io.pravega.common.util

Class SequencedItemList<T extends SequencedItemList.Element>

java.lang.Object

io.pravega.common.util.SequencedItemList<T>

Type Parameters:

T - The type of the list items.

public class SequencedItemList<T extends SequencedItemList.Element>
extends java.lang.Object

Represents a List that can append only on one end and can truncate from the other, which provides random reads.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static interface	SequencedItemList.Element Defines an Element that can be added to a SequencedItemList.

Constructor Summary

Constructors

Constructor and Description
SequencedItemList() Creates a new instance of the TruncateableList class.

Method Summary

Modifier and Type	Method and Description
boolean	add(T item) Adds a new item at the end of the list, but only if the given item has a Sequence Number higher than the last element in the list.
void	clear() Clears the list.
T	getLast() Gets the last element in the list, if any.
java.util.Iterator<T>	read(long afterSequenceNumber, int count) Reads a number of items starting with the first one that has a Sequence Number higher than the given one.
int	truncate(long upToSequenceNumber) Truncates items from the beginning of the list up to, and including, the element with the given Sequence Number.

Methods inherited from class java.lang.Object

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

Constructor Detail

SequencedItemList

public SequencedItemList()

Creates a new instance of the TruncateableList class.

Method Detail

add

public boolean add(T item)

Adds a new item at the end of the list, but only if the given item has a Sequence Number higher than the last element in the list.

Parameters:

item - The item to append.

Returns:

True if the item was added (meets sequencing criteria or list was empty), false otherwise.

truncate

public int truncate(long upToSequenceNumber)

Truncates items from the beginning of the list up to, and including, the element with the given Sequence Number.

Parameters:

upToSequenceNumber - The Sequence Number to truncate up to.

Returns:

The number of truncated items.

clear

public void clear()

Clears the list.

getLast

public T getLast()

Gets the last element in the list, if any.

Returns:

The last element, or null if the list is empty.

read

public java.util.Iterator<T> read(long afterSequenceNumber,
                                  int count)

Reads a number of items starting with the first one that has a Sequence Number higher than the given one.

Parameters:

afterSequenceNumber - The sequence to search from.

count - The maximum number of items to read.

Returns:

An Iterator with the resulting items. If no results are available for the given parameters, an empty iterator is returned.