Remove client feature tracking

server/src/main/java/org/elasticsearch/cluster/ClusterState.java

@@ -65,7 +65,6 @@
 import java.util.Locale;
 import java.util.Map;
 import java.util.Objects;
-import java.util.Optional;
 import java.util.Set;
 import java.util.stream.StreamSupport;
 
@@ -95,40 +94,7 @@ public class ClusterState implements ToXContentFragment, Diffable<ClusterState>
 
     public static final ClusterState EMPTY_STATE = builder(ClusterName.CLUSTER_NAME_SETTING.getDefault(Settings.EMPTY)).build();
 
-    /**
-     * An interface that implementors use when a class requires a client to maybe have a feature.
-     */
-    public interface FeatureAware {
-
-        /**
-         * An optional feature that is required for the client to have.
-         *
-         * @return an empty optional if no feature is required otherwise a string representing the required feature
-         */
-        default Optional<String> getRequiredFeature() {
-            return Optional.empty();
-        }
-
-        /**
-         * Tests whether or not the custom should be serialized. The criteria are:
-         * <ul>
-         * <li>the output stream must be at least the minimum supported version of the custom</li>
-         * </ul>
-         * <p>
-         * That is, we only serialize customs to clients than can understand the custom based on the version of the client.
-         *
-         * @param out    the output stream
-         * @param custom the custom to serialize
-         * @param <T>    the type of the custom
-         * @return true if the custom should be serialized and false otherwise
-         */
-        static <T extends VersionedNamedWriteable & FeatureAware> boolean shouldSerialize(final StreamOutput out, final T custom) {
-            return out.getVersion().onOrAfter(custom.getMinimalSupportedVersion());
-        }
-
-    }
-
-    public interface Custom extends NamedDiffable<Custom>, ToXContentFragment, FeatureAware {
+    public interface Custom extends NamedDiffable<Custom>, ToXContentFragment {
 
         /**
          * Returns <code>true</code> iff this {@link Custom} is private to the cluster and should never be send to a client.
@@ -777,13 +743,13 @@ public void writeTo(StreamOutput out) throws IOException {
         // filter out custom states not supported by the other node
         int numberOfCustoms = 0;
         for (final ObjectCursor<Custom> cursor : customs.values()) {
-            if (FeatureAware.shouldSerialize(out, cursor.value)) {
+            if (VersionedNamedWriteable.shouldSerialize(out, cursor.value)) {
                 numberOfCustoms++;
             }
         }
         out.writeVInt(numberOfCustoms);
         for (final ObjectCursor<Custom> cursor : customs.values()) {
-            if (FeatureAware.shouldSerialize(out, cursor.value)) {
+            if (VersionedNamedWriteable.shouldSerialize(out, cursor.value)) {
                 out.writeNamedWriteable(cursor.value);
             }
         }

server/src/main/java/org/elasticsearch/cluster/metadata/MetaData.java

@@ -27,8 +27,6 @@
 import org.apache.lucene.util.CollectionUtil;
 import org.elasticsearch.Version;
 import org.elasticsearch.action.AliasesRequest;
-import org.elasticsearch.cluster.ClusterState;
-import org.elasticsearch.cluster.ClusterState.FeatureAware;
 import org.elasticsearch.cluster.Diff;
 import org.elasticsearch.cluster.Diffable;
 import org.elasticsearch.cluster.DiffableUtils;
@@ -44,6 +42,7 @@
 import org.elasticsearch.common.collect.ImmutableOpenMap;
 import org.elasticsearch.common.io.stream.StreamInput;
 import org.elasticsearch.common.io.stream.StreamOutput;
+import org.elasticsearch.common.io.stream.VersionedNamedWriteable;
 import org.elasticsearch.common.regex.Regex;
 import org.elasticsearch.common.settings.Setting;
 import org.elasticsearch.common.settings.Setting.Property;
@@ -125,7 +124,7 @@ public enum XContentContext {
      */
     public static EnumSet<XContentContext> ALL_CONTEXTS = EnumSet.allOf(XContentContext.class);
 
-    public interface Custom extends NamedDiffable<Custom>, ToXContentFragment, ClusterState.FeatureAware {
+    public interface Custom extends NamedDiffable<Custom>, ToXContentFragment {
 
