net.sf.appia.protocols.group
Class ViewID

java.lang.Object
  net.sf.appia.protocols.group.ViewID

All Implemented Interfaces:

java.io.Externalizable, java.io.Serializable

Direct Known Subclasses:

AppiaMembershipID

public class ViewID
extends java.lang.Object
implements java.io.Externalizable

The unique identifier of a ViewState.
It is constructed from the coordinator and logical time of the view.

Version:

0.1

Author:

Alexandre Pinto

See Also:

ViewState, Serialized Form

Field Summary

Endpt	coord The Endpt of the coordinator of the view.
long	ltime The logical time of the view.

Constructor Summary

ViewID()
Constructs a new empty ViewID.

ViewID(long ltime, Endpt coord)
Constructs a new ViewID.

Method Summary

boolean	equals(java.lang.Object o) Redefines Object.equals().
boolean	equals(ViewID vid) Compares if the given ViewID is equal to the current one.
int	hashCode() Redefines Object.hashCode().
ViewID	merge(ViewID view_id, Endpt new_coord) Constructs a new ViewID that follows the current and the given ViewIDs.
ViewID	next() Constructs a new ViewID that follows the current ViewID.
ViewID	next(Endpt new_coord) Constructs a new ViewID that follows the current ViewID, but there is a different coordinator.
static ViewID	peek(Message message)
static ViewID	pop(Message message)
static void	push(ViewID viewid, Message message)
void	readExternal(java.io.ObjectInput in)
java.lang.String	toString() Creates a String representation of the ViewID.
void	writeExternal(java.io.ObjectOutput out)

Methods inherited from class java.lang.Object

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

Field Detail

ltime

public long ltime

The logical time of the view.

coord

public Endpt coord

The Endpt of the coordinator of the view.

Constructor Detail

ViewID

public ViewID()

Constructs a new empty ViewID. Needed for Externalizable interface.

ViewID

public ViewID(long ltime,
              Endpt coord)

Constructs a new ViewID.

Parameters:

coord - the coordinator of the view

ltime - the logical time of the view

Method Detail

next

public ViewID next()

Constructs a new ViewID that follows the current ViewID.

Returns:

the new ViewID

next

public ViewID next(Endpt new_coord)

Constructs a new ViewID that follows the current ViewID, but there is a different coordinator.

Parameters:

new_coord - the coordinator of the view

Returns:

the new ViewID

merge

public ViewID merge(ViewID view_id,
                    Endpt new_coord)

Constructs a new ViewID that follows the current and the given ViewIDs. The coordinator is the given one.

Parameters:

new_coord - The new view coordinator

view_id - the other ViewID

Returns:

the new ViewID

equals

public boolean equals(ViewID vid)

Compares if the given ViewID is equal to the current one.

Parameters:

vid - the other ViewID to compare to

Returns:

true if the ViewIDs are equal, false otherwise

equals

public boolean equals(java.lang.Object o)

Redefines Object.equals().

Overrides:

equals in class java.lang.Object

Parameters:

o - The object to compare with.

Returns:

True if this and the given object represent the same ViewID.

toString

public java.lang.String toString()

Creates a String representation of the ViewID.

Overrides:

toString in class java.lang.Object

Returns:

the String representation

hashCode

public int hashCode()

Redefines Object.hashCode().
The hashcode is equal to coordinator_hashcode ^ ((logical_time * 0x5DEECE66DL + 0xBL) & ((1L << 48)-1));. This is based on java.math.Random that was based in a linear congruential pseudorandom number generator, as defined by D. H. Lehmer and described by Donald E. Knuth in The Art of Computer Programming, Volume 2: Seminumerical Algorithms, section 3.2.1.

Overrides:

hashCode in class java.lang.Object

Returns:

hashcode for this ViewID

push

public static void push(ViewID viewid,
                        Message message)

pop

public static ViewID pop(Message message)

peek

public static ViewID peek(Message message)

writeExternal

public void writeExternal(java.io.ObjectOutput out)
                   throws java.io.IOException

Specified by:

writeExternal in interface java.io.Externalizable

Throws:

java.io.IOException

readExternal

public void readExternal(java.io.ObjectInput in)
                  throws java.io.IOException,
                         java.lang.ClassNotFoundException

Specified by:

readExternal in interface java.io.Externalizable

Throws:

java.io.IOException

java.lang.ClassNotFoundException