bftsmart.tom.core

Class TOMLayer

java.lang.Object

java.lang.Thread

bftsmart.tom.core.TOMLayer

All Implemented Interfaces:

RequestReceiver, java.lang.Runnable

public final class TOMLayer
extends java.lang.Thread
implements RequestReceiver

This class implements a thread that uses the PaW algorithm to provide the application a layer of total ordered messages

Nested Class Summary

Nested classes/interfaces inherited from class java.lang.Thread

java.lang.Thread.State, java.lang.Thread.UncaughtExceptionHandler

Field Summary

Fields

Modifier and Type	Field and Description
Acceptor	acceptor
ClientsManager	clientsManager Store requests received but still not ordered
ServerViewController	controller
ExecutionManager	execManager
LeaderModule	lm
RequestsTimer	requestsTimer Manage timers for pending requests

Fields inherited from class java.lang.Thread

MAX_PRIORITY, MIN_PRIORITY, NORM_PRIORITY

Constructor Summary

Constructors

Constructor and Description
TOMLayer(ExecutionManager manager, ServiceReplica receiver, Recoverable recoverer, LeaderModule lm, Acceptor a, ServerCommunicationSystem cs, ServerViewController controller) Creates a new instance of TOMulticastLayer

Method Summary

Methods

Modifier and Type	Method and Description
TOMMessage[]	checkProposedValue(byte[] proposedValue, boolean addToClientManager) Verify if the value being proposed for a round is valid.
byte[]	computeHash(byte[] data) Computes an hash for a TOM message
void	decided(Consensus cons) Called by the current consensus's execution, to notify the TOM layer that a value was decided
void	deliverTimeoutRequest(LCMessage msg) This method is called by the MessageHandler each time it received messages related to the leader change
void	forwardRequestToLeader(TOMMessage request)
ServerCommunicationSystem	getCommunication() Retrieve Communication system between replicas
int	getInExec() Gets the ID of the consensus currently beign executed
int	getLastExec() Gets the ID of the consensus which was established as the last executed
LCManager	getLCManager()
StateManager	getStateManager()
void	imAmTheLeader()
boolean	isRetrievingState()
void	processOutOfContext()
void	requestReceived(TOMMessage msg) This method is invoked by the communication system to deliver a request.
void	resumeLC()
void	run() This is the main code for this thread.
void	setInExec(int inEx) Sets which consensus is being executed at the moment
void	setLastExec(int last) Sets which consensus was the last to be executed
void	setNoExec()
java.security.SignedObject	sign(java.io.Serializable obj)
void	triggerTimeout(java.util.List<TOMMessage> requestList) This method is called when there is a timeout and the request has already been forwarded to the leader
boolean	verifySignature(java.security.SignedObject so, int sender) Verifies the signature of a signed object
void	waitForPaxosToFinish() This method blocks until the PaW algorithm is finished

Methods inherited from class java.lang.Thread

activeCount, checkAccess, clone, countStackFrames, currentThread, destroy, dumpStack, enumerate, getAllStackTraces, getContextClassLoader, getDefaultUncaughtExceptionHandler, getId, getName, getPriority, getStackTrace, getState, getThreadGroup, getUncaughtExceptionHandler, holdsLock, interrupt, interrupted, isAlive, isDaemon, isInterrupted, join, join, join, resume, setContextClassLoader, setDaemon, setDefaultUncaughtExceptionHandler, setName, setPriority, setUncaughtExceptionHandler, sleep, sleep, start, stop, stop, suspend, toString, yield

Methods inherited from class java.lang.Object

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

Field Detail

execManager

public ExecutionManager execManager

lm

public LeaderModule lm

acceptor

public Acceptor acceptor

requestsTimer

public RequestsTimer requestsTimer

Manage timers for pending requests

clientsManager

public ClientsManager clientsManager

Store requests received but still not ordered

controller

public ServerViewController controller

Constructor Detail

TOMLayer

public TOMLayer(ExecutionManager manager,
        ServiceReplica receiver,
        Recoverable recoverer,
        LeaderModule lm,
        Acceptor a,
        ServerCommunicationSystem cs,
        ServerViewController controller)

Creates a new instance of TOMulticastLayer

Parameters:

manager - Execution manager

receiver - Object that receives requests from clients

lm - Leader module

a - Acceptor role of the PaW algorithm

cs - Communication system between replicas

controller - Reconfiguration Manager

Method Detail

computeHash

public final byte[] computeHash(byte[] data)

Computes an hash for a TOM message

Parameters:

data - Data from which to generate the hash

Returns:

Hash for the specified TOM message

sign

public java.security.SignedObject sign(java.io.Serializable obj)

verifySignature

public boolean verifySignature(java.security.SignedObject so,
                      int sender)

Verifies the signature of a signed object

Parameters:

so - Signed object to be verified

sender - Replica id that supposedly signed this object

Returns:

True if the signature is valid, false otherwise

getCommunication

public ServerCommunicationSystem getCommunication()

Retrieve Communication system between replicas

Returns:

Communication system between replicas

imAmTheLeader

public void imAmTheLeader()

setLastExec

public void setLastExec(int last)

Sets which consensus was the last to be executed

Parameters:

last - ID of the consensus which was last to be executed

getLastExec

public int getLastExec()

Gets the ID of the consensus which was established as the last executed

Returns:

ID of the consensus which was established as the last executed

setInExec

public void setInExec(int inEx)

Sets which consensus is being executed at the moment

Parameters:

inEx - ID of the consensus being executed at the moment

waitForPaxosToFinish

public void waitForPaxosToFinish()

This method blocks until the PaW algorithm is finished

getInExec

public int getInExec()

Gets the ID of the consensus currently beign executed

Returns:

ID of the consensus currently beign executed (if no consensus ir executing, -1 is returned)

requestReceived

public void requestReceived(TOMMessage msg)

This method is invoked by the communication system to deliver a request. It assumes that the communication system delivers the message in FIFO order.

Specified by:

requestReceived in interface RequestReceiver

Parameters:

msg - The request being received

run

public void run()

This is the main code for this thread. It basically waits until this replica becomes the leader, and when so, proposes a value to the other acceptors

Specified by:

run in interface java.lang.Runnable

Overrides:

run in class java.lang.Thread

decided

public void decided(Consensus cons)

Called by the current consensus's execution, to notify the TOM layer that a value was decided

Parameters:

cons - The decided consensus

checkProposedValue

public TOMMessage[] checkProposedValue(byte[] proposedValue,
                              boolean addToClientManager)

Verify if the value being proposed for a round is valid. It verifies the client signature of all batch requests. TODO: verify timestamps and nonces

Parameters:

proposedValue - the value being proposed

Returns:

Valid messages contained in the proposed value

forwardRequestToLeader

public void forwardRequestToLeader(TOMMessage request)

isRetrievingState

public boolean isRetrievingState()

setNoExec

public void setNoExec()

processOutOfContext

public void processOutOfContext()

getStateManager

public StateManager getStateManager()

getLCManager

public LCManager getLCManager()

triggerTimeout

public void triggerTimeout(java.util.List<TOMMessage> requestList)

This method is called when there is a timeout and the request has already been forwarded to the leader

Parameters:

requestList - List of requests that the replica wanted to order but didn't manage to

deliverTimeoutRequest

public void deliverTimeoutRequest(LCMessage msg)

This method is called by the MessageHandler each time it received messages related to the leader change

Parameters:

msg - Message received from the other replica

resumeLC

public void resumeLC()