redis 分布式锁（redis 分布式锁失效时间）

最近抽空优化了之前已有的redis分布式锁，主要用于解决高并发的问题，比如抢红包，多个人同时操作红包库存，当在库存只剩下1个的时候，一个人的减库存的操作事务没提交，另一个人的查库存操作刚好同步执行，这样就会出现很尴尬的事情，1个红包会被2个人抢走，这个时候，我们就要依托锁，将请求入口锁住，当然锁有很多种方式，这边就记录一下比较好用的redis分布式锁。

方式有很多setNX 、set、incr等等，setNX只要通过逻辑防止死锁就可以了

直接上代码：

public boolean keyLock(final String key, final long keepMin) {
 boolean obj = false;
 try {
 obj = (boolean) redisTemplateSerializable.execute(new RedisCallback<Object>() {
 
 @Override
 public Object doInRedis(RedisConnection connection)
 throws DataAccessException {
 try{
 Long incr = connection.incr(key.getBytes());
 if(incr == 1){
 connection.setEx(key.getBytes(), keepMin, incr.toString().getBytes());
 return true;
 }else{
 Long ttl = connection.ttl(key.getBytes());
 if(ttl == -1){
 //设置失败,重新设置过期时间
 connection.setEx(key.getBytes(), keepMin, incr.toString().getBytes());
 return true;
 }
 }
 }catch (Exception e) {
 logger.error("加锁异常", e);
 connection.del(key.getBytes());
 return true;
 }
 
 return false;
 }
 
 });
 }catch (Exception e) {
 logger.error(e.getMessage());
 }
 
 return obj;
 }

注解

package com.tp.soft.common.interceptor;
import java.lang.annotation.Documented;
import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;
import java.util.concurrent.TimeUnit;
/**
 * redis锁注解
 * 
 * @author taop
 */
@Retention(RetentionPolicy.RUNTIME)
@Target({ ElementType.METHOD })
@Documented
public @interface RedisLock {
 String lockName() default ""; // 锁名
 int retryTimes() default 0; // 重试次数
 long retryWait() default 200; // 重试等待时间,单位 : ms
 int keeyMinTime() default 1; //锁自动失效时间 1秒
}

aop

package com.tp.soft.aop.redis;
import java.lang.reflect.Method;
import java.util.HashMap;
import java.util.Map;
import javax.annotation.Resource;
import org.apache.commons.lang.StringUtils;
import org.aspectj.lang.ProceedingJoinPoint;
import org.aspectj.lang.Signature;
import org.aspectj.lang.annotation.Around;
import org.aspectj.lang.annotation.Aspect;
import org.aspectj.lang.annotation.Pointcut;
import org.aspectj.lang.reflect.MethodSignature;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.core.LocalVariableTableParameterNameDiscoverer;
import org.springframework.expression.ExpressionParser;
import org.springframework.expression.spel.standard.SpelExpressionParser;
import org.springframework.expression.spel.support.StandardEvaluationContext;
import org.springframework.stereotype.Component;
import cn.hutool.core.lang.Assert;
import com.tp.soft.common.interceptor.Cacheable;
import com.tp.soft.common.interceptor.RedisLock;
import com.tp.soft.redis.RedisCacheSvc;
@Aspect
@Component
public class RedisLockAop {
 private static final Logger log = LoggerFactory.getLogger(RedisLockAop.class);
 
 private static final String LOCK_NAME = "lockName";
 private static final String RETRY_TIMES = "retryTimes";
 private static final String RETRY_WAIT = "retryWait";
 private static final String KEEP_MIN_TIME = "keepMinTime";
 @Resource
 private RedisCacheSvc redisCacheSvc;
 @Pointcut("@annotation(com.tp.soft.common.interceptor.RedisLock)")
 public void redisLockAspect() {
 }
 @Around("redisLockAspect()")
 public Object lockAroundAction(ProceedingJoinPoint pjp) throws Throwable {
 Method method = returnMethod(pjp);
 
