Added a custom request plugin (#444)

* Added a custom request plugin

* Spotless apply

* Changed how routes are defined and added tests

* Alphabetized code block

* Re-ran buildGrpcGateway after merge

* Added path as a parameter to RequestProcessor

* Added id and path as request parameters

* Testing path and added some javadoc for RequestProcessor

* Spotless apply

clientlib/src/main/proto/yelp/nrtsearch/luceneserver.proto

@@ -361,6 +361,16 @@ service LuceneServer {
       body: "*"
     };
     }
+
+    /*
+    Process request in a plugin which implements CustomRequestPlugin interface.
+    */
+    rpc custom(CustomRequest) returns (CustomResponse) {
+        option (google.api.http) = {
+            post: "/v1/custom/{id}/{path}"
+            body: "*"
+        };
+    }
 }
 
 //The ReplicationServer service definition.
@@ -1048,4 +1058,14 @@ message IndexStateInfo {
     IndexLiveSettings liveSettings = 5;
     // Registered fields
     map<string, Field> fields = 6;
+}
+
+message CustomRequest {
+    string id = 1; // ID defined for custom requests in a plugin
+    string path = 2; // Custom path that is defined in a plugin that maps to a route
+    map<string, string> params = 3; // Parameters that can be processed by the plugin at the specified path
+}
+
+message CustomResponse {
+    map<string, string> response = 1; // Custom response sent by the plugin
 }

grpc-gateway/luceneserver.swagger.json

@@ -233,6 +233,51 @@
         ]
       }
     },
+    "/v1/custom/{id}/{path}": {
+      "post": {
+        "summary": "Process request in a plugin which implements CustomRequestPlugin interface.",
+        "operationId": "LuceneServer_custom",
+        "responses": {
+          "200": {
+            "description": "A successful response.",
+            "schema": {
+              "$ref": "#/definitions/luceneserverCustomResponse"
+            }
+          },
+          "default": {
+            "description": "An unexpected error response.",
+            "schema": {
+              "$ref": "#/definitions/runtimeError"
+            }
+          }
+        },
+        "parameters": [
+          {
+            "name": "id",
+            "in": "path",
+            "required": true,
+            "type": "string"
+          },
+          {
+            "name": "path",
+            "in": "path",
+            "required": true,
+            "type": "string"
+          },
+          {
+            "name": "body",
+            "in": "body",
+            "required": true,
+            "schema": {
+              "$ref": "#/definitions/luceneserverCustomRequest"
+            }
+          }
+        ],
+        "tags": [
+          "LuceneServer"
+        ]
+      }
+    },
     "/v1/delete": {
       "post": {
         "summary": "Delete documents",
@@ -2352,6 +2397,34 @@
         }
       }
     },
+    "luceneserverCustomRequest": {
+      "type": "object",
+      "properties": {
+        "id": {
+          "type": "string"
+        },
+        "path": {
+          "type": "string"
+        },
+        "params": {
+          "type": "object",
+          "additionalProperties": {
+            "type": "string"
+          }
+        }
+      }
+    },
+    "luceneserverCustomResponse": {
+      "type": "object",
+      "properties": {
+        "response": {
+          "type": "object",
+          "additionalProperties": {
+            "type": "string"
+          }
+        }
+      }
+    },
     "luceneserverDeleteAllDocumentsRequest": {
       "type": "object",
       "properties": {

