org.jgroups

Class View

java.lang.Object

java.util.AbstractCollection<E>

java.util.AbstractList<Address>

org.jgroups.View

All Implemented Interfaces:

java.lang.Comparable<View>, java.lang.Iterable<Address>, java.util.Collection<Address>, java.util.List<Address>, Streamable

Direct Known Subclasses:

DeltaView, MergeView

public class View
extends java.util.AbstractList<Address>
implements java.lang.Comparable<View>, Streamable, java.lang.Iterable<Address>

A view is a local representation of the current membership of a group. Only one view is installed in a channel at a time. Views contain the address of its creator, an ID and a list of member addresses. These addresses are ordered, and the first address is always the coordinator of the view. This way, each member of the group knows who the new coordinator will be if the current one crashes or leaves the group. The views are sent between members using the VIEW_CHANGE event

Since:

2.0

Author:

Bela Ban

Field Summary

Fields

Modifier and Type	Field and Description
protected Address[]	members An array containing all the members of the view.
protected static boolean	suppress_view_size
protected ViewId	view_id A view is uniquely identified by its ViewID.

Fields inherited from class java.util.AbstractList

modCount

Constructor Summary

Constructors

Constructor and Description
View() Creates an empty view, should not be used, only used by (de-)serialization
View(Address creator, long id, java.util.List<Address> members) Creates a new view
View(ViewId view_id, Address[] members) Creates a new view.
View(ViewId view_id, java.util.Collection<Address> members) Creates a new view

Method Summary

Modifier and Type	Method and Description
int	compareTo(View o)
boolean	containsMember(Address mbr) Returns true if this view contains a certain member
boolean	containsMembers(Address... mbrs) Returns true if all mbrs are elements of this view, false otherwise
View	copy() Deprecated. View is immutable, so copy() is unnecessary
static View	create(Address coord, long id, Address... members)
static View	create(Address coord, long id, java.util.Collection<Address> members)
boolean	deepEquals(View other)
static Address[][]	diff(View from, View to) Returns the difference between 2 views from and to.
boolean	equals(java.lang.Object obj)
Address	get(int index)
Address	getCoord()
Address	getCreator() Returns the creator of this view if this view was created with the empty constructur, null will be returned
java.util.List<Address>	getMembers() Returns the member list
Address[]	getMembersRaw() Returns the underlying array.
ViewId	getVid() Deprecated.
ViewId	getViewId() Returns the view ID of this view if this view was created with the empty constructur, null will be returned
int	hashCode()
java.util.Iterator<Address>	iterator()
static java.util.List<Address>	leftMembers(View one, View two) Returns a list of members which left from view one to two
void	readFrom(java.io.DataInput in) Read the state of the current object (including superclasses) from instream Note that the input stream must not be closed
int	serializedSize()
int	size() Returns the number of members in this view
java.lang.String	toString()
void	writeTo(java.io.DataOutput out) Write the entire state of the current object (including superclasses) to outstream.

Methods inherited from class java.util.AbstractList

add, add, addAll, clear, indexOf, lastIndexOf, listIterator, listIterator, remove, removeRange, set, subList

Methods inherited from class java.util.AbstractCollection

addAll, contains, containsAll, isEmpty, remove, removeAll, retainAll, toArray, toArray

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Methods inherited from interface java.lang.Iterable

forEach, spliterator

Methods inherited from interface java.util.List

addAll, contains, containsAll, isEmpty, remove, removeAll, replaceAll, retainAll, sort, spliterator, toArray, toArray

Methods inherited from interface java.util.Collection

parallelStream, removeIf, stream

Field Detail

view_id

protected ViewId view_id

A view is uniquely identified by its ViewID. The view id contains the creator address and a Lamport time. The Lamport time is the highest timestamp seen or sent from a view. if a view change comes in with a lower Lamport time, the event is discarded.

members

protected Address[] members

An array containing all the members of the view. This array is always ordered, with the coordinator being the first member. The second member will be the new coordinator if the current one disappears or leaves the group.

suppress_view_size

protected static final boolean suppress_view_size

Constructor Detail

View

public View()

Creates an empty view, should not be used, only used by (de-)serialization

View

public View(ViewId view_id,
            java.util.Collection<Address> members)

Creates a new view

Parameters:

view_id - The view id of this view (can not be null)

members - Contains a list of all the members in the view, can be empty but not null.

