com.bigdata.ganglia

Class GangliaState

java.lang.Object

com.bigdata.ganglia.GangliaState

All Implemented Interfaces:

IGangliaState

public class GangliaState
extends Object
implements IGangliaState

The metadata and metric state for a ganglia service, including the metadata for all known metrics and the metrics for all known metrics on all known hosts.

Constructor Summary

Constructors

Constructor and Description
GangliaState(String hostName, IGangliaMetadataFactory metadataFactory)

Method Summary

Methods

Modifier and Type	Method and Description
void	deleteHost(String hostName) Drop counters for the named host.
String	getHostName() Return the name of this host.
String[]	getKnownHosts() Return a snapshot of the known hosts.
IGangliaMetadataMessage	getMetadata(String metricName) Return the metadata for the given metric.
IGangliaMetadataFactory	getMetadataFactory() The factory used to create declarations for new metrics and resolve received declarations to objects with a richer behavior (such as value translation and scaling).
TimestampMetricValue	getMetric(String hostName, String metricName) Return current TimestampMetricValue of metric on host (thread-safe).
Iterator<TimestampMetricValue>	iterator(String hostName) Return an iterator which will visit all timestamped metrics for the specified host.
void	purgeOldHostsAndMetrics(int dmax) Purge all metrics for any host whose heartbeat has not been updated in at the last dmax seconds and any counter which has not been updated within its dmax seconds.
IGangliaMetadataMessage	putIfAbsent(IGangliaMetadataMessage decl) Atomically declare/resolve the metadata for a metric (thread-safe).
void	reset() Reset the soft state, clearing metadata declarations and metric values for all hosts.

Methods inherited from class java.lang.Object

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

Constructor Detail

GangliaState

public GangliaState(String hostName,
            IGangliaMetadataFactory metadataFactory)

Parameters:

hostName - The name of this host.

metadataFactory - The factory used to create declarations for new metrics.

Method Detail

getHostName

public String getHostName()

Description copied from interface: IGangliaState

Return the name of this host.

Specified by:

getHostName in interface IGangliaState

getMetadataFactory

public IGangliaMetadataFactory getMetadataFactory()

The factory used to create declarations for new metrics and resolve received declarations to objects with a richer behavior (such as value translation and scaling).

getKnownHosts

public String[] getKnownHosts()

Description copied from interface: IGangliaState

Return a snapshot of the known hosts.

Specified by:

getKnownHosts in interface IGangliaState

Returns:

The names of the known hosts and never null.

iterator

public Iterator<TimestampMetricValue> iterator(String hostName)

Description copied from interface: IGangliaState

Return an iterator which will visit all timestamped metrics for the specified host.

Specified by:

iterator in interface IGangliaState

Parameters:

hostName - The host name.

Returns:

The iterator and never null.

getMetadata

public IGangliaMetadataMessage getMetadata(String metricName)

Description copied from interface: IGangliaState

Return the metadata for the given metric.

Specified by:

getMetadata in interface IGangliaState

Parameters:

metricName - The metric name (as it appears in ganglia messages).

Returns:

The metadata for that metric iff it is a known metric and otherwise null.

putIfAbsent

public IGangliaMetadataMessage putIfAbsent(IGangliaMetadataMessage decl)

Atomically declare/resolve the metadata for a metric (thread-safe).

Parameters:

decl - The declaration.

Returns:

Either decl, a version of the declaration which was resolved by the IGangliaMetadataFactory.resolve(IGangliaMetadataMessage), or the pre-existing declaration for the same metric.

getMetric

public TimestampMetricValue getMetric(String hostName,
                             String metricName)

Description copied from interface: IGangliaState

Return current TimestampMetricValue of metric on host (thread-safe).

If an IGangliaMetadataMessage is declared for that name, then either the pre-existing TimestampMetricValue will be returned -or- a new TimestampMetricValue will be atomically created and returned.

Otherwise, this method will return null since it lacks the necessary information to create an IGangliaMetadataMessage by itself.

Specified by:

getMetric in interface IGangliaState

Parameters:

hostName - The name of the host.

metricName - The name of the metric.

Returns:

The current value of the metric on that host -or- null if there is no IGangliaMetadataMessage for that metric.

purgeOldHostsAndMetrics

public void purgeOldHostsAndMetrics(int dmax)

Purge all metrics for any host whose heartbeat has not been updated in at the last dmax seconds and any counter which has not been updated within its dmax seconds.

Note: This method should be invoked periodically to age out hosts and metrics which have not reported in for a long time.

Parameters:

dmax - The global DMax value.

deleteHost

public void deleteHost(String hostName)

Drop counters for the named host.

Note:There may be some interactions if another thread is currently in the middle of adding a counter for the host. What can happen is that the other thread gets the counters for the host and then returns the TMV for the metric while this method concurrently deletes the entry for the host from knownHosts. This would mean that the other thread has returned a TMV entry which is not going to remain visible. If there is a problem, it will be related to what is then done with that TMV entry.

Parameters:

hostName - The host name.

reset

public void reset()

Reset the soft state, clearing metadata declarations and metric values for all hosts.