基于redis的分布式锁

package sc.whorl.system.commons.preventresubmit;

import org.apache.commons.lang3.StringUtils;
import org.apache.commons.lang3.concurrent.BasicThreadFactory;
import org.springframework.boot.autoconfigure.AutoConfigureAfter;
import org.springframework.boot.autoconfigure.data.redis.RedisAutoConfiguration;
import org.springframework.context.annotation.Configuration;
import org.springframework.data.redis.connection.RedisStringCommands;
import org.springframework.data.redis.core.RedisCallback;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.data.redis.core.types.Expiration;

import java.util.concurrent.ScheduledExecutorService;
import java.util.concurrent.ScheduledThreadPoolExecutor;
import java.util.concurrent.TimeUnit;
import java.util.regex.Pattern;

/**
 * 基于redis的分布式锁
 * // TODO 基于redis的分布式锁
 */
@Configuration
@AutoConfigureAfter(RedisAutoConfiguration.class)
public class RedisLockHelper {


    private static final String DELIMITER = "|";

    /**
     * 如果要求比较高可以通过注入的方式分配
     */
    private static final ScheduledExecutorService EXECUTOR_SERVICE = new ScheduledThreadPoolExecutor(10,
            new BasicThreadFactory.Builder().namingPattern("sen-unit-schedule-pool-%d").daemon(true).build());


    private final StringRedisTemplate stringRedisTemplate;

    public RedisLockHelper(StringRedisTemplate stringRedisTemplate) {

        this.stringRedisTemplate = stringRedisTemplate;
    }

    /**
     * 获取锁（存在死锁风险）
     *
     * @param lockKey
     *         lockKey
     * @param value
     *         value
     * @param time
     *         超时时间
     * @param unit
     *         过期单位
     * @return true or false
     */
    public boolean tryLock(final String lockKey, final String value, final long time, final TimeUnit unit) {
        return stringRedisTemplate.execute((RedisCallback<Boolean>) connection -> connection.set(lockKey.getBytes(), value.getBytes(), Expiration.from(time, unit), RedisStringCommands.SetOption.SET_IF_ABSENT));
    }

    /**
     * 删除对应的key参数
     *
     * @param lockKey
     */
    public void unlock(final String lockKey) {
        stringRedisTemplate.delete(lockKey);
    }


    /**
     * *****************************************************************************************************
     * 华丽的分割线
     * *****************************************************************************************************
     */














    /**
     * 获取锁
     *
     * @param lockKey
     *         lockKey
     * @param uuid
     *         UUID
     * @param timeout
     *         超时时间
     * @param unit
     *         过期单位
     * @return true or false
     */
    public boolean lock(String lockKey, final String uuid, long timeout, final TimeUnit unit) {
        final long milliseconds = Expiration.from(timeout, unit).getExpirationTimeInMilliseconds();
        boolean success = stringRedisTemplate.opsForValue().setIfAbsent(lockKey, (System.currentTimeMillis() + milliseconds) + DELIMITER + uuid);
        if (success) {
            stringRedisTemplate.expire(lockKey, timeout, TimeUnit.SECONDS);
        } else {
            String oldVal = stringRedisTemplate.opsForValue().getAndSet(lockKey, (System.currentTimeMillis() + milliseconds) + DELIMITER + uuid);
            final String[] oldValues = oldVal.split(Pattern.quote(DELIMITER));
            if (Long.parseLong(oldValues[0]) + 1 <= System.currentTimeMillis()) {
                return true;
            }
        }
        return success;
    }


    /**
     * 立即释放锁
     * @see <a href="http://redis.io/commands/set">Redis Documentation: SET</a>
     */
    public void unlock(String lockKey, String value) {
        unlock(lockKey, value, 0, TimeUnit.MILLISECONDS);
    }

    /**
     * 延迟unlock
     *
     * @param lockKey
     *         key
     * @param uuid
     *         client(最好是唯一键的)
     * @param delayTime
     *         延迟时间
     * @param unit
     *         时间单位
     */
    public void unlock(final String lockKey, final String uuid, long delayTime, TimeUnit unit) {
        if (StringUtils.isEmpty(lockKey)) {
            return;
        }
        if (delayTime <= 0) {
            doUnlock(lockKey, uuid);
        } else {
            EXECUTOR_SERVICE.schedule(() -> {
                doUnlock(lockKey, uuid);
            }, delayTime, unit);
        }
    }

    /**
     * @param lockKey
     *         key
     * @param uuid
     *         client(最好是唯一键的)
     */
    private void doUnlock(final String lockKey, final String uuid) {
        String val = stringRedisTemplate.opsForValue().get(lockKey);
        final String[] values = val.split(Pattern.quote(DELIMITER));
        if (values.length <= 0) {
            return;
        }
        if (uuid.equals(values[1])) {
            stringRedisTemplate.delete(lockKey);
        }
    }


}