com.google.devtools.build.lib.skyframe.serialization.MultimapCodec.java Source code

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Here is the source code for com.google.devtools.build.lib.skyframe.serialization.MultimapCodec.java

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// Copyright 2018 The Bazel Authors. All rights reserved.
//
// Licensed 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 com.google.devtools.build.lib.skyframe.serialization;

import com.google.common.collect.ImmutableList;
import com.google.common.collect.ImmutableListMultimap;
import com.google.common.collect.ImmutableMultimap;
import com.google.common.collect.ImmutableSetMultimap;
import com.google.common.collect.LinkedHashMultimap;
import com.google.common.collect.ListMultimap;
import com.google.common.collect.Multimap;
import com.google.common.collect.SetMultimap;
import com.google.protobuf.CodedInputStream;
import com.google.protobuf.CodedOutputStream;
import java.io.IOException;
import java.util.Collection;
import java.util.List;
import java.util.Map;

/**
 * A codec for {@link Multimap}. Handles {@link ImmutableListMultimap}, {@link ImmutableSetMultimap}
 * and {@link LinkedHashMultimap}. Makes all multimaps immutable, since serialized state shouldn't
 * be mutable.
 */
public class MultimapCodec<K, V> implements ObjectCodec<Multimap<K, V>> {
    @SuppressWarnings("unchecked")
    @Override
    public Class<? extends ImmutableMultimap<K, V>> getEncodedClass() {
        return (Class<ImmutableMultimap<K, V>>) ((Class<?>) ImmutableMultimap.class);
    }

    @SuppressWarnings("unchecked")
    @Override
    public List<Class<? extends Multimap<K, V>>> additionalEncodedClasses() {
        return ImmutableList.of((Class<? extends Multimap<K, V>>) (Class<?>) LinkedHashMultimap.class);
    }

    @Override
    public void serialize(SerializationContext context, Multimap<K, V> obj, CodedOutputStream codedOut)
            throws SerializationException, IOException {
        if (obj instanceof ListMultimap) {
            codedOut.writeBoolNoTag(true);
        } else if (obj instanceof SetMultimap) {
            codedOut.writeBoolNoTag(false);
        } else {
            throw new SerializationException("Unexpected multimap type: " + obj.getClass());
        }
        codedOut.writeInt32NoTag(obj.asMap().size());
        for (Map.Entry<K, Collection<V>> entry : obj.asMap().entrySet()) {
            context.serialize(entry.getKey(), codedOut);
            context.serialize(entry.getValue(), codedOut);
        }
    }

    @Override
    public ImmutableMultimap<K, V> deserialize(DeserializationContext context, CodedInputStream codedIn)
            throws SerializationException, IOException {
        ImmutableMultimap.Builder<K, V> result;
        if (codedIn.readBool()) {
            result = ImmutableListMultimap.builder();
        } else {
            result = ImmutableSetMultimap.builder();
        }
        int length = codedIn.readInt32();
        for (int i = 0; i < length; i++) {
            K key = context.deserialize(codedIn);
            Collection<V> values = context.deserialize(codedIn);
            result.putAll(key, values);
        }
        return result.build();
    }
}