| /* |
| * 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.beam.sdk.coders; |
| |
| import java.io.DataInputStream; |
| import java.io.DataOutputStream; |
| import java.io.IOException; |
| import java.io.InputStream; |
| import java.io.OutputStream; |
| import java.util.Arrays; |
| import java.util.Collections; |
| import java.util.Iterator; |
| import java.util.List; |
| import java.util.Map; |
| import java.util.Map.Entry; |
| import org.apache.beam.sdk.util.common.ElementByteSizeObserver; |
| import org.apache.beam.sdk.values.TypeDescriptor; |
| import org.apache.beam.sdk.values.TypeParameter; |
| import org.apache.beam.vendor.guava.v26_0_jre.com.google.common.collect.Maps; |
| |
| /** |
| * A {@link Coder} for {@link Map Maps} that encodes them according to provided coders for keys and |
| * values. |
| * |
| * @param <K> the type of the keys of the KVs being transcoded |
| * @param <V> the type of the values of the KVs being transcoded |
| */ |
| public class MapCoder<K, V> extends StructuredCoder<Map<K, V>> { |
| /** Produces a MapCoder with the given keyCoder and valueCoder. */ |
| public static <K, V> MapCoder<K, V> of(Coder<K> keyCoder, Coder<V> valueCoder) { |
| return new MapCoder<>(keyCoder, valueCoder); |
| } |
| |
| public Coder<K> getKeyCoder() { |
| return keyCoder; |
| } |
| |
| public Coder<V> getValueCoder() { |
| return valueCoder; |
| } |
| |
| ///////////////////////////////////////////////////////////////////////////// |
| |
| private Coder<K> keyCoder; |
| private Coder<V> valueCoder; |
| |
| private MapCoder(Coder<K> keyCoder, Coder<V> valueCoder) { |
| this.keyCoder = keyCoder; |
| this.valueCoder = valueCoder; |
| } |
| |
| @Override |
| public void encode(Map<K, V> map, OutputStream outStream) throws IOException, CoderException { |
| encode(map, outStream, Context.NESTED); |
| } |
| |
| @Override |
| public void encode(Map<K, V> map, OutputStream outStream, Context context) |
| throws IOException, CoderException { |
| if (map == null) { |
| throw new CoderException("cannot encode a null Map"); |
| } |
| DataOutputStream dataOutStream = new DataOutputStream(outStream); |
| |
| int size = map.size(); |
| dataOutStream.writeInt(size); |
| if (size == 0) { |
| return; |
| } |
| |
| // Since we handled size == 0 above, entry is guaranteed to exist before and after loop |
| Iterator<Entry<K, V>> iterator = map.entrySet().iterator(); |
| Entry<K, V> entry = iterator.next(); |
| while (iterator.hasNext()) { |
| keyCoder.encode(entry.getKey(), outStream); |
| valueCoder.encode(entry.getValue(), outStream); |
| entry = iterator.next(); |
| } |
| |
| keyCoder.encode(entry.getKey(), outStream); |
| valueCoder.encode(entry.getValue(), outStream, context); |
| // no flush needed as DataOutputStream does not buffer |
| } |
| |
| @Override |
| public Map<K, V> decode(InputStream inStream) throws IOException, CoderException { |
| return decode(inStream, Context.NESTED); |
| } |
| |
| @Override |
| public Map<K, V> decode(InputStream inStream, Context context) |
| throws IOException, CoderException { |
| DataInputStream dataInStream = new DataInputStream(inStream); |
| int size = dataInStream.readInt(); |
| if (size == 0) { |
| return Collections.emptyMap(); |
| } |
| |
| Map<K, V> retval = Maps.newHashMapWithExpectedSize(size); |
| for (int i = 0; i < size - 1; ++i) { |
| K key = keyCoder.decode(inStream); |
| V value = valueCoder.decode(inStream); |
| retval.put(key, value); |
| } |
| |
| K key = keyCoder.decode(inStream); |
| V value = valueCoder.decode(inStream, context); |
| retval.put(key, value); |
| return retval; |
| } |
| |
| /** |
| * {@inheritDoc} |
| * |
| * @return a {@link List} containing the key coder at index 0 at the and value coder at index 1. |
| */ |
| @Override |
| public List<? extends Coder<?>> getCoderArguments() { |
| return Arrays.asList(keyCoder, valueCoder); |
| } |
| |
| /** |
| * {@inheritDoc} |
| * |
| * @throws NonDeterministicException always. Not all maps have a deterministic encoding. For |
| * example, {@code HashMap} comparison does not depend on element order, so two {@code |
| * HashMap} instances may be equal but produce different encodings. |
| */ |
| @Override |
| public void verifyDeterministic() throws NonDeterministicException { |
| throw new NonDeterministicException( |
| this, "Ordering of entries in a Map may be non-deterministic."); |
| } |
| |
| @Override |
| public boolean consistentWithEquals() { |
| return keyCoder.consistentWithEquals() && valueCoder.consistentWithEquals(); |
| } |
| |
| @Override |
| public Object structuralValue(Map<K, V> value) { |
| if (consistentWithEquals()) { |
| return value; |
| } else { |
| Map<Object, Object> ret = Maps.newHashMapWithExpectedSize(value.size()); |
| for (Map.Entry<K, V> entry : value.entrySet()) { |
| ret.put( |
| keyCoder.structuralValue(entry.getKey()), valueCoder.structuralValue(entry.getValue())); |
| } |
| return ret; |
| } |
| } |
| |
| @Override |
| public void registerByteSizeObserver(Map<K, V> map, ElementByteSizeObserver observer) |
| throws Exception { |
| observer.update(4L); |
| if (map.isEmpty()) { |
| return; |
| } |
| Iterator<Entry<K, V>> entries = map.entrySet().iterator(); |
| Entry<K, V> entry = entries.next(); |
| while (entries.hasNext()) { |
| keyCoder.registerByteSizeObserver(entry.getKey(), observer); |
| valueCoder.registerByteSizeObserver(entry.getValue(), observer); |
| entry = entries.next(); |
| } |
| keyCoder.registerByteSizeObserver(entry.getKey(), observer); |
| valueCoder.registerByteSizeObserver(entry.getValue(), observer); |
| } |
| |
| @Override |
| public TypeDescriptor<Map<K, V>> getEncodedTypeDescriptor() { |
| return new TypeDescriptor<Map<K, V>>() {}.where( |
| new TypeParameter<K>() {}, keyCoder.getEncodedTypeDescriptor()) |
| .where(new TypeParameter<V>() {}, valueCoder.getEncodedTypeDescriptor()); |
| } |
| } |