View

public View(ViewId view_id,
            Address[] members)

Creates a new view.

Parameters:

view_id - The new view-id

members - The members. Note that the parameter is not copied.

View

public View(Address creator,
            long id,
            java.util.List<Address> members)

Creates a new view

Parameters:

creator - The creator of this view (can not be null)

id - The lamport timestamp of this view

members - Contains a list of all the members in the view, can be empty but not null.

Method Detail

create

public static View create(Address coord,
                          long id,
                          Address... members)

getVid

@Deprecated
public ViewId getVid()

Deprecated.

create

public static View create(Address coord,
                          long id,
                          java.util.Collection<Address> members)

getViewId

public ViewId getViewId()

Returns the view ID of this view if this view was created with the empty constructur, null will be returned

Returns:

the view ID of this view

getCreator

public Address getCreator()

Returns the creator of this view if this view was created with the empty constructur, null will be returned

Returns:

the creator of this view in form of an Address object

getCoord

public Address getCoord()

getMembers

public java.util.List<Address> getMembers()

Returns the member list

Returns:

an immutable list of the members

getMembersRaw

public Address[] getMembersRaw()

Returns the underlying array. The caller must not modify the contents. Should not be used by application code ! This method may be removed at any time, so don't use it !

containsMember

public boolean containsMember(Address mbr)

Returns true if this view contains a certain member

Parameters:

mbr - - the address of the member,

Returns:

true if this view contains the member, false if it doesn't

containsMembers

public boolean containsMembers(Address... mbrs)

Returns true if all mbrs are elements of this view, false otherwise

compareTo

public int compareTo(View o)

Specified by:

compareTo in interface java.lang.Comparable<View>

equals

public boolean equals(java.lang.Object obj)

Specified by:

equals in interface java.util.Collection<Address>

Specified by:

equals in interface java.util.List<Address>

Overrides:

equals in class java.util.AbstractList<Address>

deepEquals

public boolean deepEquals(View other)

hashCode

public int hashCode()

Specified by:

hashCode in interface java.util.Collection<Address>

Specified by:

hashCode in interface java.util.List<Address>

Overrides:

hashCode in class java.util.AbstractList<Address>

size

public int size()

Returns the number of members in this view

Specified by:

size in interface java.util.Collection<Address>

Specified by:

size in interface java.util.List<Address>

Specified by:

size in class java.util.AbstractCollection<Address>

Returns:

the number of members in this view 0..n

copy

@Deprecated
public View copy()

Deprecated. View is immutable, so copy() is unnecessary

Creates a copy of a view

Returns:

toString

public java.lang.String toString()

Overrides:

toString in class java.util.AbstractCollection<Address>

writeTo

public void writeTo(java.io.DataOutput out)
             throws java.lang.Exception

Description copied from interface: Streamable

Write the entire state of the current object (including superclasses) to outstream. Note that the output stream must not be closed

Specified by:

writeTo in interface Streamable

Throws:

java.lang.Exception

readFrom

public void readFrom(java.io.DataInput in)
              throws java.lang.Exception

Description copied from interface: Streamable

Read the state of the current object (including superclasses) from instream Note that the input stream must not be closed

Specified by:

readFrom in interface Streamable

Throws:

java.lang.Exception

serializedSize

public int serializedSize()

leftMembers

public static java.util.List<Address> leftMembers(View one,
                                                  View two)

Returns a list of members which left from view one to two

Parameters:

one -

two -

Returns:

diff

public static Address[][] diff(View from,
                               View to)

Returns the difference between 2 views from and to. It is assumed that view 'from' is logically prior to view 'to'.

Parameters:

from - The first view

to - The second view

Returns:

an array of 2 Address arrays: index 0 has the addresses of the joined member, index 1 those of the left members

iterator

public java.util.Iterator<Address> iterator()

Specified by:

iterator in interface java.lang.Iterable<Address>

Specified by:

iterator in interface java.util.Collection<Address>

Specified by:

iterator in interface java.util.List<Address>

Overrides:

iterator in class java.util.AbstractList<Address>

get

public Address get(int index)

Specified by:

get in interface java.util.List<Address>

Specified by:

get in class java.util.AbstractList<Address>