nizhikov commented on code in PR #10314: URL: https://github.com/apache/ignite/pull/10314#discussion_r1027664227
########## modules/core/src/main/java/org/apache/ignite/internal/processors/cache/consistentcut/ConsistentCutManager.java: ########## @@ -0,0 +1,212 @@ +/* + * 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.processors.cache.consistentcut; + +import java.util.UUID; +import java.util.concurrent.atomic.AtomicReferenceFieldUpdater; +import org.apache.ignite.IgniteCheckedException; +import org.apache.ignite.internal.pagemem.wal.record.ConsistentCutFinishRecord; +import org.apache.ignite.internal.pagemem.wal.record.ConsistentCutStartRecord; +import org.apache.ignite.internal.processors.cache.GridCacheMessage; +import org.apache.ignite.internal.processors.cache.GridCacheSharedManagerAdapter; +import org.apache.ignite.internal.processors.cache.distributed.dht.preloader.GridDhtPartitionsExchangeFuture; +import org.apache.ignite.internal.processors.cache.distributed.dht.preloader.PartitionsExchangeAware; +import org.apache.ignite.internal.processors.cache.transactions.IgniteInternalTx; +import org.apache.ignite.internal.processors.cache.transactions.IgniteTxAdapter; +import org.apache.ignite.internal.util.typedef.internal.U; +import org.jetbrains.annotations.Nullable; + +import static org.apache.ignite.internal.processors.cache.GridCacheUtils.baselineNode; + +/** + * Processes all stuff related to Consistent Cut. + * <p> + * ConsistentCut is a distributed algorithm that splits WAL on 2 global areas - BEFORE and AFTER. It guarantees that every + * transaction committed Before also will be committed Before on every other node participated in the transaction. + * It means that an Ignite nodes can safely recover themselves to the consistent BEFORE state without any coordination with each other. + * <p> + * The algorithm starts on Ignite node by snapshot creation command. Other nodes are notified with discovery message of snapshot + * distributed process or by transaction messages {@link ConsistentCutAwareMessage}. + * <p> + * The algorithm consist of steps: + * 1. On receiving new Consistent Cut ID it immediately creates new {@link ConsistentCut} before processing the message. + * 2. It starts wrapping all transaction messages to {@link ConsistentCutAwareMessage}. + * 3. Every transaction holds {@link IgniteTxAdapter#cutId()} AFTER which it committed. Value of this field is defined + * at node that commits first in distributed transaction. + * 3. On baseline nodes: + * - it writes {@link ConsistentCutStartRecord} to limit amount of transactions on the AFTER side of Consistent Cut. + * After writing this record it's safe to miss transactions on the AFTER side. + * - it collects active transactions to check which side of Consistent Cut they belong to. This collection contains all + * not-committed yet transactions that are on the BEFORE side. + * - it awaits every transaction in this collection to be committed to decide which side of Consistent Cut they belong to. + * - after the all active transactions finished it finishes Consistent Cut with writing {@link ConsistentCutFinishRecord} that contains + * collection of transactions on the BEFORE and AFTER sides. + * 8. After Consistent Cut finished globally, it clears {@link ConsistentCut} variable and stops wrapping messages. + */ +public class ConsistentCutManager extends GridCacheSharedManagerAdapter implements PartitionsExchangeAware { + /** It serves updates of {@link #cut} with CAS. */ + protected static final AtomicReferenceFieldUpdater<ConsistentCutManager, ConsistentCut> CONSISTENT_CUT = + AtomicReferenceFieldUpdater.newUpdater(ConsistentCutManager.class, ConsistentCut.class, "cut"); + + /** Current Consistent Cut, {@code null} if not running. */ + private volatile @Nullable ConsistentCut cut; + + /** ID of the last finished {@link ConsistentCut}. Required to avoid re-run {@link ConsistentCut} with the same id. */ + protected volatile UUID lastFinishedCutId; + + /** {@inheritDoc} */ + @Override public void start0() throws IgniteCheckedException { + super.start0(); + + cctx.exchange().registerExchangeAwareComponent(this); + } + + /** {@inheritDoc} */ + @Override public void stop0(boolean cancel) { + cancelCut(new IgniteCheckedException("Ignite node is stopping.")); + } + + /** + * Stops Consistent Cut in case of baseline topology changed. + */ + @Override public void onInitBeforeTopologyLock(GridDhtPartitionsExchangeFuture fut) { + if (fut.changedBaseline() || fut.isBaselineNodeFailed()) + cancelCut(new IgniteCheckedException("Ignite topology changed, can't finish Consistent Cut.")); + } + + /** + * Registers transaction before it starts committing. + * + * @param tx Transaction. + * @param firstCommit If {@code true} then it is first commit for distributed transaction. + */ + public void registerBeforeCommit(IgniteInternalTx tx, boolean firstCommit) { Review Comment: Let's make naming consistent registerBeforeCommit -> onRemoveActiveTransaction or registerBeforeCommit -> onBeforeCommit onRemoveActiveTransaction -> onBeforeCommit -- This is an automated message from the Apache Git Service. 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