jedis实现分布式锁（悲观锁）

redis需单点部署（非集群）
redis分布式锁解决多个应用进程间同步操作

整理了很多网上文档 发现都没有解决如下问题。。。

参考

http://www.cnblogs.com/it-cen/p/4984272.html

...

1.时间同步问题

2.在一个进程cash后失效时间后自动释放锁

3.有些多线程race condition没有考虑到

以下java版本实现彻底解决 充分测试

** 方案一（推荐）**

import java.util.List;
import java.util.UUID;

import redis.clients.jedis.Jedis;
import redis.clients.jedis.JedisPool;
import redis.clients.jedis.Transaction;
import redis.clients.jedis.exceptions.JedisException;

/**
 * Jedis实现分布式锁
 * 
 * @author 三文鱼
 *
 */
public class DistributionLock {
    private final JedisPool jedisPool;

    public DistributionLock(JedisPool jedisPool) {
        this.jedisPool = jedisPool;
    }

    /**
     * 获取分布式锁
     * 
     * @param lockName
     *            竞争获取锁key
     * @param acquireTimeoutInMS
     *            获取锁超时时间
     * @param lockTimeoutInMS
     *            锁的超时时间
     * @return 获取锁标识
     */
    public String acquireLockWithTimeout(String lockName,
            long acquireTimeoutInMS, long lockTimeoutInMS) {
        Jedis conn = null;
        boolean broken = false;
        String retIdentifier = null;
        try {
            conn = jedisPool.getResource();
            String identifier = UUID.randomUUID().toString();
            String lockKey = "lock:" + lockName;
            int lockExpire = (int) (lockTimeoutInMS / 1000);

            long end = System.currentTimeMillis() + acquireTimeoutInMS;
            while (System.currentTimeMillis() < end) {
                if (conn.setnx(lockKey, identifier) == 1) {
                    conn.expire(lockKey, lockExpire);
                    retIdentifier = identifier;
                }
                if (conn.ttl(lockKey) == -1) {
                    conn.expire(lockKey, lockExpire);
                }

                try {
                    Thread.sleep(10);
                } catch (InterruptedException ie) {
                    Thread.currentThread().interrupt();
                }
            }
        } catch (JedisException je) {
            if (conn != null) {
                broken = true;
                jedisPool.returnBrokenResource(conn);
            }
        } finally {
            if (conn != null && !broken) {
                jedisPool.returnResource(conn);
            }
        }
        return retIdentifier;
    }

    /**
     * 释放锁
     * @param lockName 竞争获取锁key
     * @param identifier 释放锁标识
     * @return
     */
    public boolean releaseLock(String lockName, String identifier) {
        Jedis conn = null;
        boolean broken = false;
        String lockKey = "lock:" + lockName;
        boolean retFlag = false;
        try {
            conn = jedisPool.getResource();
            while (true) {
                conn.watch(lockKey);
                if (identifier.equals(conn.get(lockKey))) {
                    Transaction trans = conn.multi();
                    trans.del(lockKey);
                    List<Object> results = trans.exec();
                    if (results == null) {
                        continue;
                    }
                    retFlag = true;
                }
                conn.unwatch();
                break;
            }

        } catch (JedisException je) {
            if (conn != null) {
                broken = true;
                jedisPool.returnBrokenResource(conn);
            }
        } finally {
            if (conn != null && !broken) {
                jedisPool.returnResource(conn);
            }
        }
        return retFlag;
    }

}

**

方案二（不完善，比如unlock没有做所有者校验等，如果误删其他线程持有的锁也会造成问题）**

/** 
 * @author http://blog.csdn.net/java2000_wl 
 * @version <b>1.0.0</b> 
 */  
public class RedisBillLockHandler implements IBatchBillLockHandler {  
  
    private static final Logger LOGGER = LoggerFactory.getLogger(RedisBillLockHandler.class);  
  
    private static final int DEFAULT_SINGLE_EXPIRE_TIME = 3;  
      
    private static final int DEFAULT_BATCH_EXPIRE_TIME = 6;  
  
    private final JedisPool jedisPool;  
      
    /** 
     * 构造 
     * @author http://blog.csdn.net/java2000_wl 
     */  
    public RedisBillLockHandler(JedisPool jedisPool) {  
        this.jedisPool = jedisPool;  
    }  
  
