org.apache.accumulo.core.iterators
Interface SortedKeyValueIterator<K extends org.apache.hadoop.io.WritableComparable<?>,V extends org.apache.hadoop.io.Writable>

All Known Subinterfaces:

FileSKVIterator, InterruptibleIterator

All Known Implementing Classes:

AggregatingIterator, BloomFilterLayer.Reader, ColumnFamilyCounter, ColumnFamilySkippingIterator, CountingIterator, DebugIterator, DeletingIterator, DevNull, FamilyIntersectingIterator, FileCFSkippingIterator, FilteringIterator, FirstEntryInRowIterator, GrepIterator, HeapIterator, IntersectingIterator, LargeRowFilter, MapFileOperations.RangeIterator, MultiIterator, MyMapFile.Reader, NoLabelIterator, OrIterator, RegExIterator, RFile.Reader, RowDeletingIterator, ScanCache, SequenceFileIterator, SkippingIterator, SortedKeyIterator, SortedMapIterator, SourceSwitchingIterator, SystemScanIterator, VersioningIterator, WholeRowIterator, WrappingIterator

public interface SortedKeyValueIterator<K extends org.apache.hadoop.io.WritableComparable<?>,V extends org.apache.hadoop.io.Writable>

An iterator that supports iterating over key and value pairs. Anything implementing this interface should return keys in sorted order.

Method Summary

SortedKeyValueIterator<K,V>	deepCopy(IteratorEnvironment env) Creates a deep copy of this iterator as though seek had not yet been called.
K	getTopKey() Returns top key.
V	getTopValue() Returns top value.
boolean	hasTop() Returns true if the iterator has more elements.
void	init(SortedKeyValueIterator<K,V> source, java.util.Map<java.lang.String,java.lang.String> options, IteratorEnvironment env) Initializes the iterator.
void	next() Advances to the next K,V pair.
void	seek(Range range, java.util.Collection<ByteSequence> columnFamilies, boolean inclusive) An iterator must seek to the first key in the range taking inclusiveness into account.

Method Detail

init

void init(SortedKeyValueIterator<K,V> source,
          java.util.Map<java.lang.String,java.lang.String> options,
          IteratorEnvironment env)
          throws java.io.IOException

Initializes the iterator. Data should not be read from the source in this method.

Parameters:

source - SortedKeyValueIterator source to read data from.

options - Map map of string option names to option values.

env - IteratorEnvironment environment in which iterator is being run.

Throws:

java.io.IOException - unused.

java.lang.IllegalArgumentException - if there are problems with the options.

java.lang.UnsupportedOperationException - if not supported.

hasTop

boolean hasTop()

Returns true if the iterator has more elements.

Returns:

true if the iterator has more elements.

Throws:

java.lang.IllegalStateException - if called before seek.

next

void next()
          throws java.io.IOException

Advances to the next K,V pair.

Throws:

java.io.IOException - if an I/O error occurs.

java.lang.IllegalStateException - if called before seek.

NoSuchElementException - if next element doesn't exist.

seek

void seek(Range range,
          java.util.Collection<ByteSequence> columnFamilies,
          boolean inclusive)
          throws java.io.IOException

An iterator must seek to the first key in the range taking inclusiveness into account. However, an iterator does not have to stop at the end of the range. The whole range is provided so that iterators can make optimizations.

Parameters:

range - Range of keys to iterate over.

columnFamilies - Collection of column families to include or exclude.

inclusive - boolean that indicates whether to include (true) or exclude (false) column families.

Throws:

java.io.IOException - if an I/O error occurs.

java.lang.IllegalArgumentException - if there are problems with the parameters.

getTopKey

K getTopKey()

Returns top key. Can be called 0 or more times without affecting behavior of next() or hasTop().

Returns:

K

Throws:

java.lang.IllegalStateException - if called before seek.

NoSuchElementException - if top element doesn't exist.

getTopValue

V getTopValue()

Returns top value. Can be called 0 or more times without affecting behavior of next() or hasTop().

Returns:

V

Throws:

java.lang.IllegalStateException - if called before seek.

NoSuchElementException - if top element doesn't exist.

deepCopy

SortedKeyValueIterator<K,V> deepCopy(IteratorEnvironment env)

Creates a deep copy of this iterator as though seek had not yet been called. init should be called on an iterator before deepCopy is called. init should not need to be called on the copy that is returned by deepCopy; that is, when necessary init should be called in the deepCopy method on the iterator it returns. The behavior is unspecified if init is called after deepCopy either on the original or the copy.

Parameters:

env - IteratorEnvironment environment in which iterator is being run.

Returns:

SortedKeyValueIterator a copy of this iterator (with the same source and settings).

Throws:

java.lang.UnsupportedOperationException - if not supported.