Change signature of Get Repositories Response (#30333)

The Get Repositories response object held a list of RepositoryMetaData
entries. This object does not have the from/toXContent methods that are
needed to expose this to the high level REST client. The
RepositoriesMetaData, however, does, and it also contains a list of
RepositoryMetaData objects within it. So rather than duplicate this
logic or move it (RepositoriesMetaData is a fragment object used by
cluster state), the object holding state in the Response was changed to
use the RepositoriesMetaData instead. This also cleans up the read/write
methods in the response, as they can now use the same read/write in
RepositoriesMetaData, which also were not present in the singular class.

server/src/main/java/org/elasticsearch/action/admin/cluster/repositories/get/GetRepositoriesResponse.java

@@ -20,29 +20,30 @@
 package org.elasticsearch.action.admin.cluster.repositories.get;
 
 import org.elasticsearch.action.ActionResponse;
+import org.elasticsearch.cluster.metadata.RepositoriesMetaData;
 import org.elasticsearch.cluster.metadata.RepositoryMetaData;
 import org.elasticsearch.common.io.stream.StreamInput;
 import org.elasticsearch.common.io.stream.StreamOutput;
-import org.elasticsearch.common.settings.Settings;
+import org.elasticsearch.common.xcontent.ToXContentObject;
+import org.elasticsearch.common.xcontent.XContentBuilder;
 
 import java.io.IOException;
-import java.util.ArrayList;
 import java.util.Collections;
 import java.util.Iterator;
 import java.util.List;
 
 /**
  * Get repositories response
  */
-public class GetRepositoriesResponse extends ActionResponse implements Iterable<RepositoryMetaData> {
-
-    private List<RepositoryMetaData> repositories = Collections.emptyList();
+public class GetRepositoriesResponse extends ActionResponse implements ToXContentObject {
 
+    private RepositoriesMetaData repositories;
 
     GetRepositoriesResponse() {
+        repositories = new RepositoriesMetaData(Collections.emptyList());
     }
 
-    GetRepositoriesResponse(List<RepositoryMetaData> repositories) {
+    GetRepositoriesResponse(RepositoriesMetaData repositories) {
         this.repositories = repositories;
     }
 
@@ -52,43 +53,25 @@ public class GetRepositoriesResponse extends ActionResponse implements Iterable<
      * @return list or repositories
      */
     public List<RepositoryMetaData> repositories() {
-        return repositories;
+        return repositories.repositories();
     }
 
 
     @Override
     public void readFrom(StreamInput in) throws IOException {
-        super.readFrom(in);
-        int size = in.readVInt();
-        List<RepositoryMetaData> repositoryListBuilder = new ArrayList<>(size);
-        for (int j = 0; j < size; j++) {
-            repositoryListBuilder.add(new RepositoryMetaData(
-                    in.readString(),
-                    in.readString(),
-                    Settings.readSettingsFromStream(in))
-            );
-        }
-        repositories = Collections.unmodifiableList(repositoryListBuilder);
+        repositories = new RepositoriesMetaData(in);
     }
 
     @Override
     public void writeTo(StreamOutput out) throws IOException {
-        super.writeTo(out);
-        out.writeVInt(repositories.size());
-        for (RepositoryMetaData repository : repositories) {
-            out.writeString(repository.name());
-            out.writeString(repository.type());
-            Settings.writeSettingsToStream(repository.settings(), out);
-        }
+        repositories.writeTo(out);
     }
 
-    /**
-     * Iterator over the repositories data
-     *
-     * @return iterator over the repositories data
-     */
     @Override
-    public Iterator<RepositoryMetaData> iterator() {
-        return repositories.iterator();
+    public XContentBuilder toXContent(XContentBuilder builder, Params params) throws IOException {
+        builder.startObject();
+        repositories.toXContent(builder, params);
+        builder.endObject();
+        return builder;
     }
 }

server/src/main/java/org/elasticsearch/action/admin/cluster/repositories/get/TransportGetRepositoriesAction.java

