Improve segmented journal actor metrics

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

diff --git a/opendaylight/md-sal/sal-akka-raft/src/main/java/org/opendaylight/controller/cluster/raft/ElectionTerm.java b/opendaylight/md-sal/sal-akka-raft/src/main/java/org/opendaylight/controller/cluster/raft/ElectionTerm.java
index 9f0d02edb9d5aa111b841f0972c0d82ca07a7df8..61aafef51354e88ab678dcfeb4f43970e308e636 100644 (file)
--- a/opendaylight/md-sal/sal-akka-raft/src/main/java/org/opendaylight/controller/cluster/raft/ElectionTerm.java
+++ b/opendaylight/md-sal/sal-akka-raft/src/main/java/org/opendaylight/controller/cluster/raft/ElectionTerm.java
@@ -5,50 +5,51 @@
  * terms of the Eclipse Public License v1.0 which accompanies this distribution,
  * and is available at http://www.eclipse.org/legal/epl-v10.html
  */
-
 package org.opendaylight.controller.cluster.raft;
 
+import org.eclipse.jdt.annotation.Nullable;
+
 /**
  * ElectionTerm contains information about a RaftActors election term.
+ *
  * <p>
  * This information includes the last known current term of the RaftActor
- * and which peer was voted for by the RaftActor in that term
+ * and which candidate was voted for by the RaftActor in that term.
+ *
  * <p>
- * This class ensures that election term information is persisted
+ * This class ensures that election term information is persisted.
  */
 public interface ElectionTerm {
     /**
-     * latest term server has seen (initialized to 0
-     * on first boot, increases monotonically)
+     * Returns the current leader's Raft term.
+     *
+     * @return the current leader's Raft term.
      */
     long getCurrentTerm();
 
     /**
-     * candidateId that received vote in current
-     * term (or null if none)
+     * Returns the id of the candidate that this server voted for in current term.
+     *
+     * @return candidate id that received the vote or null if no candidate was voted for.
      */
-    String getVotedFor();
+    @Nullable String getVotedFor();
 
     /**
-     * To be called mainly when we are recovering in-memory election state from
-     * persistent storage
+     * This method updates the in-memory election term state. This method should be called when recovering election
+     * state from persistent storage.
      *
-     * @param currentTerm
-     * @param votedFor
+     * @param term the election term.
+     * @param votedFor the candidate id that was voted for.
      */
-    void update(long currentTerm, String votedFor);
+    void update(long term, @Nullable String votedFor);
 
     /**
-     * To be called when we need to update the current term either because we
-     * received a message from someone with a more up-to-date term or because we
-     * just voted for someone
-     * <p>
-     * This information needs to be persisted so that on recovery the replica
-     * can start itself in the right term and know if it has already voted in
-     * that term or not
+     * This method updates the in-memory election term state and persists it so it can be recovered on next restart.
+     * This method should be called when starting a new election or when a Raft RPC message is received  with a higher
+     * term.
      *
-     * @param currentTerm
-     * @param votedFor
+     * @param term the election term.
+     * @param votedFor the candidate id that was voted for.
      */
-    void updateAndPersist(long currentTerm, String votedFor);
+    void updateAndPersist(long term, @Nullable String votedFor);
 }