edu.umass.cs.reconfiguration

Class PaxosReplicaCoordinator<NodeIDType>

java.lang.Object

edu.umass.cs.reconfiguration.AbstractReplicaCoordinator<NodeIDType>

edu.umass.cs.reconfiguration.PaxosReplicaCoordinator<NodeIDType>

Type Parameters:

NodeIDType -

All Implemented Interfaces:

Application, AppRequestParser, AppRequestParserBytes, Replicable, Reconfigurable, ReplicaCoordinator<NodeIDType>, Repliconfigurable

Direct Known Subclasses:

NoopAppCoordinator, RepliconfigurableReconfiguratorDB

public class PaxosReplicaCoordinator<NodeIDType>
extends AbstractReplicaCoordinator<NodeIDType>

Author:

arun

Field Summary

Fields

Modifier and Type	Field and Description
protected static java.util.logging.Logger	log

Fields inherited from class edu.umass.cs.reconfiguration.AbstractReplicaCoordinator

app, messenger

Constructor Summary

Constructors

Constructor and Description
PaxosReplicaCoordinator(Replicable app, NodeIDType myID, Stringifiable<NodeIDType> unstringer, Messenger<NodeIDType,?> niot)
PaxosReplicaCoordinator(Replicable app, NodeIDType myID, Stringifiable<NodeIDType> unstringer, Messenger<NodeIDType,?> niot, int outOfOrderLimit)

Method Summary

Modifier and Type	Method and Description
boolean	coordinateRequest(Request request, ExecutedCallback callback) Start of abstract methods
boolean	coordinateRequest(java.lang.String paxosGroupID, Request request, ExecutedCallback callback)
boolean	createReplicaGroup(java.util.Map<java.lang.String,java.lang.String> nameStates, java.util.Set<NodeIDType> nodes) Default implementation that can be overridden for more batching optimization.
boolean	createReplicaGroup(java.lang.String groupName, int epoch, java.lang.String state, java.util.Set<NodeIDType> nodes) This method should return true if the replica group is successfully created or one already exists with the same set of nodes.
boolean	deleteFinalState(java.lang.String name, int epoch) Garbage-collects the final state for name, epoch.
boolean	deleteReplicaGroup(java.lang.String serviceName, int epoch) This method should result in all state corresponding to serviceName being deleted
boolean	existsOrHigher(java.lang.String name, int epoch)
protected void	forceCheckpoint(java.lang.String paxosID)
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.
protected StringContainer	getFinalStateContainer(java.lang.String name, int epoch) Used by ActiveReplica and similar to getFinalState but wraps it in a container so that we can distinguish between null final state (a possibly legitimate value of the state) and no state at all (because the paxos group has moved on and deleted the state or never created it in the first place.
java.util.Set<NodeIDType>	getReplicaGroup(java.lang.String serviceName) This method must return the replica group that was most recently successfully created for the serviceName using createReplicaGroup.
java.util.Set<IntegerPacketType>	getRequestTypes()
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.
java.util.Set<NodeIDType>	removeDead(java.util.Set<NodeIDType> nodes)
protected PaxosReplicaCoordinator<NodeIDType>	setOutOfOrderLimit(int limit)
void	stop() End of private helper methods
boolean	stopFailureMonitoring(NodeIDType node)
java.lang.String	toString()

Methods inherited from class edu.umass.cs.reconfiguration.AbstractReplicaCoordinator

callCallback, checkpoint, execute, execute, execute, getAppRequestTypes, getARARNodesAsString, getARRCNodesAsString, getCallback, getCoordinatorRequestTypes, getMessenger, getMutualAuthAppRequestTypes, getMyID, getRequest, getRequest, getRequest, handleIncoming, hasLargeCheckpoints, registerCoordination, restore, sendAllLazy, setCallback, setLargeCheckpoints, setMessenger, setStopCallback

Methods inherited from class java.lang.Object

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

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

getMutualAuthRequestTypes, getServerAuthRequestTypes

Field Detail

log

protected static final java.util.logging.Logger log

Constructor Detail

PaxosReplicaCoordinator

public PaxosReplicaCoordinator(Replicable app,
                               NodeIDType myID,
                               Stringifiable<NodeIDType> unstringer,
                               Messenger<NodeIDType,?> niot)

Parameters:

app -

myID -

unstringer -

niot -

PaxosReplicaCoordinator

public PaxosReplicaCoordinator(Replicable app,
                               NodeIDType myID,
                               Stringifiable<NodeIDType> unstringer,
                               Messenger<NodeIDType,?> niot,
                               int outOfOrderLimit)

Parameters:

app -

myID -

unstringer -

niot -

outOfOrderLimit -

Method Detail

setOutOfOrderLimit

protected PaxosReplicaCoordinator<NodeIDType> setOutOfOrderLimit(int limit)

getRequestTypes

public java.util.Set<IntegerPacketType> getRequestTypes()

Returns:

The set of request types that the application expects to process.

coordinateRequest

public boolean coordinateRequest(Request request,
                                 ExecutedCallback callback)
                          throws java.io.IOException,
                                 RequestParseException

Description copied from class: AbstractReplicaCoordinator

Start of abstract methods

Specified by:

coordinateRequest in interface ReplicaCoordinator<NodeIDType>

Specified by:

coordinateRequest in class AbstractReplicaCoordinator<NodeIDType>

Returns:

Success of coordination.

