Lazy loading and caching for attributes set in _loadData(..) (#1510)

* feat: Implemented a caching mecahnism for PlexObject classes

- Cached properties are defined using a `cached_data_property` decorator
- Property caches are automatically invalidated whenever the `_data` atribute is changed
- The implementation uses a metaclass to collect and track all cached properties across class inheritances

* perf: Cache all data attributes that are computation heavy

These attributes include those that call `findItems` and `listAttrs`

* fix: Don't invalidate property cache on object initialization

* refactor: For all Plex objects, call the base class's loadData function to do cache invalidation

* perf: Convert attributes that call `findItem` to cached data properties

* perf: Attempt to parse XML strings without cleaning (which is expensive) before trying again with cleaning

* Revert "perf: Attempt to parse XML strings without cleaning (which is expensive) before trying again with cleaning"

This reverts commit e8348df.

* fix: Use the correct attribute name when deleting invalidated cached data

* fix: Follow the same behavior as before the introduction of cached properties and don't call the super class' _loadData

* fix: Typo in declaring cached data property attributes

* test: Don't use ` __dict__` to access attributes

* test: Don't reload objects for the test_video_Movie_reload_kwargs test

* fix: Ensure `PlexObject._loadData` is called in child classes that override loadData

* fix: Handle special cache invalidation for LibrarySection objects

* test: Tests for cache invalidation in library and video objects

* test: Removed unexpected exception from test_library_section_cache_invalidation

* test: Replaced incorrect object ID comparisons with string string repr comparisons

* refactor: Removed uneeded variable assignment

Co-authored-by: JonnyWong16 <9099342+JonnyWong16@users.noreply.github.com>

* perf: Convert languageCodes and mediaTypes to lazy-loaded cached properties

* refactor: Delegate cache invalidation logic to the reload function instead of _loadData

* style: Removed unecessary explicit object inheritence (implicit since Python3)

* perf: Lazy load expensive attributes in PlexSession

* docs: Make it clearer that Playable, PlexSession, and PlexHistory are mixins

* fix: Handle special reload cache invalidation logic for MyPlexAccount and PlexClient

* refactor: Unused import

* style: Reorder functions for more accurate order of operation

* docs: Removed typo

* refactor: Fixed all flake8 unused import warning

* fix: Invalidate the cache after all PUT queries in the PlayQueue object

* refactor: Call loadData with invalidation in the Settings class for future compatability

* refactor: Better align the items and reload functions with the internal caching mechanism

* fix: Reset the state of Hub pagination metadata on reloads

* docs: Updated docstring for `Hub.reload(...)` changes

---------

Co-authored-by: JonnyWong16 <9099342+JonnyWong16@users.noreply.github.com>

Author: eliasbenb

plexapi/audio.py

@@ -8,7 +8,7 @@
 from typing import Any, Dict, List, Optional, TypeVar
 
 from plexapi import media, utils
-from plexapi.base import Playable, PlexPartialObject, PlexHistory, PlexSession
+from plexapi.base import Playable, PlexPartialObject, PlexHistory, PlexSession, cached_data_property
 from plexapi.exceptions import BadRequest
 from plexapi.mixins import (
     AdvancedSettingsMixin, SplitMergeMixin, UnmatchMatchMixin, ExtrasMixin, HubsMixin, PlayedUnplayedMixin, RatingMixin,
@@ -59,14 +59,11 @@ class Audio(PlexPartialObject, PlayedUnplayedMixin):
 
