Shellmen/src/libs/watchdog/observers/polling.py

146 lines
4.7 KiB
Python

# Copyright 2011 Yesudeep Mangalapilly <yesudeep@gmail.com>
# Copyright 2012 Google, Inc & contributors.
#
# 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.
"""
:module: libs.watchdog.observers.polling
:synopsis: Polling emitter implementation.
:author: yesudeep@google.com (Yesudeep Mangalapilly)
:author: contact@tiger-222.fr (Mickaël Schoentgen)
Classes
-------
.. autoclass:: PollingObserver
:members:
:show-inheritance:
.. autoclass:: PollingObserverVFS
:members:
:show-inheritance:
:special-members:
"""
from __future__ import annotations
import os
import threading
from functools import partial
from libs.watchdog.events import (
DirCreatedEvent,
DirDeletedEvent,
DirModifiedEvent,
DirMovedEvent,
FileCreatedEvent,
FileDeletedEvent,
FileModifiedEvent,
FileMovedEvent,
)
from libs.watchdog.observers.api import DEFAULT_EMITTER_TIMEOUT, DEFAULT_OBSERVER_TIMEOUT, BaseObserver, EventEmitter
from libs.watchdog.utils.dirsnapshot import DirectorySnapshot, DirectorySnapshotDiff
class PollingEmitter(EventEmitter):
"""
Platform-independent emitter that polls a directory to detect file
system changes.
"""
def __init__(
self,
event_queue,
watch,
timeout=DEFAULT_EMITTER_TIMEOUT,
stat=os.stat,
listdir=os.scandir,
):
super().__init__(event_queue, watch, timeout)
self._snapshot = None
self._lock = threading.Lock()
self._take_snapshot = lambda: DirectorySnapshot(
self.watch.path, self.watch.is_recursive, stat=stat, listdir=listdir
)
def on_thread_start(self):
self._snapshot = self._take_snapshot()
def queue_events(self, timeout):
# We don't want to hit the disk continuously.
# timeout behaves like an interval for polling emitters.
if self.stopped_event.wait(timeout):
return
with self._lock:
if not self.should_keep_running():
return
# Get event diff between fresh snapshot and previous snapshot.
# Update snapshot.
try:
new_snapshot = self._take_snapshot()
except OSError:
self.queue_event(DirDeletedEvent(self.watch.path))
self.stop()
return
events = DirectorySnapshotDiff(self._snapshot, new_snapshot)
self._snapshot = new_snapshot
# Files.
for src_path in events.files_deleted:
self.queue_event(FileDeletedEvent(src_path))
for src_path in events.files_modified:
self.queue_event(FileModifiedEvent(src_path))
for src_path in events.files_created:
self.queue_event(FileCreatedEvent(src_path))
for src_path, dest_path in events.files_moved:
self.queue_event(FileMovedEvent(src_path, dest_path))
# Directories.
for src_path in events.dirs_deleted:
self.queue_event(DirDeletedEvent(src_path))
for src_path in events.dirs_modified:
self.queue_event(DirModifiedEvent(src_path))
for src_path in events.dirs_created:
self.queue_event(DirCreatedEvent(src_path))
for src_path, dest_path in events.dirs_moved:
self.queue_event(DirMovedEvent(src_path, dest_path))
class PollingObserver(BaseObserver):
"""
Platform-independent observer that polls a directory to detect file
system changes.
"""
def __init__(self, timeout=DEFAULT_OBSERVER_TIMEOUT):
super().__init__(emitter_class=PollingEmitter, timeout=timeout)
class PollingObserverVFS(BaseObserver):
"""
File system independent observer that polls a directory to detect changes.
"""
def __init__(self, stat, listdir, polling_interval=1):
"""
:param stat: stat function. See ``os.stat`` for details.
:param listdir: listdir function. See ``os.scandir`` for details.
:type polling_interval: float
:param polling_interval: interval in seconds between polling the file system.
"""
emitter_cls = partial(PollingEmitter, stat=stat, listdir=listdir)
super().__init__(emitter_class=emitter_cls, timeout=polling_interval)