Package org.apache.accumulo.core.iteratorsImpl.system

Class LocalityGroupIterator

java.lang.Object

org.apache.accumulo.core.iteratorsImpl.system.HeapIterator

org.apache.accumulo.core.iteratorsImpl.system.LocalityGroupIterator

All Implemented Interfaces:

SortedKeyValueIterator<Key,Value>, YieldingKeyValueIterator<Key,Value>, InterruptibleIterator

public class LocalityGroupIterator
extends HeapIterator
implements InterruptibleIterator

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static class	LocalityGroupIterator.LocalityGroup
static class	LocalityGroupIterator.LocalityGroupContext
static class	LocalityGroupIterator.LocalityGroupSeekCache	This will cache the arguments used in the seek call along with the locality groups seeked.

Constructor Summary

Constructors

Constructor	Description
LocalityGroupIterator(LocalityGroupIterator.LocalityGroup[] groups)

Method Summary

Modifier and Type	Method	Description
SortedKeyValueIterator<Key,Value>	deepCopy(IteratorEnvironment env)	Creates a deep copy of this iterator as though seek had not yet been called.
void	init(SortedKeyValueIterator<Key,Value> source, Map<String,String> options, IteratorEnvironment env)	Initializes the iterator.
void	seek(Range range, Collection<ByteSequence> columnFamilies, boolean inclusive)	Seeks to the first key in the Range, restricting the resulting K,V pairs to those with the specified columns.
static LocalityGroupIterator.LocalityGroupSeekCache	seek(HeapIterator hiter, LocalityGroupIterator.LocalityGroupContext lgContext, Range range, Collection<ByteSequence> columnFamilies, boolean inclusive, LocalityGroupIterator.LocalityGroupSeekCache lgSeekCache)	This seek method will reuse the supplied LocalityGroupSeekCache if it can.
void	setInterruptFlag(AtomicBoolean flag)

Methods inherited from class org.apache.accumulo.core.iteratorsImpl.system.HeapIterator

addSource, clear, createHeap, getTopKey, getTopValue, hasTop, next

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.apache.accumulo.core.iterators.SortedKeyValueIterator

getTopKey, getTopValue, hasTop, next

Methods inherited from interface org.apache.accumulo.core.iterators.YieldingKeyValueIterator

enableYielding

Constructor Detail

LocalityGroupIterator

public LocalityGroupIterator(LocalityGroupIterator.LocalityGroup[] groups)

Method Detail

init

public void init(SortedKeyValueIterator<Key,Value> source,
                 Map<String,String> options,
                 IteratorEnvironment env)
          throws IOException

Description copied from interface: SortedKeyValueIterator

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

Specified by:

init in interface SortedKeyValueIterator<Key,Value>

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:

IOException - unused.

seek

public static LocalityGroupIterator.LocalityGroupSeekCache seek(HeapIterator hiter,
                                                                LocalityGroupIterator.LocalityGroupContext lgContext,
                                                                Range range,
                                                                Collection<ByteSequence> columnFamilies,
                                                                boolean inclusive,
                                                                LocalityGroupIterator.LocalityGroupSeekCache lgSeekCache)
                                                         throws IOException

This seek method will reuse the supplied LocalityGroupSeekCache if it can. Otherwise it will delegate to the _seek method.

Parameters:

hiter - The heap iterator

lgContext - The locality groups

range - The range to seek

columnFamilies - The column fams to seek

inclusive - The inclusiveness of the column fams

lgSeekCache - A cache returned by the previous call to this method

Returns:

A cache for this seek call

Throws:

IOException - thrown if an locality group seek fails

seek

public void seek(Range range,
                 Collection<ByteSequence> columnFamilies,
                 boolean inclusive)
          throws IOException

Description copied from interface: SortedKeyValueIterator

Seeks to the first key in the Range, restricting the resulting K,V pairs to those with the specified columns. An iterator does not have to stop at the end of the range. The whole range is provided so that iterators can make optimizations. Seek may be called multiple times with different parameters after SortedKeyValueIterator.init(org.apache.accumulo.core.iterators.SortedKeyValueIterator<K, V>, java.util.Map<java.lang.String, java.lang.String>, org.apache.accumulo.core.iterators.IteratorEnvironment) is called. Iterators that examine groups of adjacent key/value pairs (e.g. rows) to determine their top key and value should be sure that they properly handle a seek to a key in the middle of such a group (e.g. the middle of a row). Even if the client always seeks to a range containing an entire group (a,c), the tablet server could send back a batch of entries corresponding to (a,b], then reseek the iterator to range (b,c) when the scan is continued. columnFamilies is used, at the lowest level, to determine which data blocks inside of an RFile need to be opened for this iterator. This set of data blocks is also the set of locality groups defined for the given table. If no columnFamilies are provided, the data blocks for all locality groups inside of the correct RFile will be opened and seeked in an attempt to find the correct start key, regardless of the startKey in the range. In an Accumulo instance in which multiple locality groups exist for a table, it is important to ensure that columnFamilies is properly set to the minimum required column families to ensure that data from separate locality groups is not inadvertently read.

Specified by:

seek in interface SortedKeyValueIterator<Key,Value>

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:

IOException - if an I/O error occurs.

deepCopy

public SortedKeyValueIterator<Key,Value> deepCopy(IteratorEnvironment env)

Description copied from interface: SortedKeyValueIterator

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. A proper implementation would call deepCopy on the source.

Specified by:

deepCopy in interface SortedKeyValueIterator<Key,Value>

Parameters:

env - IteratorEnvironment environment in which iterator is being run.

Returns:

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

setInterruptFlag

public void setInterruptFlag(AtomicBoolean flag)

Specified by:

setInterruptFlag in interface InterruptibleIterator