Improve follower term conflict resolution

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

diff --git a/opendaylight/md-sal/sal-akka-raft/src/main/java/org/opendaylight/controller/cluster/raft/FollowerLogInformation.java b/opendaylight/md-sal/sal-akka-raft/src/main/java/org/opendaylight/controller/cluster/raft/FollowerLogInformation.java
index fe836362c819211dc0720daadbbdaa89c8c8dd5d..ca3de5944b6c4c9c732230d495f12dfefd57bd42 100644 (file)
--- a/opendaylight/md-sal/sal-akka-raft/src/main/java/org/opendaylight/controller/cluster/raft/FollowerLogInformation.java
+++ b/opendaylight/md-sal/sal-akka-raft/src/main/java/org/opendaylight/controller/cluster/raft/FollowerLogInformation.java
@@ -89,16 +89,23 @@ public final class FollowerLogInformation {
     }
 
     /**
-     * Decrements the value of the follower's next index.
+     * Decrements the value of the follower's next index, taking into account its reported last log index.
      *
-     * @return true if the next index was decremented, ie it was previously >= 0, false otherwise.
+     * @param followerLastIndex follower's last reported index.
+     * @return true if the next index was decremented, i.e. it was previously >= 0, false otherwise.
      */
-    public boolean decrNextIndex() {
+    public boolean decrNextIndex(final long followerLastIndex) {
         if (nextIndex < 0) {
             return false;
         }
 
-        nextIndex--;
+        if (followerLastIndex >= 0 && nextIndex > followerLastIndex) {
+            // If the follower's last log index is lower than nextIndex, jump directly to it, so we converge
+            // on a common index more quickly.
+            nextIndex = followerLastIndex;
+        } else {
+            nextIndex--;
+        }
         return true;
     }