com.bigdata.rdf.sail.webapp.lbs.policy.counters

Class CountersLBSPolicy

java.lang.Object

com.bigdata.rdf.sail.webapp.lbs.AbstractLBSPolicy

com.bigdata.rdf.sail.webapp.lbs.AbstractHostLBSPolicy

com.bigdata.rdf.sail.webapp.lbs.policy.counters.CountersLBSPolicy

All Implemented Interfaces:

QuorumListener, IHALoadBalancerPolicy, IHAPolicyLifeCycle, Serializable

public class CountersLBSPolicy
extends AbstractHostLBSPolicy

Stochastically proxy the request to the services based on their load.

Note: This IHALoadBalancerPolicy has a dependency on the PlatformStatsPlugIn. The plugin must be setup to publish out performance counters using the CounterServlet. This policy will periodically query the different HAJournalServer instances to obtain their current metrics using that CountersServlet.

This is not as efficient as using ganglia. However, this plugin creates fewer dependencies and is significantly easier to administer if the network does not support UDP multicast.

Author:

Bryan Thompson

See Also:

Serialized Form

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static interface	CountersLBSPolicy.InitParams Servlet init-param values understood by the CountersLBSPolicy.

Field Summary

Fields inherited from class com.bigdata.rdf.sail.webapp.lbs.AbstractLBSPolicy

journalRef, serviceIDRef, serviceTableRef

Constructor Summary

Constructors

Constructor and Description
CountersLBSPolicy()

Method Summary

Methods

Modifier and Type	Method and Description
void	destroy() Destroy the policy (stop any asynchronous processing, release any resources).
protected String	getDefaultScoringRule() Return the name of the IHostScoringRule that provides default value for the AbstractHostLBSPolicy.InitParams.HOST_SCORING_RULE configuration parameter.
protected Map<String,IHostMetrics>	getHostReportForKnownServices(IHostScoringRule scoringRule, ServiceScore[] serviceScores) Return a map from the known canonical hostnames (as self-reported by the services) of the joined services to the IHostMetricss for those hosts.
void	init(javax.servlet.ServletConfig servletConfig, IIndexManager indexManager) Initialize the policy.
protected void	toString(StringBuilder sb) Extension hook for AbstractLBSPolicy.toString() - implementation MUST NOT block.

Methods inherited from class com.bigdata.rdf.sail.webapp.lbs.AbstractHostLBSPolicy

conditionallyForwardReadRequest, conditionallyUpdateServiceTable, getHostDiscoveryDelay, getReaderURI, setLocalForwardThreshold, updateHostTable, updateServiceTable

Methods inherited from class com.bigdata.rdf.sail.webapp.lbs.AbstractLBSPolicy

getJournal, getLeaderURI, getLocalServiceScore, getServiceScoreForHostname, notify, service, toString

Methods inherited from class java.lang.Object

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

Constructor Detail

CountersLBSPolicy

public CountersLBSPolicy()

Method Detail

toString

protected void toString(StringBuilder sb)

Description copied from class: AbstractLBSPolicy

Extension hook for AbstractLBSPolicy.toString() - implementation MUST NOT block.

Overrides:

toString in class AbstractHostLBSPolicy

Parameters:

sb - Buffer where you can write additional state.

init

public void init(javax.servlet.ServletConfig servletConfig,
        IIndexManager indexManager)
          throws javax.servlet.ServletException

Description copied from interface: IHAPolicyLifeCycle

Initialize the policy.

Specified by:

init in interface IHAPolicyLifeCycle

Overrides:

init in class AbstractHostLBSPolicy

Throws:

javax.servlet.ServletException

destroy

public void destroy()

Description copied from interface: IHAPolicyLifeCycle

Destroy the policy (stop any asynchronous processing, release any resources).

Specified by:

destroy in interface IHAPolicyLifeCycle

Overrides:

destroy in class AbstractHostLBSPolicy

getHostReportForKnownServices

protected Map<String,IHostMetrics> getHostReportForKnownServices(IHostScoringRule scoringRule,
                                                     ServiceScore[] serviceScores)

Return a map from the known canonical hostnames (as self-reported by the services) of the joined services to the IHostMetricss for those hosts.

This implementation issues HTTP requests to obtain the up to date performance counters for each host on which a service is known to be running.

Specified by:

getHostReportForKnownServices in class AbstractHostLBSPolicy

Parameters:

scoringRule - The IHostScoringRule to be applied.

serviceScores - The set of known services.

Returns:

The map. TODO If there is more than one service on the same host, then we will have one record per host, not per service. This means that we can not support JVM specific metrics, such as GC time. This could be fixed if the map was indexed by Service UUID and the host metrics were combined into the map once for each service.

getDefaultScoringRule

protected String getDefaultScoringRule()

Description copied from class: AbstractHostLBSPolicy

Return the name of the IHostScoringRule that provides default value for the AbstractHostLBSPolicy.InitParams.HOST_SCORING_RULE configuration parameter.

Note: The policy needs to be specific to the LBS implementation since the names of the host metrics depend on the system that is being used to collect and report them.

Specified by:

getDefaultScoringRule in class AbstractHostLBSPolicy