org.hawkular.inventory.base

Class Traversal<BE,E extends AbstractElement<?,?>>

java.lang.Object

org.hawkular.inventory.base.Traversal<BE,E>

Direct Known Subclasses:

BaseData.Multiple, BaseData.Read, BaseData.ReadWrite, BaseData.Single, BaseEnvironments.Multiple, BaseEnvironments.Read, BaseEnvironments.ReadContained, BaseEnvironments.ReadWrite, BaseEnvironments.Single, BaseFeeds.Multiple, BaseFeeds.Read, BaseFeeds.ReadContained, BaseFeeds.ReadWrite, BaseFeeds.Single, BaseMetrics.Multiple, BaseMetrics.Read, BaseMetrics.ReadAssociate, BaseMetrics.ReadContained, BaseMetrics.ReadWrite, BaseMetrics.Single, BaseMetricTypes.Multiple, BaseMetricTypes.Read, BaseMetricTypes.ReadAssociate, BaseMetricTypes.ReadContained, BaseMetricTypes.ReadWrite, BaseMetricTypes.Single, BaseRelationships.Multiple, BaseRelationships.Read, BaseRelationships.ReadWrite, BaseRelationships.Single, BaseResources.Multiple, BaseResources.Read, BaseResources.ReadContained, BaseResources.ReadWrite, BaseResources.Single, BaseResourceTypes.Multiple, BaseResourceTypes.Read, BaseResourceTypes.ReadContained, BaseResourceTypes.ReadWrite, BaseResourceTypes.Single, BaseTenants.Multiple, BaseTenants.Read, BaseTenants.ReadContained, BaseTenants.ReadWrite, BaseTenants.Single

public abstract class Traversal<BE,E extends AbstractElement<?,?>>
extends Object

A base class for all the inventory traversal interfaces. Contains only a minimal set of helper methods and holds the traversal context.

Since:

0.1.0

Author:

Lukas Krejci

Field Summary

Fields

Modifier and Type	Field and Description
protected TraversalContext<BE,E>	context

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	Traversal(TraversalContext<BE,E> context)

Method Summary

Modifier and Type	Method and Description
protected BE	getSingle(Query query, Class<? extends Entity<?,?>> entityType) A helper method to retrieve a single result from the query or throw an exception if the query yields no results.
protected boolean	isApplicable(AbstractElement<?,?> result) If the inventory configuration provided a ResultFilter, this calls it to tell whether provided element is applicable.
protected <R> R	mutating(Util.PotentiallyCommittingPayload<R> payload) Runs the payload in transaction.
protected <R> R	readOnly(Supplier<R> payload) A "shortcut" method for executing read-only payloads in transaction.

Methods inherited from class java.lang.Object

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

Field Detail

context

protected final TraversalContext<BE,E extends AbstractElement<?,?>> context

Constructor Detail

Traversal

protected Traversal(TraversalContext<BE,E> context)

Method Detail

isApplicable

protected boolean isApplicable(AbstractElement<?,?> result)

If the inventory configuration provided a ResultFilter, this calls it to tell whether provided element is applicable. If the result filter is not provided by the configuration, true will always be returned.

Parameters:

result - the potential result to be checked for applicability in the result set

Returns:

true or false (!!!)

getSingle

protected BE getSingle(Query query,
                       Class<? extends Entity<?,?>> entityType)

A helper method to retrieve a single result from the query or throw an exception if the query yields no results.

Parameters:

query - the query to run

entityType - the expected type of the entity (used only for error reporting)

Returns:

the single result

Throws:

EntityNotFoundException - if the query doesn't return any results

mutating

protected <R> R mutating(Util.PotentiallyCommittingPayload<R> payload)

Runs the payload in transaction. It is the payload's responsibility to commit the transaction at some point during its execution. If the payload throws an exception the transaction is automatically rolled back and the exception rethrown.

WARNING: the payload might be called multiple times if the transaction it runs within fails. It is therefore dangerous to keep any mutable state outside of the payload function that the function depends on.

Type Parameters:

R - the return type

Parameters:

payload - the payload to execute in transaction

Returns:

the return value provided by the payload

readOnly

protected <R> R readOnly(Supplier<R> payload)

A "shortcut" method for executing read-only payloads in transaction. Such payloads don't have to have a reference to the transaction in which they're being executed.

WARNING: the payload might be called multiple times if the transaction it runs within fails. It is therefore dangerous to keep any mutable state outside of the payload function that the function depends on.

Type Parameters:

R - the type of the return value

Parameters:

payload - the read-only payload to execute

Returns:

the return value provided by the payload