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 * 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.action.admin.cluster.state;

import com.carrotsearch.hppc.cursors.ObjectObjectCursor;
import org.elasticsearch.Version;
import org.elasticsearch.action.ActionListener;
import org.elasticsearch.action.support.ActionFilters;
import org.elasticsearch.action.support.master.TransportMasterNodeReadAction;
import org.elasticsearch.cluster.ClusterState;
import org.elasticsearch.cluster.block.ClusterBlockException;
import org.elasticsearch.cluster.metadata.IndexMetaData;
import org.elasticsearch.cluster.metadata.IndexNameExpressionResolver;
import org.elasticsearch.cluster.metadata.MetaData;
import org.elasticsearch.cluster.metadata.MetaData.Custom;
import org.elasticsearch.cluster.routing.RoutingTable;
import org.elasticsearch.cluster.service.ClusterService;
import org.elasticsearch.common.inject.Inject;
import org.elasticsearch.common.settings.Settings;
import org.elasticsearch.threadpool.ThreadPool;
import org.elasticsearch.transport.TransportService;

import java.io.IOException;

import static org.elasticsearch.discovery.zen.PublishClusterStateAction.serializeFullClusterState;

public class TransportClusterStateAction extends TransportMasterNodeReadAction<ClusterStateRequest, ClusterStateResponse> {


    @Inject
    public TransportClusterStateAction(Settings settings, TransportService transportService, ClusterService clusterService, ThreadPool threadPool,
                                       ActionFilters actionFilters, IndexNameExpressionResolver indexNameExpressionResolver) {
        super(settings, ClusterStateAction.NAME, false, transportService, clusterService, threadPool, actionFilters, ClusterStateRequest::new, indexNameExpressionResolver);
    }

    @Override
    protected String executor() {
        // very lightweight operation in memory, no need to fork to a thread
        return ThreadPool.Names.SAME;
    }

    @Override
    protected ClusterBlockException checkBlock(ClusterStateRequest request, ClusterState state) {
        // cluster state calls are done also on a fully blocked cluster to figure out what is going
        // on in the cluster. For example, which nodes have joined yet the recovery has not yet kicked
        // in, we need to make sure we allow those calls
        // return state.blocks().globalBlockedException(ClusterBlockLevel.METADATA);
        return null;
    }

    @Override
    protected ClusterStateResponse newResponse() {
        return new ClusterStateResponse();
    }

    @Override
    protected void masterOperation(final ClusterStateRequest request, final ClusterState state,
                                   final ActionListener<ClusterStateResponse> listener) throws IOException {
        ClusterState currentState = clusterService.state();
        logger.trace("Serving cluster state request using version {}", currentState.version());
        ClusterState.Builder builder = ClusterState.builder(currentState.getClusterName());
        builder.version(currentState.version());
        builder.stateUUID(currentState.stateUUID());
        if (request.nodes()) {
            builder.nodes(currentState.nodes());
        }
        if (request.routingTable()) {
            if (request.indices().length > 0) {
                RoutingTable.Builder routingTableBuilder = RoutingTable.builder();
                String[] indices = indexNameExpressionResolver.concreteIndexNames(currentState, request);
                for (String filteredIndex : indices) {
                    if (currentState.routingTable().getIndicesRouting().containsKey(filteredIndex)) {
                        routingTableBuilder.add(currentState.routingTable().getIndicesRouting().get(filteredIndex));
                    }
                }
                builder.routingTable(routingTableBuilder.build());
            } else {
                builder.routingTable(currentState.routingTable());
            }
        }
        if (request.blocks()) {
            builder.blocks(currentState.blocks());
        }

        MetaData.Builder mdBuilder = MetaData.builder();
        mdBuilder.clusterUUID(currentState.metaData().clusterUUID());

        if (request.metaData()) {
            if (request.indices().length > 0) {
                String[] indices = indexNameExpressionResolver.concreteIndexNames(currentState, request);
                for (String filteredIndex : indices) {
                    IndexMetaData indexMetaData = currentState.metaData().index(filteredIndex);
                    if (indexMetaData != null) {
                        mdBuilder.put(indexMetaData, false);
                    }
                }
            } else {
                mdBuilder = MetaData.builder(currentState.metaData());
            }

            // Filter our metadata that shouldn't be returned by API
            for(ObjectObjectCursor<String, Custom> custom : currentState.metaData().customs()) {
                if(!custom.value.context().contains(MetaData.XContentContext.API)) {
                    mdBuilder.removeCustom(custom.key);
                }
            }
        }
        builder.metaData(mdBuilder);

        if (request.customs()) {
            for (ObjectObjectCursor<String, ClusterState.Custom> custom : currentState.customs()) {
                if (custom.value.isPrivate() == false) {
                    builder.putCustom(custom.key, custom.value);
                }
            }
        }
        listener.onResponse(new ClusterStateResponse(currentState.getClusterName(), builder.build(),
                                                        serializeFullClusterState(currentState, Version.CURRENT).length()));
    }


}

@@ -5525,17 +5525,17 @@
  // 
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 ilter ou
 r me
@@ -5530,17 +5530,17 @@
 ilter ou
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  metadat
@@ -5571,16 +5571,20 @@
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+the 
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@@ -5594,16 +5594,17 @@
      for
+ 
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@@ -5699,10 +5699,10 @@
   if
+ 
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@@ -5758,16 +5758,25 @@
 ext.API)
+ == false
 ) %7B%0A    

Make TransportClusterStateAction abide to our style (#30697)