edu.umass.cs.reconfiguration.reconfigurationprotocoltasks

Class WaitPrimaryExecution<NodeIDType>

java.lang.Object

edu.umass.cs.protocoltask.ThresholdProtocolTask<NodeIDType,ReconfigurationPacket.PacketType,java.lang.String>

edu.umass.cs.reconfiguration.reconfigurationprotocoltasks.WaitAckStopEpoch<NodeIDType>

edu.umass.cs.reconfiguration.reconfigurationprotocoltasks.WaitPrimaryExecution<NodeIDType>

Type Parameters:

NodeIDType - This task waits for a single replica in a replicated application to finish executing the request. This is useful when you want only one replica to execute a request in the common case but ensure that the committed request is eventually executed despite failures. This is essentially a primary backup protocol. But instead of explicitly designating a primary to execute a request and propagate it via consensus to everyone (which could require roll back in the case of primary crashes), we use paxos as usual but only have one node, say the coordinator (or any designated replica, e.g., the replica that first received the client request), actually execute the request and propagate the result to others. The other replicas normally simply wait for the result, i.e., the incremental state change, to arrive. If the change does not arrive within a timeout, they go ahead and execute it anyway. When used with paxos, each decision now consists of two parts: decision and result. The replicas store the decision until either they timeout and decide to execute the decision themselves or the result arrives.

All Implemented Interfaces:

ProtocolTask<NodeIDType,ReconfigurationPacket.PacketType,java.lang.String>, SchedulableProtocolTask<NodeIDType,ReconfigurationPacket.PacketType,java.lang.String>, Keyable<java.lang.String>

public class WaitPrimaryExecution<NodeIDType>
extends WaitAckStopEpoch<NodeIDType>

Author:

arun

Field Summary

Fields inherited from class edu.umass.cs.reconfiguration.reconfigurationprotocoltasks.WaitAckStopEpoch

DB, log, restartCount, startEpoch

Fields inherited from class edu.umass.cs.protocoltask.ThresholdProtocolTask

waitfor

Constructor Summary

Constructors

Constructor and Description
WaitPrimaryExecution(NodeIDType myID, StartEpoch<NodeIDType> startEpoch, RepliconfigurableReconfiguratorDB<NodeIDType> DB, java.util.Set<NodeIDType> replicas)

Method Summary

Modifier and Type	Method and Description
protected boolean	amObviated()
java.util.Set<ReconfigurationPacket.PacketType>	getEventTypes()
java.lang.String	getKey()
long	getPeriod() The current restart period.
java.lang.String	refreshKey() Note: Trying to start this task when one is already running will cause the executor to get stuck.
GenericMessagingTask<NodeIDType,?>[]	restart()
GenericMessagingTask<NodeIDType,?>[]	start() Actions executed in the beginning.

Methods inherited from class edu.umass.cs.reconfiguration.reconfigurationprotocoltasks.WaitAckStopEpoch

getFinalState, handleEvent, handleThresholdEvent, toString

Methods inherited from class edu.umass.cs.protocoltask.ThresholdProtocolTask

fix, handleEvent, setPeriod

Methods inherited from class java.lang.Object

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

Constructor Detail

WaitPrimaryExecution

public WaitPrimaryExecution(NodeIDType myID,
                            StartEpoch<NodeIDType> startEpoch,
                            RepliconfigurableReconfiguratorDB<NodeIDType> DB,
                            java.util.Set<NodeIDType> replicas)

Parameters:

myID -

startEpoch -

DB -

replicas -

Method Detail

start

public GenericMessagingTask<NodeIDType,?>[] start()

Description copied from interface: ProtocolTask

Actions executed in the beginning.

Specified by:

start in interface ProtocolTask<NodeIDType,ReconfigurationPacket.PacketType,java.lang.String>

Overrides:

start in class WaitAckStopEpoch<NodeIDType>

Returns:

Initial messaging task.

restart

public GenericMessagingTask<NodeIDType,?>[] restart()

Specified by:

restart in interface SchedulableProtocolTask<NodeIDType,ReconfigurationPacket.PacketType,java.lang.String>

Overrides:

restart in class WaitAckStopEpoch<NodeIDType>

Returns:

The messaging task upon each restart.

amObviated

protected boolean amObviated()

Overrides:

amObviated in class WaitAckStopEpoch<NodeIDType>

getKey

public java.lang.String getKey()

Specified by:

getKey in interface Keyable<java.lang.String>

Overrides:

getKey in class WaitAckStopEpoch<NodeIDType>

Returns:

The key.

refreshKey

public java.lang.String refreshKey()

Description copied from class: WaitAckStopEpoch

Note: Trying to start this task when one is already running will cause the executor to get stuck.

Overrides:

refreshKey in class WaitAckStopEpoch<NodeIDType>

Returns:

The refreshed key.

getEventTypes

public java.util.Set<ReconfigurationPacket.PacketType> getEventTypes()

Specified by:

getEventTypes in interface ProtocolTask<NodeIDType,ReconfigurationPacket.PacketType,java.lang.String>

Overrides:

getEventTypes in class WaitAckStopEpoch<NodeIDType>

Returns:

The event types processed by this protocol task.

getPeriod

public long getPeriod()

Description copied from class: ThresholdProtocolTask

The current restart period.

Specified by:

getPeriod in interface SchedulableProtocolTask<NodeIDType,ReconfigurationPacket.PacketType,java.lang.String>

Overrides:

getPeriod in class ThresholdProtocolTask<NodeIDType,ReconfigurationPacket.PacketType,java.lang.String>

Returns:

The restart period.