Further Guava Optional cleanups
[controller.git] / opendaylight / md-sal / sal-akka-raft / src / main / java / org / opendaylight / controller / cluster / raft / behaviors / Leader.java
index 827364c..3534ac5 100644 (file)
@@ -7,14 +7,16 @@
  */
 package org.opendaylight.controller.cluster.raft.behaviors;
 
+import static java.util.Objects.requireNonNull;
+
 import akka.actor.ActorRef;
 import akka.actor.ActorSelection;
 import com.google.common.annotations.VisibleForTesting;
-import com.google.common.base.Preconditions;
 import com.google.common.base.Stopwatch;
+import java.util.Optional;
 import java.util.concurrent.TimeUnit;
-import javax.annotation.Nonnull;
-import javax.annotation.Nullable;
+import org.eclipse.jdt.annotation.NonNull;
+import org.eclipse.jdt.annotation.Nullable;
 import org.opendaylight.controller.cluster.raft.FollowerLogInformation;
 import org.opendaylight.controller.cluster.raft.RaftActorContext;
 import org.opendaylight.controller.cluster.raft.RaftActorLeadershipTransferCohort;
@@ -23,8 +25,9 @@ import org.opendaylight.controller.cluster.raft.base.messages.TimeoutNow;
 import org.opendaylight.controller.cluster.raft.messages.AppendEntriesReply;
 
 /**
- * The behavior of a RaftActor when it is in the Leader state
- * <p/>
+ * The behavior of a RaftActor when it is in the Leader state.
+ *
+ * <p>
  * Leaders:
  * <ul>
  * <li> Upon election: send initial empty AppendEntries RPCs
@@ -34,15 +37,14 @@ import org.opendaylight.controller.cluster.raft.messages.AppendEntriesReply;
  * respond after entry applied to state machine (§5.3)
  * <li> If last log index ≥ nextIndex for a follower: send
  * AppendEntries RPC with log entries starting at nextIndex
- * <ul>
  * <li> If successful: update nextIndex and matchIndex for
  * follower (§5.3)
  * <li> If AppendEntries fails because of log inconsistency:
  * decrement nextIndex and retry (§5.3)
- * </ul>
- * <li> If there exists an N such that N > commitIndex, a majority
+ * <li> If there exists an N such that N &gt; commitIndex, a majority
  * of matchIndex[i] ≥ N, and log[N].term == currentTerm:
  * set commitIndex = N (§5.3, §5.4).
+ * </ul>
  */
 public class Leader extends AbstractLeader {
     /**
@@ -55,21 +57,21 @@ public class Leader extends AbstractLeader {
     private final Stopwatch isolatedLeaderCheck = Stopwatch.createStarted();
     private @Nullable LeadershipTransferContext leadershipTransferContext;
 
-    Leader(RaftActorContext context, @Nullable AbstractLeader initializeFromLeader) {
+    Leader(final RaftActorContext context, @Nullable final AbstractLeader initializeFromLeader) {
         super(context, RaftState.Leader, initializeFromLeader);
     }
 
-    public Leader(RaftActorContext context) {
+    public Leader(final RaftActorContext context) {
         this(context, null);
     }
 
     @Override
-    public RaftActorBehavior handleMessage(ActorRef sender, Object originalMessage) {
-        Preconditions.checkNotNull(sender, "sender should not be null");
+    public RaftActorBehavior handleMessage(final ActorRef sender, final Object originalMessage) {
+        requireNonNull(sender, "sender should not be null");
 
         if (ISOLATED_LEADER_CHECK.equals(originalMessage)) {
             if (isLeaderIsolated()) {
-                LOG.warn("{}: At least {} followers need to be active, Switching {} from Leader to IsolatedLeader",
+                log.warn("{}: At least {} followers need to be active, Switching {} from Leader to IsolatedLeader",
                     context.getId(), getMinIsolatedLeaderPeerCount(), getLeaderId());
                 return internalSwitchBehavior(new IsolatedLeader(context, this));
             } else {
@@ -81,21 +83,23 @@ public class Leader extends AbstractLeader {
     }
 
     @Override
-    protected void beforeSendHeartbeat(){
-        if(isolatedLeaderCheck.elapsed(TimeUnit.MILLISECONDS) > context.getConfigParams().getIsolatedCheckIntervalInMillis()){
+    protected void beforeSendHeartbeat() {
+        if (isolatedLeaderCheck.elapsed(TimeUnit.MILLISECONDS)
+                > context.getConfigParams().getIsolatedCheckIntervalInMillis()) {
             context.getActor().tell(ISOLATED_LEADER_CHECK, context.getActor());
             isolatedLeaderCheck.reset().start();
         }
 
-        if(leadershipTransferContext != null && leadershipTransferContext.isExpired(
+        if (leadershipTransferContext != null && leadershipTransferContext.isExpired(
                 context.getConfigParams().getElectionTimeOutInterval().toMillis())) {
-            LOG.debug("{}: Leadership transfer expired", logName());
+            log.debug("{}: Leadership transfer expired", logName());
             leadershipTransferContext = null;
         }
     }
 
