001/*
002 * (C) Copyright 2018 Nuxeo (http://nuxeo.com/) and others.
003 *
004 * Licensed under the Apache License, Version 2.0 (the "License");
005 * you may not use this file except in compliance with the License.
006 * You may obtain a copy of the License at
007 *
008 *     http://www.apache.org/licenses/LICENSE-2.0
009 *
010 * Unless required by applicable law or agreed to in writing, software
011 * distributed under the License is distributed on an "AS IS" BASIS,
012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
013 * See the License for the specific language governing permissions and
014 * limitations under the License.
015 *
016 * Contributors:
017 *       Kevin Leturc <[email protected]>
018 */
019package org.nuxeo.ecm.core.bulk.message;
020
021import static java.util.Collections.emptyMap;
022
023import java.io.IOException;
024import java.io.Serializable;
025import java.util.Arrays;
026import java.util.List;
027import java.util.Map;
028
029import org.apache.avro.Schema;
030import org.apache.avro.io.Decoder;
031import org.apache.avro.io.Encoder;
032import org.apache.avro.reflect.CustomEncoding;
033
034import com.fasterxml.jackson.databind.ObjectMapper;
035
036/**
037 * This {@link CustomEncoding} encodes/decodes {@link Map}&lt;{@link String}, {@link Serializable}&gt; to a JSON
038 * {@link String} using Jackson before encoding it in Avro format.
039 *
040 * @since 10.3
041 */
042public class MapAsJsonAsStringEncoding extends CustomEncoding<Map<String, Serializable>> {
043
044    protected static final int NULL_SCHEMA_INDEX = 0;
045
046    protected static final int STRING_SCHEMA_INDEX = 1;
047
048    protected static final ObjectMapper MAPPER = new ObjectMapper();
049
050    public MapAsJsonAsStringEncoding() {
051        List<Schema> union = Arrays.asList(Schema.create(Schema.Type.NULL), Schema.create(Schema.Type.STRING));
052        union.get(1).addProp("CustomEncoding", "MapAsJsonAsStringEncoding");
053        schema = Schema.createUnion(union);
054    }
055
056    @Override
057    @SuppressWarnings("unchecked")
058    protected void write(Object o, Encoder encoder) throws IOException {
059        if (o == null || ((Map<String, Serializable>) o).isEmpty()) {
060            // treat empty map as null to save some bytes
061            // encode the position of the data in the union
062            encoder.writeIndex(NULL_SCHEMA_INDEX);
063            encoder.writeNull();
064        } else {
065            // encode the position of the data in the union
066            encoder.writeIndex(STRING_SCHEMA_INDEX);
067            String mapAsJson = MAPPER.writeValueAsString(o);
068            encoder.writeString(mapAsJson);
069        }
070    }
071
072    @Override
073    @SuppressWarnings("unchecked")
074    protected Map<String, Serializable> read(Object o, Decoder decoder) throws IOException {
075        int index = decoder.readIndex();
076        if (index == NULL_SCHEMA_INDEX) {
077            decoder.readNull();
078            return emptyMap();
079        } else if (index == STRING_SCHEMA_INDEX) {
080            String mapAsJson = decoder.readString();
081            return new ObjectMapper().readValue(mapAsJson, Map.class);
082        } else {
083            throw new IOException("Unable to read Map as Json as String, index=" + index + " is unknown");
084        }
085    }
086}