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