Source code for traits_futures.background_progress
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Support for a progress-reporting background call.
The code in this module supports an arbitrary callable that accepts a
"progress" named argument, and can use that argument to submit progress
Every progress submission also marks a point where the callable can
from traits.api import Callable, Dict, Event, HasStrictTraits, Str, Tuple
from traits_futures.base_future import BaseFuture, BaseTask, TaskCancelled
from traits_futures.i_task_specification import ITaskSpecification
# Message types for messages from ProgressTask
# to ProgressFuture.
#: Task sends progress. Argument is a single object giving progress
#: information. This module does not interpret the contents of the argument.
PROGRESS = "progress"
Object used by the target callable to report progress.
def __init__(self, send, cancelled):
self.send = send
self.cancelled = cancelled
[docs] def report(self, progress_info):
Send progress information to the linked future.
The ``progress_info`` object will eventually be sent to the
corresponding future's ``progress`` event trait.
progress_info : object
An arbitrary object representing progress. Ideally, this
should be immutable and pickleable.
If a cancellation request for this task has already been made.
In this case, the exception will be raised before any progress
information is sent.
raise TaskCancelled("Task was cancelled")
self.send(PROGRESS, progress_info) [docs]class ProgressTask(BaseTask):
Background portion of a progress background task.
This provides the callable that will be submitted to the worker pool, and
sends messages to communicate with the ProgressFuture.
def __init__(self, callable, args, kwargs):
self.callable = callable
self.args = args
self.kwargs = kwargs
[docs] def run(self):
progress = ProgressReporter(send=self.send, cancelled=self.cancelled)
return None [docs]class ProgressFuture(BaseFuture):
Object representing the front-end handle to a ProgressTask.
#: Event fired whenever a progress message arrives from the background.
progress = Event()
# Private methods #########################################################
def _process_progress(self, progress_info):
self.progress = progress_info
Object representing the background task to be executed.
#: The callable to be executed.
callable = Callable()
#: Positional arguments to be passed to the callable.
args = Tuple()
#: Named arguments to be passed to the callable.
kwargs = Dict(Str())
[docs] def future(self, cancel):
Return a Future for the background task.
Zero-argument callable, returning no useful result. The returned
future's ``cancel`` method should call this to request cancellation
of the associated background task.
future : ProgressFuture
Future object that can be used to monitor the status of the
[docs] def task(self):
Return a background callable for this task specification.
task : ProgressTask
Callable accepting arguments ``send`` and ``cancelled``. The
callable can use ``send`` to send messages and ``cancelled`` to
check whether cancellation has been requested.
) [docs]def submit_progress(executor, callable, *args, **kwargs):
Submit a progress-reporting task to an executor.
executor : TraitsExecutor
Executor to submit the task to. This argument should always be passed
by position rather than by name. Future versions of the library may
enforce this restriction.
Callable that executes the progress-providing function. This callable
must accept a "progress" named argument, in addition to the provided
arguments. The callable may then call the "progress" argument to report
progress. This argument should always be passed by position rather than
by name. Future versions of the library may enforce this restriction.
Positional arguments to pass to the callable.
Named arguments other than "progress" to pass to the callable. These
must not include "progress".
future : ProgressFuture
Object representing the state of the background task.
if "progress" in kwargs:
raise TypeError("progress may not be passed as a named argument")
task = BackgroundProgress(callable=callable, args=args, kwargs=kwargs)