Github user kl0u commented on a diff in the pull request: https://github.com/apache/flink/pull/4901#discussion_r147657052 --- Diff: flink-runtime/src/main/java/org/apache/flink/runtime/rest/handler/legacy/metrics/SubtaskMetricsHandler.java --- @@ -0,0 +1,70 @@ +/* + * Licensed to the Apache Software Foundation (ASF) under one + * or more contributor license agreements. See the NOTICE file + * distributed with this work for additional information + * regarding copyright ownership. The ASF licenses this file + * to you 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 org.apache.flink.runtime.rest.handler.legacy.metrics; + +import org.apache.flink.runtime.rest.handler.legacy.SubtaskExecutionAttemptDetailsHandler; + +import java.util.Map; +import java.util.concurrent.Executor; + +/** + * Request handler that returns, aggregated across all subtasks of a single tasks, a list of all available metrics or the + * values for a set of metrics. + * + * <p>If the query parameters do not contain a "get" parameter the list of all metrics is returned. + * {@code {"available": [ { "name" : "X", "id" : "X" } ] } } + * + * <p>If the query parameters do contain a "get" parameter, a comma-separated list of metric names is expected as a value. + * {@code /metrics?get=X,Y} + * The handler will then return a list containing the values of the requested metrics. + * {@code [ { "id" : "X", "value" : "S" }, { "id" : "Y", "value" : "T" } ] } + * + * <p>The "agg" query parameter is used to define which aggregates should be calculated. Available aggregations are + * "sum", "max", "min" and "avg". + */ +public class SubtaskMetricsHandler extends AbstractMetricsHandler { + private static final String SUBTASK_METRICS_REST_PATH = "/jobs/:jobid/vertices/:vertexid/subtasks/:subtasknum/metrics"; + + public SubtaskMetricsHandler(Executor executor, MetricFetcher fetcher) { + super(executor, fetcher); + } + + @Override + public String[] getPaths() { + return new String[]{SUBTASK_METRICS_REST_PATH}; + } + + @Override + protected Map<String, String> getMapFor(Map<String, String> pathParams, MetricStore metrics) { + String subtaskNumString = pathParams.get(SubtaskExecutionAttemptDetailsHandler.PARAMETER_SUBTASK_INDEX); + int subtaskNum; + try { + subtaskNum = Integer.valueOf(subtaskNumString); + } catch (NumberFormatException nfe) { + return null; + } --- End diff -- Can this also be an invalid subtask number? E.g. we have 5 of them and we request subtaskid 11? In this case there should be a check that logs a warning and potentially sets he `subtaskNum` to `null` so that we go down the same path as a non-integer value.
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