edu.umass.cs.reconfiguration.interfaces

Interface Reconfigurable

All Superinterfaces:

Application, AppRequestParser, AppRequestParserBytes

All Known Subinterfaces:

Repliconfigurable

All Known Implementing Classes:

AbstractReconfigurablePaxosApp, AbstractReconfiguratorDB, AbstractReplicaCoordinator, AbstractReplicaCoordinatorPersistent, AbstractTransactor, DistTransactor, DynamoReplicaCoordinator, NoopApp, NoopApp, NoopAppCoordinator, NoopAppTesting, NoopAppTX, PaxosReplicaCoordinator, RepliconfigurableReconfiguratorDB, SQLReconfiguratorDB, TrivialRepliconfigurable

public interface Reconfigurable
extends Application

Author:

V. Arun

Method Summary

Modifier and Type	Method and Description
boolean	deleteFinalState(java.lang.String name, int epoch) Garbage-collects the final state for name, epoch.
java.lang.Integer	getEpoch(java.lang.String name) Returns the current (unique) epoch for name.
java.lang.String	getFinalState(java.lang.String name, int epoch) Return the final checkpointed state for name, epoch.
ReconfigurableRequest	getStopRequest(java.lang.String name, int epoch) Returns a stop request that when executed by the app ensures that no subsequent request after the stop is executed in that epoch.
void	putInitialState(java.lang.String name, int epoch, java.lang.String state) Inserts the specified state as the initial state for name, epoch.

Methods inherited from interface edu.umass.cs.gigapaxos.interfaces.Application

execute

Methods inherited from interface edu.umass.cs.gigapaxos.interfaces.AppRequestParser

getMutualAuthRequestTypes, getRequest, getRequest, getRequestTypes, getServerAuthRequestTypes

Method Detail

getStopRequest

ReconfigurableRequest getStopRequest(java.lang.String name,
                                     int epoch)

Returns a stop request that when executed by the app ensures that no subsequent request after the stop is executed in that epoch. We need the app to return a stop request as opposed to just exposing a stop() method because, in general, the stop may need to be coordinated across app replicas. If nothing special has to be done by the app upon an epoch stop, it is okay for this method to just return null or a no-op request. If an app is using PaxosReplicaCoordinator, nothing special needs to be done by the app upon an epoch stop, so it can return either null or a no-op request.

Parameters:

name -

epoch -

Returns:

InterfaceReconfigurableRequest corresponding to the stop request for the replica group name:epoch.

getFinalState

java.lang.String getFinalState(java.lang.String name,
                               int epoch)

Return the final checkpointed state for name, epoch. If a checkpoint does not yet exist, it has to be created. This method should return null if the app has moved on, i.e., its current epoch number is higher than epoch and it has no final state for the requested epoch (possibly because it has been garbage-collected). This method will typically get called right after a stop request has been supplied for execution to the app, so it is a good idea for the application to create the checkpoint immediately after executing an epoch stop request.

Parameters:

name -

epoch -

Returns:

The final state, or a concise handle thereof, as a String.

putInitialState

void putInitialState(java.lang.String name,
                     int epoch,
                     java.lang.String state)

Inserts the specified state as the initial state for name, epoch. This method marks the creation of an epoch. All lower epoch numbers must be marked as inactive at this point. After this method has been called, the app can only accept requests for "name" in the epoch "epoch".

Parameters:

name -

epoch -

state -

deleteFinalState

boolean deleteFinalState(java.lang.String name,
                         int epoch)

Garbage-collects the final state for name, epoch.

Parameters:

name -

epoch -

Returns:

True if final state for name:epoch was deleted or did not exist to begin with.

getEpoch

java.lang.Integer getEpoch(java.lang.String name)

Returns the current (unique) epoch for name. At most a single epoch can actively exist at any time at a replica. The app replica may maintain the final state for lower (inactive) epochs, but may not accept requests in any epoch other than the currently active epoch if one exists. This method should return null if no active replica for the name exists at this node.

Parameters:

name -

Returns:

The current epoch number for name.