com.thematchbox.db.MongoDBIterator Maven / Gradle / Ivy

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package com.thematchbox.db;

/* Copyright 2015 theMatchBox

   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.
*/


import com.mongodb.DBCursor;
import com.mongodb.DBObject;
import org.bson.types.ObjectId;

import java.util.Iterator;

public class MongoDBIterator implements Iterator {
    private final DBCursor cursor;
    private ObjectFactory objectFactory;
    private ObjectCache objectCache;

    MongoDBIterator(DBCursor cursor, ObjectFactory objectFactory, ObjectCache objectCache) {
        this.cursor = cursor;
        this.objectFactory = objectFactory;
        this.objectCache = objectCache;
    }

    public int size() {
        return cursor.size();
    }

    @Override
    public boolean hasNext() {
        return cursor.hasNext();
    }

    @Override
    public D next() {
        try {
            DBObject next = cursor.next();
            ObjectId id = objectFactory.get(next, DataObject.ID_FIELD);
            if (objectCache.containsKey(id)) {
                return objectCache.get(id);
            } else {
                D d = objectFactory.unmarshall(next);
                objectCache.put(id, d);
                return d;
            }
        } catch (MongoDBException e) {
            MongoDataSource.logger.error(e.getMessage(), e);
            return null;
        }
    }

    @Override
    public void remove() {
    }
}