ekaterinadimitrova2 commented on code in PR #2807: URL: https://github.com/apache/cassandra/pull/2807#discussion_r1375127362
########## src/java/org/apache/cassandra/tcm/AtomicLongBackedProcessor.java: ########## @@ -0,0 +1,182 @@ +/* + * 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.cassandra.tcm; + +import java.util.ArrayList; +import java.util.Collections; +import java.util.List; +import java.util.SortedMap; +import java.util.concurrent.ConcurrentSkipListMap; +import java.util.concurrent.atomic.AtomicLong; +import java.util.function.Function; + +import org.slf4j.Logger; +import org.slf4j.LoggerFactory; + +import org.apache.cassandra.tcm.log.Entry; +import org.apache.cassandra.tcm.log.LocalLog; +import org.apache.cassandra.tcm.log.LogState; +import org.apache.cassandra.tcm.log.LogStorage; +import org.apache.cassandra.tcm.log.Replication; + +/** + * This Processor should only be used for tests and for offline tools where we need to create tables without + * persisting any transformations. + */ +public class AtomicLongBackedProcessor extends AbstractLocalProcessor +{ + private static final Logger logger = LoggerFactory.getLogger(AtomicLongBackedProcessor.class); + + private final AtomicLong epochHolder; + + public AtomicLongBackedProcessor(LocalLog log) + { + this(log, false); + } + + public AtomicLongBackedProcessor(LocalLog log, boolean isReset) + { + super(log); + Epoch epoch = log.metadata().epoch; + assert epoch.is(Epoch.EMPTY) || isReset : epoch + " != " + Epoch.EMPTY; + this.epochHolder = new AtomicLong(epoch.getEpoch()); + } + + @Override + protected boolean tryCommitOne(Entry.Id entryId, Transformation transform, + Epoch previousEpoch, Epoch nextEpoch, + long previousPeriod, long nextPeriod, boolean sealPeriod) + { + if (epochHolder.get() == 0) + { + assert previousEpoch.is(Epoch.FIRST) : previousEpoch + " != " + Epoch.FIRST; + if (!epochHolder.compareAndSet(Epoch.EMPTY.getEpoch(), Epoch.FIRST.getEpoch())) + return false; + } + return epochHolder.compareAndSet(previousEpoch.getEpoch(), nextEpoch.getEpoch()); + } + + @Override + public ClusterMetadata fetchLogAndWait(Epoch waitFor, Retry.Deadline retry) + { + return log.waitForHighestConsecutive(); + } + + public static class InMemoryStorage implements LogStorage + { + private final List<Entry> entries; + public final MetadataSnapshots metadataSnapshots; + + public InMemoryStorage() + { + this.entries = new ArrayList<>(); + this.metadataSnapshots = new InMemoryMetadataSnapshots(); + } + + @Override + public synchronized void append(long period, Entry entry) + { + boolean needsSorting = entries.isEmpty() ? false : entry.epoch.isDirectlyAfter(entries.get(entries.size() - 1).epoch); + entries.add(entry); + if (needsSorting) + Collections.sort(entries); + } + + @Override + public synchronized LogState getLogState(Epoch since) + { + ClusterMetadata latestSnapshot = metadataSnapshots.getLatestSnapshotAfter(since); + LogState logState; + if (latestSnapshot == null) + logState = new LogState(null, getReplication(since)); + else + logState = new LogState(latestSnapshot, getReplication(latestSnapshot.epoch)); + + return logState; + } + + @Override + public synchronized Replication getReplication(Epoch since) + { + assert entries != null : "Preserve history is off; can't query log state"; + int idx = indexedBinarySearch(entries, since, e -> e.epoch); + if (idx < 0) + idx = 0; + return Replication.of(entries.subList(idx, entries.size())); + } + + @Override + public synchronized Replication getReplication(long startPeriod, Epoch since) + { + return getReplication(since); + } + + private static <T1, T2 extends Comparable<T2>> int indexedBinarySearch(List<T1> list, T2 key, Function<T1, T2> fn) { + int low = 0; + int high = list.size()-1; + + while (low <= high) { + int mid = (low + high) >>> 1; + T1 midVal = list.get(mid); + int cmp = fn.apply(midVal).compareTo(key); + + if (cmp < 0) + low = mid + 1; + else if (cmp > 0) + high = mid - 1; + else + return mid; // key found + } + return -(low + 1); // key not found + } + } + + public static class InMemoryMetadataSnapshots implements MetadataSnapshots + { + private SortedMap<Epoch, ClusterMetadata> snapshots; Review Comment: ```suggestion private final SortedMap<Epoch, ClusterMetadata> snapshots; ``` -- This is an automated message from the Apache Git Service. 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