All Implemented Interfaces:
Closeable, AutoCloseable

public final class FrozenEngine extends ReadOnlyEngine
This is a stand-alone read-only engine that maintains an index reader that is opened lazily on calls to Engine.SearcherSupplier.acquireSearcher(String). The index reader opened is maintained until there are no reference to it anymore and then releases itself from the engine. This is necessary to for instance release all SegmentReaders after a search phase finishes and reopen them before the next search phase starts. This together with a throttled threadpool (search_throttled) guarantees that at most N frozen shards have a low level index reader open at the same time. The internal reopen of readers is treated like a refresh and refresh listeners are called up-on reopen. This allows to consume refresh stats in order to obtain the number of reopens.