ai.grakn.engine.backgroundtasks.taskstatestorage

Class TaskStateZookeeperStore

java.lang.Object

ai.grakn.engine.backgroundtasks.taskstatestorage.TaskStateZookeeperStore

All Implemented Interfaces:

TaskStateStorage

public class TaskStateZookeeperStore
extends Object
implements TaskStateStorage

Manages the state of background BackgroundTask in a synchronized manner withing a cluster. This means that all updates must be performed by acquiring a distributed mutex so that no concurrent writes are possible.

Author:

Denis Lobanov, Alexandra Orth

Constructor Summary

Constructors

Constructor and Description
TaskStateZookeeperStore(ZookeeperConnection connection)

Method Summary

Modifier and Type	Method and Description
TaskState	getState(String id) Retrieve the TaskState associated with the given ID.
Set<TaskState>	getTasks(TaskStatus taskStatus, String taskClassName, String createdBy, int limit, int offset) This implementation will fetch all of the tasks from zookeeper and then filer them out.
String	newState(TaskState task) Create a new task state and store it, returning an ID to later access this task state.
Boolean	updateState(TaskState task) Used to update task state.

Methods inherited from class java.lang.Object

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

Constructor Detail

TaskStateZookeeperStore

public TaskStateZookeeperStore(ZookeeperConnection connection)

Method Detail

newState

public String newState(TaskState task)

Description copied from interface: TaskStateStorage

Create a new task state and store it, returning an ID to later access this task state.

Specified by:

newState in interface TaskStateStorage

Parameters:

task - State to insert.

Returns:

String form of the task id, which can be use later to update or retrieve the task state. Null if task could not be created of mandatory fields were omitted.

updateState

public Boolean updateState(TaskState task)

Description copied from interface: TaskStateStorage

Used to update task state. With the exception of @id any other fields may individually be null, however all parameters cannot be null at the same time. Setting any of the parameters to null indicates that their values should not be changed.

Specified by:

updateState in interface TaskStateStorage

Parameters:

task - State to update.

Returns:

true if inserted successfully

getState

public TaskState getState(String id)

Retrieve the TaskState associated with the given ID. Acquire a distributed mutex before executing to ensure most up-to-date state.

Specified by:

getState in interface TaskStateStorage

Parameters:

id - String id of task.

Returns:

State of the given task

getTasks

public Set<TaskState> getTasks(TaskStatus taskStatus,
                               String taskClassName,
                               String createdBy,
                               int limit,
                               int offset)

This implementation will fetch all of the tasks from zookeeper and then filer them out. ZK stores tasks by ID, so at the moment there is no more efficient way to search within the storage itself.

Specified by:

getTasks in interface TaskStateStorage

Parameters:

taskStatus - See TaskStatus enum.

taskClassName - String containing task class name. See TaskState.

createdBy - String containing created by. See TaskState.

limit - Limit the returned result set to @limit amount of entries.

offset - Use in conjunction with @limit for pagination.

Returns:

Set of TaskStates corresponding to search