com.sleepycat.je.rep.arbiter.impl

Class ArbiterImpl

java.lang.Object

java.lang.Thread

com.sleepycat.je.utilint.StoppableThread

com.sleepycat.je.rep.arbiter.impl.ArbiterImpl

All Implemented Interfaces:

Runnable

public class ArbiterImpl
extends StoppableThread

The implementation of the Arbiter. The Arbiter is a participant in elections and may acknowledge transaction commits.

The Arbiter persists the Arbiter's replication group node identifier and the highest commit VLSN that has been acknowledged. Currently the Feeder sends commit acknowledgment requests to the Arbiter if the replication factor is two and the other Rep node is not available (RepImpl.preLogCommitHook).

The VLSN is used in response to an election promise request. The priority of the response is lower than a RepNode. This allows the RepNode to be selected if the VLSN is equal. An Arbiter may not "win" an election. If the Arbiter's VLSN is the highest in the election, the election result is ignored. A NULL nodeid in a promise response is used to identify a promise response is from an Arbiter.

Two pieces of information are persisted by the Arbiter. The replication group node identifier is persisted because this information is located in the group database and the Arbiter does not have a copy of the group database. The other is the high VLSN of a Arbiter ACKed commit.

In the future, the algorithm could be changed to request commit acknowledgments when the replication factor is greater than two. This would allow for better write availability when the replication factor is an even number.

Nested Class Summary

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

Thread.State, Thread.UncaughtExceptionHandler

Field Summary

Fields inherited from class com.sleepycat.je.utilint.StoppableThread

envImpl

Fields inherited from class java.lang.Thread

MAX_PRIORITY, MIN_PRIORITY, NORM_PRIORITY

Constructor Summary

Constructors

Constructor and Description
ArbiterImpl(File arbiterHome, RepImpl repImpl) The Arbiter implementation.

Method Summary

Modifier and Type	Method and Description
ReplicatedEnvironment.State	getArbState()
Elections	getElections()
String	getHostName() Returns the hostname associated with this node.
Logger	getLogger()
int	getPort() Returns the port used by the replication node.
RepUtils.ExceptionAwareCountDownLatch	getReadyLatch()
boolean	isShutdown()
StatGroup	loadStats(StatsConfig config)
void	refreshHelperHosts()
void	resetReadyLatch(Exception exception)
void	run()
void	runArbiter()
void	setState(ReplicatedEnvironment.State state)
void	shutdown()

Methods inherited from class com.sleepycat.je.utilint.StoppableThread

cleanup, getSavedShutdownException, getTotalCpuTime, getTotalUserTime, handleUncaughtException, initiateSoftShutdown, saveShutdownException, shutdownDone, shutdownThread

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

Constructor Detail

ArbiterImpl

public ArbiterImpl(File arbiterHome,
                   RepImpl repImpl)
            throws EnvironmentNotFoundException,
                   EnvironmentLockedException,
                   DatabaseException

The Arbiter implementation. Uses the following replication parameters: RepParams.GROUP_NAME The replication group name. RepParams.ENV_UNKNOWN_STATE_TIMEOUT Timeout used for being in the unknown state. RepParams.NODE_HOST_PORT The host name and port associated with this node.

Parameters:

arbiterHome - - Arbiter home directory.

repImpl - - RepImpl

Throws:

EnvironmentNotFoundException

EnvironmentLockedException

DatabaseException

Method Detail

loadStats

public StatGroup loadStats(StatsConfig config)

runArbiter

public void runArbiter()

run

public void run()

Specified by:

run in interface Runnable

Overrides:

run in class Thread

getArbState

public ReplicatedEnvironment.State getArbState()

getElections

public Elections getElections()

setState

public void setState(ReplicatedEnvironment.State state)

shutdown

public void shutdown()

refreshHelperHosts

public void refreshHelperHosts()

isShutdown

public boolean isShutdown()

Overrides:

isShutdown in class StoppableThread

getLogger

public Logger getLogger()

Specified by:

getLogger in class StoppableThread

Returns:

a logger to use when logging uncaught exceptions.

getReadyLatch

public RepUtils.ExceptionAwareCountDownLatch getReadyLatch()

resetReadyLatch

public void resetReadyLatch(Exception exception)

getHostName

public String getHostName()

Returns the hostname associated with this node.

Returns:

the hostname

getPort

public int getPort()

Returns the port used by the replication node.

Returns:

the port number