id), ActorRef.noSender());
+            syncStatus = newSyncStatus;
+        } else {
+            LOG.trace("No change in sync status of {}, dampening message", actor);
         }
-        actor.tell(new FollowerInitialSyncUpStatus(newSyncStatus, id), ActorRef.noSender());
-        syncStatus = newSyncStatus;
     }
-}
\ No newline at end of file
+}