ai.grakn.engine.backgroundtasks

Interface TaskStateStorage

All Known Implementing Classes:

TaskStateGraphStore, TaskStateInMemoryStore, TaskStateZookeeperStore

public interface TaskStateStorage

The base StateStorage interface.

Provides common methods for storing and accessing the state of tasks.

Author:

Denis Lobanov, alexandraorth

Method Summary

Modifier and Type	Method and Description
TaskState	getState(String id) This is a copy of the internal TaskState object.
Set<TaskState>	getTasks(TaskStatus taskStatus, String taskClassName, String createdBy, int limit, int offset) Return a Set of Pairs of tasks that match any of the criteria.
String	newState(TaskState state) Create a new task state and store it, returning an ID to later access this task state.
Boolean	updateState(TaskState state) Used to update task state.

Method Detail

newState

String newState(TaskState state)
         throws EngineStorageException

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

Parameters:

state - 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.

Throws:

EngineStorageException

updateState

Boolean updateState(TaskState state)

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.

Parameters:

state - State to update.

Returns:

true if inserted successfully

getState

TaskState getState(String id)
            throws EngineStorageException

This is a copy of the internal TaskState object. It is guaranteed to be correct at the time of call, however the actual internal state may change at any time after.

Parameters:

id - String id of task.

Returns:

TaskState object or null if no TaskState with this id could be found.

Throws:

EngineStorageException

getTasks

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

Return a Set of Pairs of tasks that match any of the criteria. The first value of the Pair is the task id, whilst the second is the TaskState. Parameters may be set to null to not match against then (rather than to match null values), if *all* parameters are null then all known tasks in the system are returned.

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