Acquires the cache value of a given key. A cache entry, like an exclusive lock, can only be acquired by one instance at a time, therefore if the entry is still locked, this method throws an immediate IllegalStateException.

If the entry is still found on disk, it will be re-used, given that the configuration's accept method returns true. If the entry is not found or not accepted, a new value is produced by spawning the source in its own future (using the configuration's executionContext).

If the source naturally returns a future, use acquireWith instead.

When the value is not used any more, the caller should invoke release to make it possible for the entry to be evicted when over capacity. Only a released entry can be re-acquired.

Acquires the cache value of a given key. This method is equivalent to acquire but takes a source in the form of a future. See acquire for more details on the mechanism and requirements of this process.

Disposes this producer and makes it unavailable for future use. Any attempt to call acquireWith or release after this invocation results in an IllegalStateException being thrown.

The context used by the cache to spawn future computations. This is directly taken from its configuration, and is provided here for clients to easily import it as an implicit value, e.g. to create its own futures.

Release a cache entry. The caller must have acquired the entry for the given key, using acquire or acquireWith. If the entry is not locked, this method will throw an IllegalStateException.

Releasing the entry makes it possible to evict it from the cache if the cache capacity is exhausted.