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As an in-memory cache, Redis is the perfect choice for many applications because of its speed and performance. And the implementation of the expiration mechanism is one of the core points. Generally speaking, Redis offers two methods to realize the expiration mechanism: expire and ttl.
Expire will set the expiration time for a key. After the set time, the key will be automatically removed. The command codes is as follows:
127.0.0.1:6379>expire travelBook 3600
(integer) 1
The expire command sets the expiration time of the key travelBook to 3600 seconds. After 3600 seconds, the key will be automatically removed.
In addition to expire, ttl can also be used to get the remaining expiration time of the key. The command codes is as follows:
127.0.0.1:6379>ttl travelBook
(integer) 3470
The ttl command returns a value 3470 above, meaning there is 3470 seconds left before the key of travelBook expires.
Besides the Redis storage mechanism, the Java programming language can also be used to implement a valid expiration mechanism. In Java, we usually use atomic classes or thread pools and related timer tasks to achieve the goal. The codes are as follows:
“`java
AtomicInteger atomicInteger = new AtomicInteger(0);
new ThreadPoolExecutor(1, 1, 0L,
TimeUnit.MILLISECONDS, new LinkedBlockingQueue()).
execute(new TimerTask() {
@Override
public void run() {
if (atomicInteger.get() > 0){
//Do something
}
}
});
atomicInteger.incrementAndGet();
Timer timer = new Timer();
timer.schedule(new TimerTask() {
@Override
public void run() {
atomicInteger.decrementAndGet();
}
}, 5000
);
In this code, a thread pool is created to perform the timer task, and the atomicInteger is set to 0. An integer of 1 is set to atomicInteger, and a timer task is set to run after 5 seconds, which will then reduce the atomicInteger by 1. In this way, the expiration mechanism can be realized.
To sum up, Redis and Java programming language both provide a convenient and secure way to realize expiration mechanism. There're mainly two methods which are expire and ttl in Redis. And in Java, we can use atomic classes or thread pools and related timer tasks to achieve the goal. Choosing the most suitable one depends on the individual requirements.
