Fix findbugs & build proto only if needed

ratis-server/src/main/java/org/apache/ratis/server/impl/CommitInfoCache.java

@@ -31,33 +31,35 @@
 
 /** Caching the commit information. */
 class CommitInfoCache {
-  static Long max(Long oldCommitIndex, long newCommitIndex) {
-    return oldCommitIndex == null || newCommitIndex > oldCommitIndex ? newCommitIndex : oldCommitIndex;
-  }
-
   static BiFunction<RaftPeerId, Long, Long> remapping(long newCommitIndex) {
-    return (id, oldCommitIndex) -> max(oldCommitIndex, newCommitIndex);
+    return (id, oldCommitIndex) -> oldCommitIndex == null || newCommitIndex > oldCommitIndex ?
+        newCommitIndex : oldCommitIndex;
   }
 
   private final ConcurrentMap<RaftPeerId, Long> map = new ConcurrentHashMap<>();
 
-  CommitInfoProto get(RaftPeer peer) {
-    return ProtoUtils.toCommitInfoProto(peer, get(peer.getId()));
+  Optional<Long> get(RaftPeerId id) {
+    return Optional.ofNullable(map.get(id));
   }
 
-  long get(RaftPeerId id) {
-    return Optional.ofNullable(map.get(id)).orElse(0L);
+  long getNonNull(RaftPeerId id) {
+    return get(id).orElse(0L);
   }
 
   CommitInfoProto update(RaftPeer peer, long newCommitIndex) {
     Objects.requireNonNull(peer, "peer == null");
-    final long computed = map.compute(peer.getId(), remapping(newCommitIndex));
-    return ProtoUtils.toCommitInfoProto(peer, computed);
+    final long updated = update(peer.getId(), newCommitIndex);
+    return ProtoUtils.toCommitInfoProto(peer, updated);
+  }
+
+  long update(RaftPeerId id, long newCommitIndex) {
+    Objects.requireNonNull(id, "peer == null");
+    return map.compute(id, remapping(newCommitIndex));
   }
 
   void update(CommitInfoProto newInfo) {
-    final long newCommitIndex = newInfo.getCommitIndex();
-    map.compute(RaftPeerId.valueOf(newInfo.getServer().getId()), remapping(newCommitIndex));
+    final RaftPeerId id = RaftPeerId.valueOf(newInfo.getServer().getId());
+    update(id, newInfo.getCommitIndex());
   }
 
   @Override

ratis-server/src/main/java/org/apache/ratis/server/impl/ConfigurationManager.java

@@ -17,6 +17,9 @@
  */
 package org.apache.ratis.server.impl;
 
+import org.apache.ratis.proto.RaftProtos.RaftPeerRole;
+import org.apache.ratis.protocol.RaftPeer;
+import org.apache.ratis.protocol.RaftPeerId;
 import org.apache.ratis.server.RaftConfiguration;
 import org.apache.ratis.util.JavaUtils;
 import org.apache.ratis.util.Preconditions;
@@ -31,17 +34,29 @@
  * entries.
  */
 public class ConfigurationManager {
+  private final RaftPeerId id;
   private final RaftConfigurationImpl initialConf;
   private final NavigableMap<Long, RaftConfigurationImpl> configurations = new TreeMap<>();
   /**
    * The current raft configuration. If configurations is not empty, should be
    * the last entry of the map. Otherwise is initialConf.
    */
   private volatile RaftConfigurationImpl currentConf;
+  /** Cache the peer corresponding to {@link #id}. */
+  private volatile RaftPeer currentPeer;
 
-  ConfigurationManager(RaftConfigurationImpl initialConf) {
+  ConfigurationManager(RaftPeerId id, RaftConfigurationImpl initialConf) {
+    this.id = id;
     this.initialConf = initialConf;
-    this.currentConf = initialConf;
+    setCurrentConf(initialConf);
+  }
+
+  private void setCurrentConf(RaftConfigurationImpl currentConf) {
+    this.currentConf = currentConf;
+    final RaftPeer peer = currentConf.getPeer(id, RaftPeerRole.FOLLOWER, RaftPeerRole.LISTENER);
+    if (peer != null) {
+      this.currentPeer = peer;
+    }
   }
 
   synchronized void addConfiguration(RaftConfiguration conf) {
@@ -57,29 +72,32 @@ synchronized void addConfiguration(RaftConfiguration conf) {
   private void addRaftConfigurationImpl(long logIndex, RaftConfigurationImpl conf) {
     configurations.put(logIndex, conf);
     if (logIndex == configurations.lastEntry().getKey()) {
-      currentConf = conf;
+      setCurrentConf(conf);
     }
   }
 
