Refactor code to handle review comments and introduce new exception

Signed-off-by: Sumit Bansal <sumitsb@amazon.com>

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

@@ -325,7 +325,7 @@
 import org.opensearch.plugins.ActionPlugin;
 import org.opensearch.plugins.ActionPlugin.ActionHandler;
 import org.opensearch.rest.NamedRoute;
-import org.opensearch.rest.RequestLimitSettings;
+import org.opensearch.rest.ResponseLimitSettings;
 import org.opensearch.rest.RestController;
 import org.opensearch.rest.RestHandler;
 import org.opensearch.rest.RestHeaderDefinition;
@@ -529,7 +529,7 @@ public class ActionModule extends AbstractModule {
     private final RequestValidators<IndicesAliasesRequest> indicesAliasesRequestRequestValidators;
     private final ThreadPool threadPool;
     private final ExtensionsManager extensionsManager;
-    private final RequestLimitSettings requestLimitSettings;
+    private final ResponseLimitSettings responseLimitSettings;
 
     public ActionModule(
         Settings settings,
@@ -582,7 +582,7 @@ public ActionModule(
         );
 
         restController = new RestController(headers, restWrapper, nodeClient, circuitBreakerService, usageService);
-        requestLimitSettings = new RequestLimitSettings(clusterSettings, settings);
+        responseLimitSettings = new ResponseLimitSettings(clusterSettings, settings);
     }
 
     public Map<String, ActionHandler<?, ?>> getActions() {
@@ -963,8 +963,8 @@ public void initRestHandlers(Supplier<DiscoveryNodes> nodesInCluster) {
         registerHandler.accept(new RestClusterManagerAction());
         registerHandler.accept(new RestNodesAction());
         registerHandler.accept(new RestTasksAction(nodesInCluster));
-        registerHandler.accept(new RestIndicesAction(requestLimitSettings));
-        registerHandler.accept(new RestSegmentsAction(requestLimitSettings));
+        registerHandler.accept(new RestIndicesAction(responseLimitSettings));
+        registerHandler.accept(new RestSegmentsAction(responseLimitSettings));
         // Fully qualified to prevent interference with rest.action.count.RestCountAction
         registerHandler.accept(new org.opensearch.rest.action.cat.RestCountAction());
         // Fully qualified to prevent interference with rest.action.indices.RestRecoveryAction
@@ -1052,7 +1052,7 @@ protected void configure() {
         // register dynamic ActionType -> transportAction Map used by NodeClient
         bind(DynamicActionRegistry.class).toInstance(dynamicActionRegistry);
 
-        bind(RequestLimitSettings.class).toInstance(requestLimitSettings);
+        bind(ResponseLimitSettings.class).toInstance(responseLimitSettings);
     }
 
     public ActionFilters getActionFilters() {

server/src/main/java/org/opensearch/action/admin/cluster/shards/TransportCatShardsAction.java

@@ -19,14 +19,15 @@
 import org.opensearch.common.inject.Inject;
 import org.opensearch.core.action.ActionListener;
 import org.opensearch.core.action.NotifyOnceListener;
-import org.opensearch.core.common.breaker.CircuitBreaker;
-import org.opensearch.core.common.breaker.CircuitBreakingException;
-import org.opensearch.rest.RequestLimitSettings;
+import org.opensearch.rest.ResponseLimitBreachedException;
+import org.opensearch.rest.ResponseLimitSettings;
 import org.opensearch.tasks.CancellableTask;
 import org.opensearch.tasks.Task;
 import org.opensearch.transport.TransportService;
 
-import static org.opensearch.rest.RequestLimitSettings.BlockAction.CAT_SHARDS;
+import java.util.Objects;
+
+import static org.opensearch.rest.ResponseLimitSettings.LimitEntity.SHARDS;
 
 /**
  * Perform cat shards action
@@ -36,18 +37,18 @@
 public class TransportCatShardsAction extends HandledTransportAction<CatShardsRequest, CatShardsResponse> {
 
     private final NodeClient client;
-    private final RequestLimitSettings requestLimitSettings;
+    private final ResponseLimitSettings responseLimitSettings;
 
     @Inject
     public TransportCatShardsAction(
         NodeClient client,
         TransportService transportService,
         ActionFilters actionFilters,
-        RequestLimitSettings requestLimitSettings
+        ResponseLimitSettings responseLimitSettings
     ) {
         super(CatShardsAction.NAME, transportService, actionFilters, CatShardsRequest::new);
         this.client = client;
-        this.requestLimitSettings = requestLimitSettings;
+        this.responseLimitSettings = responseLimitSettings;
     }
 
