NealSun96 commented on a change in pull request #761: Add REST read endpoints to helix-rest for metadata store directory URL: https://github.com/apache/helix/pull/761#discussion_r380992746
########## File path: helix-rest/src/main/java/org/apache/helix/rest/server/resources/metadatastore/MetadataStoreDirectoryAccessor.java ########## @@ -111,41 +135,74 @@ public Response deleteMetadataStoreRealm(@PathParam("realm") String realm) { } /** - * Gets sharding keys mapped at path "HTTP GET /sharding-keys" which returns all sharding keys in - * a namespace, or path "HTTP GET /sharding-keys?realm={realmName}" which returns sharding keys in - * a realm. + * Gets all sharding keys mapped at paths: + * - "HTTP GET /sharding-keys" which returns all sharding keys in a namespace. + * - "HTTP GET /sharding-keys?realm={realm}" which returns sharding keys in the realm. + * - "HTTP GET /sharding-keys?prefix={prefix}" which returns sharding keys that have the prefix. + * -- JSON response example for this path: + * { + * "prefix": "/sharding/key", + * "shardingKeys": [{ + * "realm": "testRealm2", + * "shardingKey": "/sharding/key/1/f" + * }, { + * "realm": "testRealm2", + * "shardingKey": "/sharding/key/1/e" + * }, { + * "realm": "testRealm1", + * "shardingKey": "/sharding/key/1/b" + * }, { + * "realm": "testRealm1", + * "shardingKey": "/sharding/key/1/a" + * }] + * } * - * @param realm Query param in endpoint path - * @return Json representation of a map: shardingKeys -> collection of sharding keys. + * - "HTTP GET /sharding-keys?realm={realm}&prefix={prefix}" which returns sharding keys in the + * realm and that have the prefix. + * + * @param realm Query param in endpoint path: metadata store realm. + * @param prefix Query param in endpoint path: prefix substring of sharding key. + * @return Json representation for the sharding keys. */ @GET @Path("/sharding-keys") - public Response getShardingKeys(@QueryParam("realm") String realm) { - Map<String, Object> responseMap; - Collection<String> shardingKeys; + public Response getShardingKeys(@QueryParam("realm") String realm, + @QueryParam("prefix") String prefix) { try { - // If realm is not set in query param, the endpoint is: "/sharding-keys" - // to get all sharding keys in a namespace. - if (realm == null) { - shardingKeys = _metadataStoreDirectory.getAllShardingKeys(_namespace); - // To avoid allocating unnecessary resource, limit the map's capacity only for - // SHARDING_KEYS. - responseMap = new HashMap<>(1); + if (realm == null && prefix == null) { + // For endpoint: "/sharding-keys" to get all sharding keys in a namespace. + return getAllShardingKeys(); + } else if (prefix == null) { + // For endpoint: "/sharding-keys?realm={realm}" + return getAllShardingKeysInRealm(realm); + } else if (realm == null) { + // For endpoint: "/sharding-keys?prefix={prefix}" + return getAllShardingKeysUnderPath(prefix); } else { - // For endpoint: "/sharding-keys?realm={realmName}" - shardingKeys = _metadataStoreDirectory.getAllShardingKeysInRealm(_namespace, realm); - // To avoid allocating unnecessary resource, limit the map's capacity only for - // SHARDING_KEYS and SINGLE_METADATA_STORE_REALM. - responseMap = new HashMap<>(2); - responseMap.put(MetadataStoreRoutingConstants.SINGLE_METADATA_STORE_REALM, realm); + // For endpoint: "/sharding-keys?realm={realm}&prefix={prefix}" + return getRealmShardingKeysUnderPath(realm, prefix); } } catch (NoSuchElementException ex) { return notFound(ex.getMessage()); } + } - responseMap.put(MetadataStoreRoutingConstants.SHARDING_KEYS, shardingKeys); - - return JSONRepresentation(responseMap); + /** + * Gets all path-based sharding keys for a queried realm at endpoint: + * "GET /metadata-store-realms/{realm}/sharding-keys". This endpoint is equivalent to + * the endpoint: "GET /sharding-keys?realm={realm}". + * + * @param realm Queried metadata store realm to get sharding keys. + * @return All path-based sharding keys in the queried realm. + */ + @GET + @Path("/metadata-store-realms/{realm}/sharding-keys") + public Response getRealmShardingKeys(@PathParam("realm") String realm) { + try { + return getAllShardingKeysInRealm(realm); + } catch (NoSuchElementException ex) { + return notFound(ex.getMessage()); Review comment: Given my understanding to the status code, `badRequest` is more suitable than `notFound` in this situation. What `notFound` entails is that this url is not matched to anything, however in this situation, the url is correctly connecting to the endpoint. Returning `notFound` might cause confusion. I understand that `badRequest` is not perfect in this case either, but it should be more suitable than `notFound`. If you have a better idea, I'm happy to discuss. 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