Github user GJL commented on a diff in the pull request:
https://github.com/apache/flink/pull/5805#discussion_r181660436
--- Diff:
flink-runtime/src/main/java/org/apache/flink/runtime/rest/handler/job/metrics/AbstractAggregatingMetricsHandler.java
---
@@ -0,0 +1,302 @@
+/*
+ * 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.job.metrics;
+
+import org.apache.flink.api.common.time.Time;
+import org.apache.flink.runtime.rest.handler.AbstractRestHandler;
+import org.apache.flink.runtime.rest.handler.HandlerRequest;
+import org.apache.flink.runtime.rest.handler.RestHandlerException;
+import org.apache.flink.runtime.rest.handler.legacy.metrics.MetricFetcher;
+import org.apache.flink.runtime.rest.handler.legacy.metrics.MetricStore;
+import org.apache.flink.runtime.rest.messages.EmptyRequestBody;
+import
org.apache.flink.runtime.rest.messages.job.metrics.AbstractAggregatedMetricsHeaders;
+import
org.apache.flink.runtime.rest.messages.job.metrics.AbstractAggregatedMetricsParameters;
+import org.apache.flink.runtime.rest.messages.job.metrics.AggregatedMetric;
+import
org.apache.flink.runtime.rest.messages.job.metrics.AggregatedMetricsResponseBody;
+import
org.apache.flink.runtime.rest.messages.job.metrics.MetricsAggregationParameter;
+import
org.apache.flink.runtime.rest.messages.job.metrics.MetricsFilterParameter;
+import org.apache.flink.runtime.webmonitor.RestfulGateway;
+import org.apache.flink.runtime.webmonitor.retriever.GatewayRetriever;
+import org.apache.flink.util.Preconditions;
+
+import
org.apache.flink.shaded.netty4.io.netty.handler.codec.http.HttpResponseStatus;
+
+import javax.annotation.Nonnull;
+import javax.annotation.Nullable;
+
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.Collections;
+import java.util.HashSet;
+import java.util.Iterator;
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
+import java.util.concurrent.CompletableFuture;
+import java.util.concurrent.CompletionException;
+import java.util.concurrent.Executor;
+import java.util.stream.Collectors;
+
+/**
+ * Abstract request handler for querying aggregated metrics. Subclasses
return either a list of all available metrics
+ * or the aggregated values of them across all/selected entities.
+ *
+ * <p>If the query parameters do not contain a "get" parameter the list of
all metrics is returned.
+ * {@code [ { "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". If the parameter is not specified, all
aggregations will be returned.
+ * {@code /metrics?get=X,Y&agg=min,max}
+ * The handler will then return a list of objects containing the
aggregations for the requested metrics.
+ * {@code [ { "id" : "X", "min", "1", "max", "2" }, { "id" : "Y", "min",
"4", "max", "10"}]}
+ */
+public abstract class AbstractAggregatingMetricsHandler<P extends
AbstractAggregatedMetricsParameters<?>> extends
AbstractRestHandler<RestfulGateway, EmptyRequestBody,
AggregatedMetricsResponseBody, P> {
+
+ private final Executor executor;
+ private final MetricFetcher<?> fetcher;
+
+ protected AbstractAggregatingMetricsHandler(
+ CompletableFuture<String> localRestAddress,
+ GatewayRetriever<? extends RestfulGateway>
leaderRetriever,
+ Time timeout,
+ Map<String, String> responseHeaders,
+ AbstractAggregatedMetricsHeaders<P> messageHeaders,
+ Executor executor,
+ MetricFetcher<?> fetcher) {
+ super(localRestAddress, leaderRetriever, timeout,
responseHeaders, messageHeaders);
+ this.executor = Preconditions.checkNotNull(executor);
+ this.fetcher = Preconditions.checkNotNull(fetcher);
+ }
+
+ abstract Collection<? extends MetricStore.ComponentMetricStore>
getStores(MetricStore store, HandlerRequest<EmptyRequestBody, P> request);
+
+ @Override
+ protected CompletableFuture<AggregatedMetricsResponseBody>
handleRequest(@Nonnull HandlerRequest<EmptyRequestBody, P> request, @Nonnull
RestfulGateway gateway) throws RestHandlerException {
+ return CompletableFuture.supplyAsync(
+ () -> {
+ try {
+ fetcher.update();
+ List<String> requestedMetrics =
request.getQueryParameter(MetricsFilterParameter.class);
+
List<MetricsAggregationParameter.AggregationMode> requestedAggregations =
request.getQueryParameter(MetricsAggregationParameter.class);
+ MetricStore store =
fetcher.getMetricStore();
+
+ Collection<? extends
MetricStore.ComponentMetricStore> stores = getStores(store, request);
+ if (stores == null) {
--- End diff --
Imo if `getStores` is allowed to return `null`, the method should be
annotated if `@Nullable`. Here I cannot find a code path where `null` is
returned. Maybe we should not allow `null` to be returned.
---