@@ -75,9 +75,9 @@ protected void masterOperation(final GetRepositoriesRequest request, ClusterStat
         RepositoriesMetaData repositories = metaData.custom(RepositoriesMetaData.TYPE);
         if (request.repositories().length == 0 || (request.repositories().length == 1 && "_all".equals(request.repositories()[0]))) {
             if (repositories != null) {
-                listener.onResponse(new GetRepositoriesResponse(repositories.repositories()));
+                listener.onResponse(new GetRepositoriesResponse(repositories));
             } else {
-                listener.onResponse(new GetRepositoriesResponse(Collections.<RepositoryMetaData>emptyList()));
+                listener.onResponse(new GetRepositoriesResponse(new RepositoriesMetaData(Collections.emptyList())));
             }
         } else {
             if (repositories != null) {
@@ -102,7 +102,7 @@ protected void masterOperation(final GetRepositoriesRequest request, ClusterStat
                     }
                     repositoryListBuilder.add(repositoryMetaData);
                 }
-                listener.onResponse(new GetRepositoriesResponse(Collections.unmodifiableList(repositoryListBuilder)));
+                listener.onResponse(new GetRepositoriesResponse(new RepositoriesMetaData(repositoryListBuilder)));
             } else {
                 listener.onFailure(new RepositoryMissingException(request.repositories()[0]));
             }

server/src/main/java/org/elasticsearch/rest/action/admin/cluster/RestGetRepositoriesAction.java

@@ -22,25 +22,19 @@
 import org.elasticsearch.action.admin.cluster.repositories.get.GetRepositoriesRequest;
 import org.elasticsearch.action.admin.cluster.repositories.get.GetRepositoriesResponse;
 import org.elasticsearch.client.node.NodeClient;
-import org.elasticsearch.cluster.metadata.RepositoriesMetaData;
-import org.elasticsearch.cluster.metadata.RepositoryMetaData;
 import org.elasticsearch.common.Strings;
 import org.elasticsearch.common.settings.Settings;
 import org.elasticsearch.common.settings.SettingsFilter;
-import org.elasticsearch.common.xcontent.XContentBuilder;
 import org.elasticsearch.rest.BaseRestHandler;
-import org.elasticsearch.rest.BytesRestResponse;
 import org.elasticsearch.rest.RestController;
 import org.elasticsearch.rest.RestRequest;
-import org.elasticsearch.rest.RestResponse;
-import org.elasticsearch.rest.action.RestBuilderListener;
+import org.elasticsearch.rest.action.RestToXContentListener;
 
 import java.io.IOException;
 import java.util.Set;
 
 import static org.elasticsearch.client.Requests.getRepositoryRequest;
 import static org.elasticsearch.rest.RestRequest.Method.GET;
-import static org.elasticsearch.rest.RestStatus.OK;
 
 /**
  * Returns repository information
@@ -69,18 +63,8 @@ public RestChannelConsumer prepareRequest(final RestRequest request, final NodeC
         getRepositoriesRequest.local(request.paramAsBoolean("local", getRepositoriesRequest.local()));
         settingsFilter.addFilterSettingParams(request);
         return channel ->
-                client.admin().cluster().getRepositories(getRepositoriesRequest, new RestBuilderListener<GetRepositoriesResponse>(channel) {
-                    @Override
-                    public RestResponse buildResponse(GetRepositoriesResponse response, XContentBuilder builder) throws Exception {
-                        builder.startObject();
-                        for (RepositoryMetaData repositoryMetaData : response.repositories()) {
-                            RepositoriesMetaData.toXContent(repositoryMetaData, builder, request);
-                        }
-                        builder.endObject();
-
-                        return new BytesRestResponse(OK, builder);
-                    }
-        });
+                client.admin().cluster().getRepositories(getRepositoriesRequest,
+                    new RestToXContentListener<>(channel));
     }
 
     @Override