 Map<String, Object> annotationArgs = this.getAnnotationArgs(pjp);
 String lockPrefix = (String) annotationArgs.get(LOCK_NAME);
 Assert.notNull(lockPrefix, "分布式,锁名不能为空");
 
 int retryTimes = (int) annotationArgs.get(RETRY_TIMES);
 long retryWait = (long) annotationArgs.get(RETRY_WAIT);
 int keepMinTime = (int) annotationArgs.get(KEEP_MIN_TIME);
 String keyName = parseKey(lockPrefix, method, pjp.getArgs());
 
 // 获取redis锁,防止死锁
 boolean keyLock = redisCacheSvc.keyLock(keyName, keepMinTime);
 if(keyLock){
 //执行主程序
 return pjp.proceed();
 }else{
 if(retryTimes <= 0){
 log.info(String.format("{%s}已经被锁, 不重试", keyName));
 throw new RuntimeException(String.format("{%s}已经被锁, 不重试", keyName));
 }
 
 int failCount = 1;
 while (failCount <= retryTimes) {
 // 等待指定时间ms
 try {
 Thread.sleep(retryWait);
 } catch (InterruptedException e) {
 e.printStackTrace();
 }
 if (redisCacheSvc.keyLock(keyName, keepMinTime)) {
 // 执行主逻辑
 return pjp.proceed();
 } else {
 log.info(String.format("{%s}已经被锁, 正在重试[ %s/%s ],重试间隔{%s}毫秒", keyName, failCount, retryTimes, retryWait));
 failCount++;
 }
 }
 
 throw new RuntimeException("系统繁忙, 请稍等再试");
 }
 
 }
 /**
 * 获取锁参数
 * 
 * @param proceeding
 * @return
 */
 private Map<String, Object> getAnnotationArgs(ProceedingJoinPoint proceeding) {
 Class target = proceeding.getTarget().getClass();
 Method[] methods = target.getMethods();
 String methodName = proceeding.getSignature().getName();
 for (Method method : methods) {
 if (method.getName().equals(methodName)) {
 Map<String, Object> result = new HashMap<String, Object>();
 RedisLock redisLock = method.getAnnotation(RedisLock.class);
 result.put(LOCK_NAME, redisLock.lockName());
 result.put(RETRY_TIMES, redisLock.retryTimes());
 result.put(RETRY_WAIT, redisLock.retryWait());
 result.put(KEEP_MIN_TIME, redisLock.keeyMinTime());
 return result;
 }
 }
 return null;
 }
 private Method returnMethod(ProceedingJoinPoint pjp)
 throws NoSuchMethodException {
 Signature signature = pjp.getSignature();
 Class<? extends Object> cls = pjp.getTarget().getClass();
 MethodSignature methodSignature = (MethodSignature) signature;
 Method targetMethod = methodSignature.getMethod();
 Method method = cls.getDeclaredMethod(signature.getName(),
 targetMethod.getParameterTypes());
 return method;
 }
 /**
 * 获取缓存的key key 定义在注解上，支持SPEL表达式
 * 
 * @param pjp
 * @return
 */
 private String parseKey(String key, Method method, Object[] args) {
 // 获取被拦截方法参数名列表(使用Spring支持类库)
 LocalVariableTableParameterNameDiscoverer u = new LocalVariableTableParameterNameDiscoverer();
 String[] paraNameArr = u.getParameterNames(method);
 // 使用SPEL进行key的解析
 ExpressionParser parser = new SpelExpressionParser();
 // SPEL上下文
 StandardEvaluationContext context = new StandardEvaluationContext();
 // 把方法参数放入SPEL上下文中
 for (int i = 0; i < paraNameArr.length; i++) {
 context.setVariable(paraNameArr[i], args[i]);
 }
 return parser.parseExpression(key).getValue(context, String.class);
 }
}

搭建完成后直接在需要锁住的接口上注解

@RedisLock(lockName="'lock_'+#tbbId",retryTimes=5)

模拟高并发测试

for (int i = 0; i < 2; i++) {
 threadPoolTaskExecutor.execute(new StartTaskThread(redisCacheSvc, i, threadPoolTaskExecutor));
 }

效果就是这样了

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