   RaftConfigurationImpl getCurrent() {
     return currentConf;
   }
 
+  RaftPeer getCurrentPeer() {
+    return currentPeer;
+  }
+
   /**
    * Remove all the configurations whose log index is >= the given index.
+   *
    * @param index The given index. All the configurations whose log index is >=
    *              this value will be removed.
-   * @return The configuration with largest log index < the given index.
    */
-  synchronized RaftConfiguration removeConfigurations(long index) {
+  synchronized void removeConfigurations(long index) {
     // remove all configurations starting at the index
-    for(final Iterator<?> iter = configurations.tailMap(index).entrySet().iterator(); iter.hasNext();) {
-      iter.next();
-      iter.remove();
+    final SortedMap<Long, RaftConfigurationImpl> tail = configurations.tailMap(index);
+    if (tail.isEmpty()) {
+      return;
     }
-    currentConf = configurations.isEmpty() ? initialConf :
-        configurations.lastEntry().getValue();
-    return currentConf;
+    tail.clear();
+    setCurrentConf(configurations.isEmpty() ? initialConf : configurations.lastEntry().getValue());
   }
 
   synchronized int numOfConf() {

ratis-server/src/main/java/org/apache/ratis/server/impl/RaftServerImpl.java

@@ -275,7 +275,7 @@ public long[] getFollowerNextIndices() {
     this.leaderElectionMetrics = LeaderElectionMetrics.getLeaderElectionMetrics(
         getMemberId(), state::getLastLeaderElapsedTimeMs);
     this.raftServerMetrics = RaftServerMetricsImpl.computeIfAbsentRaftServerMetrics(
-        getMemberId(), commitInfoCache::get, retryCache::getStatistics);
+        getMemberId(), commitInfoCache::getNonNull, retryCache::getStatistics);
 
     this.startComplete = new AtomicBoolean(false);
     this.threadGroup = new ThreadGroup(proxy.getThreadGroup(), getMemberId().toString());
@@ -452,6 +452,12 @@ public RaftGroupMemberId getMemberId() {
     return getState().getMemberId();
   }
 
+  @Override
+  public RaftPeer getPeer() {
+    return Optional.ofNullable(getState().getCurrentPeer())
+        .orElseGet(() -> getRaftServer().getPeer());
+  }
+
   @Override
   public DivisionInfo getInfo() {
     return info;
@@ -622,7 +628,8 @@ synchronized void changeToLeader() {
   public Collection<CommitInfoProto> getCommitInfos() {
     final List<CommitInfoProto> infos = new ArrayList<>();
     // add the commit info of this server
-    infos.add(updateCommitInfoCache());
+    final long commitIndex = updateCommitInfoCache();
+    infos.add(ProtoUtils.toCommitInfoProto(getPeer(), commitIndex));
 
     // add the commit infos of other servers
     if (getInfo().isLeader()) {
@@ -634,7 +641,9 @@ public Collection<CommitInfoProto> getCommitInfos() {
               raftConf.getAllPeers(RaftPeerRole.FOLLOWER).stream(),
               raftConf.getAllPeers(RaftPeerRole.LISTENER).stream())
           .filter(peer -> !peer.getId().equals(getId()))
-          .map(commitInfoCache::get)
+          .map(peer -> commitInfoCache.get(peer.getId())
+              .map(index -> ProtoUtils.toCommitInfoProto(peer, index))
+              .orElse(null))
           .filter(Objects::nonNull)
           .forEach(infos::add);
     }
@@ -1533,8 +1542,8 @@ private void preAppendEntriesAsync(RaftPeerId leaderId, RaftGroupId leaderGroupI
     }
   }
 
-  private CommitInfoProto updateCommitInfoCache() {
-    return commitInfoCache.update(getPeer(), state.getLog().getLastCommittedIndex());
+  private long updateCommitInfoCache() {
+    return commitInfoCache.update(getId(), state.getLog().getLastCommittedIndex());
   }
 
   ExecutorService getServerExecutor() {

ratis-server/src/main/java/org/apache/ratis/server/impl/ServerState.java

@@ -109,7 +109,7 @@ class ServerState {
     final RaftConfigurationImpl initialConf = RaftConfigurationImpl.newBuilder()
         .setConf(followerPeers, listenerPeers)
         .build();
-    configurationManager = new ConfigurationManager(initialConf);
+    configurationManager = new ConfigurationManager(id, initialConf);
     LOG.info("{}: {}", getMemberId(), configurationManager);
 
     final String storageDirName = group.getGroupId().getUuid().toString();
@@ -196,6 +196,10 @@ RaftConfigurationImpl getRaftConf() {
     return configurationManager.getCurrent();
   }
 
+  RaftPeer getCurrentPeer() {
+    return configurationManager.getCurrentPeer();
+  }
+
   long getCurrentTerm() {
     return currentTerm.get();
   }