         EnumSet<XContentContext> context();
     }
@@ -916,13 +915,13 @@ public void writeTo(StreamOutput out) throws IOException {
         // filter out custom states not supported by the other node
         int numberOfCustoms = 0;
         for (final ObjectCursor<Custom> cursor : customs.values()) {
-            if (FeatureAware.shouldSerialize(out, cursor.value)) {
+            if (VersionedNamedWriteable.shouldSerialize(out, cursor.value)) {
                 numberOfCustoms++;
             }
         }
         out.writeVInt(numberOfCustoms);
         for (final ObjectCursor<Custom> cursor : customs.values()) {
-            if (FeatureAware.shouldSerialize(out, cursor.value)) {
+            if (VersionedNamedWriteable.shouldSerialize(out, cursor.value)) {
                 out.writeNamedWriteable(cursor.value);
             }
         }

server/src/main/java/org/elasticsearch/common/io/stream/VersionedNamedWriteable.java

@@ -35,4 +35,19 @@ public interface VersionedNamedWriteable extends NamedWriteable {
      * The minimal version of the recipient this object can be sent to
      */
     Version getMinimalSupportedVersion();
+
+    /**
+     * Tests whether or not the custom should be serialized. The criteria is the output stream must be at least the minimum supported
+     * version of the custom. That is, we only serialize customs to clients than can understand the custom based on the version of the
+     * client.
+     *
+     * @param out    the output stream
+     * @param custom the custom to serialize
+     * @param <T>    the type of the custom
+     * @return true if the custom should be serialized and false otherwise
+     */
+    static <T extends VersionedNamedWriteable> boolean shouldSerialize(final StreamOutput out, final T custom) {
+        return out.getVersion().onOrAfter(custom.getMinimalSupportedVersion());
+    }
+
 }

server/src/main/java/org/elasticsearch/persistent/PersistentTaskParams.java

@@ -19,13 +19,12 @@
 
 package org.elasticsearch.persistent;
 
-import org.elasticsearch.cluster.ClusterState;
 import org.elasticsearch.common.io.stream.VersionedNamedWriteable;
 import org.elasticsearch.common.xcontent.ToXContentObject;
 
 /**
  * Parameters used to start persistent task
  */
-public interface PersistentTaskParams extends VersionedNamedWriteable, ToXContentObject, ClusterState.FeatureAware {
+public interface PersistentTaskParams extends VersionedNamedWriteable, ToXContentObject {
 
 }

server/src/main/java/org/elasticsearch/persistent/PersistentTasksCustomMetaData.java

@@ -30,6 +30,7 @@
 import org.elasticsearch.common.Strings;
 import org.elasticsearch.common.io.stream.StreamInput;
 import org.elasticsearch.common.io.stream.StreamOutput;
+import org.elasticsearch.common.io.stream.VersionedNamedWriteable;
 import org.elasticsearch.common.io.stream.Writeable;
 import org.elasticsearch.common.xcontent.ConstructingObjectParser;
 import org.elasticsearch.common.xcontent.ObjectParser;
@@ -532,7 +533,7 @@ public PersistentTasksCustomMetaData(StreamInput in) throws IOException {
     public void writeTo(StreamOutput out) throws IOException {
         out.writeLong(lastAllocationId);
         Map<String, PersistentTask<?>> filteredTasks = tasks.values().stream()
-            .filter(t -> ClusterState.FeatureAware.shouldSerialize(out, t.getParams()))
+            .filter(t -> VersionedNamedWriteable.shouldSerialize(out, t.getParams()))
             .collect(Collectors.toMap(PersistentTask::getId, Function.identity()));
         out.writeMap(filteredTasks, StreamOutput::writeString, (stream, value) -> value.writeTo(stream));
     }

server/src/main/java/org/elasticsearch/plugins/Plugin.java

@@ -21,7 +21,6 @@
 
 import org.elasticsearch.bootstrap.BootstrapCheck;
 import org.elasticsearch.client.Client;
-import org.elasticsearch.cluster.ClusterState;
 import org.elasticsearch.cluster.metadata.IndexMetaData;
 import org.elasticsearch.cluster.metadata.IndexTemplateMetaData;
 import org.elasticsearch.cluster.metadata.MetaData;
@@ -49,7 +48,6 @@
 import java.util.Collections;
 import java.util.List;
 import java.util.Map;
-import java.util.Optional;
 import java.util.Set;
 import java.util.function.UnaryOperator;
 
