Ehcache: programmatically set expiry time to a cache entry

By implementing ExpiryPolicy interface, we can customize the expiry time at entry level.

 

Step 1: Implement ExpiryPolicy interface.

private static ExpiryPolicy customExpirtyPolicy = new ExpiryPolicy<Integer, CachedObject>() {

	@Override
	public Duration getExpiryForCreation(Integer key, CachedObject value) {
		return value.getExpiryTime();
	}

	@Override
	public Duration getExpiryForAccess(Integer key, Supplier<? extends CachedObject> value) {
		CachedObject cachedObject = value.get();
		return cachedObject.getExpiryTime();
	}

	@Override
	public Duration getExpiryForUpdate(Integer key, Supplier<? extends CachedObject> oldValue,
			CachedObject newValue) {
		return newValue.getExpiryTime();
	}

};

 

Step 2: Set the expiry policy while defining the cache.

Cache<Integer, CachedObject> myCache = cacheManager.createCache("myCache",
		CacheConfigurationBuilder
				.newCacheConfigurationBuilder(Integer.class, CachedObject.class, ResourcePoolsBuilder.heap(100))
				.withExpiry(customExpirtyPolicy).build());

 

Find the below working application.

 

CachedObject.java

package com.sample.app.dto;

import java.time.Duration;

public class CachedObject {
	private Object data;
	private Duration expiryTime;

	public CachedObject(Object data, Duration expiryTime) {
		this.data = data;
		this.expiryTime = expiryTime;
	}

	public Object getData() {
		return data;
	}

	public void setData(Object data) {
		this.data = data;
	}

	public Duration getExpiryTime() {
		return expiryTime;
	}

	public void setExpiryTime(Duration expiryTime) {
		this.expiryTime = expiryTime;
	}

}

 

ExpiryDemo.java

package com.sample.app;

import java.time.Duration;
import java.util.Iterator;
import java.util.concurrent.TimeUnit;
import java.util.function.Supplier;

import org.ehcache.Cache;
import org.ehcache.Cache.Entry;
import org.ehcache.CacheManager;
import org.ehcache.config.builders.CacheConfigurationBuilder;
import org.ehcache.config.builders.CacheManagerBuilder;
import org.ehcache.config.builders.ResourcePoolsBuilder;
import org.ehcache.expiry.ExpiryPolicy;

import com.sample.app.dto.CachedObject;

public class ExpiryDemo {

	private static ExpiryPolicy customExpirtyPolicy=new ExpiryPolicy<Integer,CachedObject>(){

	@Override public Duration getExpiryForCreation(Integer key,CachedObject value){return value.getExpiryTime();}

	@Override public Duration getExpiryForAccess(Integer key,Supplier<?extends CachedObject>value){CachedObject cachedObject=value.get();return cachedObject.getExpiryTime();}

	@Override public Duration getExpiryForUpdate(Integer key,Supplier<?extends CachedObject>oldValue,CachedObject newValue){return newValue.getExpiryTime();}

	};

	private static void printCacheDate(Cache<Integer, CachedObject> myCache) {
		System.out.println("\nElements in the cache are: ");

		Iterator<Entry<Integer, CachedObject>> cacheIterator = myCache.iterator();

		while (cacheIterator.hasNext()) {
			System.out.println(cacheIterator.next().getValue().getData());
		}

	}

	public static void main(String[] args) throws InterruptedException {
		CacheManager cacheManager = CacheManagerBuilder.newCacheManagerBuilder().build(true);

		Cache<Integer, CachedObject> myCache = cacheManager.createCache("myCache",
				CacheConfigurationBuilder
						.newCacheConfigurationBuilder(Integer.class, CachedObject.class, ResourcePoolsBuilder.heap(100))
						.withExpiry(customExpirtyPolicy).build());

		myCache.put(1, new CachedObject("1, Krishna, 32", Duration.ofSeconds(10)));
		myCache.put(2, new CachedObject("2, Ram, 33", Duration.ofSeconds(5)));
		myCache.put(3, new CachedObject("3, Sailu, 34", Duration.ofSeconds(7)));

		printCacheDate(myCache);

		System.out.println("\nGoing to sleep for 6 seconds");
		TimeUnit.SECONDS.sleep(6);

		printCacheDate(myCache);

		System.out.println("\nGoing to sleep for 3 seconds");
		TimeUnit.SECONDS.sleep(3);

		printCacheDate(myCache);
	}

}

 

Output

Elements in the cache are: 
1, Krishna, 32
2, Ram, 33
3, Sailu, 34

Going to sleep for 6 seconds

Elements in the cache are: 
1, Krishna, 32
3, Sailu, 34

Going to sleep for 3 seconds

Elements in the cache are: 
1, Krishna, 32

 

Can I modify the expiry duration?

Expiration duration can be modified when an entry is created, accessed or updated.

 

 

 

 

 

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