如何使用注解方式实现 Redis 分布式锁

2022-11-13 13:11:33 分布式 注解 如何使用

引入 Redisson

<dependency>
  <groupId>org.redisson</groupId>
  <artifactId>redisson-spring-boot-starter</artifactId>
  <version>3.14.1</version>
</dependency>

初始化 Redisson

@Configuration
public class RedissonConfiguration {
  
    // 此处更换自己的 Redis 地址即可
    @Value("${redis.addr}")
    private String addr;

    @Bean
    public RedissonClient redisson() {
        Config config = new Config();
        config.useSingleServer()
                .setAddress(String.fORMat("%s%s", "redis://", addr))
                .setConnectionPoolSize(64)              // 连接池大小
                .setConnectionMinimumIdleSize(8)        // 保持最小连接数
                .setConnectTimeout(1500)                // 建立连接超时时间
                .setTimeout(2000)                       // 执行命令的超时时间, 从命令发送成功时开始计时
                .setRetryAttempts(2)                    // 命令执行失败重试次数
                .setRetryInterval(1000);                // 命令重试发送时间间隔

        return Redisson.create(config);
    }
}

这样我们就可以在项目里面使用 Redisson 了。

编写 Redisson 分布式锁工具类

Redis 分布式锁的工具类,主要是调用 Redisson 客户端实现,做了轻微的封装。

@Service
@Slf4j
public class LockManager {
    
    private static final int MIN_WaiT_TIME = 10;

    @Resource
    private RedissonClient redisson;

    
    public LockResult lock(String key, long expireTime, long waitTime) {
        return lock(key, expireTime, waitTime, () -> new BizException(ResponseEnum.COMMON_FREQUENT_OPERATION_ERROR));
    }
    
    private LockResult lock(String key, long expireTime, long waitTime, Supplier<BizException> exceptionSupplier) {
        if (waitTime < MIN_WAIT_TIME) {
            waitTime = MIN_WAIT_TIME;
        }
        LockResult result = new LockResult();
        try {
            RLock rLock = redisson.getLock(key);
            try {
                if (rLock.tryLock(waitTime, expireTime, TimeUnit.MILLISECONDS)) {
                    result.setLockResultStatus(LockResultStatus.SUCCESS);
                    result.setRLock(rLock);
                } else {
                    result.setLockResultStatus(LockResultStatus.FAILURE);
                }
            } catch (InterruptedException e) {
                log.error("Redis 获取分布式锁失败, key: {}, e: {}", key, e.getMessage());
                result.setLockResultStatus(LockResultStatus.EXCEPTION);
                rLock.unlock();
            }
        } catch (Exception e) {
            log.error("Redis 获取分布式锁失败, key: {}, e: {}", key, e.getMessage());
            result.setLockResultStatus(LockResultStatus.EXCEPTION);
        }

        if (exceptionSupplier != null && LockResultStatus.FAILURE.equals(result.getLockResultStatus())) {
            log.warn("Redis 加锁失败, key: {}", key);
            throw exceptionSupplier.get();
        }

        log.info("Redis 加锁结果:{}, key: {}", result.getLockResultStatus(), key);

        return result;
    }
    
    public void unlock(RLock rLock) {
        try {
            rLock.unlock();
        } catch (Exception e) {
            log.warn("Redis 解锁失败", e);
        }
    }
}

加锁结果状态枚举类。

public enum LockResultStatus {
    
    SUCCESS,
    
    FAILURE,
    
    EXCEPTION;
}

加锁结果类封装了加锁状态和RLock。

@Setter
@Getter
public class LockResult {

    private LockResultStatus lockResultStatus;

    private RLock rLock;
}

自此我们就可以使用分布式锁了,使用方式:

@Service
@Slf4j
public class TestService {

    @Resource
    private LockManager lockManager;

    public String test(String userId) {
        // 锁:userId, 锁超时时间:5s, 锁等待时间:50ms
        LockResult lockResult = lockManager.lock(userId, 5000, 50);

        try {
            //  业务代码
        } finally {
            lockManager.unlock(lockResult.getRLock());
        }

        return "";
    }
}

为了防止程序发生异常,所以每次我们都需要在finally代码块里手动释放锁。为了更方便优雅的使用 Redis 分布式锁,我们使用注解方式实现下。

声明注解 @Lock

@Target(ElementType.METHOD)
@Retention(RetentionPolicy.RUNTIME)
public @interface Lock {
    
    String value();

    
    long expireTime() default 5000L;

    
    long waitTime() default 50L;

}

注解解析类

@Aspect
@Component
@Slf4j
public class LockAnnotationParser {

    @Resource
    private LockManager lockManager;

    
    @Pointcut(value = "@annotation(Lock)")
    private void cutMethod() {
    }
		
    
    @Around(value = "cutMethod() && @annotation(lock)")
    public Object parser(ProceedingJoinPoint point, Lock lock) throws Throwable {
        String value = lock.value();
        if (isEl(value)) {
            value = getByEl(value, point);
        }
        LockResult lockResult = lockManager.lock(getRealLockKey(value), lock.expireTime(), lock.waitTime());
        try {
            return point.proceed();
        } finally {
            lockManager.unlock(lockResult.getRLock());
        }
    }

    
    private String getByEl(String el, ProceedingJoinPoint point) {
        Method method = ((MethodSignature) point.getSignature()).getMethod();
        String[] paramNames = getParameterNames(method);
        Object[] arguments = point.getArgs();
        ExpressionParser parser = new SpelExpressionParser();
        Expression expression = parser.parseExpression(el);
        EvaluationContext context = new StandardEvaluationContext();
        for (int i = 0; i < arguments.length; i++) {
            context.setVariable(paramNames[i], arguments[i]);
        }
        return expression.getValue(context, String.class);
    }
    
    private String[] getParameterNames(Method method) {
        LocalVariableTableParameterNameDiscoverer u = new LocalVariableTableParameterNameDiscoverer();
        return u.getParameterNames(method);
    }
    private boolean isEl(String str) {
        return str.contains("#");
    }
    
    private String getRealLockKey(String value) {
        return String.format("lock:%s", value);
    }
}

下面使用注解方式使用分布式锁:

@Service
@Slf4j
public class TestService {
    @Lock("'test_'+#user.userId")
    public String test(User user) {
        // 业务代码
        return "";
    }
}

当然也可以自定义锁的超时时间和等待时间

@Service
@Slf4j
public class TestService {
    @Lock(value = "'test_'+#user.userId", expireTime = 3000, waitTime = 30)
    public String test(User user) {
        // 业务代码
        return "";
    }
}

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