@@ -72,17 +70,6 @@
  */
 public abstract class Plugin implements Closeable {
 
-    /**
-     * A feature exposed by the plugin. This should be used if a plugin exposes {@link ClusterState.Custom} or {@link MetaData.Custom}; see
-     * also {@link ClusterState.FeatureAware}.
-     *
-     * @return a feature set represented by this plugin, or the empty optional if the plugin does not expose cluster state or metadata
-     * customs
-     */
-    protected Optional<String> getFeature() {
-        return Optional.empty();
-    }
-
     /**
      * Returns components added by this plugin.
      *

server/src/main/java/org/elasticsearch/plugins/PluginsService.java

@@ -39,7 +39,6 @@
 import org.elasticsearch.common.settings.Settings;
 import org.elasticsearch.index.IndexModule;
 import org.elasticsearch.threadpool.ExecutorBuilder;
-import org.elasticsearch.transport.TransportSettings;
 
 import java.io.IOException;
 import java.lang.reflect.Constructor;
@@ -59,9 +58,7 @@
 import java.util.Locale;
 import java.util.Map;
 import java.util.Objects;
-import java.util.Optional;
 import java.util.Set;
-import java.util.TreeMap;
 import java.util.function.Function;
 import java.util.stream.Collectors;
 
@@ -202,7 +199,6 @@ private static void logPluginInfo(final List<PluginInfo> pluginInfos, final Stri
 
     public Settings updatedSettings() {
         Map<String, String> foundSettings = new HashMap<>();
-        final Map<String, String> features = new TreeMap<>();
         final Settings.Builder builder = Settings.builder();
         for (Tuple<PluginInfo, Plugin> plugin : plugins) {
             Settings settings = plugin.v2().additionalSettings();
@@ -214,23 +210,6 @@ public Settings updatedSettings() {
                 }
             }
             builder.put(settings);
-            final Optional<String> maybeFeature = plugin.v2().getFeature();
-            if (maybeFeature.isPresent()) {
-                final String feature = maybeFeature.get();
-                if (features.containsKey(feature)) {
-                    final String message = String.format(
-                            Locale.ROOT,
-                            "duplicate feature [%s] in plugin [%s], already added in [%s]",
-                            feature,
-                            plugin.v1().getName(),
-                            features.get(feature));
-                    throw new IllegalArgumentException(message);
-                }
-                features.put(feature, plugin.v1().getName());
-            }
-        }
-        for (final String feature : features.keySet()) {
-            builder.put(TransportSettings.FEATURE_PREFIX + "." + feature, true);
         }
         return builder.put(this.settings).build();
     }

server/src/main/java/org/elasticsearch/transport/InboundHandler.java

@@ -38,7 +38,6 @@
 import java.net.InetSocketAddress;
 import java.util.Collections;
 import java.util.Map;
-import java.util.Set;
 
 public class InboundHandler {
 
@@ -153,7 +152,6 @@ private void messageReceived(BytesReference reference, TcpChannel channel) throw
     }
 
     private void handleRequest(TcpChannel channel, InboundMessage.Request message, int messageLengthBytes) {
-        final Set<String> features = message.getFeatures();
         final String action = message.getActionName();
         final long requestId = message.getRequestId();
         final StreamInput stream = message.getStreamInput();
@@ -162,7 +160,7 @@ private void handleRequest(TcpChannel channel, InboundMessage.Request message, i
         TransportChannel transportChannel = null;
         try {
             if (message.isHandshake()) {
-                handshaker.handleHandshake(version, features, channel, requestId, stream);
+                handshaker.handleHandshake(version, channel, requestId, stream);
             } else {
                 final RequestHandlerRegistry reg = getRequestHandler(action);
                 if (reg == null) {
@@ -174,7 +172,7 @@ private void handleRequest(TcpChannel channel, InboundMessage.Request message, i
                 } else {
                     breaker.addWithoutBreaking(messageLengthBytes);
                 }
-                transportChannel = new TcpTransportChannel(outboundHandler, channel, action, requestId, version, features,
+                transportChannel = new TcpTransportChannel(outboundHandler, channel, action, requestId, version,
                     circuitBreakerService, messageLengthBytes, message.isCompress());
                 final TransportRequest request = reg.newRequest(stream);
                 request.remoteAddress(new TransportAddress(channel.getRemoteAddress()));
@@ -190,7 +188,7 @@ private void handleRequest(TcpChannel channel, InboundMessage.Request message, i
         } catch (Exception e) {
             // the circuit breaker tripped
             if (transportChannel == null) {
-                transportChannel = new TcpTransportChannel(outboundHandler, channel, action, requestId, version, features,
+                transportChannel = new TcpTransportChannel(outboundHandler, channel, action, requestId, version,
                     circuitBreakerService, 0, message.isCompress());
             }
             try {

