Add-on store: Improve refreshing the cache

source/_addonStore/dataManager.py

@@ -7,7 +7,6 @@
 # Can be removed in a future version of python (3.8+)
 from __future__ import annotations
 
-from datetime import datetime, timedelta
 import json
 import os
 import pathlib
@@ -42,6 +41,7 @@
 from .network import (
 	_getAddonStoreURL,
 	_getCurrentApiVersionForURL,
+	_CACHE_HASH_URL,
 	_LATEST_API_VER,
 )
 
@@ -68,7 +68,6 @@ def initialize():
 class _DataManager:
 	_cacheLatestFilename: str = "_cachedLatestAddons.json"
 	_cacheCompatibleFilename: str = "_cachedCompatibleAddons.json"
-	_cachePeriod = timedelta(hours=6)
 	_downloadsPendingInstall: Set[Tuple["AddonListItemVM", os.PathLike]] = set()
 
 	def __init__(self):
@@ -107,27 +106,43 @@ def _getLatestAddonsDataForVersion(self, apiVersion: str) -> Optional[bytes]:
 			return None
 		return response.content
 
-	def _cacheCompatibleAddons(self, addonData: str, fetchTime: datetime):
+	def _getCacheHash(self) -> Optional[str]:
+		url = _CACHE_HASH_URL
+		try:
+			response = requests.get(url)
+		except requests.exceptions.RequestException as e:
+			log.debugWarning(f"Unable to get cache hash: {e}")
+			return None
+		if response.status_code != requests.codes.OK:
+			log.error(
+				f"Unable to get data from API ({url}),"
+				f" response ({response.status_code}): {response.content}"
+			)
+			return None
+		cacheHash = response.content.decode().strip('"')
+		return cacheHash
+
+	def _cacheCompatibleAddons(self, addonData: str, cacheHash: Optional[str]):
 		if not NVDAState.shouldWriteToDisk():
 			return
 		if not addonData:
 			return
 		cacheData = {
-			"cacheDate": fetchTime.isoformat(),
+			"cacheHash": self._getCacheHash(),
 			"data": addonData,
 			"cachedLanguage": self._lang,
 			"nvdaAPIVersion": addonAPIVersion.CURRENT,
 		}
 		with open(self._cacheCompatibleFile, 'w') as cacheFile:
 			json.dump(cacheData, cacheFile, ensure_ascii=False)
 
-	def _cacheLatestAddons(self, addonData: str, fetchTime: datetime):
+	def _cacheLatestAddons(self, addonData: str, cacheHash: Optional[str]):
 		if not NVDAState.shouldWriteToDisk():
 			return
 		if not addonData:
 			return
 		cacheData = {
-			"cacheDate": fetchTime.isoformat(),
+			"cacheHash": self._getCacheHash(),
 			"data": addonData,
 			"cachedLanguage": self._lang,
 			"nvdaAPIVersion": _LATEST_API_VER,
@@ -142,10 +157,10 @@ def _getCachedAddonData(self, cacheFilePath: str) -> Optional[CachedAddonsModel]
 			cacheData = json.load(cacheFile)
 		if not cacheData:
 			return None
-		fetchTime = datetime.fromisoformat(cacheData["cacheDate"])
+		cacheHash = cacheData.get("cacheHash")
 		return CachedAddonsModel(
 			cachedAddonData=_createStoreCollectionFromJson(cacheData["data"]),
-			cachedAt=fetchTime,
+			cacheHash=cacheHash,
 			cachedLanguage=cacheData["cachedLanguage"],
 			nvdaAPIVersion=tuple(cacheData["nvdaAPIVersion"]),  # loads as list
 		)
@@ -157,24 +172,24 @@ def getLatestCompatibleAddons(
 			self,
 			onDisplayableError: Optional[DisplayableError.OnDisplayableErrorT] = None,
 	) -> "AddonGUICollectionT":
+		cacheHash = self._getCacheHash()
 		shouldRefreshData = (
 			not self._compatibleAddonCache
 			or self._compatibleAddonCache.nvdaAPIVersion != addonAPIVersion.CURRENT
-			or _DataManager._cachePeriod < (datetime.now() - self._compatibleAddonCache.cachedAt)
+			or self._compatibleAddonCache.cacheHash != cacheHash
 			or self._compatibleAddonCache.cachedLanguage != self._lang
 		)
 		if shouldRefreshData:
-			fetchTime = datetime.now()
 			apiData = self._getLatestAddonsDataForVersion(_getCurrentApiVersionForURL())
 			if apiData:
 				decodedApiData = apiData.decode()
 				self._cacheCompatibleAddons(
 					addonData=decodedApiData,
-					fetchTime=fetchTime,
+					cacheHash=cacheHash,
 				)
 				self._compatibleAddonCache = CachedAddonsModel(
 					cachedAddonData=_createStoreCollectionFromJson(decodedApiData),
-					cachedAt=fetchTime,
+					cacheHash=cacheHash,
 					cachedLanguage=self._lang,
 					nvdaAPIVersion=addonAPIVersion.CURRENT,
 				)
@@ -195,23 +210,23 @@ def getLatestAddons(
 			self,
 			onDisplayableError: Optional[DisplayableError.OnDisplayableErrorT] = None,
 	) -> "AddonGUICollectionT":
+		cacheHash = self._getCacheHash()
 		shouldRefreshData = (
 			not self._latestAddonCache
-			or _DataManager._cachePeriod < (datetime.now() - self._latestAddonCache.cachedAt)
+			or self._latestAddonCache.cacheHash != cacheHash
 			or self._latestAddonCache.cachedLanguage != self._lang
 		)
 		if shouldRefreshData:
-			fetchTime = datetime.now()
 			apiData = self._getLatestAddonsDataForVersion(_LATEST_API_VER)
 			if apiData:
 				decodedApiData = apiData.decode()
 				self._cacheLatestAddons(
 					addonData=decodedApiData,
-					fetchTime=fetchTime,
+					cacheHash=cacheHash,
 				)
 				self._latestAddonCache = CachedAddonsModel(
 					cachedAddonData=_createStoreCollectionFromJson(decodedApiData),
-					cachedAt=fetchTime,
+					cacheHash=cacheHash,
 					cachedLanguage=self._lang,
 					nvdaAPIVersion=_LATEST_API_VER,
 				)

source/_addonStore/models/addon.py

@@ -8,7 +8,6 @@
 from __future__ import annotations
 
 import dataclasses
-from datetime import datetime
 import json
 import os
 from typing import (
@@ -203,7 +202,7 @@ def isPendingInstall(self) -> bool:
 @dataclasses.dataclass
 class CachedAddonsModel:
 	cachedAddonData: "AddonGUICollectionT"
-	cachedAt: datetime
+	cacheHash: Optional[str]
 	cachedLanguage: str
 	# AddonApiVersionT or the string .network._LATEST_API_VER
 	nvdaAPIVersion: Union[addonAPIVersion.AddonApiVersionT, str]

source/_addonStore/network.py

@@ -35,6 +35,7 @@
 	from gui.message import DisplayableError
 
 
+_CACHE_HASH_URL = "https://www.nvaccess.org/addonStore/cacheHash.json"
 _LATEST_API_VER = "latest"
 """
 A string value used in the add-on store to fetch the latest version of all add-ons,