org.apache.zookeeper.server.quorum

Class Leader

java.lang.Object

org.apache.zookeeper.server.quorum.LearnerMaster

org.apache.zookeeper.server.quorum.Leader

public class Leader
extends LearnerMaster

This class has the control logic for the Leader.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	Leader.Proposal
static class	Leader.XidRolloverException

Field Summary

Fields

Modifier and Type	Field and Description
static int	ACKEPOCH This message is used by the follow to ack a proposed epoch.
protected Set<Long>	connectingFollowers
protected Set<Long>	electingFollowers
protected boolean	electionFinished
static int	LEADERINFO This message is the first that a follower receives from the leader.
static String	MAX_TIME_TO_WAIT_FOR_EPOCH
protected Leader.Proposal	newLeaderProposal
static int	PROPOSAL This message type is sent by a leader to propose a mutation.
protected boolean	quorumFormed

Constructor Summary

Constructors

Constructor and Description
Leader(QuorumPeer self, LeaderZooKeeperServer zk)

Method Summary

Modifier and Type	Method and Description
void	addLearnerHandler(LearnerHandler learner) Adds peer to the leader.
static QuorumPacket	buildInformAndActivePacket(long zxid, long designatedLeader, byte[] proposalData)
void	commit(long zxid) Create a commit packet and send it to all the members of the quorum
void	commitAndActivate(long zxid, long designatedLeader)
static int	getAckLoggingFrequency()
long	getAndDecrementFollowerCounter() decrement follower count
int	getCurrentTick() the current tick
long	getEpoch() Returns the current epoch of the leader.
long	getEpochToPropose(long sid, long lastAcceptedEpoch) get the first zxid of the next epoch
List<LearnerHandler>	getForwardingFollowers() Returns a copy of the current forwarding follower snapshot
long	getLastProposed() last proposed zxid
List<LearnerHandler>	getLearners() Returns a copy of the current learner snapshot
List<LearnerHandler>	getNonVotingFollowers()
int	getNumPendingSyncs()
List<LearnerHandler>	getObservingLearners() Returns a copy of the current observer snapshot
Iterable<Map<String,Object>>	getObservingLearnersInfo()
static String	getPacketType(int packetType) Get string representation of a given packet type
String	getPeerInfo(long sid)
BufferStats	getProposalStats()
QuorumAuthServer	getQuorumAuthServer()
byte[]	getQuorumVerifierBytes() identifier of current quorum verifier for new leader
long	getQuorumVerifierVersion() version of current quorum verifier
int	getTickOfInitialAckDeadline() next deadline tick marking observer sync (steady state)
int	getTickOfNextAckDeadline() deadline tick marking observer sync (initial)
long	getUptime()
ZKDatabase	getZKDatabase() ZKDatabase
void	inform(Leader.Proposal proposal) Create an inform packet and send it to all observers.
void	informAndActivate(Leader.Proposal proposal, long designatedLeader) Create an inform and activate packet and send it to all observers.
boolean	isQuorumSynced(QuorumVerifier qv) Returns true if a quorum in qv is connected and synced with the leader and false otherwise
void	processAck(long sid, long zxid, SocketAddress followerAddr) Keep a count of acks that are received by the leader for a particular proposal
void	processSync(LearnerSyncRequest r) Process sync requests
Leader.Proposal	propose(Request request) create a proposal and send it out to all the members
void	registerLearnerHandlerBean(LearnerHandler learnerHandler, Socket socket) registers the handler's bean
void	removeLearnerHandler(LearnerHandler peer) Remove the learner from the learner list
void	reportLookingSid(long sid)
void	resetObserverConnectionStats()
void	revalidateSession(QuorumPacket qp, LearnerHandler learnerHandler) handle revalidate packet
void	sendSync(LearnerSyncRequest r) Sends a sync message to the appropriate server
static void	setAckLoggingFrequency(int frequency)
void	setLeadingVoteSet(SyncedLearnerTracker voteSet)
static void	setMaxTimeToWaitForEpoch(int maxTimeToWaitForEpoch)
long	startForwarding(LearnerHandler handler, long lastSeenZxid) lets the leader know that a follower is capable of following and is done syncing
void	submitLearnerRequest(Request si) proxy request from learner to server
int	syncTimeout() time allowed for sync response
void	touch(long sess, int to) mark session as alive
boolean	tryToCommit(Leader.Proposal p, long zxid, SocketAddress followerAddr)
void	unregisterLearnerHandlerBean(LearnerHandler learnerHandler) unregisters the handler's bean
void	waitForEpochAck(long id, StateSummary ss) wait for the leader of the new epoch to be confirmed by followers
void	waitForNewLeaderAck(long sid, long zxid) Process NEWLEADER ack of a given sid and wait until the leader receives sufficient acks.
void	waitForStartup() wait for server to start

