com.tangosol.net
Class LoadBalancer

java.lang.Object
  com.tangosol.util.Base
      com.tangosol.net.LoadBalancer

All Implemented Interfaces:

Runnable

public class LoadBalancer
extends Base
implements Runnable

A non-sticky HTTP load-balancer.

Version:

1.0, 2002-07-29

Author:

Cameron Purdy

Nested Class Summary

static class	LoadBalancer.AddressPort An AddressPort is an immutable combination of an IP address and a port number.
static class	LoadBalancer.Queue A Queue is used to effeciently queue up items for daemon threads to work on.
class	LoadBalancer.RequestHandler A RequestHandler is a daemon thread that processes a request from a queue.
class	LoadBalancer.ResponseHandler A ResponseHandler is a daemon thread that processes an outgoing response from a destination server.
static class	LoadBalancer.SocketHandler A SocketHandler is an abstract daemon thread.

Field Summary

protected LoadBalancer.AddressPort[]	m_aAddrPortDest The AddressPort combinations that the load balancer will balance to.
protected LoadBalancer.AddressPort	m_addrportHost The AddressPort combination that the load balancer will listen on.
protected boolean	m_fRoundRobin Toggles between random and round-robin load balancing.
protected int	m_iNextDestination Round-robin index.
protected List	m_listHandler The list of RequestHandler daemons.
protected Properties	m_propOptions The optional settings that the load balancer will use.
protected LoadBalancer.Queue	m_queue The queue of pending requests.
protected Random	m_random Random number generator.
protected Thread	m_threadRunning The Thread that the load balancer is started on.

Constructor Summary

LoadBalancer(LoadBalancer.AddressPort addrportHost, LoadBalancer.AddressPort[] aAddrPortDest, Properties propOptions)
Instantiate a LoadBalancer object that will listen on a host address/port and redirect requests to destination addresses/ports.

Method Summary

LoadBalancer.AddressPort	getDestination(int i) Determine one of the AddressPort combinations that the load balancer balances requests to.
int	getDestinationCount() Determine the number of AddressPort combinations that the load balancer balances requests to.
LoadBalancer.AddressPort	getHost() Determine the AddressPort that the load balancer listens on.
protected LoadBalancer.AddressPort	getNextDestination() Determine the next AddressPort combination to route to.
Socket	getNextDestinationSocket() Open a socket to route to.
boolean	getProperty(String sName, boolean fDefault) Determine the value of a boolean option.
int	getProperty(String sName, int nDefault) Determine the value of an integer option.
String	getProperty(String sName, String sDefault) Determine the value of a String option.
protected LoadBalancer.Queue	getQueue() Determine the Queue that Socket connections are placed into.
protected LoadBalancer.AddressPort	getRandomDestination() Determine a random AddressPort combination to route to.
protected LoadBalancer.AddressPort	getRoundRobinDestination() Using a round-robin algorithm, determine the next AddressPort combination to route to.
protected LoadBalancer.Queue	instantiateQueue() Factory method: Create a queue.
protected LoadBalancer.RequestHandler	instantiateRequestHandler(LoadBalancer.Queue queue) Factory method: Create a RequestHandler.
protected LoadBalancer.ResponseHandler	instantiateResponseHandler(LoadBalancer.RequestHandler daemonRequest) Factory method: Create a ResponseHandler.
static void	main(String[] asArgs) Command-line capability to start the load balancer.
protected static String	parseThreadExtension(Daemon daemon) Parse the extension glued onto the end of a daemon's thread's name.
void	run() Start the LoadBalancer.
static void	showInstructions() Display the instructions for the command-line utility.

Field Detail

m_addrportHost

protected LoadBalancer.AddressPort m_addrportHost

The AddressPort combination that the load balancer will listen on.

m_aAddrPortDest

protected LoadBalancer.AddressPort[] m_aAddrPortDest

The AddressPort combinations that the load balancer will balance to.

m_propOptions

protected Properties m_propOptions

The optional settings that the load balancer will use.

m_threadRunning

protected Thread m_threadRunning

The Thread that the load balancer is started on.

m_queue

protected LoadBalancer.Queue m_queue

The queue of pending requests.

m_listHandler

protected List m_listHandler

The list of RequestHandler daemons.

m_fRoundRobin

protected boolean m_fRoundRobin

Toggles between random and round-robin load balancing.

m_random

protected Random m_random

Random number generator.

m_iNextDestination

protected int m_iNextDestination

Round-robin index.