Throws:

java.io.IOException

RequestParseException

coordinateRequest

public boolean coordinateRequest(java.lang.String paxosGroupID,
                                 Request request,
                                 ExecutedCallback callback)
                          throws RequestParseException

Parameters:

paxosGroupID -

request -

callback -

Returns:

True if successfully proposed to some epoch of paxosGroupID.

Throws:

RequestParseException

createReplicaGroup

public boolean createReplicaGroup(java.lang.String groupName,
                                  int epoch,
                                  java.lang.String state,
                                  java.util.Set<NodeIDType> nodes)

Description copied from interface: ReplicaCoordinator

This method should return true if the replica group is successfully created or one already exists with the same set of nodes. It should return false otherwise.

Specified by:

createReplicaGroup in interface ReplicaCoordinator<NodeIDType>

Specified by:

createReplicaGroup in class AbstractReplicaCoordinator<NodeIDType>

Returns:

True if created successfully.

createReplicaGroup

public boolean createReplicaGroup(java.util.Map<java.lang.String,java.lang.String> nameStates,
                                  java.util.Set<NodeIDType> nodes)

Description copied from class: AbstractReplicaCoordinator

Default implementation that can be overridden for more batching optimization.

Overrides:

createReplicaGroup in class AbstractReplicaCoordinator<NodeIDType>

Returns:

True if all groups successfully created.

toString

public java.lang.String toString()

Overrides:

toString in class java.lang.Object

getReplicaGroup

public java.util.Set<NodeIDType> getReplicaGroup(java.lang.String serviceName)

Description copied from interface: ReplicaCoordinator

This method must return the replica group that was most recently successfully created for the serviceName using createReplicaGroup.

Specified by:

getReplicaGroup in interface ReplicaCoordinator<NodeIDType>

Specified by:

getReplicaGroup in class AbstractReplicaCoordinator<NodeIDType>

Returns:

Set of nodes in the replica group for serviceName.

deleteReplicaGroup

public boolean deleteReplicaGroup(java.lang.String serviceName,
                                  int epoch)

Description copied from interface: ReplicaCoordinator

This method should result in all state corresponding to serviceName being deleted

Specified by:

deleteReplicaGroup in interface ReplicaCoordinator<NodeIDType>

Specified by:

deleteReplicaGroup in class AbstractReplicaCoordinator<NodeIDType>

Returns:

True if deleted without errors.

forceCheckpoint

protected void forceCheckpoint(java.lang.String paxosID)

getEpoch

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

Description copied from interface: Reconfigurable

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.

Specified by:

getEpoch in interface Reconfigurable

Overrides:

getEpoch in class AbstractReplicaCoordinator<NodeIDType>

Returns:

The current epoch number for name.

getFinalState

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

Description copied from interface: Reconfigurable

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.

Specified by:

getFinalState in interface Reconfigurable

Overrides:

getFinalState in class AbstractReplicaCoordinator<NodeIDType>

Returns:

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

getFinalStateContainer

protected StringContainer getFinalStateContainer(java.lang.String name,
                                                 int epoch)

Used by ActiveReplica and similar to getFinalState but wraps it in a container so that we can distinguish between null final state (a possibly legitimate value of the state) and no state at all (because the paxos group has moved on and deleted the state or never created it in the first place. An alternative is to disallow null as a legitimate app state, but that means forcing apps to specify a non-null initial state (currently not enforced) as initial state needs to be checkpointed for safety.

Parameters:

name -

epoch -

Returns:

The final state wrapped in StringContainer.

putInitialState

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

Description copied from interface: Reconfigurable

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".

Specified by:

putInitialState in interface Reconfigurable

Overrides:

putInitialState in class AbstractReplicaCoordinator<NodeIDType>

deleteFinalState

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

Description copied from interface: Reconfigurable

Garbage-collects the final state for name, epoch.

Specified by:

deleteFinalState in interface Reconfigurable

Overrides:

deleteFinalState in class AbstractReplicaCoordinator<NodeIDType>

Returns:

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

getStopRequest

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

Description copied from interface: Reconfigurable

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.

Specified by:

getStopRequest in interface Reconfigurable

Overrides:

getStopRequest in class AbstractReplicaCoordinator<NodeIDType>

Returns:

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

stopFailureMonitoring

public boolean stopFailureMonitoring(NodeIDType node)

Parameters:

node -

Returns:

True if was being monitored.

existsOrHigher

public boolean existsOrHigher(java.lang.String name,
                              int epoch)

Parameters:

name -

epoch -

Returns:

True if the epoch or higher version exists for name.

removeDead

public java.util.Set<NodeIDType> removeDead(java.util.Set<NodeIDType> nodes)

Parameters:

nodes -

Returns:

Same as PaxosManager.removeDead(Set).

stop

public void stop()

Description copied from class: AbstractReplicaCoordinator

End of private helper methods

Overrides:

stop in class AbstractReplicaCoordinator<NodeIDType>