Remove some Dead Code in o.e.transport (#44653) (#44734)

* None of this is used

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

@@ -92,7 +92,7 @@ final class RemoteClusterConnection implements TransportConnectionListener, Clos
     private volatile boolean skipUnavailable;
     private final ConnectHandler connectHandler;
     private final TimeValue initialConnectionTimeout;
-    private SetOnce<ClusterName> remoteClusterName = new SetOnce<>();
+    private final SetOnce<ClusterName> remoteClusterName = new SetOnce<>();
 
     /**
      * Creates a new {@link RemoteClusterConnection}

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

@@ -22,13 +22,12 @@ package org.elasticsearch.transport;
 import org.elasticsearch.Version;
 import org.elasticsearch.action.ActionListener;
 import org.elasticsearch.cluster.node.DiscoveryNode;
-import org.elasticsearch.common.breaker.CircuitBreaker;
-import org.elasticsearch.common.breaker.NoopCircuitBreaker;
 import org.elasticsearch.common.component.LifecycleComponent;
 import org.elasticsearch.common.transport.BoundTransportAddress;
 import org.elasticsearch.common.transport.TransportAddress;
 import org.elasticsearch.common.util.concurrent.ConcurrentCollections;
 import org.elasticsearch.common.util.concurrent.ConcurrentMapLong;
+
 import java.io.Closeable;
 import java.io.IOException;
 import java.net.UnknownHostException;
@@ -74,10 +73,6 @@ public interface Transport extends LifecycleComponent {
      */
     List<String> getDefaultSeedAddresses();
 
-    default CircuitBreaker getInFlightRequestBreaker() {
-        return new NoopCircuitBreaker("in-flight-noop");
-    }
-
     /**
      * Opens a new connection to the given node. When the connection is fully connected, the listener is called.
      * The ActionListener will be called on the calling thread or the generic thread pool.

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

@@ -1,76 +0,0 @@
-/*
- * Licensed to Elasticsearch under one or more contributor
- * license agreements. See the NOTICE file distributed with
- * this work for additional information regarding copyright
- * ownership. Elasticsearch licenses this file to you under
- * the Apache License, Version 2.0 (the "License"); you may
- * not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *    http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing,
- * software distributed under the License is distributed on an
- * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
- * KIND, either express or implied.  See the License for the
- * specific language governing permissions and limitations
- * under the License.
- */
-
-package org.elasticsearch.transport;
-
-import org.apache.logging.log4j.Logger;
-import org.apache.logging.log4j.message.ParameterizedMessage;
-import org.elasticsearch.common.io.stream.StreamInput;
-import org.elasticsearch.common.io.stream.Writeable;
-import org.elasticsearch.threadpool.ThreadPool;
-
-import java.io.IOException;
-
-/**
- * Base class for delegating transport response to a transport channel
- */
-public class TransportChannelResponseHandler<T extends TransportResponse> implements TransportResponseHandler<T> {
-
-    private final Logger logger;
-    private final TransportChannel channel;
-    private final String extraInfoOnError;
-    private final Writeable.Reader<T> reader;
-
-    public TransportChannelResponseHandler(Logger logger, TransportChannel channel, String extraInfoOnError,
-                                           Writeable.Reader<T> reader) {
-        this.logger = logger;
-        this.channel = channel;
-        this.extraInfoOnError = extraInfoOnError;
-        this.reader = reader;
-    }
-
-    @Override
-    public T read(StreamInput in) throws IOException {
-        return reader.read(in);
-    }
-
-    @Override
-    public void handleResponse(T response) {
-        try {
-            channel.sendResponse(response);
-        } catch (IOException e) {
-            handleException(new TransportException(e));
-        }
-    }
-
-    @Override
-    public void handleException(TransportException exp) {
-        try {
-            channel.sendResponse(exp);
-        } catch (IOException e) {
-            logger.debug(() -> new ParameterizedMessage(
-                        "failed to send failure {}", extraInfoOnError == null ? "" : "(" + extraInfoOnError + ")"), e);
-        }
-    }
-
-    @Override
-    public String executor() {
-        return ThreadPool.Names.SAME;
-    }
-}

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

@@ -732,7 +732,7 @@ public class TransportService extends AbstractLifecycleComponent implements Tran
     }
 
     private void sendLocalRequest(long requestId, final String action, final TransportRequest request, TransportRequestOptions options) {
-        final DirectResponseChannel channel = new DirectResponseChannel(logger, localNode, action, requestId, this, threadPool);
+        final DirectResponseChannel channel = new DirectResponseChannel(localNode, action, requestId, this, threadPool);
         try {
             onRequestSent(localNode, requestId, action, request, options);
             onRequestReceived(requestId, action);
@@ -1141,16 +1141,13 @@ public class TransportService extends AbstractLifecycleComponent implements Tran
     }
 
     static class DirectResponseChannel implements TransportChannel {
-        final Logger logger;
         final DiscoveryNode localNode;
         private final String action;
         private final long requestId;
         final TransportService service;
         final ThreadPool threadPool;
 
-        DirectResponseChannel(Logger logger, DiscoveryNode localNode, String action, long requestId, TransportService service,
+        DirectResponseChannel(DiscoveryNode localNode, String action, long requestId, TransportService service, ThreadPool threadPool) {
-                              ThreadPool threadPool) {
-            this.logger = logger;
             this.localNode = localNode;
             this.action = action;
             this.requestId = requestId;