org.apache.druid.segment

Interface ReferenceCountedObject

All Known Subinterfaces:

IndexedTable, Joinable, SegmentReference

All Known Implementing Classes:

BroadcastSegmentIndexedTable, HashJoinSegment, IndexedTableJoinable, JoinableClause, LookupJoinable, ReferenceCountingIndexedTable, ReferenceCountingSegment, RowBasedIndexedTable

public interface ReferenceCountedObject

Interface for an object that may have a reference acquired in the form of a Closeable. This is intended to be used with an implementation of ReferenceCountingCloseableObject, or anything else that wishes to provide a method to account for the acquire and release of a reference to the object.

Method Summary

Modifier and Type	Method and Description
Optional<Closeable>	acquireReferences() This method is expected to increment a reference count and provide a Closeable that decrements the reference count when closed.

Method Detail

acquireReferences

Optional<Closeable> acquireReferences()

This method is expected to increment a reference count and provide a Closeable that decrements the reference count when closed. This is likely just a wrapper around ReferenceCountingCloseableObject.incrementReferenceAndDecrementOnceCloseable(), but may also include any other associated references which should be incremented when this method is called, and decremented/released by the closeable. IMPORTANT NOTE: to fulfill the contract of this method, implementors must return a closeable to indicate that the reference can be acquired, even if there is nothing to close. Implementors should avoid allowing this method or the Closeable it creates to throw exceptions. For callers: if this method returns non-empty, IT MUST BE CLOSED, else reference counts can potentially leak.