ibessonov commented on a change in pull request #589: URL: https://github.com/apache/ignite-3/pull/589#discussion_r793306121
########## File path: modules/configuration/src/main/java/org/apache/ignite/internal/configuration/ConfigurationListenerHolder.java ########## @@ -0,0 +1,126 @@ +/* + * 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.configuration; + +import java.util.Collection; +import java.util.Iterator; +import java.util.NoSuchElementException; +import java.util.concurrent.CopyOnWriteArrayList; +import org.jetbrains.annotations.Nullable; + +/** + * Holder (thread safe) for configuration change listeners. + */ +class ConfigurationListenerHolder<L> { + private final Collection<Container<L>> containers = new CopyOnWriteArrayList<>(); Review comment: I don't really understand, why all fields/parameters have to be `collections`. This, for example, must be ordered (not sorted). Ordered collections are called lists, right? What's the exact motivation? I would really like to know. ########## File path: modules/configuration/src/main/java/org/apache/ignite/internal/configuration/ConfigurationListenerHolder.java ########## @@ -0,0 +1,126 @@ +/* + * 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.configuration; + +import java.util.Collection; +import java.util.Iterator; +import java.util.NoSuchElementException; +import java.util.concurrent.CopyOnWriteArrayList; +import org.jetbrains.annotations.Nullable; + +/** + * Holder (thread safe) for configuration change listeners. + */ +class ConfigurationListenerHolder<L> { + private final Collection<Container<L>> containers = new CopyOnWriteArrayList<>(); + + /** + * Adds a listener. + * + * @param listener Configuration change listener. + * @param notificationNumber Configuration notification listener number after which the listener will be called. + * @see ConfigurationListenerHolder#listeners + */ + void addListener(L listener, long notificationNumber) { + containers.add(new Container<>(listener, notificationNumber)); + } + + /** + * Removes the listener. + * + * @param listener Configuration change listener. + */ + void removeListener(L listener) { + containers.remove(new Container<>(listener, -1) { + /** {@inheritDoc} */ + @Override + public boolean equals(Object obj) { + return listener == ((Container<L>) obj).listener; + } + }); + } + + /** + * Returns an iterator of the listeners for the {@code notificationNumber} (were added for and before it). + * + * <p>NOTE: {@link Iterator#remove} - not supported. + * + * @param notificationNumber Configuration notification listener number. + * @see ConfigurationListenerHolder#addListener + */ + Iterator<L> listeners(long notificationNumber) { Review comment: Or, you could return filtered stream and not reinvent the wheel. ########## File path: modules/configuration/src/main/java/org/apache/ignite/internal/configuration/ConfigurationNode.java ########## @@ -104,22 +101,24 @@ protected ConfigurationNode( /** {@inheritDoc} */ @Override public void listen(ConfigurationListener<VIEWT> listener) { - updateListeners.add(listener); + updateListeners.addListener(listener, changer.notificationCount() + 1); Review comment: I feel like this statement breaks encapsulation. Should `+ 1` be inside of the method, not outside? ########## File path: modules/core/src/main/java/org/apache/ignite/internal/util/CollectionUtils.java ########## @@ -197,13 +202,100 @@ public T next() { }; } + /** + * Create a lazy concatenation of iterators. + * + * <p>NOTE: {@link Iterator#remove} - not supported. + * + * @param iterators Iterators. + * @param <T> Type of the elements. + * @return Concatenation of iterators. + */ + @SafeVarargs + public static <T> Iterator<T> concat(@Nullable Iterator<? extends T>... iterators) { Review comment: Why don't we use streams? ########## File path: modules/configuration/src/main/java/org/apache/ignite/internal/configuration/ConfigurationListenerHolder.java ########## @@ -0,0 +1,126 @@ +/* + * 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.configuration; + +import java.util.Collection; +import java.util.Iterator; +import java.util.NoSuchElementException; +import java.util.concurrent.CopyOnWriteArrayList; +import org.jetbrains.annotations.Nullable; + +/** + * Holder (thread safe) for configuration change listeners. + */ +class ConfigurationListenerHolder<L> { + private final Collection<Container<L>> containers = new CopyOnWriteArrayList<>(); + + /** + * Adds a listener. + * + * @param listener Configuration change listener. + * @param notificationNumber Configuration notification listener number after which the listener will be called. + * @see ConfigurationListenerHolder#listeners + */ + void addListener(L listener, long notificationNumber) { + containers.add(new Container<>(listener, notificationNumber)); + } + + /** + * Removes the listener. + * + * @param listener Configuration change listener. + */ + void removeListener(L listener) { Review comment: You know what's funny? "Nested" removes won't work properly :) ########## File path: modules/core/src/main/java/org/apache/ignite/internal/util/CollectionUtils.java ########## @@ -197,13 +202,100 @@ public T next() { }; } + /** + * Create a lazy concatenation of iterators. + * + * <p>NOTE: {@link Iterator#remove} - not supported. + * + * @param iterators Iterators. + * @param <T> Type of the elements. + * @return Concatenation of iterators. + */ + @SafeVarargs + public static <T> Iterator<T> concat(@Nullable Iterator<? extends T>... iterators) { + if (iterators == null || iterators.length == 0) { + return emptyIterator(); + } + + return new Iterator<>() { + /** Current index at {@code iterators}. */ + int idx = 0; + + /** Current iterator. */ + Iterator<? extends T> curr = emptyIterator(); + + /** {@inheritDoc} */ + @Override + public boolean hasNext() { + while (!curr.hasNext() && idx < iterators.length) { + curr = iterators[idx++]; + } + + return curr.hasNext(); + } + + /** {@inheritDoc} */ + @Override + public T next() { + if (!hasNext()) { + throw new NoSuchElementException(); + } else { + return curr.next(); + } + } + }; + } + + /** + * Create a lazy concatenation of iterators. + * + * <p>NOTE: {@link Iterator#remove} - not supported. + * + * @param iterators Iterators. + * @param <T> Type of the elements. + * @return Concatenation of iterators. + */ + public static <T> Iterator<T> concat(@Nullable Collection<Iterator<? extends T>> iterators) { Review comment: Same question, this is literally a `flatMap(Function.id())` operation ########## File path: modules/configuration/src/main/java/org/apache/ignite/internal/configuration/ConfigurationChanger.java ########## @@ -95,7 +96,10 @@ private final ConfigurationStorage storage; /** Storage trees. */ - private volatile StorageRoots storageRoots; + @Nullable private volatile StorageRoots storageRoots; Review comment: It can't be null after `start`, are you sure that `@Nullable` is really necessary here? -- This is an automated message from the Apache Git Service. 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