infoservice.agreement.paxos
Class PaxosExecution

java.lang.Object
  infoservice.agreement.paxos.PaxosObject
      infoservice.agreement.paxos.PaxosExecution

public class PaxosExecution
extends PaxosObject

Field Summary

private boolean	m_decided Indicator if this execution has been decided
private java.lang.String	m_initiator The identifier for this execution
private PaxosInstance	m_paxosInstance The PaxosInstance this execution belongs to
private java.util.Vector	m_roundLeaders
private java.util.Hashtable	m_rounds A Hashtable of all active rounds for this execution

Constructor Summary

PaxosExecution(PaxosInstance a_instance, java.lang.String a_initiator, java.util.Vector a_roundLeaders)
Creates a new PaxosExecution within the given PaxosInstance for the given initiator.

Method Summary

void	cancel() Aborts all active rounds
PaxosRound	createRound() Creates a PaxosRound with round number 0
PaxosRound	createRound(int a_round) Creates and returns a new PaxosRound with the given round number
void	decide(java.lang.String a_proposal) Decides the given proposal for this execution
java.lang.String	getGoodProposal(int a_nextRound) Returns a "good" (see Paxos at War) proposal for this execution A proposal is p good if a) There is no pending decission, i.e.
java.lang.String	getInitiator() Returns this executions initiators id
java.lang.String	getNextRoundLeader(int a_round) Returns the ID of the next rounds leader.
PaxosInstance	getPaxosInstance() Returns the PaxosInstance this execution belongs to
PaxosRound	getRound(int a_round) Returns the round with the given round number or null if there is no such round exists
boolean	isDecided() Indicates if this execution has been decided

Methods inherited from class infoservice.agreement.paxos.PaxosObject

debug, error, fatal, getLog, info, setLog

Methods inherited from class java.lang.Object

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

Field Detail

m_initiator

private java.lang.String m_initiator

The identifier for this execution

m_rounds

private java.util.Hashtable m_rounds

A Hashtable of all active rounds for this execution

m_paxosInstance

private PaxosInstance m_paxosInstance

The PaxosInstance this execution belongs to

m_roundLeaders

private java.util.Vector m_roundLeaders

m_decided

private boolean m_decided

Indicator if this execution has been decided

Constructor Detail

PaxosExecution

public PaxosExecution(PaxosInstance a_instance,
                      java.lang.String a_initiator,
                      java.util.Vector a_roundLeaders)

Creates a new PaxosExecution within the given PaxosInstance for the given initiator. A PaxosRound with round number 0 is also created and its timeout is started

Parameters:

a_instance - The instance to which the Execution belongs

a_initiator - The initiator of this execution

Method Detail

getRound

public PaxosRound getRound(int a_round)

Returns the round with the given round number or null if there is no such round exists

Parameters:

a_round - The round number

Returns:

The corresponding PaxosRound or null if no such round exists

createRound

public PaxosRound createRound(int a_round)

Creates and returns a new PaxosRound with the given round number

Parameters:

a_round - The number of the newly created round

Returns:

The newly created PaxosRound

createRound

public PaxosRound createRound()

Creates a PaxosRound with round number 0

Returns:

A PaxosRound with round number 0

getInitiator

public java.lang.String getInitiator()

Returns this executions initiators id

Returns:

This executions initiators id

getPaxosInstance

public PaxosInstance getPaxosInstance()

Returns the PaxosInstance this execution belongs to

Returns:

he PaxosInstance this execution belongs to

cancel

public void cancel()

Aborts all active rounds

decide

public void decide(java.lang.String a_proposal)

Decides the given proposal for this execution

Parameters:

proposal - The proposal that will be decided

isDecided

public boolean isDecided()

Indicates if this execution has been decided

Returns:

true if decided, false otherwise

getNextRoundLeader

public java.lang.String getNextRoundLeader(int a_round)

Returns the ID of the next rounds leader. This will only be needed if the previous round gets frozen

Parameters:

a_round - The round number of the current round

Returns:

The ID of the next rounds leader

getGoodProposal

public java.lang.String getGoodProposal(int a_nextRound)

Returns a "good" (see Paxos at War) proposal for this execution A proposal is p good if a) There is no pending decission, i.e. the set Poss is empty in all rounds and p = "NULL" b) p is in acc in some round i and in poss in all rounds i \<= k \< a_nextRound

Returns:

A good proposal for this round