Package org.apache.cassandra.io.tries

Class ValueIterator<CONCRETE extends ValueIterator<CONCRETE>>

java.lang.Object

org.apache.cassandra.io.tries.Walker<CONCRETE>

org.apache.cassandra.io.tries.ValueIterator<CONCRETE>

All Implemented Interfaces:

java.lang.AutoCloseable

Direct Known Subclasses:

PartitionIndex.IndexPosIterator

@NotThreadSafe
public class ValueIterator<CONCRETE extends ValueIterator<CONCRETE>>
extends Walker<CONCRETE>

Thread-unsafe value iterator for on-disk tries. Uses the assumptions of Walker.

The main utility of this class is the nextPayloadedNode() method, which lists all nodes that contain a payload within the requested bounds. The treatment of the bounds is non-standard (see ValueIterator(Rebufferer, long, ByteComparable, ByteComparable, boolean)), necessary to properly walk tries of prefixes and separators.

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static class	ValueIterator.IterationPosition

Nested classes/interfaces inherited from class org.apache.cassandra.io.tries.Walker

Walker.Extractor<RESULT,VALUE>, Walker.PayloadToString, Walker.TransitionBytesCollector

Field Summary

Fields

Modifier and Type	Field	Description
protected ValueIterator.IterationPosition	stack

Fields inherited from class org.apache.cassandra.io.tries.Walker

buf, BYTE_COMPARABLE_VERSION, greaterBranch, lesserBranch, nodeType, NONE, position, root

Constructor Summary

Constructors

Modifier	Constructor	Description
protected	ValueIterator(Rebufferer source, long root)
protected	ValueIterator(Rebufferer source, long root, boolean collecting)
protected	ValueIterator(Rebufferer source, long root, ByteComparable start, ByteComparable end, boolean admitPrefix)
protected	ValueIterator(Rebufferer source, long root, ByteComparable start, ByteComparable end, boolean admitPrefix, boolean collecting)	Constrained iterator.

Method Summary

Modifier and Type	Method	Description
protected long	advanceNode()
protected ByteComparable	nextCollectedValue()
protected long	nextPayloadedNode()	Returns the position of the next node with payload contained in the iterated span.
protected long	peekNode()	Returns the payload node position without advancing.

Methods inherited from class org.apache.cassandra.io.tries.Walker

close, dumpTrie, follow, followWithGreater, followWithLesser, getMaxTerm, getMinTerm, go, goMax, goMin, greaterTransition, hasChildren, hasPayload, lastTransition, lesserTransition, nodeSize, nodeTypeOrdinal, payloadFlags, payloadPosition, prefix, prefixAndNeighbours, search, toString, transition, transitionByte, transitionRange

Methods inherited from class java.lang.Object

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

Field Detail

stack

protected ValueIterator.IterationPosition stack

Constructor Detail

ValueIterator

protected ValueIterator(Rebufferer source,
                        long root)

ValueIterator

protected ValueIterator(Rebufferer source,
                        long root,
                        boolean collecting)

ValueIterator

protected ValueIterator(Rebufferer source,
                        long root,
                        ByteComparable start,
                        ByteComparable end,
                        boolean admitPrefix)

ValueIterator

protected ValueIterator(Rebufferer source,
                        long root,
                        ByteComparable start,
                        ByteComparable end,
                        boolean admitPrefix,
                        boolean collecting)

Constrained iterator. The end position is always treated as inclusive, and we have two possible treatments for the start:

• When admitPrefix=false, exact matches and any prefixes of the start are excluded.
• When admitPrefix=true, the longest prefix of the start present in the trie is also included, provided that there is no entry in the trie between that prefix and the start. An exact match also satisfies this and is included.

This behaviour is shared with the reverse counterpart ReverseValueIterator.

Method Detail

peekNode

protected long peekNode()

Returns the payload node position without advancing.

nextPayloadedNode

protected long nextPayloadedNode()

Returns the position of the next node with payload contained in the iterated span.

nextCollectedValue

protected ByteComparable nextCollectedValue()

advanceNode

protected long advanceNode()