Methods inherited from class org.apache.zookeeper.server.quorum.LearnerMaster

getLearnerDiffSyncThrottler, getLearnerSnapSyncThrottler, getMaxConcurrentDiffSyncs, getMaxConcurrentSnapSyncs, setMaxConcurrentDiffSyncs, setMaxConcurrentSnapSyncs

Methods inherited from class java.lang.Object

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

Field Detail

quorumFormed

protected boolean quorumFormed

LEADERINFO

public static final int LEADERINFO

This message is the first that a follower receives from the leader. It has the protocol version and the epoch of the leader.

See Also:

Constant Field Values

ACKEPOCH

public static final int ACKEPOCH

This message is used by the follow to ack a proposed epoch.

See Also:

Constant Field Values

PROPOSAL

public static final int PROPOSAL

This message type is sent by a leader to propose a mutation.

See Also:

Constant Field Values

newLeaderProposal

protected final Leader.Proposal newLeaderProposal

connectingFollowers

protected final Set<Long> connectingFollowers

MAX_TIME_TO_WAIT_FOR_EPOCH

public static final String MAX_TIME_TO_WAIT_FOR_EPOCH

See Also:

Constant Field Values

electingFollowers

protected final Set<Long> electingFollowers

electionFinished

protected boolean electionFinished

Constructor Detail

Leader

public Leader(QuorumPeer self,
              LeaderZooKeeperServer zk)
       throws IOException

Throws:

IOException

Method Detail

setAckLoggingFrequency

public static void setAckLoggingFrequency(int frequency)

getAckLoggingFrequency

public static int getAckLoggingFrequency()

getProposalStats

public BufferStats getProposalStats()

getLearners

public List<LearnerHandler> getLearners()

Returns a copy of the current learner snapshot

getForwardingFollowers

public List<LearnerHandler> getForwardingFollowers()

Returns a copy of the current forwarding follower snapshot

getNonVotingFollowers

public List<LearnerHandler> getNonVotingFollowers()

getObservingLearners

public List<LearnerHandler> getObservingLearners()

Returns a copy of the current observer snapshot

getObservingLearnersInfo

public Iterable<Map<String,Object>> getObservingLearnersInfo()

resetObserverConnectionStats

public void resetObserverConnectionStats()

getNumPendingSyncs

public int getNumPendingSyncs()

addLearnerHandler

public void addLearnerHandler(LearnerHandler learner)

Adds peer to the leader.

Parameters:

learner - instance of learner handle

removeLearnerHandler

public void removeLearnerHandler(LearnerHandler peer)

Remove the learner from the learner list

Parameters:

peer -

isQuorumSynced

public boolean isQuorumSynced(QuorumVerifier qv)

Returns true if a quorum in qv is connected and synced with the leader and false otherwise

Parameters:

qv - is a QuorumVerifier

getUptime

public long getUptime()

tryToCommit

public boolean tryToCommit(Leader.Proposal p,
                           long zxid,
                           SocketAddress followerAddr)

Returns:

True if committed, otherwise false.

processAck

public void processAck(long sid,
                       long zxid,
                       SocketAddress followerAddr)

Keep a count of acks that are received by the leader for a particular proposal

Parameters:

sid - is the id of the server that sent the ack

zxid - is the zxid of the proposal sent out

followerAddr -

commit

public void commit(long zxid)

Create a commit packet and send it to all the members of the quorum

Parameters:

zxid -

commitAndActivate

public void commitAndActivate(long zxid,
                              long designatedLeader)

inform

public void inform(Leader.Proposal proposal)

Create an inform packet and send it to all observers.

buildInformAndActivePacket

public static QuorumPacket buildInformAndActivePacket(long zxid,
                                                      long designatedLeader,
                                                      byte[] proposalData)

informAndActivate

public void informAndActivate(Leader.Proposal proposal,
                              long designatedLeader)

Create an inform and activate packet and send it to all observers.

getLastProposed

public long getLastProposed()

Description copied from class: LearnerMaster

last proposed zxid

Returns:

last proposed zxid

getEpoch

public long getEpoch()

Returns the current epoch of the leader.

propose

public Leader.Proposal propose(Request request)
                        throws Leader.XidRolloverException

create a proposal and send it out to all the members

Parameters:

request -

Returns:

the proposal that is queued to send to all the members

Throws:

Leader.XidRolloverException

processSync

public void processSync(LearnerSyncRequest r)

