Java7's AutoCloseable allows to manage resources more nicely using
try-with-resources statements. Since the semantics of our Releasable interface
are very close to a Closeable, let's switch to it.
Close#5689
The BigArrays utility class is useful to generate arrays of various sizes: when
small, arrays will be allocated directly on the heap while larger arrays are
going to be paged and to recycle pages through PageCacheRecycler. We already
have tracking for pages but this is not triggered very often since it only
happens on large amounts of data while our tests work on small amounts of data
in order to be fast.
Tracking arrays directly helps make sure that we never forget to release them.
This pull request also improves testing by:
- putting random content in the arrays upon release: this makes sure that
consumers don't use these arrays anymore when they are released as their
content may be subject to use for another purpose since pages are recycled
- putting random content in the arrays upon creation and resize when
`clearOnResize` is `false`.
The major difference with `master` is that the `BigArrays` class is now
instanciable, injected via Guice and usually available through the
`SearchContext`. This way, it can be mocked for tests.
Refactor cache recycling so that it only caches large arrays (pages) that can
later be used to build more complex data-structures such as hash tables.
- QueueRecycler now takes a limit like other non-trivial recyclers.
- New PageCacheRecycler (inspired of CacheRecycler) has the ability to cache
byte[], int[], long[], double[] or Object[] arrays using a fixed amount of
memory (either globally or per-thread depending on the Recycler impl, eg.
queue is global while thread_local is per-thread).
- Paged arrays in o.e.common.util can now optionally take a PageCacheRecycler
to reuse existing pages.
- All aggregators' data-structures now use PageCacheRecycler:
- for all arrays (counts, mins, maxes, ...)
- LongHash can now take a PageCacheRecycler
- there is a new BytesRefHash (inspired from Lucene but quite different,
still; for instance it cheats on BytesRef comparisons by using Unsafe)
that also takes a PageCacheRecycler
Close#4557
