esp-idf/tools/idf_monitor_base/stoppable_thread.py

73 wiersze
2.0 KiB
Python

# Copyright 2015-2021 Espressif Systems (Shanghai) CO LTD
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
import threading
try:
from typing import Optional
except ImportError:
pass
class StoppableThread(object):
"""
Provide a Thread-like class which can be 'cancelled' via a subclass-provided
cancellation method.
Can be started and stopped multiple times.
Isn't an instance of type Thread because Python Thread objects can only be run once
"""
def __init__(self):
# type: () -> None
self._thread = None # type: Optional[threading.Thread]
@property
def alive(self):
# type: () -> bool
"""
Is 'alive' whenever the internal thread object exists
"""
return self._thread is not None
def start(self):
# type: () -> None
if self._thread is None:
self._thread = threading.Thread(target=self._run_outer)
self._thread.start()
def _cancel(self):
# type: () -> None
pass # override to provide cancellation functionality
def run(self):
# type: () -> None
pass # override for the main thread behaviour
def _run_outer(self):
# type: () -> None
try:
self.run()
finally:
self._thread = None
def stop(self):
# type: () -> None
if self._thread is not None:
old_thread = self._thread
self._thread = None
self._cancel()
old_thread.join()