Constructor Detail

LoadBalancer

public LoadBalancer(LoadBalancer.AddressPort addrportHost,
                    LoadBalancer.AddressPort[] aAddrPortDest,
                    Properties propOptions)

Instantiate a LoadBalancer object that will listen on a host address/port and redirect requests to destination addresses/ports.

Parameters:

addrportHost - the AddressPort combination for this host

aAddrPortDest - the array of AddressPort combinations that requests will be sent to

Method Detail

main

public static void main(String[] asArgs)

Command-line capability to start the load balancer.

showInstructions

public static void showInstructions()

Display the instructions for the command-line utility.

run

public void run()

Start the LoadBalancer.

Specified by:

run in interface Runnable

getHost

public LoadBalancer.AddressPort getHost()

Determine the AddressPort that the load balancer listens on.

Returns:

the AddressPort that the load balancer listens on

getDestinationCount

public int getDestinationCount()

Determine the number of AddressPort combinations that the load balancer balances requests to.

getDestination

public LoadBalancer.AddressPort getDestination(int i)

Determine one of the AddressPort combinations that the load balancer balances requests to. (Indexed property "Destination".)

Parameters:

i - an index in the range 0 < i < getDesinationCount()

Returns:

the AddressPort that the load balancer listens on

getNextDestinationSocket

public Socket getNextDestinationSocket()

Open a socket to route to.

Returns:

the next available Socket to route a request to

getNextDestination

protected LoadBalancer.AddressPort getNextDestination()

Determine the next AddressPort combination to route to.

Returns:

the next AddressPort combination to route a request to

getRandomDestination

protected LoadBalancer.AddressPort getRandomDestination()

Determine a random AddressPort combination to route to.

Returns:

a random AddressPort combination to route a request to

getRoundRobinDestination

protected LoadBalancer.AddressPort getRoundRobinDestination()

Using a round-robin algorithm, determine the next AddressPort combination to route to.

Returns:

the next AddressPort combination to route a request to

getQueue

protected LoadBalancer.Queue getQueue()

Determine the Queue that Socket connections are placed into.

Returns:

the Queue of Socket objects that have been accepted

getProperty

public String getProperty(String sName,
                          String sDefault)

Determine the value of a String option.

Parameters:

sName - the property name that specifies the option to look up

sDefault - the default option value to use if the option is not set

Returns:

the value of the specified option, or the passed default value if the option is not set

getProperty

public int getProperty(String sName,
                       int nDefault)

Determine the value of an integer option.

Parameters:

sName - the property name that specifies the option to look up

nDefault - the default option value to use if the option is not set

Returns:

the value of the specified option, or the passed default value if the option is not set

getProperty

public boolean getProperty(String sName,
                           boolean fDefault)

Determine the value of a boolean option.

Parameters:

sName - the property name that specifies the option to look up

fDefault - the default option value to use if the option is not set

Returns:

the value of the specified option, or the passed default value if the option is not set

parseThreadExtension

protected static String parseThreadExtension(Daemon daemon)

Parse the extension glued onto the end of a daemon's thread's name.

Parameters:

daemon - a Daemon object

Returns:

the extension glued onto the end of a daemon's thread's name

instantiateQueue

protected LoadBalancer.Queue instantiateQueue()

Factory method: Create a queue.

Returns:

a Queue instance

instantiateRequestHandler

protected LoadBalancer.RequestHandler instantiateRequestHandler(LoadBalancer.Queue queue)

Factory method: Create a RequestHandler.

Parameters:

queue - a Queue of Socket objects

Returns:

a RequestHandler instance

instantiateResponseHandler

protected LoadBalancer.ResponseHandler instantiateResponseHandler(LoadBalancer.RequestHandler daemonRequest)

Factory method: Create a ResponseHandler.

Parameters:

daemonRequest - the RequestHandler that the ResponseHandler will belong to

Returns:

a ResponseHandler instance