++timestamp to MembershipEvent

cluster-api/src/main/java/io/scalecube/cluster/membership/MembershipEvent.java

@@ -2,6 +2,7 @@
 
 import io.scalecube.cluster.Member;
 import java.nio.ByteBuffer;
+import java.time.Instant;
 import java.util.Objects;
 import java.util.StringJoiner;
 
@@ -21,37 +22,41 @@ public enum Type {
   private final Member member;
   private final ByteBuffer oldMetadata;
   private final ByteBuffer newMetadata;
+  private final long timestamp;
 
   private MembershipEvent(
-      Type type, Member member, ByteBuffer oldMetadata, ByteBuffer newMetadata) {
+      Type type, Member member, ByteBuffer oldMetadata, ByteBuffer newMetadata, long timestamp) {
     this.type = type;
     this.member = member;
     this.oldMetadata = oldMetadata;
     this.newMetadata = newMetadata;
+    this.timestamp = timestamp;
   }
 
   /**
    * Creates REMOVED membership event with cluster member and its metadata (optional).
    *
    * @param member cluster member; not null
    * @param metadata member metadata; optional
+   * @param timestamp event timestamp
    * @return membership event
    */
-  public static MembershipEvent createRemoved(Member member, ByteBuffer metadata) {
+  public static MembershipEvent createRemoved(Member member, ByteBuffer metadata, long timestamp) {
     Objects.requireNonNull(member, "member must be not null");
-    return new MembershipEvent(Type.REMOVED, member, metadata, null);
+    return new MembershipEvent(Type.REMOVED, member, metadata, null, timestamp);
   }
 
   /**
    * Creates ADDED membership event with cluster member and its metadata.
    *
    * @param member cluster memeber; not null
    * @param metadata member metadata; not null
+   * @param timestamp event timestamp
    * @return membership event
    */
-  public static MembershipEvent createAdded(Member member, ByteBuffer metadata) {
+  public static MembershipEvent createAdded(Member member, ByteBuffer metadata, long timestamp) {
     Objects.requireNonNull(member, "member must be not null");
-    return new MembershipEvent(Type.ADDED, member, null, metadata);
+    return new MembershipEvent(Type.ADDED, member, null, metadata, timestamp);
   }
 
   /**
@@ -60,12 +65,13 @@ public static MembershipEvent createAdded(Member member, ByteBuffer metadata) {
    * @param member cluster member; not null
    * @param oldMetadata previous metadata; not null
    * @param newMetadata new metadata; not null
+   * @param timestamp event timestamp
    * @return membership event
    */
   public static MembershipEvent createUpdated(
-      Member member, ByteBuffer oldMetadata, ByteBuffer newMetadata) {
+      Member member, ByteBuffer oldMetadata, ByteBuffer newMetadata, long timestamp) {
     Objects.requireNonNull(member, "member must be not null");
-    return new MembershipEvent(Type.UPDATED, member, oldMetadata, newMetadata);
+    return new MembershipEvent(Type.UPDATED, member, oldMetadata, newMetadata, timestamp);
   }
 
   public Type type() {
@@ -96,16 +102,25 @@ public ByteBuffer newMetadata() {
     return newMetadata;
   }
 
+  public long timestamp() {
+    return timestamp;
+  }
+
   @Override
   public String toString() {
     return new StringJoiner(", ", MembershipEvent.class.getSimpleName() + "[", "]")
         .add("type=" + type)
         .add("member=" + member)
         .add("oldMetadata=" + metadataAsString(oldMetadata))
         .add("newMetadata=" + metadataAsString(newMetadata))
+        .add("timestamp=" + timestampAsString(timestamp))
         .toString();
   }
 
+  private String timestampAsString(long timestamp) {
+    return Instant.ofEpochMilli(timestamp).toString();
+  }
+
   private String metadataAsString(ByteBuffer metadata) {
     if (metadata == null) {
       return null;

cluster/src/main/java/io/scalecube/cluster/membership/MembershipProtocolImpl.java

@@ -583,7 +583,8 @@ private Mono<Void> onDeadMemberDetected(MembershipRecord r) {
           membershipTable.remove(member.id());
           // removed
           ByteBuffer metadata0 = metadataStore.removeMetadata(member);
-          MembershipEvent event = MembershipEvent.createRemoved(member, metadata0);
+          MembershipEvent event =
+              MembershipEvent.createRemoved(member, metadata0, System.currentTimeMillis());
           LOGGER_MEMBERSHIP.debug("Emitting membership event {}", event);
           sink.next(event);
         });
@@ -597,10 +598,11 @@ private void onAliveMemberDetected(
     boolean memberExists = members.containsKey(member.id());
 
     MembershipEvent event = null;
+    long timestamp = System.currentTimeMillis();
     if (!memberExists) {
-      event = MembershipEvent.createAdded(member, metadata1);
+      event = MembershipEvent.createAdded(member, metadata1, timestamp);
     } else if (!metadata1.equals(metadata0)) {
-      event = MembershipEvent.createUpdated(member, metadata0, metadata1);
+      event = MembershipEvent.createUpdated(member, metadata0, metadata1, timestamp);
     }
 
     members.put(member.id(), member);

cluster/src/test/java/io/scalecube/cluster/fdetector/FailureDetectorTest.java

@@ -416,7 +416,7 @@ private FailureDetectorImpl createFd(
         Flux.fromIterable(addresses)
             .filter(address -> !transport.address().equals(address))
             .map(address -> new Member("member-" + address.port(), null, address))
-            .map(member -> MembershipEvent.createAdded(member, null));
+            .map(member -> MembershipEvent.createAdded(member, null, 0));
 
     CorrelationIdGenerator cidGenerator = new CorrelationIdGenerator(localMember.id());
 

cluster/src/test/java/io/scalecube/cluster/gossip/GossipProtocolTest.java

@@ -262,7 +262,7 @@ private GossipProtocolImpl initGossipProtocol(Transport transport, List<Address>
         Flux.fromIterable(members)
             .filter(address -> !transport.address().equals(address))
             .map(address -> new Member("member-" + address.port(), null, address))
-            .map(member -> MembershipEvent.createAdded(member, null));
+            .map(member -> MembershipEvent.createAdded(member, null, 0));
 
     GossipProtocolImpl gossipProtocol =
         new GossipProtocolImpl(localMember, transport, membershipFlux, gossipConfig, scheduler);

examples/src/main/java/io/scalecube/examples/MembershipEventsExample.java

@@ -26,6 +26,7 @@ public static void main(String[] args) throws Exception {
     // Alice init cluster
     Cluster alice =
         new ClusterImpl()
+            .config(opts -> opts.memberAlias("Alice"))
             .config(opts -> opts.metadata(Collections.singletonMap("name", "Alice")))
             .handler(
                 cluster -> {
@@ -42,6 +43,7 @@ public void onMembershipEvent(MembershipEvent event) {
     // Bob join cluster
     Cluster bob =
         new ClusterImpl()
+            .config(opts -> opts.memberAlias("Bob"))
             .config(opts -> opts.metadata(Collections.singletonMap("name", "Bob")))
             .membership(opts -> opts.seedMembers(alice.address()))
             .handler(
@@ -59,6 +61,7 @@ public void onMembershipEvent(MembershipEvent event) {
     // Carol join cluster
     Cluster carol =
         new ClusterImpl()
+            .config(opts -> opts.memberAlias("Carol"))
             .config(opts -> opts.metadata(Collections.singletonMap("name", "Carol")))
             .membership(opts -> opts.seedMembers(alice.address(), bob.address()))
             .handler(