com.bennavetta.aeneas.zookeeper.node.Util.java Source code

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Here is the source code for com.bennavetta.aeneas.zookeeper.node.Util.java

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/**
 * Copyright 2015 Benjamin Navetta
 *
 * 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.
 */
package com.bennavetta.aeneas.zookeeper.node;

import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import com.bennavetta.aeneas.zookeeper.IdGenerator;
import com.bennavetta.aeneas.zookeeper.ZkException;
import com.google.common.base.Charsets;

/**
 * Static helper methods for running a server.
 */
public class Util {
    private static final Logger LOG = LoggerFactory.getLogger(Util.class);

    /**
     * Get the node ID from the ZooKeeper data directory or allocate a new one
     */
    public static int obtainId(IdGenerator idGenerator, Configuration configuration)
            throws IOException, ZkException {
        if (configuration.getStatic("dataDir") != null) {
            Path dataDir = Paths.get(configuration.getStatic("dataDir"));
            if (Files.isDirectory(dataDir)) {
                Path idFile = dataDir.resolve("myid");
                if (Files.isReadable(idFile)) {
                    int id = Integer.parseInt(new String(Files.readAllBytes(idFile), Charsets.US_ASCII));
                    LOG.debug("Read existing id: {}", id);
                    return id;
                } else {
                    throw new IllegalStateException("Data directory exists but cannot read 'myid' file");
                }
            }
        }

        int id = idGenerator.generateId();
        LOG.debug("Allocated new id: {}", id);
        return id;
    }
}