Package bftsmart.tom.server

Interface Recoverable

All Known Implementing Classes:

CounterServer, DefaultRecoverable, DefaultSingleRecoverable, DurabilityCoordinator, MapServer, RecoveryTestServer, SimpleServiceServer, ThroughputLatencyServer, ThroughputLatencyServer, YCSBServer

public interface Recoverable

Classes that implement this interface should implement a state transfer protocol. Typically, classes should both implement this interface and one of the executables.

Method Summary

Modifier and Type	Method	Description
ApplicationState	getState(int cid, boolean sendState)	This method should return a representation of the application state
StateManager	getStateManager()	Recoverers implementing this interface will have to chose among different options of state managers like DurableStateManager or StandardStateManager.
void	noOp(int CID, byte[][] operations, MessageContext[] msgCtx)	This method is invoked by ServiceReplica to indicate that a consensus instance finished without delivering anything to the application (e.g., an instance only decided a single reconfiguration operation. or an instance where the client operation was not delivered because its view was outdated).
void	Op(int CID, byte[] requests, MessageContext msgCtx)	This method is invoked by ServiceReplica to pass information that was decided in a particular consensus instance.
void	setClientsManager(ClientsManager clientsManager)	Recoverers implement this interface to access and save replies from the ClientManager as replies need to be transfered to a recovering replica as part of its replica state (which is enriched by a replies storage object) To access the clientManager, the recoverer needs to set its reference
void	setReplicaContext(ReplicaContext replicaContext)	Sets the replica context
int	setState(ApplicationState state)	Sets the state to the representation obtained in the state transfer protocol

Method Detail

setReplicaContext

void setReplicaContext(ReplicaContext replicaContext)

Sets the replica context

Parameters:

replicaContext - The replica context

getState

ApplicationState getState(int cid,
                          boolean sendState)

This method should return a representation of the application state

Parameters:

cid - Consensus up to which the application should return an Application state

sendState - true if the replica should send a complete representation of the state instead of only the hash. False otherwise

Returns:

A representation of the application state

setState

int setState(ApplicationState state)

Sets the state to the representation obtained in the state transfer protocol

Parameters:

state - State obtained in the state transfer protocol

Returns:

getStateManager

StateManager getStateManager()

Recoverers implementing this interface will have to chose among different options of state managers like DurableStateManager or StandardStateManager. The recoverer class can also define a new strategy to manage the state and return it in this method.

Returns:

the implementation of state manager that suplies the strategy defined

setClientsManager

void setClientsManager(ClientsManager clientsManager)

Recoverers implement this interface to access and save replies from the ClientManager as replies need to be transfered to a recovering replica as part of its replica state (which is enriched by a replies storage object) To access the clientManager, the recoverer needs to set its reference

Op

void Op(int CID,
        byte[] requests,
        MessageContext msgCtx)

This method is invoked by ServiceReplica to pass information that was decided in a particular consensus instance. This method is always invoked before the executor. However, multiple invocations for the same consensus ID may occur, so developers must take this behavior into consideration when developing their own logging and checkpointing. If there is no information to be passed to the application, noOp(...) is invoked instead.

Parameters:

CID - the consensus instance ID associated with the request

requests - A request decided in CID

msgCtx - Message context associated with the client request and the consensus instance where it was ordered. msgCtx.getConsensusId() will be equal to CID.

noOp

void noOp(int CID,
          byte[][] operations,
          MessageContext[] msgCtx)

This method is invoked by ServiceReplica to indicate that a consensus instance finished without delivering anything to the application (e.g., an instance only decided a single reconfiguration operation. or an instance where the client operation was not delivered because its view was outdated). To allow the underlying state transfer protocol to execute correctly, it needs to be notified of this special case In the current protocols included, it suffices to register a NOOP operation in the logs used within the state transfer, but never deliver it to the application

Parameters:

CID - the consensus instance where the aforementioned condition occurred

operations - Operations decided in CID

msgCtx - Message context associated with the consensus instance. furthermore msgCtx.getConsensusId() will be equal to CID.