org.hawkular.metrics.tasks.api

Interface Task2

All Known Implementing Classes:

Task2Impl

public interface Task2

Author:

jsanda

Method Summary

Modifier and Type	Method and Description
String	getGroupKey() The group key provides a way to logically and physically group tasks.
UUID	getId() This is essentially a primary key that uniquely identifies a task.
String	getName() Identifies the type of task.
int	getOrder() Defines the order of execution of tasks within a group.
Map<String,String>	getParameters() An optional, arbitrary set of key/value parameters that the task receives upon execution.
Trigger	getTrigger() Defines the execution policy of the task, like when the task is scheduled to execute, how many times it should execute, etc.

Method Detail

getId

UUID getId()

This is essentially a primary key that uniquely identifies a task.

getGroupKey

String getGroupKey()

The group key provides a way to logically and physically group tasks. In conjunction with the priority it can be used to control the order of execution of tasks which is desirable when there are interdependencies between tasks. For example, suppose we have a task, T1, that aggregates data from multiple time series to produce a new time series. Then we have a task, T2, that aggregates the data from the time series produced by T2. T2 in effect depends on T1. They should use the same group key.

For Hawkular the group key will generally be the tenant ID. It is a good choice because tenants and all of their data are isolated from one another.

In terms of implementation, all tasks with the same group key will be stored in the same queue shard, which means that they will all be stored within the same physical partition. This should be taken into consideration when choosing a group key because you do not want to wind up with queue shards/partitions that are excessively large.

getName

String getName()

Identifies the type of task. Multiple tasks can have the same name.

getOrder

int getOrder()

Defines the order of execution of tasks within a group. Lower values are executed first. Note that this ordering only applies to tasks within the same group, which is defined by the group key.

getParameters

Map<String,String> getParameters()

An optional, arbitrary set of key/value parameters that the task receives upon execution.

getTrigger

Trigger getTrigger()

Defines the execution policy of the task, like when the task is scheduled to execute, how many times it should execute, etc.