d08f43e6be
- max_instances renamed to max_running - consider_args parameter: if True, $max_running of this function with the same arguments can be running, else: $max_running of this function, no matter the arguments, can be running - discard_if_max_running: if True and there are already the maximum possible number of running functions running, cancel this task (previous default behavior), else: Wait for a spot to be free before running
147 lines
4.4 KiB
Python
147 lines
4.4 KiB
Python
# Copyright 2019 miruka
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# This file is part of harmonyqml, licensed under GPLv3.
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import functools
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import logging as log
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import sys
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import time
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import traceback
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from concurrent.futures import Executor, Future
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from typing import Callable, Deque, Optional, Tuple, Union
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from PyQt5.QtCore import QObject, pyqtProperty, pyqtSignal, pyqtSlot
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class PyQtFuture(QObject):
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gotResult = pyqtSignal("QVariant")
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def __init__(self, future: Future, parent: QObject) -> None:
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super().__init__(parent)
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self.future = future
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self._result = None
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self.future.add_done_callback(
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lambda future: self.gotResult.emit(future.result())
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)
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def __repr__(self) -> str:
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return "%s(%s)" % (type(self).__name__, repr(self.future))
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@pyqtSlot()
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def cancel(self):
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self.future.cancel()
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@pyqtProperty(bool)
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def cancelled(self):
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return self.future.cancelled()
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@pyqtProperty(bool)
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def running(self):
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return self.future.running()
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@pyqtProperty(bool)
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def done(self):
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return self.future.done()
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@pyqtSlot(result="QVariant")
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@pyqtSlot(int, result="QVariant")
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@pyqtSlot(float, result="QVariant")
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def result(self, timeout: Optional[Union[int, float]] = None):
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return self.future.result(timeout)
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@pyqtProperty("QVariant", notify=gotResult)
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def value(self):
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return self.future.result() if self.done else None
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def add_done_callback(self, fn: Callable[[Future], None]) -> None:
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self.future.add_done_callback(fn)
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_Task = Tuple[Executor, Callable, Optional[tuple], Optional[dict]]
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_RUNNING: Deque[_Task] = Deque()
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_PENDING: Deque[_Task] = Deque()
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def futurize(max_running: Optional[int] = None,
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consider_args: bool = False,
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discard_if_max_running: bool = False,
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pyqt: bool = True) -> Callable:
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def decorator(func: Callable) -> Callable:
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@functools.wraps(func)
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def wrapper(self, *args, **kws) -> Optional[PyQtFuture]:
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task: _Task = (
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self.pool,
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func,
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args if consider_args else None,
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kws if consider_args else None,
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)
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def can_run_now() -> bool:
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if max_running is not None and \
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_RUNNING.count(task) >= max_running:
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log.debug("!! Max %d tasks of this kind running: %r",
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max_running, task[1:])
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return False
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if not consider_args or not _PENDING:
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return True
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log.debug(".. Pending: %r\n Queue: %r", task[1:], _PENDING)
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candidate_task = next((
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pending for pending in _PENDING
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if pending[0] == self.pool and pending[1] == func
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), None)
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if candidate_task is None:
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log.debug(">> No other candidate, starting: %r", task[1:])
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return True
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if candidate_task[2] == args and candidate_task[3] == kws:
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log.debug(">> Candidate is us: %r", candidate_task[1:])
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return True
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log.debug("XX Other candidate: %r", candidate_task[1:])
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return False
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if not can_run_now() and discard_if_max_running:
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log.debug("\\/ Discarding task: %r", task[1:])
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return None
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def run_and_catch_errs():
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if not can_run_now():
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log.debug("~~ Can't start now: %r", task[1:])
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_PENDING.append(task)
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while not can_run_now():
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time.sleep(0.05)
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_RUNNING.append(task)
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log.debug("Starting: %r", task[1:])
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# Without this, exceptions are silently ignored
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try:
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return func(self, *args, **kws)
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except Exception:
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traceback.print_exc()
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log.error("Exiting thread/process due to exception.")
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sys.exit(1)
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finally:
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del _RUNNING[_RUNNING.index(task)]
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future = self.pool.submit(run_and_catch_errs)
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return PyQtFuture(future, self) if pyqt else future
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return wrapper
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return decorator
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