org.jboss.ha.framework.interfaces: public class: FirstAvailable

org.jboss.ha.framework.interfaces
public class: FirstAvailable [javadoc | source]

java.lang.Object
   org.jboss.ha.framework.interfaces.FirstAvailable

All Implemented Interfaces:
LoadBalancePolicy

LoadBalancingPolicy implementation that always favor the first available target i.e. no load balancing occurs. Nevertheless, the first target is randomly selected. This does not mean that fail-over will not occur if the first member in the list dies. In this case, fail-over will occur, and a new target will become the first member and invocation will continously be invoked on the same new target until its death. Each proxy using this policy will elect its own prefered target: the target is not shared accross the proxy family (for this behaviour please take a look at FirstAvailableIdenticalAllProxies)

Also see:

org.jboss.ha.framework.interfaces.LoadBalancePolicy

Revisions:

2002/08/24: Sacha Labourey

Use the target repository
First choice is randomly selected to distribute the initial load
When the list of targets change, we try to keep using the same previously elected target node if it still exists. Previously, we were working with the position id of the target node, thus if the list order changed, we were switching to another node while our prefered node was still up

author: < - a href="mailto:bill@burkecentral.com">Bill Burke.

author: < - a href="mailto:sacha.labourey@cogito-info.ch">Sacha Labourey.

version: $ - Revision: 56192 $

Field Summary
protected transient Object	electedTarget

Method from org.jboss.ha.framework.interfaces.FirstAvailable Summary:
chooseTarget, chooseTarget, init

Methods from java.lang.Object:
equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method from org.jboss.ha.framework.interfaces.FirstAvailable Detail:
public Object chooseTarget(FamilyClusterInfo clusterFamily) { return chooseTarget(clusterFamily, null); }
public Object chooseTarget(FamilyClusterInfo clusterFamily, Invocation routingDecision) { List targets = clusterFamily.getTargets (); if (targets.size () == 0) return null; if ( (this.electedTarget != null) && targets.contains (this.electedTarget) ) { return this.electedTarget; } else { int cursor = RandomRobin.localRandomizer.nextInt(targets.size()); this.electedTarget = targets.get(cursor); return this.electedTarget; } }
public void init(HARMIClient father) { // Static -------------------------------------------------------- // Constructors -------------------------------------------------- // Public -------------------------------------------------------- // do not use the HARMIClient in this policy }

Method from org.jboss.ha.framework.interfaces.FirstAvailable Detail:

 public Object chooseTarget(FamilyClusterInfo clusterFamily) {
      return chooseTarget(clusterFamily, null);
}

 public Object chooseTarget(FamilyClusterInfo clusterFamily,
    Invocation routingDecision) {
      List targets = clusterFamily.getTargets ();
      if (targets.size () == 0)
         return null;
      if ( (this.electedTarget != null) && targets.contains (this.electedTarget) )
      {
         return this.electedTarget;
      }
      else
      {
         int cursor = RandomRobin.localRandomizer.nextInt(targets.size());
         this.electedTarget = targets.get(cursor);
         return this.electedTarget;
      }
}

 public  void init(HARMIClient father) {
   
   // Static --------------------------------------------------------
   // Constructors --------------------------------------------------
    // Public --------------------------------------------------------
      // do not use the HARMIClient in this policy
}