做长图网站,wordpress 占用内存,申诉网站风险,网站建设的公司推荐1、手写 Redis 分布式锁#xff0c;包括上锁、解锁、自动续期。
此功能实现采用 Lua脚本实现#xff0c;Lua脚本可以保证原子性。
setnx可以实现分布式锁#xff0c;但是无法实现可重入锁#xff0c;所以用hset来代替setnx实现可重入的分布式锁。
-- lock
if redis.call…1、手写 Redis 分布式锁包括上锁、解锁、自动续期。
此功能实现采用 Lua脚本实现Lua脚本可以保证原子性。
setnx可以实现分布式锁但是无法实现可重入锁所以用hset来代替setnx实现可重入的分布式锁。
-- lock
if redis.call(exists,KEYS[1]) 0 or redis.call(hexists,KEYS[1],ARGV[1]) 1 thenredis.call(hincrby,KEYS[1],ARGV[1],1)redis.call(expire,KEYS[1],ARGV[2])return 1
elsereturn 0
end
-- unlock
if redis.call(hexists,KEYS[1],ARGV[1]) 0 thenreturn nil
elseif redis.call(hincrby,KEYS[1],ARGV[1],-1) 0 thenreturn redis.call(del,KEYS[1])
elsereturn 0
end
-- expire
if redis.call(hexists,KEYS[1],ARGV[1]) 0 thenreturn redis.call(expire,KEYS[1],ARGV[2])
elsereturn 0
end
2、工具类如下
/*** author xxx* descpription: 自定义redis分布式锁* date 2024/7/24*/
public class MyRedissonLua implements Lock {/*** 加锁脚本*/private static final String lockScript if redis.call(exists,KEYS[1]) 0 or redis.call(hexists,KEYS[1],ARGV[1]) 1 then redis.call(hincrby,KEYS[1],ARGV[1],1) redis.call(expire,KEYS[1],ARGV[2]) return 1 else return 0 end;/*** 解锁脚本*/private static final String unLockScript if redis.call(HEXISTS,KEYS[1],ARGV[1]) 0 then return nil elseif redis.call(HINCRBY,KEYS[1],ARGV[1],-1) 0 then return redis.call(del,KEYS[1]) else return 0 end;/*** 续期脚本*/private static final String expireScript if redis.call(HEXISTS,KEYS[1],ARGV[1]) 0 then return redis.call(EXPIRE,KEYS[1],ARGV[2]) else return 0 end;private StringRedisTemplate stringRedisTemplate;/*** KEYS[1]*/private String lockName;/*** ARGV[1]*/private String uuidValue;/*** ARGV[2]*/private Long expireTime;public MyRedissonLua(StringRedisTemplate stringRedisTemplate, String lockName,String uuid) {this.stringRedisTemplate stringRedisTemplate;this.lockName lockName;this.uuidValue uuid : Thread.currentThread().getId();this.expireTime 30L;}Overridepublic void lock() {tryLock();}Overridepublic void unlock() {Long flag stringRedisTemplate.execute(new DefaultRedisScript(unLockScript, Long.class), Arrays.asList(lockName), uuidValue);System.out.println(unlock lockName: lockName \tuuidValue: uuidValue \t expireTime: expireTime);if(flag null) {throw new IllegalMonitorStateException(释放锁异常);}else {System.out.println(释放锁成功);}}Overridepublic boolean tryLock() {boolean result;try {result tryLock(-1L, TimeUnit.SECONDS);} catch (InterruptedException e) {throw new RuntimeException(e);}return result;}Overridepublic boolean tryLock(long time, TimeUnit unit) throws InterruptedException {if (time -1L){System.out.println(lockName: lockName \tuuidValue: uuidValue \t expireTime: expireTime);//可重入while (!stringRedisTemplate.execute(new DefaultRedisScript(lockScript, Boolean.class), Arrays.asList(lockName), uuidValue, String.valueOf(expireTime))){TimeUnit.MILLISECONDS.sleep(60);}//后台扫描程序检测key的ttl来实现续期reExpire();return true;}return false;}private void reExpire() {//每 10s 续期一次new Timer().schedule(new TimerTask(){Overridepublic void run() {System.out.println(Thread.currentThread().getName() 续期);if (stringRedisTemplate.execute(new DefaultRedisScript(lockScript, Boolean.class), Arrays.asList(lockName), uuidValue, String.valueOf(expireTime))){reExpire();}}},(this.expireTime * 1000) / 3);}Overridepublic void lockInterruptibly() {}Overridepublic Condition newCondition() {return null;}
}
3、由于实现分布式锁的方式有很多故采用工厂模式
/*** author xxx* descpription: 工厂模式生产分布式锁* date 2024/7/24*/
Component
public class DistributedLockFactory {private String lockName;private String uuid;Resourceprivate StringRedisTemplate stringRedisTemplate;public DistributedLockFactory() {this.uuid IdUtil.simpleUUID();}public Lock getDistributedLock(String lockType){if (lockType null) {return null;}if (lockType.equals(REDIS)){lockName zzyyRedisLock;return new MyRedissonLua(stringRedisTemplate, lockName,uuid);} else if (lockType.equals(ZOOKEEPER)) {lockName zzyyZookeeperLock;//...Zookeeper版本的分布式锁return null;}return null;}
}
4、业务代码
import cn.hutool.core.util.IdUtil;
import com.coco.service.ICardService;
import com.coco.utils.lua.DistributedLockFactory;
import org.redisson.api.RedissonClient;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.data.redis.core.script.DefaultRedisScript;
import org.springframework.stereotype.Service;import javax.annotation.Resource;
import java.util.Arrays;
import java.util.Objects;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.locks.Lock;/*** author xxx* descpription: * date 2024/7/18*/
Service
