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package com.jeesuite.common2.lock.redis;

import java.util.Arrays;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.locks.Condition;
import java.util.concurrent.locks.Lock;

import com.jeesuite.common2.lock.LockException;

import redis.clients.jedis.Jedis;


/**
 * 基于redis的锁
 * @description 

 * @author vakin
 * @date 2018年3月22日
 */
public class RedisDistributeLock implements Lock {
	
	private static final String GET_LOCK_FLAG = "1";

	private static RedisLockCoordinator coordinator = new RedisLockCoordinator();

	private static String getLockLua = "local res = redis.call('setnx', KEYS[1],'1')\n" + 
                    "if tonumber(res) > 0 then\n" + 
                    "	redis.call('expire', KEYS[1], ARGV[1])\n" + 
                    "	return 1\n" + 
                    "else \n" + 
                    "	return 0\n" + 
                    "end";

	private static final String LOCK_KEY_PREFIX = "dlock:";
	private static final int _DEFAULT_MAX_WAIT = 60;
	private String lockName;
	private int maxLiveSeconds;
	
	
	
	/**
	 * 默认最大存活时间60秒
	 * @param lockName
	 */
	public RedisDistributeLock(String lockName) {
		this(lockName, _DEFAULT_MAX_WAIT);
	}

	/**
	 * 
	 * @param lockName
	 * @param maxLiveSeconds 锁最大存活时间（秒）
	 */
	public RedisDistributeLock(String lockName,int maxLiveSeconds) {
		this.lockName = LOCK_KEY_PREFIX + lockName;
		this.maxLiveSeconds = maxLiveSeconds;
	}

	@Override
	public void lock() {

		boolean locked = false;
		try {
			locked = tryLock(maxLiveSeconds, TimeUnit.SECONDS);
		} catch (InterruptedException e) {
			throw new LockException(e);
		}
		if(!locked){
			unlock();
			throw new LockException("Lock["+lockName+"] timeout");
		}
	
	}

	@Override
	public void lockInterruptibly() throws InterruptedException {
		
	}

	@Override
	public boolean tryLock() {
		Jedis client = coordinator.getRedisClient();
		try {		
			return checkLock(client);
		} finally {
			coordinator.release(client);
		}
	
	}

	@Override
	public boolean tryLock(long time, TimeUnit unit) throws InterruptedException {
		Jedis client = coordinator.getRedisClient();
		try {
			long start = System.currentTimeMillis();
			boolean res = checkLock(client);
			if(res)return res;
			
			long sleep = 300;
			while (!res) {
				try {
					TimeUnit.MILLISECONDS.sleep(sleep);
				} catch (InterruptedException e) {
					throw e;
				}
				
				res = checkLock(client);
				
				if (res){
					return res;
				}else if(sleep > 10){
					sleep = sleep - 10;
				}
				
				if (System.currentTimeMillis() - start > unit.toMillis(time)) {
					return false;
				}
			}
		}  finally {
			coordinator.release(client);
		}
		return false;
	}

	@Override
	public void unlock() {
		Jedis client = coordinator.getRedisClient();
    	try {			
    		client.del(lockName);
		} finally {
			coordinator.release(client);
		}
	}

	@Override
	public Condition newCondition() {
		return null;
	}
	
	private boolean checkLock(Jedis client){
		Object result = client.evalsha(client.scriptLoad(getLockLua), Arrays.asList(lockName), Arrays.asList(String.valueOf(maxLiveSeconds)));
		return GET_LOCK_FLAG.equals(String.valueOf(result));
	}

}