io.druid.indexing.overlord

Interface TaskRunner

All Known Subinterfaces:

WorkerTaskRunner

All Known Implementing Classes:

ForkingTaskRunner, RemoteTaskRunner, ThreadPoolTaskRunner

public interface TaskRunner

Interface for handing off tasks. Managed by a TaskQueue. Holds state

Method Summary

Modifier and Type	Method and Description
Collection<? extends TaskRunnerWorkItem>	getKnownTasks()
Collection<? extends TaskRunnerWorkItem>	getPendingTasks()
Collection<? extends TaskRunnerWorkItem>	getRunningTasks()
com.google.common.base.Optional<ScalingStats>	getScalingStats() Some runners are able to scale up and down their capacity in a dynamic manner.
void	registerListener(TaskRunnerListener listener, Executor executor) Register a listener with this task runner.
List<Pair<Task,com.google.common.util.concurrent.ListenableFuture<TaskStatus>>>	restore() Some task runners can restart previously-running tasks after being bounced.
com.google.common.util.concurrent.ListenableFuture<TaskStatus>	run(Task task) Run a task.
void	shutdown(String taskid) Inform the task runner it can clean up any resources associated with a task.
void	start() Start the state of the runner
void	stop() Stop this task runner.
void	unregisterListener(String listenerId)

Method Detail

restore

List<Pair<Task,com.google.common.util.concurrent.ListenableFuture<TaskStatus>>> restore()

Some task runners can restart previously-running tasks after being bounced. This method does that, and returns the list of tasks (and status futures).

registerListener

void registerListener(TaskRunnerListener listener,
                      Executor executor)

Register a listener with this task runner. On registration, the listener will get events corresponding to the current state of known tasks. Listener notifications are submitted to the executor in the order they occur, but it is up to the executor to decide when to actually run the notifications. If your listeners will not block, feel free to use a same-thread executor. Listeners that may block should use a separate executor, generally a single-threaded one with a fifo queue so the order of notifications is retained.

Parameters:

listener - the listener

executor - executor to run callbacks in

unregisterListener

void unregisterListener(String listenerId)

run

com.google.common.util.concurrent.ListenableFuture<TaskStatus> run(Task task)

Run a task. The returned status should be some kind of completed status.

Parameters:

task - task to run

Returns:

task status, eventually

shutdown

void shutdown(String taskid)

Inform the task runner it can clean up any resources associated with a task. This implies shutdown of any currently-running tasks.

Parameters:

taskid - task ID to clean up resources for

stop

void stop()

Stop this task runner. This may block until currently-running tasks can be gracefully stopped. After calling stopping, "run" will not accept further tasks.

getRunningTasks

Collection<? extends TaskRunnerWorkItem> getRunningTasks()

getPendingTasks

Collection<? extends TaskRunnerWorkItem> getPendingTasks()

getKnownTasks

Collection<? extends TaskRunnerWorkItem> getKnownTasks()

getScalingStats

com.google.common.base.Optional<ScalingStats> getScalingStats()

Some runners are able to scale up and down their capacity in a dynamic manner. This returns stats on those activities

Returns:

ScalingStats if the runner has an underlying resource which can scale, Optional.absent() otherwise

start

void start()

Start the state of the runner