    /** 
     * 获取锁  如果锁可用   立即返回true，  否则返回false 
     * @author http://blog.csdn.net/java2000_wl 
     * @param billIdentify 
     * @return 
     */  
    public boolean tryLock(IBillIdentify billIdentify) {  
        return tryLock(billIdentify, 0L, null);  
    }  
  
    /** 
     * 锁在给定的等待时间内空闲，则获取锁成功 返回true， 否则返回false 
     * @author http://blog.csdn.net/java2000_wl 
     * @param billIdentify 
     * @param timeout 
     * @param unit 
     * @return 
     */  
    public boolean tryLock(IBillIdentify billIdentify, long timeout, TimeUnit unit) {  
        String key = (String) billIdentify.uniqueIdentify();  
        Jedis jedis = null;  
        try {  
            jedis = getResource();  
            long nano = System.nanoTime();  
            do {  
                LOGGER.debug("try lock key: " + key);  
                Long i = jedis.setnx(key, key);  
                if (i == 1) {   
                    jedis.expire(key, DEFAULT_SINGLE_EXPIRE_TIME);  
                    LOGGER.debug("get lock, key: " + key + " , expire in " + DEFAULT_SINGLE_EXPIRE_TIME + " seconds.");  
                    return Boolean.TRUE;  
                } else { // 存在锁  
                    if (LOGGER.isDebugEnabled()) {  
                        String desc = jedis.get(key);  
                        LOGGER.debug("key: " + key + " locked by another business：" + desc);  
                    }  
                }  
                if (timeout == 0) {  
                    break;  
                }  
                Thread.sleep(300);  
            } while ((System.nanoTime() - nano) < unit.toNanos(timeout));  
            return Boolean.FALSE;  
        } catch (JedisConnectionException je) {  
            LOGGER.error(je.getMessage(), je);  
            returnBrokenResource(jedis);  
        } catch (Exception e) {  
            LOGGER.error(e.getMessage(), e);  
        } finally {  
            returnResource(jedis);  
        }  
        return Boolean.FALSE;  
    }  
  
    /** 
     * 如果锁空闲立即返回   获取失败 一直等待 
     * @author http://blog.csdn.net/java2000_wl 
     * @param billIdentify 
     */  
    public void lock(IBillIdentify billIdentify) {  
        String key = (String) billIdentify.uniqueIdentify();  
        Jedis jedis = null;  
        try {  
            jedis = getResource();  
            do {  
                LOGGER.debug("lock key: " + key);  
                Long i = jedis.setnx(key, key);  
                if (i == 1) {   
                    jedis.expire(key, DEFAULT_SINGLE_EXPIRE_TIME);  
                    LOGGER.debug("get lock, key: " + key + " , expire in " + DEFAULT_SINGLE_EXPIRE_TIME + " seconds.");  
                    return;  
                } else {  
                    if (LOGGER.isDebugEnabled()) {  
                        String desc = jedis.get(key);  
                        LOGGER.debug("key: " + key + " locked by another business：" + desc);  
                    }  
                }  
                Thread.sleep(300);   
            } while (true);  
        } catch (JedisConnectionException je) {  
            LOGGER.error(je.getMessage(), je);  
            returnBrokenResource(jedis);  
        } catch (Exception e) {  
            LOGGER.error(e.getMessage(), e);  
        } finally {  
            returnResource(jedis);  
        }  
    }  
  
    /** 
     * 释放锁 
     * @author http://blog.csdn.net/java2000_wl 
     * @param billIdentify 
     */  
    public void unLock(IBillIdentify billIdentify) {  
        List<IBillIdentify> list = new ArrayList<IBillIdentify>();  
        list.add(billIdentify);  
        unLock(list);  
    }  
  
    /** 
     * 批量获取锁  如果全部获取   立即返回true, 部分获取失败 返回false 
     * @author http://blog.csdn.net/java2000_wl 
     * @date 2013-7-22 下午10:27:44 
     * @param billIdentifyList 
     * @return 
     */  
    public boolean tryLock(List<IBillIdentify> billIdentifyList) {  
        return tryLock(billIdentifyList, 0L, null);  
    }  
      