     @Override
@@ -85,10 +86,7 @@ protected void innerOnFailure(Exception e) {
             client.admin().cluster().state(clusterStateRequest, new ActionListener<ClusterStateResponse>() {
                 @Override
                 public void onResponse(ClusterStateResponse clusterStateResponse) {
-                    if (shardsRequest.isRequestLimitCheckSupported()
-                        && requestLimitSettings.isCircuitLimitBreached(clusterStateResponse.getState(), CAT_SHARDS)) {
-                        listener.onFailure(new CircuitBreakingException("Too many shards requested.", CircuitBreaker.Durability.TRANSIENT));
-                    }
+                    validateRequestLimit(shardsRequest, clusterStateResponse, cancellableListener);
                     catShardsResponse.setClusterStateResponse(clusterStateResponse);
                     IndicesStatsRequest indicesStatsRequest = new IndicesStatsRequest();
                     indicesStatsRequest.setShouldCancelOnTimeout(true);
@@ -123,4 +121,21 @@ public void onFailure(Exception e) {
         }
 
     }
+
+    private void validateRequestLimit(
+        final CatShardsRequest shardsRequest,
+        final ClusterStateResponse clusterStateResponse,
+        final ActionListener<CatShardsResponse> listener
+    ) {
+        if (shardsRequest.isRequestLimitCheckSupported()
+            && Objects.nonNull(clusterStateResponse)
+            && Objects.nonNull(clusterStateResponse.getState())) {
+            int limit = responseLimitSettings.getCatShardsResponseLimit();
+            if (ResponseLimitSettings.isResponseLimitBreached(clusterStateResponse.getState().getRoutingTable(), SHARDS, limit)) {
+                listener.onFailure(
+                    new ResponseLimitBreachedException("Too many shards requested. Can not request shards beyond {" + limit + "}")
+                );
+            }
+        }
+    }
 }

server/src/main/java/org/opensearch/common/settings/ClusterSettings.java

@@ -155,7 +155,7 @@
 import org.opensearch.repositories.blobstore.BlobStoreRepository;
 import org.opensearch.repositories.fs.FsRepository;
 import org.opensearch.rest.BaseRestHandler;
-import org.opensearch.rest.RequestLimitSettings;
+import org.opensearch.rest.ResponseLimitSettings;
 import org.opensearch.script.ScriptService;
 import org.opensearch.search.SearchService;
 import org.opensearch.search.aggregations.MultiBucketConsumerService;
@@ -799,9 +799,10 @@ public void apply(Settings value, Settings current, Settings previous) {
                 WorkloadManagementSettings.NODE_LEVEL_MEMORY_REJECTION_THRESHOLD,
                 WorkloadManagementSettings.NODE_LEVEL_MEMORY_CANCELLATION_THRESHOLD,
 
-                RequestLimitSettings.CAT_INDICES_LIMIT_SETTING,
-                RequestLimitSettings.CAT_SHARDS_LIMIT_SETTING,
-                RequestLimitSettings.CAT_SEGMENTS_LIMIT_SETTING
+                // Settings to be used for limiting rest requests
+                ResponseLimitSettings.CAT_INDICES_RESPONSE_LIMIT_SETTING,
+                ResponseLimitSettings.CAT_SHARDS_RESPONSE_LIMIT_SETTING,
+                ResponseLimitSettings.CAT_SEGMENTS_RESPONSE_LIMIT_SETTING
             )
         )
     );

server/src/main/java/org/opensearch/rest/ResponseLimitBreachedException.java

@@ -0,0 +1,36 @@
+/*
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * The OpenSearch Contributors require contributions made to
+ * this file be licensed under the Apache-2.0 license or a
+ * compatible open source license.
+ */
+
+package org.opensearch.rest;
+
+import org.opensearch.OpenSearchException;
+import org.opensearch.core.common.io.stream.StreamInput;
+import org.opensearch.core.rest.RestStatus;
+
+import java.io.IOException;
+
+/**
+ * Thrown when api response limit threshold exceeds
+ *
+ * @opensearch.internal
+ */
+public class ResponseLimitBreachedException extends OpenSearchException {
+
+    public ResponseLimitBreachedException(String msg) {
+        super(msg);
+    }
+
+    public ResponseLimitBreachedException(StreamInput in) throws IOException {
+        super(in);
+    }
+
+    @Override
+    public RestStatus status() {
+        return RestStatus.TOO_MANY_REQUESTS;
+    }
+}