Cours/venv/lib/python3.12/site-packages/watchdog/observers/api.py

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2024-09-02 16:55:06 +00:00
from __future__ import annotations
import contextlib
import queue
import threading
from collections import defaultdict
from pathlib import Path
from typing import TYPE_CHECKING
from watchdog.utils import BaseThread
from watchdog.utils.bricks import SkipRepeatsQueue
if TYPE_CHECKING:
from watchdog.events import FileSystemEvent, FileSystemEventHandler
DEFAULT_EMITTER_TIMEOUT = 1.0 # in seconds
DEFAULT_OBSERVER_TIMEOUT = 1.0 # in seconds
class EventQueue(SkipRepeatsQueue):
"""Thread-safe event queue based on a special queue that skips adding
the same event (:class:`FileSystemEvent`) multiple times consecutively.
Thus avoiding dispatching multiple event handling
calls when multiple identical events are produced quicker than an observer
can consume them.
"""
class ObservedWatch:
"""An scheduled watch.
:param path:
Path string.
:param recursive:
``True`` if watch is recursive; ``False`` otherwise.
:param event_filter:
Optional collection of :class:`watchdog.events.FileSystemEvent` to watch
"""
def __init__(self, path: str | Path, *, recursive: bool, event_filter: list[type[FileSystemEvent]] | None = None):
self._path = str(path) if isinstance(path, Path) else path
self._is_recursive = recursive
self._event_filter = frozenset(event_filter) if event_filter is not None else None
@property
def path(self) -> str:
"""The path that this watch monitors."""
return self._path
@property
def is_recursive(self) -> bool:
"""Determines whether subdirectories are watched for the path."""
return self._is_recursive
@property
def event_filter(self) -> frozenset[type[FileSystemEvent]] | None:
"""Collection of event types watched for the path"""
return self._event_filter
@property
def key(self) -> tuple[str, bool, frozenset[type[FileSystemEvent]] | None]:
return self.path, self.is_recursive, self.event_filter
def __eq__(self, watch: object) -> bool:
if not isinstance(watch, ObservedWatch):
return NotImplemented
return self.key == watch.key
def __ne__(self, watch: object) -> bool:
if not isinstance(watch, ObservedWatch):
return NotImplemented
return self.key != watch.key
def __hash__(self) -> int:
return hash(self.key)
def __repr__(self) -> str:
if self.event_filter is not None:
event_filter_str = "|".join(sorted(_cls.__name__ for _cls in self.event_filter))
event_filter_str = f", event_filter={event_filter_str}"
else:
event_filter_str = ""
return f"<{type(self).__name__}: path={self.path!r}, is_recursive={self.is_recursive}{event_filter_str}>"
# Observer classes
class EventEmitter(BaseThread):
"""Producer thread base class subclassed by event emitters
that generate events and populate a queue with them.
:param event_queue:
The event queue to populate with generated events.
:type event_queue:
:class:`watchdog.events.EventQueue`
:param watch:
The watch to observe and produce events for.
:type watch:
:class:`ObservedWatch`
:param timeout:
Timeout (in seconds) between successive attempts at reading events.
:type timeout:
``float``
:param event_filter:
Collection of event types to emit, or None for no filtering (default).
:type event_filter:
Iterable[:class:`watchdog.events.FileSystemEvent`] | None
"""
def __init__(
self,
event_queue: EventQueue,
watch: ObservedWatch,
*,
timeout: float = DEFAULT_EMITTER_TIMEOUT,
event_filter: list[type[FileSystemEvent]] | None = None,
) -> None:
super().__init__()
self._event_queue = event_queue
self._watch = watch
self._timeout = timeout
self._event_filter = frozenset(event_filter) if event_filter is not None else None
@property
def timeout(self) -> float:
"""Blocking timeout for reading events."""
return self._timeout
@property
def watch(self) -> ObservedWatch:
"""The watch associated with this emitter."""
return self._watch
def queue_event(self, event: FileSystemEvent) -> None:
"""Queues a single event.
:param event:
Event to be queued.
:type event:
An instance of :class:`watchdog.events.FileSystemEvent`
or a subclass.
"""
if self._event_filter is None or any(isinstance(event, cls) for cls in self._event_filter):
self._event_queue.put((event, self.watch))
def queue_events(self, timeout: float) -> None:
"""Override this method to populate the event queue with events
per interval period.
:param timeout:
Timeout (in seconds) between successive attempts at
reading events.
:type timeout:
``float``
"""
def run(self) -> None:
while self.should_keep_running():
self.queue_events(self.timeout)
class EventDispatcher(BaseThread):
"""Consumer thread base class subclassed by event observer threads
that dispatch events from an event queue to appropriate event handlers.
:param timeout:
Timeout value (in seconds) passed to emitters
constructions in the child class BaseObserver.
:type timeout:
``float``
"""
stop_event = object()
"""Event inserted into the queue to signal a requested stop."""
def __init__(self, *, timeout: float = DEFAULT_OBSERVER_TIMEOUT) -> None:
super().__init__()
self._event_queue = EventQueue()
self._timeout = timeout
@property
def timeout(self) -> float:
"""Timeout value to construct emitters with."""
return self._timeout
def stop(self) -> None:
BaseThread.stop(self)
with contextlib.suppress(queue.Full):
self.event_queue.put_nowait(EventDispatcher.stop_event)
@property
def event_queue(self) -> EventQueue:
"""The event queue which is populated with file system events
by emitters and from which events are dispatched by a dispatcher
thread.
"""
return self._event_queue
def dispatch_events(self, event_queue: EventQueue) -> None:
"""Override this method to consume events from an event queue, blocking
on the queue for the specified timeout before raising :class:`queue.Empty`.
