org.apache.druid.segment

Class ReferenceCountingSegment

java.lang.Object

org.apache.druid.segment.ReferenceCountingCloseableObject<Segment>

org.apache.druid.segment.ReferenceCountingSegment

All Implemented Interfaces:

Closeable, AutoCloseable, ReferenceCountedObject, Segment, SegmentReference, Overshadowable<ReferenceCountingSegment>

public class ReferenceCountingSegment
extends ReferenceCountingCloseableObject<Segment>
implements SegmentReference, Overshadowable<ReferenceCountingSegment>

Segment that is also a ReferenceCountingSegment, allowing query engines that operate directly on segments to track references so that dropping a Segment can be done safely to ensure there are no in-flight queries.

Field Summary

Fields inherited from class org.apache.druid.segment.ReferenceCountingCloseableObject

baseObject, referents

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.
QueryableIndex	asQueryableIndex()
StorageAdapter	asStorageAdapter()
short	getAtomicUpdateGroupSize()
Segment	getBaseSegment()
org.joda.time.Interval	getDataInterval()
int	getEndRootPartitionId()
SegmentId	getId()
short	getMinorVersion()
int	getStartRootPartitionId()
String	getVersion()
boolean	overshadows(ReferenceCountingSegment other)
static ReferenceCountingSegment	wrapRootGenerationSegment(Segment baseSegment)
static ReferenceCountingSegment	wrapSegment(Segment baseSegment, ShardSpec shardSpec)

Methods inherited from class org.apache.druid.segment.ReferenceCountingCloseableObject

close, decrement, decrementOnceCloseable, getNumReferences, increment, incrementReferenceAndDecrementOnceCloseable, isClosed

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface org.apache.druid.segment.Segment

as

Methods inherited from interface java.io.Closeable

close

Methods inherited from interface org.apache.druid.timeline.Overshadowable

containsRootPartition

Method Detail

wrapRootGenerationSegment

public static ReferenceCountingSegment wrapRootGenerationSegment(Segment baseSegment)

wrapSegment

public static ReferenceCountingSegment wrapSegment(Segment baseSegment,
                                                   ShardSpec shardSpec)

getBaseSegment

@Nullable
public Segment getBaseSegment()

getId

@Nullable
public SegmentId getId()

Specified by:

getId in interface Segment

getDataInterval

@Nullable
public org.joda.time.Interval getDataInterval()

Specified by:

getDataInterval in interface Segment

asQueryableIndex

@Nullable
public QueryableIndex asQueryableIndex()

Specified by:

asQueryableIndex in interface Segment

asStorageAdapter

@Nullable
public StorageAdapter asStorageAdapter()

Specified by:

asStorageAdapter in interface Segment

overshadows

public boolean overshadows(ReferenceCountingSegment other)

Specified by:

overshadows in interface Overshadowable<ReferenceCountingSegment>

getStartRootPartitionId

public int getStartRootPartitionId()

Specified by:

getStartRootPartitionId in interface Overshadowable<ReferenceCountingSegment>

getEndRootPartitionId

public int getEndRootPartitionId()

Specified by:

getEndRootPartitionId in interface Overshadowable<ReferenceCountingSegment>

getVersion

public String getVersion()

Specified by:

getVersion in interface Overshadowable<ReferenceCountingSegment>

getMinorVersion

public short getMinorVersion()

Specified by:

getMinorVersion in interface Overshadowable<ReferenceCountingSegment>

getAtomicUpdateGroupSize

public short getAtomicUpdateGroupSize()

Specified by:

getAtomicUpdateGroupSize in interface Overshadowable<ReferenceCountingSegment>

acquireReferences

public Optional<Closeable> acquireReferences()

Description copied from interface: ReferenceCountedObject

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.

Specified by:

acquireReferences in interface ReferenceCountedObject