DbMachineIdProvider.java

package com.robert.vesta.service.impl.provider;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.dao.EmptyResultDataAccessException;
import org.springframework.jdbc.core.JdbcTemplate;
import org.springframework.util.StringUtils;

import com.robert.vesta.util.IpUtils;

public class DbMachineIdProvider implements MachineIdProvider {
	private static final Logger log = LoggerFactory
			.getLogger(DbMachineIdProvider.class);

	private long machineId;

	private JdbcTemplate jdbcTemplate;

	public DbMachineIdProvider() {
		log.debug("IpConfigurableMachineIdProvider constructed.");
	}

	public void init() {
		String ip = IpUtils.getHostIp();

		if (StringUtils.isEmpty(ip)) {
			String msg = "Fail to get host IP address. Stop to initialize the DbMachineIdProvider provider.";

			log.error(msg);
			throw new IllegalStateException(msg);
		}

		Long id = null;
		try {
			id = jdbcTemplate.queryForObject(
					"select ID from DB_MACHINE_ID_PROVIDER where IP = ?",
					new Object[] { ip }, Long.class);

		} catch (EmptyResultDataAccessException e) {
			// Ignore the exception
			log.error("No allocation before for ip {}.", ip);
		}

		if (id != null) {
			machineId = id;
			return;
		}

		log.info(
				"Fail to get ID from DB for host IP address {}. Next step try to allocate one.",
				ip);

		int count = jdbcTemplate
				.update("update DB_MACHINE_ID_PROVIDER set IP = ? where IP is null limit 1",
						ip);

		if (count <= 0 || count > 1) {
			String msg = String
					.format("Fail to allocte ID for host IP address {}. The {} records are updated. Stop to initialize the DbMachineIdProvider provider.",
							ip, count);

			log.error(msg);
			throw new IllegalStateException(msg);
		}

		try {
			id = jdbcTemplate.queryForObject(
					"select ID from DB_MACHINE_ID_PROVIDER where IP = ?",
					new Object[] { ip }, Long.class);

		} catch (EmptyResultDataAccessException e) {
			// Ignore the exception
			log.error("Fail to do allocation for ip {}.", ip);
		}

		if (id == null) {
			String msg = String
					.format("Fail to get ID from DB for host IP address {} after allocation. Stop to initialize the DbMachineIdProvider provider.",
							ip);

			log.error(msg);
			throw new IllegalStateException(msg);
		}

		machineId = id;
	}

	public long getMachineId() {
		return machineId;
	}

	public void setMachineId(long machineId) {
		this.machineId = machineId;
	}

	public JdbcTemplate getJdbcTemplate() {
		return jdbcTemplate;
	}

	public void setJdbcTemplate(JdbcTemplate jdbcTemplate) {
		this.jdbcTemplate = jdbcTemplate;
	}
}