EHCache 3.5 Get All Cache Keys / Entries

Question

I'm using EHCache 3.5.2 and having trouble getting all cache keys and cache entries.

I am using the CacheManager to create a cache. I'm then populating it with some data. I'd then like to retrieve all entries in the cache.

Some sample code:

Cache<String, Foo> cache = cacheManager.createCache("fooCache",
     CacheConfigurationBuilder.newCacheConfigurationBuilder(String.class, Foo.class,
         ResourcePoolsBuilder.heap(20)).build());

cache.putAll(repository.findAll().stream().collect(toMap(Foo::getId, foo -> foo)));

List<Foo> foos = cache.???
List<String> keys = cache.???

Is this possible with v3.5? It seems it was possible in older versions of EHCache.

thanks

Answer 1

By design, this is not a simple API call in Ehcache. Because of the tiering model it supports, realising all keys or values on heap could cause the JVM to run out of memory.

As shown by the other answers, there are ways to achieve this.

But it is considered a caching anti-pattern to have to get the whole content of the cache at once.

Answer 2

Why not something like this?

Map<String, Foo> foos = StreamSupport.stream(cache.spliterator(), false)
  .collect(Collectors.toMap(Cache.Entry::getKey, Cache.Entry::getValue));

or

List<Cache.Entry<String, Foo>> foos = StreamSupport.stream(cache.spliterator(), false)
  .collect(Collectors.toList());

or (old style)

List<Cache.Entry<String, Foo>> foos = new ArrayList<>();
for(Cache.Entry<String, Foo> entry : cache) {
  foos.add(entry);
}