5.2.4. vlcp.event.future¶

Note

This document is generated from the source file.

Created on 2016/9/28

author:	hubo

Future is a helper class to simplify the process of retrieving a result from other routines. The implementation is straight-forward: first check the return value, if not set, wait for the event. Multiple routines can wait for the same Future object.

The interface is similar to asyncio, but:

Cancel is not supported - you should terminate the sender routine instead. But RoutineFuture supports close() (and cancel() which is the same)
Callback is not supported - start a subroutine to wait for the result instead.
result() returns None if the result is not ready; exception() is not supported.
New wait() generator function: get the result, or wait for the result until available. It is always the recommended way to use a future; result() is not recommended.
ensure_result() which returns a context manager: this should be used in the sender routine, to ensure that a result is always set after exit the with scope. If the result is not set, it is set to None; if an exception is raised, it is set with set_exception.

class vlcp.event.future.Future(scheduler)¶

Basic future object

__init__(scheduler)¶: Initialize self. See help(type(self)) for accurate signature.

done()¶

Returns:	True if the result is available; False otherwise.

ensure_result(supress_exception=False, defaultresult=None)¶: Context manager to ensure returning the result

result()¶

Returns:	None if the result is not ready, the result from set_result, or raise the exception from set_exception. If the result can be None, it is not possible to tell if the result is available; use done() to determine that.

set_exception(exception)¶

Set an exception to Future object, wake up all the waiters

Parameters:	exception – exception to set

set_result(result)¶

Set the result to Future object, wake up all the waiters

Parameters:	result – result to set

wait(container)¶

Parameters:	container – container of current routine
Returns:	The result, or raise the exception from set_exception. The result is returned to container.retvalue.

exception vlcp.event.future.FutureCancelledException¶

class vlcp.event.future.FutureEvent(*args, **kwargs)¶

class vlcp.event.future.RoutineFuture(subprocess, container)¶

Quick wrapper to create a subroutine and return the result to a Future object

__init__(subprocess, container)¶

Start the subprocess

Parameters:	subprocess – a generator process, which returns the result to container.retvalue on exit container – the routine container to run the subprocess with

cancel()¶: Same as close()

close()¶: Terminate the subprocess