:param event_queue:
Event queue to populate with one set of events.
:type event_queue:
:class:`EventQueue`
:raises:
:class:`queue.Empty`
"""
def run(self) -> None:
while self.should_keep_running():
try:
self.dispatch_events(self.event_queue)
except queue.Empty:
continue
class BaseObserver(EventDispatcher):
"""Base observer."""
def __init__(self, emitter_class: type[EventEmitter], *, timeout: float = DEFAULT_OBSERVER_TIMEOUT) -> None:
super().__init__(timeout=timeout)
self._emitter_class = emitter_class
self._lock = threading.RLock()
self._watches: set[ObservedWatch] = set()
self._handlers: defaultdict[ObservedWatch, set[FileSystemEventHandler]] = defaultdict(set)
self._emitters: set[EventEmitter] = set()
self._emitter_for_watch: dict[ObservedWatch, EventEmitter] = {}
def _add_emitter(self, emitter: EventEmitter) -> None:
self._emitter_for_watch[emitter.watch] = emitter
self._emitters.add(emitter)
def _remove_emitter(self, emitter: EventEmitter) -> None:
del self._emitter_for_watch[emitter.watch]
self._emitters.remove(emitter)
emitter.stop()
with contextlib.suppress(RuntimeError):
emitter.join()
def _clear_emitters(self) -> None:
for emitter in self._emitters:
emitter.stop()
for emitter in self._emitters:
with contextlib.suppress(RuntimeError):
emitter.join()
self._emitters.clear()
self._emitter_for_watch.clear()
def _add_handler_for_watch(self, event_handler: FileSystemEventHandler, watch: ObservedWatch) -> None:
self._handlers[watch].add(event_handler)
def _remove_handlers_for_watch(self, watch: ObservedWatch) -> None:
del self._handlers[watch]
@property
def emitters(self) -> set[EventEmitter]:
"""Returns event emitter created by this observer."""
return self._emitters
def start(self) -> None:
for emitter in self._emitters.copy():
try:
emitter.start()
except Exception:
self._remove_emitter(emitter)
raise
super().start()
def schedule(
self,
event_handler: FileSystemEventHandler,
path: str,
*,
recursive: bool = False,
event_filter: list[type[FileSystemEvent]] | None = None,
) -> ObservedWatch:
"""Schedules watching a path and calls appropriate methods specified
in the given event handler in response to file system events.
:param event_handler:
An event handler instance that has appropriate event handling
methods which will be called by the observer in response to
file system events.
:type event_handler:
:class:`watchdog.events.FileSystemEventHandler` or a subclass
:param path:
Directory path that will be monitored.
:type path:
``str``
:param recursive:
``True`` if events will be emitted for sub-directories
traversed recursively; ``False`` otherwise.
:type recursive:
``bool``
:param event_filter:
Collection of event types to emit, or None for no filtering (default).
:type event_filter:
Iterable[:class:`watchdog.events.FileSystemEvent`] | None
:return:
An :class:`ObservedWatch` object instance representing
a watch.
"""
with self._lock:
watch = ObservedWatch(path, recursive=recursive, event_filter=event_filter)
self._add_handler_for_watch(event_handler, watch)
# If we don't have an emitter for this watch already, create it.
if watch not in self._emitter_for_watch:
emitter = self._emitter_class(self.event_queue, watch, timeout=self.timeout, event_filter=event_filter)
if self.is_alive():
emitter.start()
self._add_emitter(emitter)
self._watches.add(watch)
return watch
def add_handler_for_watch(self, event_handler: FileSystemEventHandler, watch: ObservedWatch) -> None:
"""Adds a handler for the given watch.
:param event_handler:
An event handler instance that has appropriate event handling
methods which will be called by the observer in response to
file system events.
:type event_handler:
:class:`watchdog.events.FileSystemEventHandler` or a subclass
:param watch:
The watch to add a handler for.
:type watch:
An instance of :class:`ObservedWatch` or a subclass of
:class:`ObservedWatch`
"""
with self._lock:
self._add_handler_for_watch(event_handler, watch)
def remove_handler_for_watch(self, event_handler: FileSystemEventHandler, watch: ObservedWatch) -> None:
"""Removes a handler for the given watch.
:param event_handler:
An event handler instance that has appropriate event handling
methods which will be called by the observer in response to
file system events.
:type event_handler:
:class:`watchdog.events.FileSystemEventHandler` or a subclass
:param watch:
The watch to remove a handler for.
:type watch:
An instance of :class:`ObservedWatch` or a subclass of
:class:`ObservedWatch`
"""
with self._lock:
self._handlers[watch].remove(event_handler)
def unschedule(self, watch: ObservedWatch) -> None:
"""Unschedules a watch.
:param watch:
The watch to unschedule.
:type watch:
An instance of :class:`ObservedWatch` or a subclass of
:class:`ObservedWatch`
"""
with self._lock:
emitter = self._emitter_for_watch[watch]
del self._handlers[watch]
self._remove_emitter(emitter)
self._watches.remove(watch)
def unschedule_all(self) -> None:
"""Unschedules all watches and detaches all associated event handlers."""
with self._lock:
self._handlers.clear()
self._clear_emitters()
self._watches.clear()
def on_thread_stop(self) -> None:
self.unschedule_all()
def dispatch_events(self, event_queue: EventQueue) -> None:
entry = event_queue.get(block=True)
if entry is EventDispatcher.stop_event:
return
event, watch = entry
with self._lock:
# To allow unschedule/stop and safe removal of event handlers
# within event handlers itself, check if the handler is still
# registered after every dispatch.
for handler in self._handlers[watch].copy():
if handler in self._handlers[watch]:
handler.dispatch(event)
event_queue.task_done()