Redisson 框架中的分布式锁实现方法

<!--        pom.xml文件-->
<dependency>
    <groupId>org.redisson</groupId>
    <artifactId>redisson-spring-boot-starter</artifactId>
    <version>3.17.7</version>
</dependency>

spring:
  redis:
    redisson:
      config:
        singleServerConfig:
          address: redis://127.0.0.1:6379
          database: 0
          password: null
          timeout: 3000

package top.emanjusaka;
import org.redisson.api.RLock;
import org.redisson.api.RedissonClient;
import org.springframework.stereotype.Service;
import javax.annotation.Resource;
import java.util.concurrent.TimeUnit;
/**
 * @Author emanjusaka www.emanjusaka.top
 * @Date 2024/2/28 16:41
 * @Version 1.0
 */
@Service
public class Lock {
    @Resource
    private RedissonClient redissonClient;
    public void lock() {
        // 写入redis的key值
        String lockKey = "lock-test";
        // 获取一个Rlock锁对象
        RLock lock = redissonClient.getLock(lockKey);
        // 获取锁，并为其设置过期时间为10s
        lock.lock(10, TimeUnit.SECONDS);
        try {
            // 执行业务逻辑....
            System.out.println("获取锁成功！");
        } finally {
            // 释放锁
            lock.unlock();
            System.out.println("释放锁成功！");
        }
    }
}

<T> RFuture<T> tryLockInnerAsync(long waitTime, long leaseTime, TimeUnit unit, long threadId, RedisStrictCommand<T> command) {
        return commandExecutor.syncedEval(getRawName(), LongCodec.INSTANCE, command,
                "if ((redis.call('exists', KEYS[1]) == 0) " +
                       "or (redis.call('hexists', KEYS[1], ARGV[2]) == 1)) then " +
                        "redis.call('hincrby', KEYS[1], ARGV[2], 1); " +
                        "redis.call('pexpire', KEYS[1], ARGV[1]); " +
                        "return nil; " +
                    "end; " +
                    "return redis.call('pttl', KEYS[1]);",
                Collections.singletonList(getRawName()), unit.toMillis(leaseTime), getLockName(threadId));
    }

// 省去了那些无关重要的代码
private void lock(long leaseTime, TimeUnit unit, boolean interruptibly) throws InterruptedException {
    long threadId = Thread.currentThread().getId();
    // tryAcquire就是上面分析的lua完整脚本
    Long ttl = tryAcquire(-1, leaseTime, unit, threadId);
    // 返回null就代表上锁成功。
    if (ttl == null) {
        return;
    }
    // 如果没成功，也就是锁的剩余时间不是null的话，那么就执行下面的逻辑
    // 其实就是说 如果有锁（锁剩余时间不是null），那就死循环等待重新抢锁。
    try {
        while (true) {
            // 重新抢锁
            ttl = tryAcquire(-1, leaseTime, unit, threadId);
            // 抢锁成功就break退出循环
            if (ttl == null) {
                break;
            }
            // 省略一些代码
        }
    } finally {}
}

    protected RFuture<Boolean> unlockInnerAsync(long threadId) {
        return evalWriteAsync(getRawName(), LongCodec.INSTANCE, RedisCommands.EVAL_BOOLEAN,
              "if (redis.call('hexists', KEYS[1], ARGV[3]) == 0) then " +
                        "return nil;" +
                    "end; " +
                    "local counter = redis.call('hincrby', KEYS[1], ARGV[3], -1); " +
                    "if (counter > 0) then " +
                        "redis.call('pexpire', KEYS[1], ARGV[2]); " +
                        "return 0; " +
                    "else " +
                        "redis.call('del', KEYS[1]); " +
                        "redis.call(ARGV[4], KEYS[2], ARGV[1]); " +
                        "return 1; " +
                    "end; " +
                    "return nil;",
                Arrays.asList(getRawName(), getChannelName()),
                LockPubSub.UNLOCK_MESSAGE, internalLockLeaseTime, getLockName(threadId), getSubscribeService().getPublishCommand());
    }