com.atlassian.messagequeue.internal.scheduler

Class SchedulerMessageRunnerService

java.lang.Object

com.atlassian.messagequeue.internal.scheduler.SchedulerMessageRunnerService

All Implemented Interfaces:

MessageRunnerService

public class SchedulerMessageRunnerService
extends Object
implements MessageRunnerService

An implementation of MessageRunnerService that is backed by the SchedulerService that provides at-least-once delivery semantics.

When a Message is passed to addMessage(Message), a job is scheduled to run as-soon-as-possible to process this Message.

When the processing of a Message fails (i.e. MessageRunner.processMessage(MessageContext) throws an exception), the Message will be delivered up to a total of maxDeliveryCount times at intervals of deliveryIntervalMillis milliseconds until it is processed successfully. The values of these parameters can be specified when constructing an instance of this class.

The processing time of a Message can exceed deliveryIntervalMillis. When this happens, re-delivery of the Message is skipped. Another re-delivery will be attempted after deliveryIntervalMillis milliseconds. Therefore, only one MessageRunner will be processing a particular Message at any given time.

The processing time of a Message is not currently limited. However long processing times are discouraged.

If a Message fails to be processed successfully after maxDeliveryCount attempts, a RunDetails instance is recorded to note this occurence. A collection of RunDetails can be viewed as a dead letter queue.

When constructing an instance of this class with a SchedulerService implementation that supports persistence of jobs, all Messages passed to addMessage(Message) will be persisted.

To properly initialise an instance of this service, a client must call init() after constructing an instance (or else ensure the dependency injection framework will automatically invoke methods annotated with @PostConstruct).

To properly dispose of an instance of this service, a client must call shutdown() (or else ensure the dependency injection framework will automatically invoke methods annotated with @PreDestroy).

Constructor Summary

Constructors

Constructor and Description
SchedulerMessageRunnerService(com.atlassian.scheduler.SchedulerService schedulerService, MessageRunnerRegistryHelper messageRunnerRegistryHelper, MessageInformationService messageInformationService, NestedMessageSerializer nestedMessageSerializer) Constructs a new instance of SchedulerMessageRunnerService.
SchedulerMessageRunnerService(com.atlassian.scheduler.SchedulerService schedulerService, MessageRunnerRegistryHelper messageRunnerRegistryHelper, MessageInformationService messageInformationService, NestedMessageSerializer nestedMessageSerializer, long deliveryIntervalMillis, int maxDeliveryCount) Constructs a new instance of SchedulerMessageRunnerService.

Method Summary

Modifier and Type	Method and Description
void	addMessage(Message message) Adds a message that will be executed at some future point.
protected Date	getFirstDeliveryTime() Returns message first delivery time.
void	init() Initialises this instance.
void	shutdown() Shuts down this instance.

Methods inherited from class java.lang.Object

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

Constructor Detail

SchedulerMessageRunnerService

public SchedulerMessageRunnerService(com.atlassian.scheduler.SchedulerService schedulerService,
                                     MessageRunnerRegistryHelper messageRunnerRegistryHelper,
                                     MessageInformationService messageInformationService,
                                     NestedMessageSerializer nestedMessageSerializer)

Constructs a new instance of SchedulerMessageRunnerService.

Parameters:

schedulerService - the scheduler service

messageRunnerRegistryHelper - the message runner registry helper

messageInformationService - message information service

nestedMessageSerializer - the nested message serializer

SchedulerMessageRunnerService

public SchedulerMessageRunnerService(com.atlassian.scheduler.SchedulerService schedulerService,
                                     MessageRunnerRegistryHelper messageRunnerRegistryHelper,
                                     MessageInformationService messageInformationService,
                                     NestedMessageSerializer nestedMessageSerializer,
                                     long deliveryIntervalMillis,
                                     int maxDeliveryCount)

Constructs a new instance of SchedulerMessageRunnerService.

Parameters:

schedulerService - the scheduler service

messageRunnerRegistryHelper - the message runner registry helper

messageInformationService - message information service

nestedMessageSerializer - nested message serializer

deliveryIntervalMillis - the time interval in milliseconds between successive deliveries of a message (must be greater than 0)

maxDeliveryCount - the maximum number of times to deliver a message if message processing fails and the message is not acknowledged (must be greater than 0)

Method Detail

init

@PostConstruct
public void init()

Initialises this instance.

shutdown

@PreDestroy
public void shutdown()

Shuts down this instance.

addMessage

public void addMessage(Message message)

Description copied from interface: MessageRunnerService

Adds a message that will be executed at some future point. Messages may not be executed in the order in which they are added.

Specified by:

addMessage in interface MessageRunnerService

Parameters:

message - message specification

getFirstDeliveryTime

protected Date getFirstDeliveryTime()

Returns message first delivery time.

Returns:

null to delivery as soon as possible; deeper in the past means sooner (higher priority)