public class ICardServiceImpl implements ICardService {Resourceprivate StringRedisTemplate stringRedisTemplate;private static final String KEY sale001;Value(${server.port})private String port;Resourceprivate RedissonClient redissonClient;/*** 自定义的redis分布式锁*/
// private Lock lock new MyRedissonLua(stringRedisTemplate, zzyyRedisLock);/*** 通过工厂获取自定义的redis分布式锁*/Resourceprivate DistributedLockFactory distributedLockFactory;Overridepublic String sale() {version7();return success;}private void version7() {Lock lock distributedLockFactory.getDistributedLock(REDIS);lock.lock();try{String countStr stringRedisTemplate.opsForValue().get(KEY);Integer count countStr null ? 0 : Integer.parseInt(countStr);if (count 0) {stringRedisTemplate.opsForValue().set(KEY,String.valueOf(--count));System.out.println(剩余库存为 stringRedisTemplate.opsForValue().get(KEY) 服务端口 port);//演示自动续期try {TimeUnit.SECONDS.sleep(120);} catch (InterruptedException e) {throw new RuntimeException(e);}}else {System.out.println(没有库存了);}}finally {lock.unlock();}}/*** 可重入锁*/private void version6() {Lock lock distributedLockFactory.getDistributedLock(REDIS);lock.lock();try{String countStr stringRedisTemplate.opsForValue().get(KEY);Integer count countStr null ? 0 : Integer.parseInt(countStr);if (count 0) {stringRedisTemplate.opsForValue().set(KEY,String.valueOf(--count));System.out.println(剩余库存为 stringRedisTemplate.opsForValue().get(KEY) 服务端口 port);//可重入testReEntry();}else {System.out.println(没有库存了);}}finally {lock.unlock();}}/*** 可重入锁*/private void testReEntry() {Lock lock distributedLockFactory.getDistributedLock(REDIS);lock.lock();try {System.out.println(再次获取锁);} finally {lock.unlock();}}/*** 通过Lua脚本实现分布式锁解锁*/private void version5() {String key zzyyRedisLock;String uuidValue IdUtil.simpleUUID() : Thread.currentThread().getId();//分布式锁(自旋)while (!stringRedisTemplate.opsForValue().setIfAbsent(key, uuidValue,10,TimeUnit.SECONDS)) {try {TimeUnit.MILLISECONDS.sleep(20);} catch (InterruptedException e) {throw new RuntimeException(e);}}try {String countStr stringRedisTemplate.opsForValue().get(KEY);Integer count countStr null ? 0 : Integer.parseInt(countStr);if (count 0) {stringRedisTemplate.opsForValue().set(KEY,String.valueOf(--count));System.out.println(剩余库存为 stringRedisTemplate.opsForValue().get(KEY) 服务端口 port);}else {System.out.println(没有库存了);}} finally {String script if redis.call(\get\,KEYS[1]) ARGV[1] then\n return redis.call(\del\,KEYS[1])\n else\n return 0\n end;stringRedisTemplate.execute(new DefaultRedisScript(script, Boolean.class),Arrays.asList(key), uuidValue);}}/*** 添加判断防止解锁解的不是同一把锁*/private void version4() {String key zzyyRedisLock;String uuidValue IdUtil.simpleUUID(): Thread.currentThread().getId();//分布式锁(自旋)while (!stringRedisTemplate.opsForValue().setIfAbsent(key, uuidValue,10,TimeUnit.SECONDS)) {try {TimeUnit.MILLISECONDS.sleep(20);} catch (InterruptedException e) {throw new RuntimeException(e);}}try {String countStr stringRedisTemplate.opsForValue().get(KEY);Integer count countStr null ? 0 : Integer.parseInt(countStr);if (count 0) {stringRedisTemplate.opsForValue().set(KEY,String.valueOf(--count));System.out.println(剩余库存为 stringRedisTemplate.opsForValue().get(KEY) 服务端口 port);}else {System.out.println(没有库存了);}} finally {if (Objects.equals(uuidValue, stringRedisTemplate.opsForValue().get(key))){stringRedisTemplate.delete(key);}}}/*** 通过setnx实现redis分布式锁*/private void version3() {String key zzyyRedisLock;String uuidValue IdUtil.simpleUUID(): Thread.currentThread().getId();//分布式锁Boolean flag stringRedisTemplate.opsForValue().setIfAbsent(key, uuidValue);if (flag) {try {String countStr stringRedisTemplate.opsForValue().get(KEY);Integer count countStr null ? 0 : Integer.parseInt(countStr);if (count 0) {stringRedisTemplate.opsForValue().set(KEY,String.valueOf(--count));System.out.println(剩余库存为 stringRedisTemplate.opsForValue().get(KEY) 服务端口 port);}else {System.out.println(没有库存了);}} finally {if (Objects.equals(uuidValue, stringRedisTemplate.opsForValue().get(key))){stringRedisTemplate.delete(key);}}}else {try {TimeUnit.MILLISECONDS.sleep(20);} catch (InterruptedException e) {throw new RuntimeException(e);}sale();}}/*** juc的lock锁*/private void version2() {
// lock.lock();
// try {
// Integer count (Integer) redisTemplate.opsForValue().get(KEY);
// if (count 0) {
// redisTemplate.opsForValue().decrement(KEY);
// System.out.println(剩余库存为 redisTemplate.opsForValue().get(KEY) 服务端口 port);
// }else {
// System.out.println(没有库存了);
// }
// } finally {
// lock.unlock();
// }}
}
