Migrating Code from Ehcache v2
This guide provides sample code snippets to help migrate Ehcache v2 code to Ehcache v10 code.
Per Mapping Expiry
Per mapping expiry covers use cases where a subset of mappings have different expiration settings than the ones configured at the cache level.
Ehcache 2.x Code
Here we are creating a cache manager that has a default time-to-live (TTL) expiry.
Before adding, we verify the expiry and set it on the Element only when different than the Cache expiry.
int defaultCacheTTLInSeconds = 20;
CacheManager cacheManager = initCacheManager();
CacheConfiguration cacheConfiguration = new CacheConfiguration().name("cache")
.maxEntriesLocalHeap(100)
.timeToLiveSeconds(defaultCacheTTLInSeconds); // 1
cacheManager.addCache(new Cache(cacheConfiguration));
Element element = new Element(10L, "Hello");
int ttlInSeconds = getTimeToLiveInSeconds((Long)element.getObjectKey(),
(String)element.getObjectValue()); // 2
if (ttlInSeconds != defaultCacheTTLInSeconds) { // 3
element.setTimeToLive(ttlInSeconds);
}
cacheManager.getCache("cache").put(element);
System.out.println(cacheManager.getCache("cache").get(10L).getObjectValue());
sleep(2100); // 4
// Now the returned element should be null, as the mapping is expired.
System.out.println(cacheManager.getCache("cache").get(10L));
1 | Expiry duration defined at the cache level. |
2 | Compute the mapping expiry using the helper method getTimeToLiveInSeconds. |
3 | Only setting the computed expiry on element if other than default expiry. |
4 | Waiting for 2.1 seconds - assuming 2 seconds is the custom expiry duration - to get the mapping to be expired. |
Corresponding Ehcache 10.x Code
Here we are creating a cache manager with a cache configuration specifying a custom expiry, having dedicated logic in the methods called during the lifecycle of added and updated mappings.
CacheManager cacheManager = initCacheManager();
CacheConfigurationBuilder<Long, String> configuration =
CacheConfigurationBuilder.newCacheConfigurationBuilder(Long.class,
String.class, ResourcePoolsBuilder
.heap(100))
.withExpiry(new Expiry<Long, String>() { // 1
@Override
public Duration getExpiryForCreation(Long key, String value) {
return getTimeToLiveDuration(key, value); // 2
}
@Override
public Duration getExpiryForAccess(Long key, ValueSupplier<?
extends String> value) {
return null; // Keeping the existing expiry
}
@Override
public Duration getExpiryForUpdate(Long key, ValueSupplier<?
extends String> oldValue, String newValue) {
return null; // Keeping the existing expiry
}
});
cacheManager.createCache("cache", configuration);
Cache<Long, String> cache = cacheManager.getCache("cache", Long.class,
String.class);
cache.put(10L, "Hello");
System.out.println(cache.get(10L));
sleep(2100); // 3
// Now the returned value should be null, as mapping is expired.
System.out.println(cache.get(10L));
1 | Defining custom expiry to be called during the lifecycle of added mappings. |
2 | During mapping creation, defining expiry duration using the helper method getTimeToLiveDuration. |
3 | Waiting for 2.1 seconds - assuming 2 seconds is the custom expiry duration - to get the mapping to be expired. |
So to migrate the former Ehcache per mapping expiry code to the current version of Ehcache, move the expiry computation logic to the getExpiryForCreation method of the created custom expiry.