java.lang.Object
- org.jgroups.View

All Implemented Interfaces:

java.lang.Comparable<View>, java.lang.Iterable<Address>, Constructable<View>, SizeStreamable, Streamable

Direct Known Subclasses:

DeltaView, MergeView
```
public class View
extends java.lang.Object
implements java.lang.Comparable<View>, SizeStreamable, java.lang.Iterable<Address>, Constructable<View>
```
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	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.

Constructor Summary

Constructors
Constructor	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, java.util.Collection<Address> members)`	Creates a new view
`View(ViewId view_id, Address[] members)`	Creates a new view.

Method Summary

All Methods Static Methods Instance Methods Concrete Methods
Modifier and Type	Method	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
`java.util.function.Supplier<? extends View>`	`create()`	Creates an instance of the class implementing this interface
`static View`	`create(Address coord, long id, java.util.Collection<Address> members)`
`static View`	`create(Address coord, long id, 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`	`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`	`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
`static java.util.List<Address>`	`newMembers(View old, View new_view)`
`static java.lang.String`	`printDiff(Address[][] diff)`
`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
`static boolean`	`sameMembers(View v1, View v2)`	Checks if two views have the same members regardless of order.
`static boolean`	`sameMembersOrdered(View v1, View v2)`	Checks if two views have the same members observing order.
`static boolean`	`sameViews(java.util.Collection<View> views)`
`static boolean`	`sameViews(View... views)`	Returns true if all views are the same.
`int`	`serializedSize()`	Returns the size (in bytes) of the marshalled object
`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.lang.Object
clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Methods inherited from interface java.lang.Iterable
forEach, spliterator

- 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)
```
  - create
```
public static View create(Address coord,
                          long id,
                          java.util.Collection<Address> members)
```
  - create
```
public java.util.function.Supplier<? extends View> create()
```
    Description copied from interface: Constructable
    
    Creates an instance of the class implementing this interface
    
    Specified by:
    
    create in interface Constructable<View>
  - 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)
```
    Overrides:
    
    equals in class java.lang.Object
  - deepEquals
```
public boolean deepEquals(View other)
```
  - hashCode
```
public int hashCode()
```
    Overrides:
    
    hashCode in class java.lang.Object
  - size
```
public int size()
```
    Returns the number of members in this view
    
    Returns:
    
    the number of members in this view 0..n
  - toString
```
public java.lang.String toString()
```
    Overrides:
    
    toString in class java.lang.Object
  - writeTo
```
public void writeTo(java.io.DataOutput out)
             throws java.io.IOException
```
    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.io.IOException
  - readFrom
```
public void readFrom(java.io.DataInput in)
              throws java.io.IOException,
                     java.lang.ClassNotFoundException
```
    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.io.IOException
    
    java.lang.ClassNotFoundException
  - serializedSize
```
public int serializedSize()
```
    Description copied from interface: SizeStreamable
    
    Returns the size (in bytes) of the marshalled object
    
    Specified by:
    
    serializedSize in interface SizeStreamable
  - 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 -
  - newMembers
```
public static java.util.List<Address> newMembers(View old,
                                                 View new_view)
```
  - 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
  - printDiff
```
public static java.lang.String printDiff(Address[][] diff)
```
  - sameViews
```
public static boolean sameViews(View... views)
```
    Returns true if all views are the same. Uses the view IDs for comparison
  - sameViews
```
public static boolean sameViews(java.util.Collection<View> views)
```
  - sameMembers
```
public static boolean sameMembers(View v1,
                                  View v2)
```
    Checks if two views have the same members regardless of order. E.g. {A,B,C} and {B,A,C} returns true
  - sameMembersOrdered
```
public static boolean sameMembersOrdered(View v1,
                                         View v2)
```
    Checks if two views have the same members observing order. E.g. {A,B,C} and {B,A,C} returns false, {A,C,B} and {A,C,B} returns true
  - iterator
```
public java.util.Iterator<Address> iterator()
```
    Specified by:
    
    iterator in interface java.lang.Iterable<Address>

Class View

Field Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Methods inherited from interface java.lang.Iterable

Field Detail

view_id

members

suppress_view_size

Constructor Detail

View

View

View

View

Method Detail

create

create

create

getViewId

getCreator

getCoord

getMembers

getMembersRaw

containsMember

containsMembers

compareTo

equals

deepEquals

hashCode

size

toString

writeTo

readFrom

serializedSize

leftMembers

newMembers

diff

printDiff

sameViews

sameViews

sameMembers

sameMembersOrdered

iterator