io.druid.collections

Class OrderedMergeSequence<T>

java.lang.Object

io.druid.collections.OrderedMergeSequence<T>

All Implemented Interfaces:

Sequence<T>

public class OrderedMergeSequence<T>
extends Object
implements Sequence<T>

An OrderedMergeIterator is an iterator that merges together multiple sorted iterators. It is written assuming that the input Iterators are provided in order. That is, it places an extra restriction in the input iterators. Normally a merge operation could operate with the actual input iterators in any order as long as the actual values in the iterators are sorted. This requires that not only the individual values be sorted, but that the iterators be provided in the order of the first element of each iterator. If this doesn't make sense, check out OrderedMergeSequenceTest.testScrewsUpOnOutOfOrderBeginningOfList() It places this extra restriction on the input data in order to implement an optimization that allows it to remain as lazy as possible in the face of a common case where the iterators are just appended one after the other.

Constructor Summary

Constructors

Constructor and Description
OrderedMergeSequence(com.google.common.collect.Ordering<T> ordering, Sequence<Sequence<T>> sequences)

Method Summary

Modifier and Type	Method and Description
<OutType> OutType	accumulate(OutType initValue, Accumulator<OutType,T> accumulator) Accumulate this sequence using the given accumulator.
<OutType> Yielder<OutType>	toYielder(OutType initValue, YieldingAccumulator<OutType,T> accumulator) Return an Yielder for accumulated sequence.

Methods inherited from class java.lang.Object

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

Constructor Detail

OrderedMergeSequence

public OrderedMergeSequence(com.google.common.collect.Ordering<T> ordering,
                            Sequence<Sequence<T>> sequences)

Method Detail

accumulate

public <OutType> OutType accumulate(OutType initValue,
                                    Accumulator<OutType,T> accumulator)

Description copied from interface: Sequence

Accumulate this sequence using the given accumulator.

Specified by:

accumulate in interface Sequence<T>

Type Parameters:

OutType - the type of accumulated value.

Parameters:

initValue - the initial value to pass along to start the accumulation.

accumulator - the accumulator which is responsible for accumulating input values.

Returns:

accumulated value.

toYielder

public <OutType> Yielder<OutType> toYielder(OutType initValue,
                                            YieldingAccumulator<OutType,T> accumulator)

Description copied from interface: Sequence

Return an Yielder for accumulated sequence.

Specified by:

toYielder in interface Sequence<T>

Type Parameters:

OutType - the type of accumulated value.

Parameters:

initValue - the initial value to pass along to start the accumulation.

accumulator - the accumulator which is responsible for accumulating input values.

Returns:

an Yielder for accumulated sequence.

See Also:

Yielder