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- #!/usr/bin/env python
- # -*- coding: utf-8 -*-
- #
- # Copyright 2011 Yesudeep Mangalapilly <yesudeep@gmail.com>
- # Copyright 2012 Google, Inc.
- #
- # 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: watchdog.observers.polling
- :synopsis: Polling emitter implementation.
- :author: yesudeep@google.com (Yesudeep Mangalapilly)
- Classes
- -------
- .. autoclass:: PollingObserver
- :members:
- :show-inheritance:
- .. autoclass:: PollingObserverVFS
- :members:
- :show-inheritance:
- :special-members:
- """
- from __future__ import with_statement
- import threading
- from functools import partial
- from watchdog.utils import stat as default_stat
- from watchdog.utils.dirsnapshot import DirectorySnapshot, DirectorySnapshotDiff
- from watchdog.observers.api import (
- EventEmitter,
- BaseObserver,
- DEFAULT_OBSERVER_TIMEOUT,
- DEFAULT_EMITTER_TIMEOUT
- )
- from watchdog.events import (
- DirMovedEvent,
- DirDeletedEvent,
- DirCreatedEvent,
- DirModifiedEvent,
- FileMovedEvent,
- FileDeletedEvent,
- FileCreatedEvent,
- FileModifiedEvent
- )
- try:
- from os import scandir
- except ImportError:
- from os import listdir as scandir
- 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=default_stat, listdir=scandir):
- EventEmitter.__init__(self, 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):
- BaseObserver.__init__(self, 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.listdir`` 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)
- BaseObserver.__init__(self, emitter_class=emitter_cls, timeout=polling_interval)
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