Interface TaskWrapper

public interface TaskWrapper

A TaskWrapper is a facility to wrap Runnable background tasks before they are passed to the Executor. Use-cases include injection of thread-local context variables, or more fine-granular error handling.

All sub-queries sent by the federation engine that make use of the concurrency infrastructure (e.g. ControlledWorkerScheduler) are passing this wrapper.

The concrete implementation can be configured using FedXConfig.withTaskWrapper(TaskWrapper).

Author:

Andreas Schwarte

See Also:

• ControlledWorkerScheduler
• FedXConfig.withTaskWrapper(TaskWrapper)

Method Summary

Modifier and Type	Method	Description
Runnable	wrap(Runnable runnable)	Wrap the given Runnable and add custom logic.
<T> Callable<T>	wrap(Callable<T> callable)	Wrap the given Callable and add custom logic.

Method Details

wrap

Runnable wrap(Runnable runnable)

Wrap the given Runnable and add custom logic.

Use cases include injection of state into the thread-local context, or more fine granular error handling.

Note that when modifying state in ThreadLocal it must be reset properly in a try/finally block.

Parameters:

runnable - the task as generated by the FedX engine

Returns:

the wrapped Runnable

wrap

<T> Callable<T> wrap(Callable<T> callable)

Wrap the given Callable and add custom logic.

Use cases include injection of state into the thread-local context, or more fine granular error handling.

Note that when modifying state in ThreadLocal it must be reset properly in a try/finally block.

Parameters:

callable - the task as generated by the FedX engine

Returns:

the wrapped Callable