Process sync requests

Parameters:

r - the request

sendSync

public void sendSync(LearnerSyncRequest r)

Sends a sync message to the appropriate server

startForwarding

public long startForwarding(LearnerHandler handler,
                            long lastSeenZxid)

lets the leader know that a follower is capable of following and is done syncing

Parameters:

handler - handler of the follower

lastSeenZxid - zxid of learner

Returns:

last proposed zxid

waitForStartup

public void waitForStartup()
                    throws InterruptedException

Description copied from class: LearnerMaster

wait for server to start

Throws:

InterruptedException

setMaxTimeToWaitForEpoch

public static void setMaxTimeToWaitForEpoch(int maxTimeToWaitForEpoch)

setLeadingVoteSet

public void setLeadingVoteSet(SyncedLearnerTracker voteSet)

reportLookingSid

public void reportLookingSid(long sid)

getEpochToPropose

public long getEpochToPropose(long sid,
                              long lastAcceptedEpoch)
                       throws InterruptedException,
                              IOException

Description copied from class: LearnerMaster

get the first zxid of the next epoch

Parameters:

sid - learner id

Returns:

the first zxid of the next epoch

Throws:

InterruptedException

IOException

getZKDatabase

public ZKDatabase getZKDatabase()

Description copied from class: LearnerMaster

ZKDatabase

Returns:

ZKDatabase

waitForEpochAck

public void waitForEpochAck(long id,
                            StateSummary ss)
                     throws IOException,
                            InterruptedException

Description copied from class: LearnerMaster

wait for the leader of the new epoch to be confirmed by followers

Parameters:

id - learner id

Throws:

IOException

InterruptedException

waitForNewLeaderAck

public void waitForNewLeaderAck(long sid,
                                long zxid)
                         throws InterruptedException

Process NEWLEADER ack of a given sid and wait until the leader receives sufficient acks.

Parameters:

sid -

zxid - zxid at learner

Throws:

InterruptedException

getPacketType

public static String getPacketType(int packetType)

Get string representation of a given packet type

Parameters:

packetType -

Returns:

string representing the packet type

getCurrentTick

public int getCurrentTick()

Description copied from class: LearnerMaster

the current tick

Returns:

the current tick

syncTimeout

public int syncTimeout()

Description copied from class: LearnerMaster

time allowed for sync response

Returns:

time allowed for sync response

getTickOfNextAckDeadline

public int getTickOfNextAckDeadline()

Description copied from class: LearnerMaster

deadline tick marking observer sync (initial)

Returns:

deadline tick marking observer sync (initial)

getTickOfInitialAckDeadline

public int getTickOfInitialAckDeadline()

Description copied from class: LearnerMaster

next deadline tick marking observer sync (steady state)

Returns:

next deadline tick marking observer sync (steady state)

getAndDecrementFollowerCounter

public long getAndDecrementFollowerCounter()

Description copied from class: LearnerMaster

decrement follower count

Returns:

previous follower count

touch

public void touch(long sess,
                  int to)

Description copied from class: LearnerMaster

mark session as alive

Parameters:

sess - session id

to - timeout

submitLearnerRequest

public void submitLearnerRequest(Request si)

Description copied from class: LearnerMaster

proxy request from learner to server

Parameters:

si - request

getQuorumVerifierVersion

public long getQuorumVerifierVersion()

Description copied from class: LearnerMaster

version of current quorum verifier

Returns:

version of current quorum verifier

getPeerInfo

public String getPeerInfo(long sid)

Parameters:

sid - server id

Returns:

server information in the view

getQuorumVerifierBytes

public byte[] getQuorumVerifierBytes()

Description copied from class: LearnerMaster

identifier of current quorum verifier for new leader

Returns:

identifier of current quorum verifier for new leader

getQuorumAuthServer

public QuorumAuthServer getQuorumAuthServer()

revalidateSession

public void revalidateSession(QuorumPacket qp,
                              LearnerHandler learnerHandler)
                       throws IOException

Description copied from class: LearnerMaster

handle revalidate packet

Parameters:

qp - session packet

learnerHandler - learner

Throws:

IOException

registerLearnerHandlerBean

public void registerLearnerHandlerBean(LearnerHandler learnerHandler,
                                       Socket socket)

Description copied from class: LearnerMaster

registers the handler's bean

Parameters:

learnerHandler - handler

socket - connection to learner

unregisterLearnerHandlerBean

public void unregisterLearnerHandlerBean(LearnerHandler learnerHandler)

Description copied from class: LearnerMaster

unregisters the handler's bean

Parameters:

learnerHandler - handler