ParkNPark.client
Class FaultTolerantClientManager.BackgroundThread

java.lang.Object
  java.lang.Thread
      ParkNPark.client.FaultTolerantClientManager.BackgroundThread

All Implemented Interfaces:

Runnable

Enclosing class:

FaultTolerantClientManager

protected class FaultTolerantClientManager.BackgroundThread
extends Thread

Background thread that performs the following actions in a loop continuously:

1. Recover from a fault on the primary server if one was detected by either this thread or by the main thread
2. Refresh the list of servers from the naming service
3. Poke each server serially and, upon fault detection, remove that server from the list of servers. If that server was the primary server, then enter the fault recovery mode
4. If the current primary server is no longer registered in the naming service, then enter the fault recovery mode
5. Wait for the fault detection timeout time if no faults were detected in the current loop iteration
This permits the server list to remain up-to-date, relevant, and accurate for quick failover. When a fault is detected, the affected server's entry is not used for at least five times the fault detection timeout to give the replication manager ample time to unregister its name if it really is down. This match is performed via IOR so that a faulty server that gets restarted can be used quickly after it becomes available

Nested Class Summary

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

Thread.State, Thread.UncaughtExceptionHandler

Field Summary

protected int	detectionTimeout The fault detection timeout
protected boolean	exit True when we should exit or false when we should not
protected SortedMap<Long,Server>	faultyServers Map of fault detection times to their faulty servers
protected NameService	nameService Our name server instance
protected int	serverIndex The index of the current server in the list of servers

Fields inherited from class java.lang.Thread

MAX_PRIORITY, MIN_PRIORITY, NORM_PRIORITY

Constructor Summary

FaultTolerantClientManager.BackgroundThread(ORB orb, int detectionTimeout)
Creates a new background thread instance

Method Summary

void	beginExit() Tells this thread to gracefully shut down
protected boolean	connectToAnyServer(LogEntry logEntry) Connects to any registered server, which is chosen randomly
protected boolean	findPrimary() Finds the primary server in the List of servers and returns whether or not one was found
protected boolean	initialConnection() Create the initial connection to a server and return whether or not it worked
protected void	processFaultyServers() Maintains the faulty server list and removes them from the current set of servers.
void	run() Background thread's execution

Methods inherited from class java.lang.Thread

activeCount, checkAccess, 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

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

Field Detail

nameService

protected NameService nameService

Our name server instance

serverIndex

protected int serverIndex

The index of the current server in the list of servers

detectionTimeout

protected int detectionTimeout

The fault detection timeout

exit

protected boolean exit

True when we should exit or false when we should not

faultyServers

protected SortedMap<Long,Server> faultyServers

Map of fault detection times to their faulty servers

Constructor Detail

FaultTolerantClientManager.BackgroundThread

public FaultTolerantClientManager.BackgroundThread(ORB orb,
                                                   int detectionTimeout)

Creates a new background thread instance

Parameters:

orb - The ORB to operate with

detectionTimeout - The fault detection timeout to use

Method Detail

beginExit

public void beginExit()

Tells this thread to gracefully shut down

run

public void run()

Background thread's execution

Specified by:

run in interface Runnable

Overrides:

run in class Thread

processFaultyServers

protected void processFaultyServers()

Maintains the faulty server list and removes them from the current set of servers. Faulty servers that have been faulty for more than detectionTimeout * 5 milliseconds are removed from the faulty list

initialConnection

protected boolean initialConnection()

Create the initial connection to a server and return whether or not it worked

Returns:

True if the initial connection exists or false if it does not exist

findPrimary

protected boolean findPrimary()

Finds the primary server in the List of servers and returns whether or not one was found

Returns:

True if the primary server was found or false if it was not

connectToAnyServer

protected boolean connectToAnyServer(LogEntry logEntry)

Connects to any registered server, which is chosen randomly

Parameters:

logEntry - The LogEntry object to write performance data to when not null

Returns:

True when a connection with a server was successfully established or false if a server connection could not be established