/**
* 保证一定能读到最新数据,修改期间,写锁是一个排他锁(互斥锁)。读锁是一个共享锁
* 写锁没释放,读就必须等待
*/
@GetMapping("/read")
@ResponseBody
public String readValue() {
RReadWriteLock readWriteLock = redisson.getReadWriteLock("rw-lock");
String s = "";
RLock rLock = readWriteLock.readLock();
try {
rLock.lock();
s = stringRedisTemplate.opsForValue().get("writeValue");
} catch (Exception e) {
e.printStackTrace();
} finally {
rLock.unlock();
}
return s;
}
@GetMapping("/write")
@ResponseBody
public String writeValue() {
RReadWriteLock readWriteLock = redisson.getReadWriteLock("rw-lock");
String s = "";
RLock rLock = readWriteLock.writeLock();
try {
//1、改数据加写锁,读数据加读锁
rLock.lock();
TimeUnit.SECONDS.sleep(10);
s = UUID.randomUUID().toString();
stringRedisTemplate.opsForValue().set("writeValue", s);
} catch (InterruptedException e) {
e.printStackTrace();
} finally {
rLock.unlock();
}
return s;
}
读 + 读 :相当于无锁,并发读,只会在redis中记录好,所有当前的读锁,他们都会同时加锁成功。
写 + 读 :等待写锁释放。
写 + 写:阻塞方式
读 + 写:有读锁,写也需要等待
/只要有写的存在,都必须等待