server/src/main/java/org/elasticsearch/transport/InboundMessage.java

@@ -31,10 +31,6 @@
 
 import java.io.Closeable;
 import java.io.IOException;
-import java.util.Arrays;
-import java.util.Collections;
-import java.util.Set;
-import java.util.TreeSet;
 
 public abstract class InboundMessage extends NetworkMessage implements Closeable {
 
@@ -96,15 +92,12 @@ InboundMessage deserialize(BytesReference reference) throws IOException {
 
                 InboundMessage message;
                 if (TransportStatus.isRequest(status)) {
-                    final String[] featuresFound = streamInput.readStringArray();
-                    final Set<String> features;
-                    if (featuresFound.length == 0) {
-                        features = Collections.emptySet();
-                    } else {
-                        features = Collections.unmodifiableSet(new TreeSet<>(Arrays.asList(featuresFound)));
+                    if (streamInput.getVersion().before(Version.V_8_0_0)) {
+                        // discard features
+                        streamInput.readStringArray();
                     }
                     final String action = streamInput.readString();
-                    message = new Request(threadContext, remoteVersion, status, requestId, action, features, streamInput);
+                    message = new Request(threadContext, remoteVersion, status, requestId, action, streamInput);
                 } else {
                     message = new Response(threadContext, remoteVersion, status, requestId, streamInput);
                 }
@@ -146,22 +139,17 @@ private static void ensureVersionCompatibility(Version version, Version currentV
     public static class Request extends InboundMessage {
 
         private final String actionName;
-        private final Set<String> features;
 
-        Request(ThreadContext threadContext, Version version, byte status, long requestId, String actionName, Set<String> features,
+        Request(ThreadContext threadContext, Version version, byte status, long requestId, String actionName,
                 StreamInput streamInput) {
             super(threadContext, version, status, requestId, streamInput);
             this.actionName = actionName;
-            this.features = features;
         }
 
         String getActionName() {
             return actionName;
         }
 
-        Set<String> getFeatures() {
-            return features;
-        }
     }
 
     public static class Response extends InboundMessage {

server/src/main/java/org/elasticsearch/transport/OutboundHandler.java

@@ -49,17 +49,15 @@ final class OutboundHandler {
 
     private final String nodeName;
     private final Version version;
-    private final String[] features;
     private final ThreadPool threadPool;
     private final BigArrays bigArrays;
     private final TransportLogger transportLogger;
     private volatile TransportMessageListener messageListener = TransportMessageListener.NOOP_LISTENER;
 
-    OutboundHandler(String nodeName, Version version, String[] features, ThreadPool threadPool, BigArrays bigArrays,
+    OutboundHandler(String nodeName, Version version, ThreadPool threadPool, BigArrays bigArrays,
                     TransportLogger transportLogger) {
         this.nodeName = nodeName;
         this.version = version;
-        this.features = features;
         this.threadPool = threadPool;
         this.bigArrays = bigArrays;
         this.transportLogger = transportLogger;
@@ -83,8 +81,8 @@ void sendRequest(final DiscoveryNode node, final TcpChannel channel, final long
                      final TransportRequest request, final TransportRequestOptions options, final Version channelVersion,
                      final boolean compressRequest, final boolean isHandshake) throws IOException, TransportException {
         Version version = Version.min(this.version, channelVersion);
-        OutboundMessage.Request message = new OutboundMessage.Request(threadPool.getThreadContext(), features, request, version, action,
-            requestId, isHandshake, compressRequest);
+        OutboundMessage.Request message =
+            new OutboundMessage.Request(threadPool.getThreadContext(), request, version, action, requestId, isHandshake, compressRequest);
         ActionListener<Void> listener = ActionListener.wrap(() ->
             messageListener.onRequestSent(node, requestId, action, request, options));
         sendMessage(channel, message, listener);