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

Class HeapIterator

java.lang.Object

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

All Implemented Interfaces:

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

Direct Known Subclasses:

LocalityGroupIterator, MultiIterator, RFile.Reader

public abstract class HeapIterator
extends Object
implements SortedKeyValueIterator<Key,Value>

Constructs a PriorityQueue of multiple SortedKeyValueIterators. Provides a simple way to interact with multiple SortedKeyValueIterators in sorted order.

Constructor Summary

Constructors

Modifier	Constructor	Description
protected	HeapIterator()
protected	HeapIterator(int maxSize)

Method Summary

Modifier and Type	Method	Description
protected void	addSource(SortedKeyValueIterator<Key,Value> source)
protected void	clear()
protected void	createHeap(int maxSize)
Key	getTopKey()	Returns top key.
Value	getTopValue()	Returns top value.
boolean	hasTop()	Returns true if the iterator has more elements.
void	next()	Advances to the next K,V pair.

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

deepCopy, init, isRunningLowOnMemory, seek

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

enableYielding

Constructor Detail

HeapIterator

protected HeapIterator()

HeapIterator

protected HeapIterator(int maxSize)

Method Detail

createHeap

protected void createHeap(int maxSize)

getTopKey

public final Key getTopKey()

Description copied from interface: SortedKeyValueIterator

Returns top key. Can be called 0 or more times without affecting behavior of next() or hasTop(). Note that in minor compaction scope and in non-full major compaction scopes the iterator may see deletion entries. These entries should be preserved by all iterators except ones that are strictly scan-time iterators that will never be configured for the minc or majc scopes. Deletion entries are only removed during full major compactions.

For performance reasons, iterators reserve the right to reuse objects returned by getTopKey when SortedKeyValueIterator.next() is called, changing the data that the object references. Iterators that need to save an object returned by getTopKey ought to copy the object's data into a new object in order to avoid aliasing bugs.

Specified by:

getTopKey in interface SortedKeyValueIterator<Key,Value>

Returns:

K

getTopValue

public final Value getTopValue()

Description copied from interface: SortedKeyValueIterator

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

For performance reasons, iterators reserve the right to reuse objects returned by getTopValue when SortedKeyValueIterator.next() is called, changing the underlying data that the object references. Iterators that need to save an object returned by getTopValue ought to copy the object's data into a new object in order to avoid aliasing bugs.

Specified by:

getTopValue in interface SortedKeyValueIterator<Key,Value>

Returns:

V

hasTop

public final boolean hasTop()

Description copied from interface: SortedKeyValueIterator

Returns true if the iterator has more elements. Note that if this iterator has yielded (@see YieldingKeyValueIterator.enableYielding(YieldCallback)), this this method must return false.

Specified by:

hasTop in interface SortedKeyValueIterator<Key,Value>

Returns:

true if the iterator has more elements.

next

public final void next()
                throws IOException

Description copied from interface: SortedKeyValueIterator

Advances to the next K,V pair. Note that in minor compaction scope and in non-full major compaction scopes the iterator may see deletion entries. These entries should be preserved by all iterators except ones that are strictly scan-time iterators that will never be configured for the minc or majc scopes. Deletion entries are only removed during full major compactions.

Specified by:

next in interface SortedKeyValueIterator<Key,Value>

Throws:

IOException - if an I/O error occurs.

clear

protected final void clear()

addSource

protected final void addSource(SortedKeyValueIterator<Key,Value> source)