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# coding: utf-8
# /*##########################################################################
#
# Copyright (c) 2018 European Synchrotron Radiation Facility
#
# Permission is hereby granted, free of charge, to any person obtaining a copy
# of this software and associated documentation files (the "Software"), to deal
# in the Software without restriction, including without limitation the rights
# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
# copies of the Software, and to permit persons to whom the Software is
# furnished to do so, subject to the following conditions:
#
# The above copyright notice and this permission notice shall be included in
# all copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
# THE SOFTWARE.
#
# ###########################################################################*/
"""This module allows to run a function in Qt main thread from another thread
"""
from __future__ import absolute_import
__authors__ = ["T. Vincent"]
__license__ = "MIT"
__date__ = "09/03/2018"
from concurrent.futures import Future
from .. import qt
class _QtExecutor(qt.QObject):
"""Executor of tasks in Qt main thread"""
__sigSubmit = qt.Signal(Future, object, tuple, dict)
"""Signal used to run tasks."""
def __init__(self):
super(_QtExecutor, self).__init__(parent=None)
# Makes sure the executor lives in the main thread
app = qt.QApplication.instance()
assert app is not None
mainThread = app.thread()
if self.thread() != mainThread:
self.moveToThread(mainThread)
self.__sigSubmit.connect(self.__run)
def submit(self, fn, *args, **kwargs):
"""Submit fn(*args, **kwargs) to Qt main thread
:param callable fn: Function to call in main thread
:return: Future object to retrieve result
:rtype: concurrent.future.Future
"""
future = Future()
self.__sigSubmit.emit(future, fn, args, kwargs)
return future
def __run(self, future, fn, args, kwargs):
"""Run task in Qt main thread
:param concurrent.future.Future future:
:param callable fn: Function to run
:param tuple args: Arguments
:param dict kwargs: Keyword arguments
"""
if not future.set_running_or_notify_cancel():
return
try:
result = fn(*args, **kwargs)
except BaseException as e:
future.set_exception(e)
else:
future.set_result(result)
_executor = None
"""QObject running the tasks in main thread"""
def submitToQtMainThread(fn, *args, **kwargs):
"""Run fn(args, kwargs) in Qt's main thread.
If not called from the main thread, this is run asynchronously.
:param callable fn: Function to call in main thread.
:return: A future object to retrieve the result
:rtype: concurrent.future.Future
"""
global _executor
if _executor is None: # Lazy-loading
_executor = _QtExecutor()
return _executor.submit(fn, *args, **kwargs)
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