Cache invalidation in Ehcache

Question

I am using Ehcache in Hibernate.

How can I notify the cache that the database has changed? How can I invalidate the cached data? How can I programmatically achieve this?

More

Answer 1

What do exactly mean? There are 2 ways to make a change in the database: inside the app & outside the app

Inside the app you can trigger easily an invalidation. The second one is a harder to solve. Cache elements are stored with a key and based on that key you can delete it.

CacheManager manager = CacheManager.getInstance();
cache = manager.getCache(cacheName);
cache.remove(key);

or 

cache.removeAll();

Depending how you configured ehcache of course. But you need to know the name of the cache that holds the object.

Iconium

Answer 2

This is how you can invalidate all EhCache items without bothering what the individual cache names are:

CacheManager manager = CacheManager.getInstance();

String[] names = manager.getCacheNames();

for (String name : names)
{
    Cache cache = manager.getCache(name);

    cache.removeAll();
}

Greatnephew

While this may have worked well at the time of writing, I had to replace .getCache with .getEhcache, and Cache with Ehcache. Otherwise, .getCache returns null even for caches which exist. – Cavy

Didn't work for me as my configurations being hibernate ehcache timeToLiveSeconds not working – Firstborn

Answer 3

Try:

CacheManager.create().clearAll()

It will clear all caches in CacheManager.

To clear only one particular cache, get it from cache manager and remove all elements:

CacheManager cacheManager = CacheManager.create();
Ehcache cache = cacheManager.getEhcache(cacheConfiguration.getName());
cache.removeAll();    

Cirillo

Answer 4

Set cache expiration so data is refreshed as or more often than the database changes .

Also you can update in cache only elements that change in the database .

Showy

Can you explain how to set "cache expiration"? – Audi

Cache Expiration is defined by the timeToLiveSeconds field in ehcache.xml ... when the value of timeToLiveSeconds is elapsed , the cached element is considered invalid and will be fetched from the source when requested ... fetching will incur caching thus resetting the timer of timeToLiveSeconds ... For Example : <cache name="thisCache" maxEntriesLocalHeap="10000" maxEntriesLocalDisk="1000" eternal="false" diskSpoolBufferSizeMB="20" timeToIdleSeconds="500" timeToLiveSeconds="900" memoryStoreEvictionPolicy="LFU" diskPersistent="false" transactionalMode="off"> </cache> – Showy

not applicable to persistent cache entries that never change – Galanti

Answer 5

In case if you want to remove a specific cache (eg:employeeCache)

@Autowired
CacheManager cacheManager;

place where you want to invalidate cache, use below code

    Cache cache = cacheManager.getCache("employeeCache");
    cache.removeAll();

Exciseman