new serializer API

Author: rashtao

src/main/java/com/arangodb/serde/ArangoSerde.java

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+package com.arangodb.serde;
+
+import com.fasterxml.jackson.databind.ObjectMapper;
+
+import java.lang.reflect.Type;
+
+/**
+ * Contract for serialization/deserialization of user data.
+ * Implementations of this interface could be used for customizing serialization/deserialization of user related data
+ * using serialization/deserialization libraries other than Jackson Databind, like:
+ * - serialization libraries for specific JVM languages (e.g. Scala, Kotlin, ...)
+ * - serialization libraries already in use in frameworks (e.g. JSON-B, Micronaut Serialization, ...)
+ * - high performance serialization libraries (e.g. supporting compile-time databinding code generation)
+ * - lower level libraries without support to data binding
+ * <p>
+ * This interface should not be directly implemented as an adapter to Jackson Databind. A more performant way to provide
+ * custom implementations based on Jackson Databind is by extending {@link JacksonSerde}, which exposes additional
+ * methods based on Jackson's types.
+ * Furthermore, existing implementations {@link JacksonSerde} can be instantiated providing a custom configured Jackson
+ * ObjectMapper, see {@link JacksonSerde#of(DataType, ObjectMapper)}.
+ */
+public interface ArangoSerde {
+
+    /**
+     * @return the data type supported by this implementation
+     */
+    DataType getDataType();
+
+    /**
+     * Serializes the object into the target data type. For data type {@link DataType#JSON}, the serialized JSON string
+     * must be encoded into a byte array using the UTF-8 charset.
+     *
+     * @param value object to serialize
+     * @return serialized byte array
+     */
+    byte[] serialize(Object value);
+
+    /**
+     * Deserializes the content and binds it to the target data type.
+     * For data type {@link DataType#JSON}, the byte array is the JSON string encoded using the UTF-8 charset.
+     *
+     * @param content byte array to deserialize
+     * @param clazz   class of target data type
+     * @return deserialized object
+     */
+    default <T> T deserialize(byte[] content, Class<T> clazz) {
+        return deserialize(content, (Type) clazz);
+    }
+
+    /**
+     * Deserializes the content and binds it to the target data type.
+     * For data type {@link DataType#JSON}, the byte array is the JSON string encoded using the UTF-8 charset.
+     *
+     * @param content byte array to deserialize
+     * @param type    target data type
+     * @return deserialized object
+     */
+    <T> T deserialize(byte[] content, Type type);
+
+}

src/main/java/com/arangodb/serde/DataType.java

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+/*
+ * DISCLAIMER
+ *
+ * Copyright 2016 ArangoDB GmbH, Cologne, Germany
+ *
+ * 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.
+ *
+ * Copyright holder is ArangoDB GmbH, Cologne, Germany
+ */
+package com.arangodb.serde;
+
+public enum DataType {
+    JSON, VPACK
+}

src/main/java/com/arangodb/serde/JacksonSerde.java

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+package com.arangodb.serde;
+
+import com.arangodb.jackson.dataformat.velocypack.VPackMapper;
+import com.fasterxml.jackson.databind.JsonNode;
+import com.fasterxml.jackson.databind.ObjectMapper;
+
+import java.lang.reflect.Type;
+
+/**
+ * Contract for serialization/deserialization of user data, based on Jackson Databind.
+ * In comparison to {@link ArangoSerde}, this API improves the deserialization performance by allowing reusing the JSON
+ * tree already parsed by the root deserializer.
+ */
+public interface JacksonSerde extends ArangoSerde {
+
+    static JacksonSerde of(final DataType dataType) {
+        ObjectMapper mapper;
+        switch (dataType) {
+            case JSON:
+                mapper = new ObjectMapper();
+                break;
+            case VPACK:
+                mapper = new VPackMapper();
+                break;
+            default:
+                throw new IllegalStateException("Unexpected value: " + dataType);
+        }
+        return of(dataType, mapper);
+    }
+
+    static JacksonSerde of(final DataType dataType, final ObjectMapper mapper) {
+        return new JacksonSerdeImpl(dataType, mapper);
+    }
+
+    /**
+     * Deserializes the parsed json node and binds it to the target data type.
+     *
+     * @param node  parsed json node
+     * @param clazz class of target data type
+     * @return deserialized object
+     */
+    default <T> T deserialize(JsonNode node, Class<T> clazz) {
+        return deserialize(node, (Type) clazz);
+    }
+
+    /**
+     * Deserializes the parsed json node and binds it to the target data type.
+     *
+     * @param node parsed json node
+     * @param type target data type
+     * @return deserialized object
+     */
+    <T> T deserialize(JsonNode node, Type type);
+
+}

src/main/java/com/arangodb/serde/JacksonSerdeImpl.java

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+package com.arangodb.serde;
+
+import com.arangodb.ArangoDBException;
+import com.fasterxml.jackson.core.JsonProcessingException;
+import com.fasterxml.jackson.databind.JsonNode;
+import com.fasterxml.jackson.databind.ObjectMapper;
+
+import java.io.IOException;
+import java.lang.reflect.Type;
+import java.nio.charset.StandardCharsets;
+
+final class JacksonSerdeImpl implements JacksonSerde {
+
+    private final DataType dataType;
+    private final ObjectMapper mapper;
+    private final ObjectMapper jsonMapper = new ObjectMapper();
+
+    JacksonSerdeImpl(final DataType dataType, final ObjectMapper mapper) {
+        this.dataType = dataType;
+        this.mapper = mapper;
+    }
+
+    /**
+     * Used for logging and debugging.
+     *
+     * @param content byte array
+     * @return JSON string
+     */
+    public String toJsonString(final byte[] content) {
+        switch (dataType) {
+            case JSON:
+                return new String(content, StandardCharsets.UTF_8);
+            case VPACK:
+                try {
+                    JsonNode tree = mapper.readTree(content);
+                    return jsonMapper.writeValueAsString(tree);
+                } catch (IOException e) {
+                    throw new ArangoDBException(e);
+                }
+            default:
+                throw new IllegalStateException("Unexpected value: " + dataType);
+        }
+    }
+
+    /**
+     * Extract the nested content pointed by the json pointer.
+     * Used for extracting nested user data.
+     *
+     * @param content     byte array
+     * @param jsonPointer location of user data
+     * @return byte array
+     */
+    public byte[] extract(byte[] content, String jsonPointer) {
+        try {
+            JsonNode target = mapper.readTree(content).at(jsonPointer);
+            return mapper.writeValueAsBytes(target);
+        } catch (IOException e) {
+            throw new ArangoDBException(e);
+        }
+    }
+
+    @Override
+    public DataType getDataType() {
+        return dataType;
+    }
+
+    @Override
+    public byte[] serialize(final Object value) {
+        try {
+            return mapper.writeValueAsBytes(value);
+        } catch (JsonProcessingException e) {
+            throw new ArangoDBException(e);
+        }
+    }
+
+    @Override
+    public <T> T deserialize(final byte[] content, final Type type) {
+        try {
+            return mapper.readerFor(mapper.constructType(type)).readValue(content);
+        } catch (IOException e) {
+            throw new ArangoDBException(e);
+        }
+    }
+
+    @Override
+    public <T> T deserialize(final JsonNode node, final Type type) {
+        try {
+            return mapper.readerFor(mapper.constructType(type)).readValue(node);
+        } catch (IOException e) {
+            throw new ArangoDBException(e);
+        }
+    }
+
+}