nizhikov commented on code in PR #11044: URL: https://github.com/apache/ignite/pull/11044#discussion_r1401041090
########## modules/core/src/main/java/org/apache/ignite/internal/cdc/CdcManager.java: ########## @@ -0,0 +1,104 @@ +/* + * 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.cdc; + +import java.nio.ByteBuffer; +import java.util.Iterator; +import org.apache.ignite.IgniteCheckedException; +import org.apache.ignite.IgniteSystemProperties; +import org.apache.ignite.cdc.CdcConsumer; +import org.apache.ignite.internal.pagemem.wal.IgniteWriteAheadLogManager; +import org.apache.ignite.internal.pagemem.wal.record.CdcManagerRecord; +import org.apache.ignite.internal.pagemem.wal.record.CdcManagerStopRecord; +import org.apache.ignite.internal.processors.cache.GridCacheSharedManager; +import org.apache.ignite.internal.processors.cache.persistence.wal.WALPointer; +import org.apache.ignite.plugin.PluginContext; +import org.apache.ignite.plugin.PluginProvider; +import org.jetbrains.annotations.Nullable; + +/** + * CDC manager responsible for logic of capturing data within Ignite node. There is a contract between {@link CdcManager} + * and {@link CdcMain}. Communication between these components are built with WAL records. {@link CdcManager} can + * write some records, while {@link CdcMain} must listen to them. + * <ul> + * <li> + * This manager can write {@link CdcManagerRecord} that contains info about consumer state. + * This record will be handled by {@link CdcMain} the same way it handles {@link CdcConsumer#onEvents(Iterator)} + * when it returns {@code true}. + * </li> + * <li> + * This manager must write {@link CdcManagerStopRecord} after it stopped handling records by any reason. + * {@link CdcMain} will start consume records instead since {@link CdcManagerRecord#walState()} of + * last consumed {@link CdcManagerRecord}. + * </li> + * <li> + * Apache Ignite provides a default implementation - {@link CdcUtilityActiveCdcManager}. It will set the CDC mode to + * {@link CdcMode#CDC_UTILITY_ACTIVE} on node start up. + * </li> + * </ul> + * + * Ignite can be extended with custom CDC manager. It's required to implement this interface, create own {@link PluginProvider} + * that will return the implementation with {@link PluginProvider#createComponent(PluginContext, Class)} method. + * The {@code Class} parameter in the method is {@code CdcManager} class. + * + * @see CdcConsumer#onEvents(Iterator) + * @see CdcConsumerState#saveCdcMode(CdcMode) + */ +public interface CdcManager extends GridCacheSharedManager { + /** + * Callback is invoked once, after Ignite restores memory on start-up. It runs within Ignite start thread before + * {@link IgniteWriteAheadLogManager} enables writing new WAL records. WALPointer {@code restoredPtr} points + * to the head of the WAL, or {@code null} if no WAL records had written yet. + * + * This method invoked before first call of {@link #collect(ByteBuffer)}. The first collected buffer starts from + * the next pointer after {@code restoredPtr}. + * + * @param restoredPtr Pointer to WAL head record, {@code null} if no WAL records had written yet. + */ + public void afterMemoryRestore(@Nullable WALPointer restoredPtr) throws IgniteCheckedException; Review Comment: If this callback really required - please, add comment - what expected checks and behaviour of implementations. -- 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]