src/main/java/com/yelp/nrtsearch/server/grpc/LuceneServer.java

@@ -40,6 +40,7 @@
 import com.yelp.nrtsearch.server.luceneserver.*;
 import com.yelp.nrtsearch.server.luceneserver.AddDocumentHandler.DocumentIndexer;
 import com.yelp.nrtsearch.server.luceneserver.analysis.AnalyzerCreator;
+import com.yelp.nrtsearch.server.luceneserver.custom.request.CustomRequestProcessor;
 import com.yelp.nrtsearch.server.luceneserver.field.FieldDefCreator;
 import com.yelp.nrtsearch.server.luceneserver.index.IndexStateManager;
 import com.yelp.nrtsearch.server.luceneserver.index.handlers.FieldUpdateHandler;
@@ -396,6 +397,7 @@ private void initExtendableComponents(
         LuceneServerConfiguration configuration, List<Plugin> plugins) {
       AnalyzerCreator.initialize(configuration, plugins);
       CollectorCreator.initialize(configuration, plugins);
+      CustomRequestProcessor.initialize(configuration, plugins);
       FetchTaskCreator.initialize(configuration, plugins);
       FieldDefCreator.initialize(configuration, plugins);
       RescorerCreator.initialize(configuration, plugins);
@@ -1796,6 +1798,17 @@ public void forceMergeDeletes(
       responseObserver.onNext(response);
       responseObserver.onCompleted();
     }
+
+    @Override
+    public void custom(CustomRequest request, StreamObserver<CustomResponse> responseObserver) {
+      try {
+        CustomResponse response = CustomRequestProcessor.processCustomRequest(request);
+        responseObserver.onNext(response);
+        responseObserver.onCompleted();
+      } catch (Exception e) {
+        responseObserver.onError(e);
+      }
+    }
   }
 
   static class ReplicationServerImpl extends ReplicationServerGrpc.ReplicationServerImplBase {

src/main/java/com/yelp/nrtsearch/server/luceneserver/custom/request/CustomRequestProcessor.java

@@ -0,0 +1,70 @@
+/*
+ * Copyright 2022 Yelp Inc.
+ *
+ * Licensed 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 com.yelp.nrtsearch.server.luceneserver.custom.request;
+
+import com.yelp.nrtsearch.server.config.LuceneServerConfiguration;
+import com.yelp.nrtsearch.server.grpc.CustomRequest;
+import com.yelp.nrtsearch.server.grpc.CustomResponse;
+import com.yelp.nrtsearch.server.plugins.CustomRequestPlugin;
+import com.yelp.nrtsearch.server.plugins.Plugin;
+import java.util.HashMap;
+import java.util.Map;
+
+public class CustomRequestProcessor {
+
+  private static CustomRequestProcessor instance;
+  private final Map<String, Map<String, CustomRequestPlugin.RequestProcessor>> routeMapping =
+      new HashMap<>();
+
+  public CustomRequestProcessor(LuceneServerConfiguration configuration) {}
+
+  public static void initialize(LuceneServerConfiguration configuration, Iterable<Plugin> plugins) {
+    instance = new CustomRequestProcessor(configuration);
+    for (Plugin plugin : plugins) {
+      if (plugin instanceof CustomRequestPlugin) {
+        instance.registerRoutes((CustomRequestPlugin) plugin);
+      }
+    }
+  }
+
+  public static CustomResponse processCustomRequest(CustomRequest request) {
+    if (!instance.routeMapping.containsKey(request.getId())) {
+      throw new RouteNotFoundException(request.getId());
+    }
+    Map<String, CustomRequestPlugin.RequestProcessor> routesForId =
+        instance.routeMapping.get(request.getId());
+    if (!routesForId.containsKey(request.getPath())) {
+      throw new RouteNotFoundException(request.getId(), request.getPath());
+    }
+    Map<String, String> response =
+        routesForId.get(request.getPath()).process(request.getPath(), request.getParamsMap());
+    return CustomResponse.newBuilder().putAllResponse(response).build();
+  }
+
+  private void registerRoutes(CustomRequestPlugin plugin) {
+    String id = plugin.id();
+    if (routeMapping.containsKey(id)) {
+      throw new DuplicateRouteException(id);
+    }
+    Map<String, CustomRequestPlugin.RequestProcessor> routesForId = new HashMap<>();
+    for (Map.Entry<String, CustomRequestPlugin.RequestProcessor> route :
+        plugin.getRoutes().entrySet()) {
+      String path = route.getKey();
+      routesForId.put(path, route.getValue());
+    }
+    routeMapping.put(id, routesForId);
+  }
+}