LayoutDeserializer.java

package org.corfudb.runtime.view;

import com.google.gson.*;
import java.lang.reflect.Type;
import java.util.ArrayList;

/**
 * Created by rmichoud on 4/13/17.
 *
 * These classes will be used to force the json deserialized object to be created by
 * the constructor. Proper validation of the object is done in the Layout class constructor.
 */
public class LayoutDeserializer implements JsonDeserializer {
    @Override
    public Layout deserialize(JsonElement arg0, Type arg1, JsonDeserializationContext arg2)
            throws JsonParseException {
        Gson g = new Gson();
        Layout unsafeLayout = g.fromJson(arg0, Layout.class);

        /* Unresponsive servers is an optional field in the json, if it is not present
         * we need to create an empty list (by default gson will set it to null)
         */
        if (unsafeLayout.unresponsiveServers == null) {
            unsafeLayout.unresponsiveServers = new ArrayList<>();
        }

        /* Similar to a copy constructor. This constructor holds all the validation for constructing a layout. */
        Layout safeLayout = new Layout(unsafeLayout.layoutServers, unsafeLayout.sequencers,
                unsafeLayout.segments, unsafeLayout.unresponsiveServers, unsafeLayout.epoch);

        return safeLayout;

    }
}