     @Override
-    protected RaftActorBehavior handleAppendEntriesReply(ActorRef sender, AppendEntriesReply appendEntriesReply) {
+    protected RaftActorBehavior handleAppendEntriesReply(final ActorRef sender,
+            final AppendEntriesReply appendEntriesReply) {
         RaftActorBehavior returnBehavior = super.handleAppendEntriesReply(sender, appendEntriesReply);
         tryToCompleteLeadershipTransfer(appendEntriesReply.getFollowerId());
         return returnBehavior;
@@ -107,20 +111,20 @@ public class Leader extends AbstractLeader {
      * <li>Start a timer (Stopwatch).</li>
      * <li>Send an initial AppendEntries heartbeat to all followers.</li>
      * <li>On AppendEntriesReply, check if the follower's new match Index matches the leader's last index</li>
-     * <li>If it matches, </li>
+     * <li>If it matches,
      *   <ul>
      *   <li>Send an additional AppendEntries to ensure the follower has applied all its log entries to its state.</li>
      *   <li>Send an ElectionTimeout to the follower to immediately start an election.</li>
      *   <li>Notify {@link RaftActorLeadershipTransferCohort#transferComplete}.</li>
-     *   </ul>
+     *   </ul></li>
      * <li>Otherwise if the election time out period elapses, notify
-     *     {@link RaftActorLeadershipTransferCohort#abortTtransfer}.</li>
+     *     {@link RaftActorLeadershipTransferCohort#abortTransfer}.</li>
      * </ul>
      *
-     * @param leadershipTransferCohort
+     * @param leadershipTransferCohort the cohort participating in the leadership transfer
      */
-    public void transferLeadership(@Nonnull RaftActorLeadershipTransferCohort leadershipTransferCohort) {
-        LOG.debug("{}: Attempting to transfer leadership", logName());
+    public void transferLeadership(@NonNull final RaftActorLeadershipTransferCohort leadershipTransferCohort) {
+        log.debug("{}: Attempting to transfer leadership", logName());
 
         leadershipTransferContext = new LeadershipTransferContext(leadershipTransferCohort);
 
@@ -128,24 +132,31 @@ public class Leader extends AbstractLeader {
         sendAppendEntries(0, false);
     }
 
-    private void tryToCompleteLeadershipTransfer(String followerId) {
-        if(leadershipTransferContext == null) {
+    private void tryToCompleteLeadershipTransfer(final String followerId) {
+        if (leadershipTransferContext == null) {
+            return;
+        }
+
+        final Optional<String> requestedFollowerIdOptional
+                = leadershipTransferContext.transferCohort.getRequestedFollowerId();
+        if (requestedFollowerIdOptional.isPresent() && !requestedFollowerIdOptional.get().equals(followerId)) {
+            // we want to transfer leadership to specific follower
             return;
         }
 
         FollowerLogInformation followerInfo = getFollower(followerId);
-        if(followerInfo == null) {
+        if (followerInfo == null) {
             return;
         }
 
         long lastIndex = context.getReplicatedLog().lastIndex();
         boolean isVoting = context.getPeerInfo(followerId).isVoting();
 
-        LOG.debug("{}: tryToCompleteLeadershipTransfer: followerId: {}, matchIndex: {}, lastIndex: {}, isVoting: {}",
+        log.debug("{}: tryToCompleteLeadershipTransfer: followerId: {}, matchIndex: {}, lastIndex: {}, isVoting: {}",
                 logName(), followerId, followerInfo.getMatchIndex(), lastIndex, isVoting);
 
-        if(isVoting && followerInfo.getMatchIndex() == lastIndex) {
-            LOG.debug("{}: Follower's log matches - sending ElectionTimeout", logName());
+        if (isVoting && followerInfo.getMatchIndex() == lastIndex) {
+            log.debug("{}: Follower's log matches - sending ElectionTimeout", logName());
 
             // We can't be sure if the follower has applied all its log entries to its state so send an
             // additional AppendEntries with the latest commit index.
@@ -155,7 +166,7 @@ public class Leader extends AbstractLeader {
             ActorSelection followerActor = context.getPeerActorSelection(followerId);
             followerActor.tell(TimeoutNow.INSTANCE, context.getActor());
 
-            LOG.debug("{}: Leader transfer complete", logName());
+            log.debug("{}: Leader transfer complete", logName());
 
             leadershipTransferContext.transferCohort.transferComplete();
             leadershipTransferContext = null;
@@ -164,7 +175,7 @@ public class Leader extends AbstractLeader {
 
     @Override
     public void close() {
-        if(leadershipTransferContext != null) {
+        if (leadershipTransferContext != null) {
             LeadershipTransferContext localLeadershipTransferContext = leadershipTransferContext;
             leadershipTransferContext = null;
             localLeadershipTransferContext.transferCohort.abortTransfer();
@@ -174,12 +185,12 @@ public class Leader extends AbstractLeader {
     }
 
     @VisibleForTesting
-    void markFollowerActive(String followerId) {
+    void markFollowerActive(final String followerId) {
         getFollower(followerId).markFollowerActive();
     }
 
     @VisibleForTesting
-    void markFollowerInActive(String followerId) {
+    void markFollowerInActive(final String followerId) {
         getFollower(followerId).markFollowerInActive();
     }
 
@@ -187,12 +198,12 @@ public class Leader extends AbstractLeader {
         RaftActorLeadershipTransferCohort transferCohort;
         Stopwatch timer = Stopwatch.createStarted();
 
-        LeadershipTransferContext(RaftActorLeadershipTransferCohort transferCohort) {
+        LeadershipTransferContext(final RaftActorLeadershipTransferCohort transferCohort) {
             this.transferCohort = transferCohort;
         }
 
-        boolean isExpired(long timeout) {
-            if(timer.elapsed(TimeUnit.MILLISECONDS) >= timeout) {
+        boolean isExpired(final long timeout) {
+            if (timer.elapsed(TimeUnit.MILLISECONDS) >= timeout) {
                 transferCohort.abortTransfer();
                 return true;
             }

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