redis 分布式锁基本实现
import cn.xa87.common.lock.AbstractDistributedLock;import lombok.extern.slf4j.Slf4j;import org.springframework.data.redis.core.RedisCallback;import org.springframework.data.redis.core.RedisTemplate;import org.springframework.util.StringUtils;import redis.clients.jedis.Jedis;import redis.clients.jedis.JedisCluster;import redis.clients.jedis.JedisCommands;import java.util.ArrayList;import java.util.List;import java.util.UUID;@Slf4jpublic class RedisDistributedLock extends AbstractDistributedLock { private RedisTemplate<String, String> redisTemplate; private ThreadLocal<String> lockFlag = new ThreadLocal<>(); private static final String UNLOCK_LUA; /* * 通过lua脚本释放锁,来达到释放锁的原子操作 */ static { UNLOCK_LUA = "if redis.call(\"get\",KEYS[1]) == ARGV[1] " + "then " + " return redis.call(\"del\",KEYS[1]) " + "else " + " return 0 " + "end "; } public RedisDistributedLock(RedisTemplate<String, String> redisTemplate) { super(); this.redisTemplate = redisTemplate; } /** * 获取锁 * * @param key key * @param expire 获取锁超时时间 * @param retryTimes 重试次数 * @param sleepMillis 获取锁失败的重试间隔 * @return 成功/失败 */ @Override public boolean lock(String key, long expire, int retryTimes, long sleepMillis) { boolean result = setRedis(key, expire); // 如果获取锁失败，按照传入的重试次数进行重试 while ((!result) && retryTimes-- > 0) { try { log.debug("get redisDistributeLock failed, retrying..." + retryTimes); Thread.sleep(sleepMillis); } catch (InterruptedException e) { return false; } result = setRedis(key, expire); } return result; } private boolean setRedis(final String key, final long expire) { try { String result = redisTemplate.execute((RedisCallback<String>) connection -> { JedisCommands commands = (JedisCommands) connection.getNativeConnection(); String uuid = UUID.randomUUID().toString(); lockFlag.set(uuid); return commands.set(key, uuid, "NX", "PX", expire); }); return !StringUtils.isEmpty(result); } catch (Exception e) { log.error("set redisDistributeLock occured an exception", e); } return false; } @Override public boolean releaseLock(String key) { // 释放锁的时候，有可能因为持锁之后方法执行时间大于锁的有效期，此时有可能已经被另外一个线程持有锁，所以不能直接删除 try { final List<String> keys = new ArrayList<>(); keys.add(key); final List<String> args = new ArrayList<>(); args.add(lockFlag.get()); // 使用lua脚本删除redis中匹配value的key，可以避免由于方法执行时间过长而redis锁自动过期失效的时候误删其他线程的锁 // spring自带的执行脚本方法中，集群模式直接抛出不支持执行脚本的异常，所以只能拿到原redis的connection来执行脚本 Long result = redisTemplate.execute((RedisCallback<Long>) connection -> { Object nativeConnection = connection.getNativeConnection(); // 集群模式和单机模式虽然执行脚本的方法一样，但是没有共同的接口，所以只能分开执行 // 集群模式 if (nativeConnection instanceof JedisCluster) { return (Long) ((JedisCluster) nativeConnection).eval(UNLOCK_LUA, keys, args); } // 单机模式 else if (nativeConnection instanceof Jedis) { return (Long) ((Jedis) nativeConnection).eval(UNLOCK_LUA, keys, args); } return 0L; }); return result != null && result > 0; } catch (Exception e) { log.error("release redisDistributeLock occured an exception", e); } finally { lockFlag.remove(); } return false; }}/** * 分布式锁抽象类 * */public abstract class AbstractDistributedLock implements DistributedLock{ /** * 获取锁 * * @param key key * @return 成功/失败 */ @Override public boolean lock(String key) { return lock(key, TIMEOUT_MILLIS, RETRY_TIMES, SLEEP_MILLIS); } /** * 获取锁 * * @param key key * @param retryTimes 重试次数 * @return 成功/失败 */ @Override public boolean lock(String key, int retryTimes) { return lock(key, TIMEOUT_MILLIS, retryTimes, SLEEP_MILLIS); } /** * 获取锁 * * @param key key * @param retryTimes 重试次数 * @param sleepMillis 获取锁失败的重试间隔 * @return 成功/失败 */ @Override public boolean lock(String key, int retryTimes, long sleepMillis) { return lock(key, TIMEOUT_MILLIS, retryTimes, sleepMillis); } /** * 获取锁 * * @param key key * @param expire 获取锁超时时间 * @return 成功/失败 */ @Override public boolean lock(String key, long expire) { return lock(key, expire, RETRY_TIMES, SLEEP_MILLIS); } /** * 获取锁 * * @param key key * @param expire 获取锁超时时间 * @param retryTimes 重试次数 * @return 成功/失败 */ @Override public boolean lock(String key, long expire, int retryTimes) { return lock(key, expire, retryTimes, SLEEP_MILLIS); }}/** * 分布式锁顶级接口 * */public interface DistributedLock { /** * 默认超时时间 */ long TIMEOUT_MILLIS = 3000; int RETRY_TIMES = 2; long SLEEP_MILLIS = 100; /** * 获取锁 * * @param key key * @return 成功/失败 */ boolean lock(String key); /** * 获取锁 * * @param key key * @param retryTimes 重试次数 * @return 成功/失败 */ boolean lock(String key, int retryTimes); /** * 获取锁 * * @param key key * @param retryTimes 重试次数 * @param sleepMillis 获取锁失败的重试间隔 * @return 成功/失败 */ boolean lock(String key, int retryTimes, long sleepMillis); /** * 获取锁 * * @param key key * @param expire 获取锁超时时间 * @return 成功/失败 */ boolean lock(String key, long expire); /** * 获取锁 * * @param key key * @param expire 获取锁超时时间 * @param retryTimes 重试次数 * @return 成功/失败 */ boolean lock(String key, long expire, int retryTimes); /** * 获取锁 * * @param key key * @param expire 获取锁超时时间 * @param retryTimes 重试次数 * @param sleepMillis 获取锁失败的重试间隔 * @return 成功/失败 */ boolean lock(String key, long expire, int retryTimes, long sleepMillis); /** * 释放锁 * * @param key key值 * @return 释放结果 */ boolean releaseLock(String key);} 相关推荐
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