    /** 
     * 锁在给定的等待时间内空闲，则获取锁成功 返回true， 否则返回false 
     * @author http://blog.csdn.net/java2000_wl 
     * @param billIdentifyList 
     * @param timeout 
     * @param unit 
     * @return 
     */  
    public boolean tryLock(List<IBillIdentify> billIdentifyList, long timeout, TimeUnit unit) {  
        Jedis jedis = null;  
        try {  
            List<String> needLocking = new CopyOnWriteArrayList<String>();    
            List<String> locked = new CopyOnWriteArrayList<String>();     
            jedis = getResource();  
            long nano = System.nanoTime();  
            do {  
                // 构建pipeline，批量提交  
                Pipeline pipeline = jedis.pipelined();  
                for (IBillIdentify identify : billIdentifyList) {  
                    String key = (String) identify.uniqueIdentify();  
                    needLocking.add(key);  
                    pipeline.setnx(key, key);  
                }  
                LOGGER.debug("try lock keys: " + needLocking);  
                // 提交redis执行计数  
                List<Object> results = pipeline.syncAndReturnAll();  
                for (int i = 0; i < results.size(); ++i) {  
                    Long result = (Long) results.get(i);  
                    String key = needLocking.get(i);  
                    if (result == 1) {  // setnx成功，获得锁  
                        jedis.expire(key, DEFAULT_BATCH_EXPIRE_TIME);  
                        locked.add(key);  
                    }   
                }  
                needLocking.removeAll(locked);  // 已锁定资源去除  
                  
                if (CollectionUtils.isEmpty(needLocking)) {  
                    return true;  
                } else {      
                    // 部分资源未能锁住  
                    LOGGER.debug("keys: " + needLocking + " locked by another business：");  
                }  
                  
                if (timeout == 0) {   
                    break;  
                }  
                Thread.sleep(500);    
            } while ((System.nanoTime() - nano) < unit.toNanos(timeout));  
  
            // 得不到锁，释放锁定的部分对象，并返回失败  
            if (!CollectionUtils.isEmpty(locked)) {  
                jedis.del(locked.toArray(new String[0]));  
            }  
            return false;  
        } catch (JedisConnectionException je) {  
            LOGGER.error(je.getMessage(), je);  
            returnBrokenResource(jedis);  
        } catch (Exception e) {  
            LOGGER.error(e.getMessage(), e);  
        } finally {  
            returnResource(jedis);  
        }  
        return true;  
    }  
  
    /** 
     * 批量释放锁 
     * @author http://blog.csdn.net/java2000_wl 
     * @param billIdentifyList 
     */  
    public void unLock(List<IBillIdentify> billIdentifyList) {  
        List<String> keys = new CopyOnWriteArrayList<String>();  
        for (IBillIdentify identify : billIdentifyList) {  
            String key = (String) identify.uniqueIdentify();  
            keys.add(key);  
        }  
        Jedis jedis = null;  
        try {  
            jedis = getResource();  
            jedis.del(keys.toArray(new String[0]));  
            LOGGER.debug("release lock, keys :" + keys);  
        } catch (JedisConnectionException je) {  
            LOGGER.error(je.getMessage(), je);  
            returnBrokenResource(jedis);  
        } catch (Exception e) {  
            LOGGER.error(e.getMessage(), e);  
        } finally {  
            returnResource(jedis);  
        }  
    }  
      
    /** 
     * @author http://blog.csdn.net/java2000_wl 
     * @date 2013-7-22 下午9:33:45 
     * @return 
     */  
    private Jedis getResource() {  
        return jedisPool.getResource();  
    }  
      
    /** 
     * 销毁连接 
     * @author http://blog.csdn.net/java2000_wl 
     * @param jedis 
     */  
    private void returnBrokenResource(Jedis jedis) {  
        if (jedis == null) {  
            return;  
        }  
        try {  
            //容错  
            jedisPool.returnBrokenResource(jedis);  
        } catch (Exception e) {  
            LOGGER.error(e.getMessage(), e);  
        }  
    }  
      
    /** 
     * @author http://blog.csdn.net/java2000_wl 
     * @param jedis 
     */  
    private void returnResource(Jedis jedis) {  
        if (jedis == null) {  
            return;  
        }  
        try {  
            jedisPool.returnResource(jedis);  
        } catch (Exception e) {  
            LOGGER.error(e.getMessage(), e);  
        }  
    }  

来源：oschina

链接：https://my.oschina.net/u/2917935/blog/755265