Collapse REST resize handlers (#30229)

The REST resize handlers for shrink/split operations are effectively the
same code with a minor difference. This commit collapse these handlers
into a single base class.

Author: jasontedor

server/src/main/java/org/elasticsearch/action/ActionModule.java

@@ -241,6 +241,7 @@
 import org.elasticsearch.rest.action.admin.cluster.RestRestoreSnapshotAction;
 import org.elasticsearch.rest.action.admin.cluster.RestSnapshotsStatusAction;
 import org.elasticsearch.rest.action.admin.cluster.RestVerifyRepositoryAction;
+import org.elasticsearch.rest.action.admin.indices.RestResizeHandler;
 import org.elasticsearch.rest.action.admin.indices.RestAnalyzeAction;
 import org.elasticsearch.rest.action.admin.indices.RestClearIndicesCacheAction;
 import org.elasticsearch.rest.action.admin.indices.RestCloseIndexAction;
@@ -270,8 +271,6 @@
 import org.elasticsearch.rest.action.admin.indices.RestRecoveryAction;
 import org.elasticsearch.rest.action.admin.indices.RestRefreshAction;
 import org.elasticsearch.rest.action.admin.indices.RestRolloverIndexAction;
-import org.elasticsearch.rest.action.admin.indices.RestShrinkIndexAction;
-import org.elasticsearch.rest.action.admin.indices.RestSplitIndexAction;
 import org.elasticsearch.rest.action.admin.indices.RestSyncedFlushAction;
 import org.elasticsearch.rest.action.admin.indices.RestUpdateSettingsAction;
 import org.elasticsearch.rest.action.admin.indices.RestUpgradeAction;
@@ -569,8 +568,8 @@ public void initRestHandlers(Supplier<DiscoveryNodes> nodesInCluster) {
         registerHandler.accept(new RestIndexPutAliasAction(settings, restController));
         registerHandler.accept(new RestIndicesAliasesAction(settings, restController));
         registerHandler.accept(new RestCreateIndexAction(settings, restController));
-        registerHandler.accept(new RestShrinkIndexAction(settings, restController));
-        registerHandler.accept(new RestSplitIndexAction(settings, restController));
+        registerHandler.accept(new RestResizeHandler.RestShrinkIndexAction(settings, restController));
+        registerHandler.accept(new RestResizeHandler.RestSplitIndexAction(settings, restController));
         registerHandler.accept(new RestRolloverIndexAction(settings, restController));
         registerHandler.accept(new RestDeleteIndexAction(settings, restController));
         registerHandler.accept(new RestCloseIndexAction(settings, restController));

server/src/main/java/org/elasticsearch/rest/action/admin/indices/RestShrinkIndexAction.java renamed to server/src/main/java/org/elasticsearch/rest/action/admin/indices/RestResizeHandler.java

@@ -31,26 +31,66 @@
 
 import java.io.IOException;
 
-public class RestShrinkIndexAction extends BaseRestHandler {
-    public RestShrinkIndexAction(Settings settings, RestController controller) {
+public abstract class RestResizeHandler extends BaseRestHandler {
+
+    RestResizeHandler(final Settings settings) {
         super(settings);
-        controller.registerHandler(RestRequest.Method.PUT, "/{index}/_shrink/{target}", this);
-        controller.registerHandler(RestRequest.Method.POST, "/{index}/_shrink/{target}", this);
     }
 
     @Override
-    public String getName() {
-        return "shrink_index_action";
-    }
+    public abstract String getName();
+
+    abstract ResizeType getResizeType();
 
     @Override
-    public RestChannelConsumer prepareRequest(final RestRequest request, final NodeClient client) throws IOException {
+    public final RestChannelConsumer prepareRequest(final RestRequest request, final NodeClient client) throws IOException {
         final ResizeRequest resizeRequest = new ResizeRequest(request.param("target"), request.param("index"));
-        resizeRequest.setResizeType(ResizeType.SHRINK);
+        resizeRequest.setResizeType(getResizeType());
         request.applyContentParser(resizeRequest::fromXContent);
         resizeRequest.timeout(request.paramAsTime("timeout", resizeRequest.timeout()));
         resizeRequest.masterNodeTimeout(request.paramAsTime("master_timeout", resizeRequest.masterNodeTimeout()));
         resizeRequest.setWaitForActiveShards(ActiveShardCount.parseString(request.param("wait_for_active_shards")));
         return channel -> client.admin().indices().resizeIndex(resizeRequest, new RestToXContentListener<>(channel));
     }
+
+    public static class RestShrinkIndexAction extends RestResizeHandler {
+
+        public RestShrinkIndexAction(final Settings settings, final RestController controller) {
+            super(settings);
+            controller.registerHandler(RestRequest.Method.PUT, "/{index}/_shrink/{target}", this);
+            controller.registerHandler(RestRequest.Method.POST, "/{index}/_shrink/{target}", this);
+        }
+
+        @Override
+        public String getName() {
+            return "shrink_index_action";
+        }
+
+        @Override
+        protected ResizeType getResizeType() {
+            return ResizeType.SHRINK;
+        }
+
+    }
+
+    public static class RestSplitIndexAction extends RestResizeHandler {
+
+        public RestSplitIndexAction(final Settings settings, final RestController controller) {
+            super(settings);
+            controller.registerHandler(RestRequest.Method.PUT, "/{index}/_split/{target}", this);
+            controller.registerHandler(RestRequest.Method.POST, "/{index}/_split/{target}", this);
+        }
+
+        @Override
+        public String getName() {
+            return "split_index_action";
+        }
+
+        @Override
+        protected ResizeType getResizeType() {
+            return ResizeType.SPLIT;
+        }
+
+    }
+
 }