nizhikov commented on a change in pull request #49: URL: https://github.com/apache/ignite-extensions/pull/49#discussion_r652424609
########## File path: modules/cdc-ext/src/main/java/org/apache/ignite/cdc/conflictresolve/CacheVersionConflictResolverImpl.java ########## @@ -0,0 +1,160 @@ +/* + * 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.cdc.conflictresolve; + +import org.apache.ignite.IgniteLogger; +import org.apache.ignite.binary.BinaryObject; +import org.apache.ignite.internal.processors.cache.CacheObjectValueContext; +import org.apache.ignite.internal.processors.cache.version.CacheVersionConflictResolver; +import org.apache.ignite.internal.processors.cache.version.GridCacheVersionConflictContext; +import org.apache.ignite.internal.processors.cache.version.GridCacheVersionedEntryEx; +import org.apache.ignite.internal.util.typedef.internal.U; + +/** + * This class implements simple conflict resolution algorithm. + * Algorithm decides which version of the entry should be used "new" or "old". + * The following steps performed: + * <ul> + * <li>If entry is freshly created then new version used - {@link GridCacheVersionedEntryEx#isStartVersion()}.</li> + * <li>If change made in this cluster then new version used - {@link GridCacheVersionedEntryEx#dataCenterId()}.</li> + * <li>If cluster of new entry equal to cluster of old entry + * then entry with the greater {@link GridCacheVersionedEntryEx#order()} used.</li> + * <li>If {@link #conflictResolveField} provided and field of new entry greater then new version used.</li> + * <li>If {@link #conflictResolveField} provided and field of old entry greater then old version used.</li> + * <li>Entry with the lower value of {@link GridCacheVersionedEntryEx#dataCenterId()} used.</li> + * </ul> + * + * Note, data center with lower value has greater priority e.g first (1) data center is main in case conflict can't be resolved + * automatically. + */ +public class CacheVersionConflictResolverImpl implements CacheVersionConflictResolver { + /** + * Cluster id. + * Note, cluster with lower value has greater priority e.g first (1) cluster is main in case conflict can't be resolved automatically. + */ + private final byte clusterId; + + /** + * Field for conflict resolve. + * Value of this field will be used to compare two entries in case of conflicting changes. + * values of this field must implement {@link Comparable} interface. + * <pre><i>Note, value of this field used to resolve conflict for external updates only.</i> + * + * @see CacheVersionConflictResolverImpl + */ + private final String conflictResolveField; + + /** Logger. */ + private final IgniteLogger log; + + /** If {@code true} then conflict resolving with the value field enabled. */ + private boolean conflictResolveFieldEnabled; + + /** + * @param clusterId Data center id. + * @param conflictResolveField Field to resolve conflicts. + * @param log Logger. + */ + public CacheVersionConflictResolverImpl(byte clusterId, String conflictResolveField, IgniteLogger log) { + this.clusterId = clusterId; + this.conflictResolveField = conflictResolveField; + this.log = log; + + conflictResolveFieldEnabled = conflictResolveField != null; + } + + /** {@inheritDoc} */ + @Override public <K, V> GridCacheVersionConflictContext<K, V> resolve( + CacheObjectValueContext ctx, + GridCacheVersionedEntryEx<K, V> oldEntry, + GridCacheVersionedEntryEx<K, V> newEntry, + boolean atomicVerComparator + ) { + GridCacheVersionConflictContext<K, V> res = new GridCacheVersionConflictContext<>(ctx, oldEntry, newEntry); + + if (isUseNew(ctx, oldEntry, newEntry)) + res.useNew(); + else { + log.warning("Skip update due to the conflict [key=" + newEntry.key() + ", fromCluster=" + newEntry.dataCenterId() + + ", toCluster=" + oldEntry.dataCenterId() + ']'); + + res.useOld(); + } + + return res; + } + + /** + * @param ctx Context. + * @param oldEntry Old entry. + * @param newEntry New entry. + * @param <K> Key type. + * @param <V> Key type. + * @return {@code True} is should use new entry. + */ + @SuppressWarnings({"unchecked", "rawtypes"}) + private <K, V> boolean isUseNew( + CacheObjectValueContext ctx, + GridCacheVersionedEntryEx<K, V> oldEntry, + GridCacheVersionedEntryEx<K, V> newEntry + ) { + if (newEntry.dataCenterId() == clusterId) // Update made on the local cluster always win. + return true; + + if (oldEntry.isStartVersion()) // New entry. + return true; + + if (oldEntry.dataCenterId() == newEntry.dataCenterId()) + return newEntry.version().compareTo(oldEntry.version()) > 0; // New version from the same cluster. + + if (conflictResolveFieldEnabled) { + Object oldVal = oldEntry.value(ctx); + Object newVal = newEntry.value(ctx); + + if (oldVal != null && newVal != null) { + Comparable o; + Comparable n; + + try { + if (oldVal instanceof BinaryObject) { + o = ((BinaryObject)oldVal).field(conflictResolveField); + n = ((BinaryObject)newVal).field(conflictResolveField); + } + else { + o = U.field(oldVal, conflictResolveField); + n = U.field(newVal, conflictResolveField); + } + + if (o == null || n == null) Review comment: Conflict resolver is extremely hot code so I don't think we can insert logging here. -- This is an automated message from the Apache Git Service. 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