denis-chudov commented on code in PR #957: URL: https://github.com/apache/ignite-3/pull/957#discussion_r943541154
########## modules/metrics/src/main/java/org/apache/ignite/internal/metrics/MetricRegistry.java: ########## @@ -0,0 +1,300 @@ +/* + * 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.ignite.internal.metrics; + +import static java.util.Objects.requireNonNull; + +import java.util.Iterator; +import java.util.Map; +import java.util.TreeMap; +import java.util.concurrent.atomic.AtomicReference; +import java.util.concurrent.locks.Lock; +import java.util.concurrent.locks.ReentrantLock; +import java.util.function.Function; +import org.apache.ignite.internal.util.FilteringIterator; +import org.apache.ignite.internal.util.TransformingIterator; +import org.apache.ignite.lang.IgniteBiTuple; +import org.jetbrains.annotations.NotNull; + +/** + * Metric registry. Metrics source (see {@link MetricSource} must be registered in this metrics registry after initialization + * of corresponding component and must be unregistered in case of component is destroyed or stopped. Metrics registry also + * provides access to all enabled metrics through corresponding metrics sets. Metrics registry lifetime is equal to the node lifetime. + * <br> + * Implements an {@link Iterable} over the metric sets for enabled metric sources. + */ +public class MetricRegistry implements Iterable<MetricSet> { + private final Lock lock = new ReentrantLock(); + + /** Map of metric sources' names to tuples of registered sources with metric sets, if enabled. */ + private volatile Map<String, IgniteBiTuple<MetricSource, MetricSet>> sources = new TreeMap<>(); + + /** Version always should be changed on metrics enabled/disabled action. */ + private volatile long version; + + /** + * Register metric source. It must be registered in this metrics registry after initialization of corresponding component + * and must be unregistered in case of component is destroyed or stopped, see {@link #unregisterSource(MetricSource)}. + * By registering, the metric source isn't enabled implicitly. + * + * @param src Metric source. + * @throws IllegalStateException If metric source with the given name already exists. + */ + public void registerSource(MetricSource src) { + modifySources(sources -> { + IgniteBiTuple<MetricSource, MetricSet> s = new IgniteBiTuple<>(src, null); + + IgniteBiTuple<MetricSource, MetricSet> old = sources.putIfAbsent(src.name(), s); + + if (old != null) { + throw new IllegalStateException("Metrics source with given name already exists: " + src.name()); + } + + // Now we sure that this metric source wasn't registered before. + assert !src.enabled() : "Metric source shouldn't be enabled before registration in registry."; + + return true; + }); + } + + /** + * Unregister metric source. It must be unregistered in case of corresponding component is destroyed or stopped. + * Metric source is also disabled while unregistered, see {@link #disable(String)}. + * + * @param src Metric source. + */ + public void unregisterSource(MetricSource src) { + unregisterSource(src.name()); + } + + /** + * Unregister metric source. It must be unregistered in case of corresponding component is destroyed or stopped. + * Metric source is also disabled while unregistered, see {@link #disable(String)}. + * + * @param srcName Metric source name. + */ + public void unregisterSource(String srcName) { + modifySources(sources -> { + IgniteBiTuple<MetricSource, MetricSet> s = sources.get(srcName); + + if (s == null) { + return false; + } + + assert s.get1() != null; + + s.get1().disable(); + + sources.remove(srcName); + + return true; + }); + } + + /** + * Enable metric set for the given metric source. + * + * @param src Metric source. + * @return Metric set, or {@code null} if the metric set is already enabled. + * @throws IllegalStateException If metric source isn't registered. + * @throws IllegalArgumentException If metric source isn't the same as registered. + */ + public MetricSet enable(@NotNull MetricSource src) { + AtomicReference<MetricSet> metricSetRef = new AtomicReference<>(); + + modifySources(sources -> { + IgniteBiTuple<MetricSource, MetricSet> registered = checkRegistered(sources, src); + + if (registered.get2() != null) { + assert src.enabled(); + return false; + } + + MetricSet metricSet = src.enable(); + + assert metricSet != null; + + IgniteBiTuple<MetricSource, MetricSet> updated = new IgniteBiTuple<>(src, metricSet); + + sources.put(src.name(), updated); + + metricSetRef.set(metricSet); + + return true; + }); + + return metricSetRef.get(); + } + + /** + * Enable metric set for the given metric source. + * + * @param srcName Metric source name. + * @return Metric set, or {@code null} if the metric set is already enabled. + * @throws IllegalStateException If metric source with the given name doesn't exist. + */ + public MetricSet enable(final String srcName) { + AtomicReference<MetricSet> metricSetRef = new AtomicReference<>(); + + modifySources(sources -> { + IgniteBiTuple<MetricSource, MetricSet> registered = sources.get(srcName); + + if (registered == null) { + throw new IllegalStateException("Metrics source with given name doesn't exist: " + srcName); + } + + MetricSource src = registered.get1(); + + if (registered.get2() != null) { + assert src.enabled(); + return false; + } + + MetricSet metricSet = src.enable(); + assert metricSet != null; + + IgniteBiTuple<MetricSource, MetricSet> updated = new IgniteBiTuple<>(src, metricSet); + + sources.put(src.name(), updated); + + metricSetRef.set(metricSet); + + return true; + }); + + return metricSetRef.get(); + } + + /** + * Disable metric set for the given metric source. + * + * @param src Metric source. + * @throws IllegalStateException If metric source isn't registered. + * @throws IllegalArgumentException If metric source isn't the same as registered. + */ + public void disable(@NotNull MetricSource src) { + modifySources(sources -> { + checkRegistered(sources, src); + + src.disable(); + + IgniteBiTuple<MetricSource, MetricSet> updated = new IgniteBiTuple<>(src, null); + + sources.put(src.name(), updated); + + return true; + }); + } + + /** + * Disable metric set for the given metric source. + * + * @param srcName Metric source name. + * @throws IllegalStateException If metric source with given name doesn't exists. + */ + public void disable(final String srcName) { + modifySources(sources -> { + IgniteBiTuple<MetricSource, MetricSet> registered = sources.get(srcName); + + if (registered == null) { + throw new IllegalStateException("Metrics source with given name doesn't exists: " + srcName); + } + + MetricSource src = registered.get1(); + + src.disable(); + + IgniteBiTuple<MetricSource, MetricSet> updated = new IgniteBiTuple<>(src, null); + + sources.put(src.name(), updated); + + return true; + }); + } + + /** + * Check that the given metric source is registered. + * + * @param sources Sources map. + * @param src Metric source. + * @return Registered pair of metric source and metric set. + * @throws IllegalStateException If metric source isn't registered. + * @throws IllegalArgumentException If metric source isn't the same as registered. + */ + @NotNull + private IgniteBiTuple<MetricSource, MetricSet> checkRegistered( + Map<String, IgniteBiTuple<MetricSource, MetricSet>> sources, + @NotNull MetricSource src + ) { + requireNonNull(src); + + IgniteBiTuple<MetricSource, MetricSet> registered = sources.get(src.name()); + + if (registered == null) { + throw new IllegalStateException("Metrics source isn't registered: " + src.name()); + } + + if (!src.equals(registered.get1())) { + throw new IllegalArgumentException("Given metric source is not the same as registered by the same name: " + src.name()); + } + + return registered; + } + + /** + * Updates {@link MetricRegistry#sources} map using copy-on-write principle. Increments version of registry. + * + * @param modifier Modifier for the sources map. Accepts the new, modifiable version of the map. Returns boolean value, whether + * the map was modified. + */ + private void modifySources(Function<Map<String, IgniteBiTuple<MetricSource, MetricSet>>, Boolean> modifier) { + lock.lock(); + + try { + Map<String, IgniteBiTuple<MetricSource, MetricSet>> sources0 = new TreeMap<>(sources); + + boolean modified = modifier.apply(sources0); + + if (modified) { + sources = sources0; + + version++; Review Comment: I fixed this and added the tests for checking the correctness of version. Registering the new source seems to be the only case when the map changes and version doesnt, and the old implementation didnt provide copy-on-write semantics so I will leave the current one, in general. -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. 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