vldpyatkov commented on a change in pull request #631: URL: https://github.com/apache/ignite-3/pull/631#discussion_r801609796
########## File path: modules/core/src/main/java/org/apache/ignite/internal/causality/VersionedValue.java ########## @@ -0,0 +1,220 @@ +/* + * 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.causality; + +import java.util.Map.Entry; +import java.util.concurrent.CompletableFuture; +import java.util.concurrent.ConcurrentNavigableMap; +import java.util.concurrent.ConcurrentSkipListMap; +import java.util.function.BiConsumer; +import java.util.function.Consumer; +import org.apache.ignite.lang.IgniteStringFormatter; +import org.jetbrains.annotations.Nullable; + +/** + * Parametrized type to store several versions of the value. + * A value can be available through the causality token, which is represented by long. + * + * @param <T> Type of real value. + */ +public class VersionedValue<T> { + /** Last applied casualty token. */ + private volatile long actualToken; + + /** Size of stored history. */ + private final int historySize; + + /** Closure applied on storage revision update. */ + private final BiConsumer<VersionedValue<T>, Long> onStorageRevisionUpdate; + + /** Bersoned value storage. */ + private final ConcurrentNavigableMap<Long, CompletableFuture<T>> history = new ConcurrentSkipListMap<>(); + + /** + * Constructor. + * + * @param onStorageRevisionUpdate Closure applied on storage revision update (see {@link #onStorageRevisionUpdate(long)}. + * @param observableRevisionUpdater A closure intended to connect this VersionedValue with a revision updater, that this VersionedValue + * should be able to listen to, for receiving storage revision updates. This closure is called once on + * a construction of this VersionedValue and accepts a {@link Consumer<Long>} that should be called on + * every update of storage revision as a listener. + * @param historySize Size of the history of changes to store, including last applied token. + */ + public VersionedValue( + @Nullable BiConsumer<VersionedValue<T>, Long> onStorageRevisionUpdate, + Consumer<Consumer<Long>> observableRevisionUpdater, + int historySize + ) { + this.onStorageRevisionUpdate = onStorageRevisionUpdate == null ? (versionedValue, token) -> { + Entry<Long, CompletableFuture<T>> entry = history.floorEntry(token); + + assert entry != null : IgniteStringFormatter.format("No future by token [token={}]", token); + + if (!entry.getValue().isDone()) { + Entry<Long, CompletableFuture<T>> entryBefore = history.headMap(token).lastEntry(); + + assert entryBefore != null && entryBefore.getValue().isDone() : IgniteStringFormatter.format( + "No future by token [token={}]", token); + + entryBefore.getValue().whenComplete((t, throwable) -> { + if (throwable != null) { + entry.getValue().completeExceptionally(throwable); + } else { + entry.getValue().complete(t); + } + }); + } + } : onStorageRevisionUpdate; + + observableRevisionUpdater.accept(this::onStorageRevisionUpdate); + + this.historySize = historySize; + } + + /** + * Constructor with default history size that equals 2. See {@link #VersionedValue(BiConsumer, int)}. + * + * @param onStorageRevisionUpdate Closure applied on storage revision update (see {@link #onStorageRevisionUpdate(long)}. + * @param observableRevisionUpdater A closure intended to connect this VersionedValue with a revision updater, that this VersionedValue + * should be able to listen to, for receiving storage revision updates. This closure is called once on + * a construction of this VersionedValue and accepts a {@link Consumer<Long>} that should be called on + * every update of storage revision as a listener. + */ + public VersionedValue( + @Nullable BiConsumer<VersionedValue<T>, Long> onStorageRevisionUpdate, + Consumer<Consumer<Long>> observableRevisionUpdater + ) { + this(null, observableRevisionUpdater, 2); + } + + /** + * Constructor with default history size that equals 2 and no closure. + * + * @param observableRevisionUpdater A closure intended to connect this VersionedValue with a revision updater, that this VersionedValue + * should be able to listen to, for receiving storage revision updates. This closure is called once on + * a construction of this VersionedValue and accepts a {@link Consumer<Long>} that should be called on + * every update of storage revision as a listener. + */ + public VersionedValue(Consumer<Consumer<Long>> observableRevisionUpdater) { + this(null, observableRevisionUpdater); + } + + /** + * Creates a future for this value and causality token, or returns it if it already exists. + * + * <p>The returned future is associated with an update having the given causality token and completes when this update is finished + * applying. + * + * @param causalityToken Causality token. Let's assume that the update associated with token N is already applied to this value. Then, + * if token N is given as an argument, a completed future will be returned. If token N - 1 is given, this method + * returns the result in the state that is actual for the given token. If the token is strongly outdated, {@link + * OutdatedTokenException} is thrown. If token N + 1 is given, this method will return a future that will be + * completed when the update associated with token N + 1 will have been applied. Tokens that greater than N by + * more than 1 should never be passed. + * @return The future. + * @throws OutdatedTokenException If outdated token is passed as an argument. + */ + public CompletableFuture<T> get(long causalityToken) throws OutdatedTokenException { + long actualToken0 = actualToken; + + if (causalityToken <= actualToken0) { + Entry<Long, CompletableFuture<T>> histEntry = history.floorEntry(causalityToken); + + if (histEntry == null) { + throw new OutdatedTokenException(causalityToken, actualToken0, historySize); + } + + return histEntry.getValue(); + } else { + var fut = new CompletableFuture<T>(); + + CompletableFuture<T> previousFut = history.putIfAbsent(causalityToken, fut); + + return previousFut == null ? fut : previousFut; + } + } + + /** + * Save the version of the value associated with the given causality token. If someone has got a future to await the value associated + * with the given causality token (see {@link #get(long)}, then the future will be completed. + * + * @param causalityToken Causality token. + * @param value Current value. + */ + public void set(long causalityToken, T value) { + long actualToken0 = actualToken; + + assert causalityToken > actualToken0 : IgniteStringFormatter.format("Token earlier than actual [token={}, actual={}]", + causalityToken, actualToken0); + + assert actualToken0 + 1 == causalityToken : IgniteStringFormatter.format( + "Previous token did not complete [token={}, previous={}]", causalityToken, causalityToken - 1); Review comment: Left only one. -- 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. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected]
