MetaDataService.java

/*
 * Licensed to ElasticSearch and Shay Banon under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership. ElasticSearch licenses this
 * file to you 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 org.elasticsearch.cluster.metadata;

import org.elasticsearch.cluster.routing.operation.hash.djb.DjbHashFunction;
import org.elasticsearch.common.component.AbstractComponent;
import org.elasticsearch.common.inject.Inject;
import org.elasticsearch.common.settings.Settings;

/**
 */
public class MetaDataService extends AbstractComponent {

    private final MdLock[] indexMdLocks;

    @Inject
    public MetaDataService(Settings settings) {
        super(settings);
        indexMdLocks = new MdLock[500];
        for (int i = 0; i < indexMdLocks.length; i++) {
            indexMdLocks[i] = new MdLock();
        }
    }

    public MdLock indexMetaDataLock(String index) {
        return indexMdLocks[Math.abs(DjbHashFunction.DJB_HASH(index) % indexMdLocks.length)];
    }

    public class MdLock {

        private boolean isLocked = false;

        public synchronized void lock() throws InterruptedException {
            while (isLocked) {
                wait();
            }
            isLocked = true;
        }

        public synchronized void unlock() {
            isLocked = false;
            notifyAll();
        }
    }
}