Question

I’m using a guava LoadingCache with eviction policy set expireAfterWrite(). I also invalidate entries on access using:

v = cache.getIfPresent( k );
if( v != null ) {
  cache.invalidate( k );
}

Is there a way to add a RemovalListener that gets fired only when entries get auto-evicted after the write timeout is hit? From documentation, it appears that the RemovalListener is called any time an entry is removed.

Answer 1

Yes, a RemovalListener will be called any time any entry is removed — but the RemovalListener will receive a RemovalNotification object, which includes the cause, which you can use to determine how an entry got removed.

CacheBuilder.newBuilder()
  .removalListener(new RemovalListener<Foo, Bar>() {
    public void onRemoval(RemovalNotification<Foo, Bar> notification) {
      if (notification.getCause() == RemovalCause.EXPIRED) {
        // we only care about these removals
      }
    }
  })
  .build();