vinothchandar commented on a change in pull request #3194: URL: https://github.com/apache/hudi/pull/3194#discussion_r663300797
########## File path: hudi-common/src/main/java/org/apache/hudi/common/util/collection/RocksDbDiskMap.java ########## @@ -0,0 +1,173 @@ +/* + * 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.hudi.common.util.collection; + +import org.apache.hudi.exception.HoodieException; +import org.apache.hudi.exception.HoodieNotSupportedException; + +import org.apache.log4j.LogManager; +import org.apache.log4j.Logger; + +import java.io.IOException; +import java.io.Serializable; +import java.util.AbstractMap; +import java.util.Collection; +import java.util.HashSet; +import java.util.Iterator; +import java.util.Map; +import java.util.Set; +import java.util.stream.Stream; + +/** + * This class provides a disk spillable only map implementation. + * All of the data is stored using the RocksDB implementation. + */ +public final class RocksDbDiskMap<T extends Serializable, R extends Serializable> implements DiskMap<T, R> { + // ColumnFamily allows partitioning data within RockDB, which allows + // independent configuration and faster deletes across partitions + // https://github.com/facebook/rocksdb/wiki/Column-Families + // For this use case, we use a single static column family/ partition + // + private static final String COLUMN_FAMILY_NAME = "spill_map"; + + private static final Logger LOG = LogManager.getLogger(RocksDbDiskMap.class); + // Stores the key and corresponding value's latest metadata spilled to disk + private final Set<T> keySet; + private final String rocksDbStoragePath; + private RocksDBDAO rocksDb; + + public RocksDbDiskMap(String rocksDbStoragePath) throws IOException { + this.keySet = new HashSet<>(); + this.rocksDbStoragePath = rocksDbStoragePath; + } + + @Override + public int size() { + return keySet.size(); + } + + @Override + public boolean isEmpty() { + return keySet.isEmpty(); + } + + @Override + public boolean containsKey(Object key) { + return keySet.contains((T) key); + } + + @Override + public boolean containsValue(Object value) { + throw new HoodieNotSupportedException("unable to compare values in map"); + } + + @Override + public R get(Object key) { + if (!containsKey(key)) { + return null; + } + return getRocksDb().get(COLUMN_FAMILY_NAME, (T) key); + } + + @Override + public R put(T key, R value) { + getRocksDb().put(COLUMN_FAMILY_NAME, key, value); + keySet.add(key); + return value; + } + + @Override + public R remove(Object key) { + R value = get(key); + if (value != null) { + keySet.remove((T) key); + getRocksDb().delete(COLUMN_FAMILY_NAME, (T) key); + } + return value; + } + + @Override + public void putAll(Map<? extends T, ? extends R> keyValues) { + getRocksDb().writeBatch(batch -> keyValues.forEach((key, value) -> getRocksDb().putInBatch(batch, COLUMN_FAMILY_NAME, key, value))); + keySet.addAll(keyValues.keySet()); + } + + @Override + public void clear() { + close(); + } + + @Override + public Set<T> keySet() { + return keySet; + } + + @Override + public Collection<R> values() { + throw new HoodieException("Unsupported Operation Exception"); + } + + @Override + public Set<Entry<T, R>> entrySet() { + Set<Entry<T, R>> entrySet = new HashSet<>(); + for (T key : keySet) { + entrySet.add(new AbstractMap.SimpleEntry<>(key, get(key))); + } + return entrySet; + } + + /** + * Custom iterator to iterate over values written to disk. + */ + @Override + public Iterator<R> iterator() { + return getRocksDb().iterator(COLUMN_FAMILY_NAME); + } + + @Override + public Stream<R> valueStream() { + return keySet.stream().map(key -> (R) get(key)); + } + + @Override + public long sizeOfFileOnDiskInBytes() { + return getRocksDb().getTotalBytesWritten(); + } + + @Override + public void close() { + keySet.clear(); + if (null != rocksDb) { + rocksDb.close(); + } + rocksDb = null; + } + + private RocksDBDAO getRocksDb() { + if (null == rocksDb) { + synchronized (this) { Review comment: if there is no actual contention, this is very cheap actually. but +1 on the general point -- This is an automated message from the Apache Git Service. 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