| /* |
| * 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.catalog.storage; |
| |
| import java.util.concurrent.CompletableFuture; |
| import org.apache.ignite.internal.hlc.HybridTimestamp; |
| import org.apache.ignite.internal.lang.IgniteInternalException; |
| import org.apache.ignite.internal.manager.IgniteComponent; |
| |
| /** |
| * Distributed log of catalog updates. |
| */ |
| public interface UpdateLog extends IgniteComponent { |
| /** |
| * Appends the given update to the log if the update with that version does not exist. |
| * |
| * <p>The version of {@link VersionedUpdate} must be greater by 1 of the version of previously |
| * appended update, otherwise current update will be rejected. The versions of already appended |
| * updates should be tracked by registering {@link OnUpdateHandler update handler} |
| * (see {@link #registerUpdateHandler(OnUpdateHandler)}). |
| * |
| * @param update An update to append to the log. |
| * @return A {@code true} if update has been successfully appended, {@code false} otherwise |
| * if update with the same version already exists, and operation should be retried with |
| * new version. |
| */ |
| CompletableFuture<Boolean> append(VersionedUpdate update); |
| |
| /** |
| * Saves a snapshot entry and drop updates of previous versions from the log, if supported, otherwise do nothing. |
| * |
| * @param snapshotEntry An entry, which represents a result of merging updates of previous versions. |
| * @return A {@code true} if snapshot has been successfully written, {@code false} otherwise |
| * if a snapshot with the same or greater version already exists. |
| */ |
| CompletableFuture<Boolean> saveSnapshot(SnapshotEntry snapshotEntry); |
| |
| /** |
| * Registers a handler to keep track of appended updates. |
| * |
| * @param handler A handler to notify when new update was appended. |
| */ |
| void registerUpdateHandler(OnUpdateHandler handler); |
| |
| /** |
| * Starts the component. |
| * |
| * <p>Log replay is a part of a component start up process, thus the handler must |
| * be registered prior to start is invoked, otherwise exception will be thrown. |
| * |
| * @return Completable future. |
| * @throws IgniteInternalException If no handler has been registered. |
| */ |
| @Override |
| CompletableFuture<Void> startAsync() throws IgniteInternalException; |
| |
| /** An interface describing a handler that will receive notification when a new update is added to the log. */ |
| @FunctionalInterface |
| interface OnUpdateHandler { |
| /** |
| * An actual handler that will be invoked when new update is appended to the log. |
| * |
| * @param update A new update. |
| * @param metaStorageUpdateTimestamp Timestamp assigned to the update by the Metastorage. |
| * @param causalityToken Causality token. |
| * @return Handler future. |
| */ |
| CompletableFuture<Void> handle(UpdateLogEvent update, HybridTimestamp metaStorageUpdateTimestamp, long causalityToken); |
| } |
| } |