mjsax commented on code in PR #22267:
URL: https://github.com/apache/kafka/pull/22267#discussion_r3229322149
##########
streams/src/main/java/org/apache/kafka/streams/state/internals/MeteredKeyValueStore.java:
##########
@@ -182,7 +182,21 @@ private void registerMetrics() {
);
if (!persistent()) {
StateStoreMetrics.addNumKeysGauge(taskId.toString(), metricsScope,
name(), streamsMetrics,
- (config, now) -> wrapped().approximateNumEntries());
+ (config, now) -> {
+ final InMemoryKeyValueStore inMemoryStore =
findInMemoryKeyValueStore(wrapped());
+ return inMemoryStore != null ?
inMemoryStore.approximateNumEntries() : -1L;
+ }
+ );
+ }
+ }
+
+ private static InMemoryKeyValueStore findInMemoryKeyValueStore(final
StateStore store) {
+ if (store instanceof InMemoryKeyValueStore) {
+ return (InMemoryKeyValueStore) store;
+ } else if (store instanceof WrappedStateStore) {
+ return findInMemoryKeyValueStore(((WrappedStateStore<?, ?, ?>)
store).wrapped());
+ } else {
+ return null;
Review Comment:
Should we maybe throw an exception here instead if returning `null`? We
should never reach this point, and if we do, we have a bug? (If yes, should
also be done for window/session case).
##########
streams/integration-tests/src/test/java/org/apache/kafka/streams/integration/InMemoryStoreMetricsIntegrationTest.java:
##########
@@ -0,0 +1,138 @@
+/*
+ * 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.kafka.streams.integration;
+
+import org.apache.kafka.common.Metric;
+import org.apache.kafka.common.MetricName;
+import org.apache.kafka.common.serialization.Serdes;
+import org.apache.kafka.common.utils.Bytes;
+import org.apache.kafka.streams.KafkaStreams;
+import org.apache.kafka.streams.StreamsBuilder;
+import org.apache.kafka.streams.StreamsConfig;
+import org.apache.kafka.streams.integration.utils.EmbeddedKafkaCluster;
+import org.apache.kafka.streams.kstream.Consumed;
+import org.apache.kafka.streams.processor.StateStore;
+import org.apache.kafka.streams.processor.StateStoreContext;
+import org.apache.kafka.streams.state.KeyValueBytesStoreSupplier;
+import org.apache.kafka.streams.state.KeyValueStore;
+import org.apache.kafka.streams.state.Stores;
+import org.apache.kafka.streams.state.internals.InMemoryKeyValueStore;
+import org.apache.kafka.test.MockApiProcessorSupplier;
+
+import org.junit.jupiter.api.AfterEach;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Tag;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.TestInfo;
+import org.junit.jupiter.api.Timeout;
+
+import java.util.Collections;
+import java.util.Map;
+import java.util.Properties;
+import java.util.concurrent.CountDownLatch;
+
+import static org.apache.kafka.streams.utils.TestUtils.safeUniqueTestName;
+import static org.junit.jupiter.api.Assertions.fail;
+
+@Timeout(120)
+@Tag("integration")
+public class InMemoryStoreMetricsIntegrationTest {
+ private static final int NUM_BROKERS = 1;
+ private static final String INPUT_TOPIC = "in-memory-num-keys-input";
+
+ private final EmbeddedKafkaCluster cluster = new
EmbeddedKafkaCluster(NUM_BROKERS);
+ private String safeTestName;
+
+ @BeforeEach
+ public void startCluster(final TestInfo testInfo) throws
InterruptedException {
+ cluster.start();
+ cluster.createTopic(INPUT_TOPIC, 1, 1);
+ safeTestName = safeUniqueTestName(testInfo);
+ }
+
+ @AfterEach
+ public void closeCluster() {
+ cluster.stop();
+ }
+
+ @Test
+ public void metricValueShouldNotThrowIfStoreIsNotInitialized() throws
Exception {
+ final CountDownLatch initLatch = new CountDownLatch(1);
+ final CountDownLatch finishLatch = new CountDownLatch(1);
+
+ final StreamsBuilder builder = new StreamsBuilder();
+ builder.addStateStore(
+ Stores.keyValueStoreBuilder(
Review Comment:
Should we add (or does it already exist) similar ones for window and session
case?
##########
streams/src/main/java/org/apache/kafka/streams/state/internals/MeteredKeyValueStore.java:
##########
@@ -182,7 +182,21 @@ private void registerMetrics() {
);
if (!persistent()) {
StateStoreMetrics.addNumKeysGauge(taskId.toString(), metricsScope,
name(), streamsMetrics,
- (config, now) -> wrapped().approximateNumEntries());
+ (config, now) -> {
+ final InMemoryKeyValueStore inMemoryStore =
findInMemoryKeyValueStore(wrapped());
+ return inMemoryStore != null ?
inMemoryStore.approximateNumEntries() : -1L;
Review Comment:
Seem we have the same `null` check in window/session store, but wondering
why we need it? If we get `null` back, would it not be a bug, and would mask
the bug with the `null` check?
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