Package org.apache.druid.segment

Class WrappedSegmentReference

java.lang.Object

org.apache.druid.segment.WrappedSegmentReference

All Implemented Interfaces:

Closeable, AutoCloseable, ReferenceCountedObject, Segment, SegmentReference

Direct Known Subclasses:

FilteredSegment, UnnestSegment

public abstract class WrappedSegmentReference
extends Object
implements SegmentReference

Simple SegmentReference implementation for a segment that wraps a base segment such as UnnestSegment or FilteredSegment

Field Summary

Fields

Modifier and Type	Field	Description
protected SegmentReference	delegate

Constructor Summary

Constructors

Constructor	Description
WrappedSegmentReference(SegmentReference delegate)

Method Summary

Modifier and Type	Method	Description
Optional<Closeable>	acquireReferences()	This method is expected to increment a reference count and provide a Closeable that decrements the reference count when closed.
<T> T	as(Class<T> clazz)	Request an implementation of a particular interface.
QueryableIndex	asQueryableIndex()
String	asString()
void	close()
org.joda.time.Interval	getDataInterval()
SegmentId	getId()
boolean	isTombstone()

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

asCursorFactory, asStorageAdapter

Field Detail

delegate

protected final SegmentReference delegate

Constructor Detail

WrappedSegmentReference

public WrappedSegmentReference(SegmentReference delegate)

Method Detail

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

getId

public SegmentId getId()

Specified by:

getId in interface Segment

getDataInterval

public org.joda.time.Interval getDataInterval()

Specified by:

getDataInterval in interface Segment

asQueryableIndex

@Nullable
public QueryableIndex asQueryableIndex()

Specified by:

asQueryableIndex in interface Segment

as

@Nullable
public <T> T as(@Nonnull
                Class<T> clazz)

Description copied from interface: Segment

Request an implementation of a particular interface.

If the passed-in interface is QueryableIndex or CursorFactory, then this method behaves identically to Segment.asQueryableIndex() or Segment.asCursorFactory(). Other interfaces are only expected to be requested by callers that have specific knowledge of extra features provided by specific segment types. For example, an extension might provide a custom Segment type that can offer both StorageAdapter and some new interface. That extension can also offer a Query that uses that new interface.

Implementations which accept classes other than QueryableIndex or CursorFactory are limited to using those classes within the extension. This means that one extension cannot rely on the `Segment.as` behavior of another extension.

Specified by:

as in interface Segment

Type Parameters:

T - desired interface

Parameters:

clazz - desired interface

Returns:

instance of clazz, or null if the interface is not supported by this segment, one of the following:

• CursorFactory, to make cursors to run queries. Never null.
• QueryableIndex, index object, if this is a memory-mapped regular segment.
• IndexedTable, table object, if this is a joinable indexed table.
• TimeBoundaryInspector, inspector for min/max timestamps, if supported by this segment.
• PhysicalSegmentInspector, inspector for physical segment details, if supported by this segment.
• MaxIngestedEventTimeInspector, inspector for DataSourceMetadataResultValue.getMaxIngestedEventTime()
• TopNOptimizationInspector, inspector containing information for topN specific optimizations
• CloseableShapeshifter, stepping stone to RowsAndColumns.
• BypassRestrictedSegment, a policy-aware segment, converted from a policy-enforced segment.

isTombstone

public boolean isTombstone()

Specified by:

isTombstone in interface Segment

close

public void close()
           throws IOException

Specified by:

close in interface AutoCloseable

Specified by:

close in interface Closeable

Throws:

IOException

asString

public String asString()

Specified by:

asString in interface Segment