nizhikov commented on code in PR #10314: URL: https://github.com/apache/ignite/pull/10314#discussion_r1066060597
########## modules/core/src/main/java/org/apache/ignite/internal/processors/cache/persistence/snapshot/ConsistentCut.java: ########## @@ -0,0 +1,130 @@ +/* + * 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.persistence.snapshot; + +import java.util.UUID; +import org.apache.ignite.internal.IgniteInternalFuture; +import org.apache.ignite.internal.pagemem.wal.record.ConsistentCutFinishRecord; +import org.apache.ignite.internal.processors.cache.GridCacheMessage; +import org.apache.ignite.internal.processors.cache.GridCacheSharedContext; +import org.apache.ignite.internal.processors.cache.persistence.wal.WALPointer; +import org.apache.ignite.internal.processors.cache.transactions.IgniteInternalTx; +import org.apache.ignite.internal.util.future.GridCompoundIdentityFuture; +import org.apache.ignite.internal.util.future.GridFutureAdapter; +import org.jetbrains.annotations.Nullable; + +import static org.apache.ignite.internal.processors.cache.GridCacheUtils.baselineNode; + +/** + * Consistent Cut is a distributed algorithm that defines two set of transactions - BEFORE and AFTER cut - on baseline nodes. + * It guarantees that every transaction was included into BEFORE on one node also included into the BEFORE on every other node + * participated in the transaction. It means that 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 wrapped in {@link ConsistentCutAwareMessage}. + * <p> + * There are two roles that node can play: + * 1. Wraps outgoing transaction messages into {@link ConsistentCutAwareMessage}. For this role every node is responsible. + * 2. Writes Consistent Cut records into WAL. Only baseline nodes do it. + * <p> + * Nodes start wrapping messages from the moment Consistent Cut started on the node, and finsihed after all baseline + * nodes complete their role 2. + */ +public class ConsistentCut { + /** Grid cache context. */ + private final GridCacheSharedContext<?, ?> cctx; + + /** Consistent Cut ID. */ + private final UUID id; + + /** + * If {@code true} it wraps messages into {@link ConsistentCutAwareMessage}. Becames {@code false} after every baseline node + * completes {@link #markWalFut}. + */ + private volatile boolean wrapMsg = true; + + /** Future that completes after last {@link ConsistentCutAwareMessage} was sent. */ + private final GridFutureAdapter<?> wrapMsgsFut = new GridFutureAdapter<>(); + + /** Future that completes after {@link ConsistentCutFinishRecord} was written. */ + private final @Nullable ConsistentCutMarkWalFuture markWalFut; + + /** */ + ConsistentCut(GridCacheSharedContext<?, ?> cctx, UUID id) { + this.cctx = cctx; + this.id = id; + + markWalFut = baselineNode(cctx.localNode(), cctx.kernalContext().state().clusterState()) + ? new ConsistentCutMarkWalFuture(cctx, id) : null; + } + + /** + * Wraps a transaction message if needed. + * + * @param txMsg Transaction message to wrap. + * @param txCutId Consistent Cut ID after which transaction committed, if specified. + */ + GridCacheMessage wrapMessage(GridCacheMessage txMsg, @Nullable UUID txCutId) { + if (wrapMsg) + return new ConsistentCutAwareMessage(txMsg, id, txCutId); + + return txMsg; + } + + /** Stops wrapping outging messages. */ + void stopWrapMessages() { + wrapMsg = false; + + GridCompoundIdentityFuture<IgniteInternalTx> activeTxsFut = new GridCompoundIdentityFuture<>(); + + for (IgniteInternalTx tx: cctx.tm().activeTransactions()) + activeTxsFut.add(tx.finishFuture()); + + activeTxsFut.markInitialized(); + + activeTxsFut.listen(f -> wrapMsgsFut.onDone()); + } + + /** */ + void init(GridCacheSharedContext<?, ?> cctx) { Review Comment: Parameter useless. `cctx` instance cached in class instance - `this.cctx`. -- This is an automated message from the Apache Git Service. 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