     def _loadData(self, data):
         """ Load attribute values from Plex XML response. """
-        self._data = data
         self.addedAt = utils.toDatetime(data.attrib.get('addedAt'))
         self.art = data.attrib.get('art')
         self.artBlurHash = data.attrib.get('artBlurHash')
         self.distance = utils.cast(float, data.attrib.get('distance'))
-        self.fields = self.findItems(data, media.Field)
         self.guid = data.attrib.get('guid')
-        self.images = self.findItems(data, media.Image)
         self.index = utils.cast(int, data.attrib.get('index'))
         self.key = data.attrib.get('key', '')
         self.lastRatedAt = utils.toDatetime(data.attrib.get('lastRatedAt'))
@@ -75,7 +72,6 @@ def _loadData(self, data):
         self.librarySectionKey = data.attrib.get('librarySectionKey')
         self.librarySectionTitle = data.attrib.get('librarySectionTitle')
         self.listType = 'audio'
-        self.moods = self.findItems(data, media.Mood)
         self.musicAnalysisVersion = utils.cast(int, data.attrib.get('musicAnalysisVersion'))
         self.ratingKey = utils.cast(int, data.attrib.get('ratingKey'))
         self.summary = data.attrib.get('summary')
@@ -88,6 +84,18 @@ def _loadData(self, data):
         self.userRating = utils.cast(float, data.attrib.get('userRating'))
         self.viewCount = utils.cast(int, data.attrib.get('viewCount', 0))
 
+    @cached_data_property
+    def fields(self):
+        return self.findItems(self._data, media.Field)
+
+    @cached_data_property
+    def images(self):
+        return self.findItems(self._data, media.Image)
+
+    @cached_data_property
+    def moods(self):
+        return self.findItems(self._data, media.Mood)
+
     def url(self, part):
         """ Returns the full URL for the audio item. Typically used for getting a specific track. """
         return self._server.url(part, includeToken=True) if part else None
@@ -205,18 +213,45 @@ def _loadData(self, data):
         Audio._loadData(self, data)
         self.albumSort = utils.cast(int, data.attrib.get('albumSort', '-1'))
         self.audienceRating = utils.cast(float, data.attrib.get('audienceRating'))
-        self.collections = self.findItems(data, media.Collection)
-        self.countries = self.findItems(data, media.Country)
-        self.genres = self.findItems(data, media.Genre)
-        self.guids = self.findItems(data, media.Guid)
         self.key = self.key.replace('/children', '')  # FIX_BUG_50
-        self.labels = self.findItems(data, media.Label)
-        self.locations = self.listAttrs(data, 'path', etag='Location')
         self.rating = utils.cast(float, data.attrib.get('rating'))
-        self.similar = self.findItems(data, media.Similar)
-        self.styles = self.findItems(data, media.Style)
         self.theme = data.attrib.get('theme')
-        self.ultraBlurColors = self.findItem(data, media.UltraBlurColors)
+
+    @cached_data_property
+    def collections(self):
+        return self.findItems(self._data, media.Collection)
+
+    @cached_data_property
+    def countries(self):
+        return self.findItems(self._data, media.Country)
+
+    @cached_data_property
+    def genres(self):
+        return self.findItems(self._data, media.Genre)
+
+    @cached_data_property
+    def guids(self):
+        return self.findItems(self._data, media.Guid)
+
+    @cached_data_property
+    def labels(self):
+        return self.findItems(self._data, media.Label)
+
+    @cached_data_property
+    def locations(self):
+        return self.listAttrs(self._data, 'path', etag='Location')
+
+    @cached_data_property
+    def similar(self):
+        return self.findItems(self._data, media.Similar)
+
+    @cached_data_property
+    def styles(self):
+        return self.findItems(self._data, media.Style)
+
+    @cached_data_property
+    def ultraBlurColors(self):
+        return self.findItem(self._data, media.UltraBlurColors)
 
