如何使用多个到期策略配置Apache Ignite缓存

Question

For example, I would like to configure the cache with the following two expiry policies:

• TouchedExpiryPolicy
• CreatedExpiryPolicy

The sample code is as below (Apache Ignite version 1.5.0.final):

public IgniteCache<String, Object> getOrCreateCache(String cacheName) {
    Ignite ignite = Ignition.ignite();

    CacheConfiguration<String, Object> cacheCfg = new CacheConfiguration<String, Object>(cacheName);
    cacheCfg.setExpiryPolicyFactory(TouchedExpiryPolicy.factoryOf(new Duration(TimeUnit.SECONDS, 10)));
    cacheCfg.setExpiryPolicyFactory(CreatedExpiryPolicy.factoryOf(new Duration(TimeUnit.SECONDS, 30)));

    IgniteCache<String, Object> igniteCache = ignite.getOrCreateCache(cacheCfg);
    return igniteCache;     
}

The problem is, however, that the second expiry policy will replace the first one. Wonder if there is any way I can configure the Ignite cache so that the cache will honour both expiry policies? Thank you.

By the way, in EhCache, I can achieve the same thing by configuring the cache the following way:

<cache name="my-cache-name" ...
    timeToIdleSeconds="10" timeToLiveSeconds="30"
    ...>        
</cache>

References:

• Apache Ignite Expiry Policies
• Ehcache configuration

Answer 1

Answering for general JCache ExpiryPolicy, maybe there are additional options in Apache Ignite.

The TouchedExpiryPolicy uses the same duration for creation and update.

You can set individual times, by subclassing the ExpiryPolicy .

Be careful about the logic implications. Setting 10 seconds expiry after access and 30 seconds after creation means for example:

• Item is created, stays 30 seconds in the cache, if not accessed
• Item is created, is accessed 5 seconds after creation, item expires 15 seconds after creation (10 seconds after access)

Probably you want to achieve something different. So the answer is: Mixing TTL and TTI isn't possible the way it is designed.