Package bftsmart.tom.server.defaultservices

Class DefaultSingleRecoverable

java.lang.Object

bftsmart.tom.server.defaultservices.DefaultSingleRecoverable

All Implemented Interfaces:

Executable, Recoverable, SingleExecutable

Direct Known Subclasses:

CounterServer, MapServer, RecoveryTestServer, SimpleServiceServer, ThroughputLatencyServer

public abstract class DefaultSingleRecoverable
extends java.lang.Object
implements Recoverable, SingleExecutable

This class provides a basic state transfer protocol using the interface 'SingleExecutable'.

Field Summary

Fields

Modifier and Type	Field	Description
protected ReplicaContext	replicaContext

Constructor Summary

Constructors

Constructor	Description
DefaultSingleRecoverable()

Method Summary

Modifier and Type	Method	Description
abstract byte[]	appExecuteOrdered(byte[] command, MessageContext msgCtx)	Execute a batch of ordered requests
abstract byte[]	appExecuteUnordered(byte[] command, MessageContext msgCtx)	Execute an unordered request
byte[]	executeOrdered(byte[] command, MessageContext msgCtx)	Method called to execute a request totally ordered.
byte[]	executeUnordered(byte[] command, MessageContext msgCtx)	Method called to execute a request totally ordered.
abstract byte[]	getSnapshot()	Returns a serialized snapshot of the application state
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.
abstract void	installSnapshot(byte[] state)	Given a snapshot received from the state transfer protocol, install it
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 or an instance where the client operation was not delivered because its view was outdated).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)	Set the ClientManager object
void	setReplicaContext(ReplicaContext replicaContext)	Sets the replica context
int	setState(ApplicationState recvState)	Sets the state to the representation obtained in the state transfer protocol

Methods inherited from class java.lang.Object

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

Methods inherited from interface bftsmart.tom.server.Executable

executeUnordered, getTOMMessage

Methods inherited from interface bftsmart.tom.server.SingleExecutable

executeOrdered

Field Detail

replicaContext

protected ReplicaContext replicaContext

Constructor Detail

DefaultSingleRecoverable

public DefaultSingleRecoverable()

Method Detail

executeOrdered

public byte[] executeOrdered(byte[] command,
                             MessageContext msgCtx)

Description copied from interface: SingleExecutable

Method called to execute a request totally ordered. The message context contains a lot of information about the request, such as timestamp, nonces and sender. The code for this method MUST use the value of timestamp instead of relying on its own local clock, and nonces instead of trying to generated its own random values. This is important because this values are the same for all replicas, and therefore, ensure the determinism required in a replicated state machine.

Specified by:

executeOrdered in interface SingleExecutable

Parameters:

command - the command issue by the client

msgCtx - information related with the command

Returns:

the reply for the request issued by the client

getState

public ApplicationState getState(int cid,
                                 boolean sendState)

Description copied from interface: Recoverable

This method should return a representation of the application state

Specified by:

getState in interface Recoverable

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

public int setState(ApplicationState recvState)

Description copied from interface: Recoverable

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

Specified by:

setState in interface Recoverable

Parameters:

recvState - State obtained in the state transfer protocol

Returns:

setReplicaContext

public void setReplicaContext(ReplicaContext replicaContext)

Description copied from interface: Recoverable

Sets the replica context

Specified by:

setReplicaContext in interface Recoverable

Parameters:

replicaContext - The replica context

getStateManager

public StateManager getStateManager()

Description copied from interface: Recoverable

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.

Specified by:

getStateManager in interface Recoverable

Returns:

the implementation of state manager that suplies the strategy defined

setClientsManager

public void setClientsManager(ClientsManager clientsManager)

Set the ClientManager object

Specified by:

setClientsManager in interface Recoverable

Parameters:

clientsManager - client manager

executeUnordered

public byte[] executeUnordered(byte[] command,
                               MessageContext msgCtx)

Description copied from interface: Executable

Method called to execute a request totally ordered. The message context contains some useful information such as the command sender.

Specified by:

executeUnordered in interface Executable

Parameters:

command - the command issue by the client

msgCtx - information related with the command

Returns:

the reply for the request issued by the client

Op

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

Description copied from interface: Recoverable

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.

Specified by:

Op in interface Recoverable

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

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

Description copied from interface: Recoverable

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

Specified by:

noOp in interface Recoverable

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.

installSnapshot

public abstract void installSnapshot(byte[] state)

Given a snapshot received from the state transfer protocol, install it

Parameters:

state - The serialized snapshot

getSnapshot

public abstract byte[] getSnapshot()

Returns a serialized snapshot of the application state

Returns:

A serialized snapshot of the application state

appExecuteOrdered

public abstract byte[] appExecuteOrdered(byte[] command,
                                         MessageContext msgCtx)

Execute a batch of ordered requests

Parameters:

command - The ordered request

msgCtx - The context associated to each request

Returns:

the reply for the request issued by the client

appExecuteUnordered

public abstract byte[] appExecuteUnordered(byte[] command,
                                           MessageContext msgCtx)

Execute an unordered request

Parameters:

command - The unordered request

msgCtx - The context associated to the request

Returns:

the reply for the request issued by the client