     def __iter__(self):
         for album in self.albums():
@@ -355,12 +390,7 @@ def _loadData(self, data):
         """ Load attribute values from Plex XML response. """
         Audio._loadData(self, data)
         self.audienceRating = utils.cast(float, data.attrib.get('audienceRating'))
-        self.collections = self.findItems(data, media.Collection)
-        self.formats = self.findItems(data, media.Format)
-        self.genres = self.findItems(data, media.Genre)
-        self.guids = self.findItems(data, media.Guid)
         self.key = self.key.replace('/children', '')  # FIX_BUG_50
-        self.labels = self.findItems(data, media.Label)
         self.leafCount = utils.cast(int, data.attrib.get('leafCount'))
         self.loudnessAnalysisVersion = utils.cast(int, data.attrib.get('loudnessAnalysisVersion'))
         self.originallyAvailableAt = utils.toDatetime(data.attrib.get('originallyAvailableAt'), '%Y-%m-%d')
@@ -372,12 +402,41 @@ def _loadData(self, data):
         self.parentTitle = data.attrib.get('parentTitle')
         self.rating = utils.cast(float, data.attrib.get('rating'))
         self.studio = data.attrib.get('studio')
-        self.styles = self.findItems(data, media.Style)
-        self.subformats = self.findItems(data, media.Subformat)
-        self.ultraBlurColors = self.findItem(data, media.UltraBlurColors)
         self.viewedLeafCount = utils.cast(int, data.attrib.get('viewedLeafCount'))
         self.year = utils.cast(int, data.attrib.get('year'))
 
+    @cached_data_property
+    def collections(self):
+        return self.findItems(self._data, media.Collection)
+
+    @cached_data_property
+    def formats(self):
+        return self.findItems(self._data, media.Format)
+
+    @cached_data_property
+    def genres(self):
+        return self.findItems(self._data, media.Genre)
+
+    @cached_data_property
+    def guids(self):
+        return self.findItems(self._data, media.Guid)
+
+    @cached_data_property
+    def labels(self):
+        return self.findItems(self._data, media.Label)
+
+    @cached_data_property
+    def styles(self):
+        return self.findItems(self._data, media.Style)
+
+    @cached_data_property
+    def subformats(self):
+        return self.findItems(self._data, media.Subformat)
+
+    @cached_data_property
+    def ultraBlurColors(self):
+        return self.findItem(self._data, media.UltraBlurColors)
+
     def __iter__(self):
         for track in self.tracks():
             yield track
@@ -495,21 +554,15 @@ def _loadData(self, data):
         Audio._loadData(self, data)
         Playable._loadData(self, data)
         self.audienceRating = utils.cast(float, data.attrib.get('audienceRating'))
-        self.chapters = self.findItems(data, media.Chapter)
         self.chapterSource = data.attrib.get('chapterSource')
-        self.collections = self.findItems(data, media.Collection)
         self.duration = utils.cast(int, data.attrib.get('duration'))
-        self.genres = self.findItems(data, media.Genre)
         self.grandparentArt = data.attrib.get('grandparentArt')
         self.grandparentGuid = data.attrib.get('grandparentGuid')
         self.grandparentKey = data.attrib.get('grandparentKey')
         self.grandparentRatingKey = utils.cast(int, data.attrib.get('grandparentRatingKey'))
         self.grandparentTheme = data.attrib.get('grandparentTheme')
         self.grandparentThumb = data.attrib.get('grandparentThumb')
         self.grandparentTitle = data.attrib.get('grandparentTitle')
-        self.guids = self.findItems(data, media.Guid)
-        self.labels = self.findItems(data, media.Label)
-        self.media = self.findItems(data, media.Media)
         self.originalTitle = data.attrib.get('originalTitle')
         self.parentGuid = data.attrib.get('parentGuid')
         self.parentIndex = utils.cast(int, data.attrib.get('parentIndex'))
@@ -525,6 +578,30 @@ def _loadData(self, data):
         self.viewOffset = utils.cast(int, data.attrib.get('viewOffset', 0))
         self.year = utils.cast(int, data.attrib.get('year'))
 
+    @cached_data_property
+    def chapters(self):
+        return self.findItems(self._data, media.Chapter)
+
+    @cached_data_property
+    def collections(self):
+        return self.findItems(self._data, media.Collection)
+
+    @cached_data_property
+    def genres(self):
+        return self.findItems(self._data, media.Genre)
+
+    @cached_data_property
+    def guids(self):
+        return self.findItems(self._data, media.Guid)
+
+    @cached_data_property
+    def labels(self):
+        return self.findItems(self._data, media.Label)
+
+    @cached_data_property
+    def media(self):
+        return self.findItems(self._data, media.Media)
+
     @property
     def locations(self):
         """ This does not exist in plex xml response but is added to have a common