[perf] Extension list cache (#3616)

lnbits/core/models/extensions.py

@@ -6,6 +6,7 @@ import json
 import os
 import shutil
 import zipfile
+from asyncio.tasks import create_task
 from pathlib import Path
 from typing import Any
 
@@ -20,6 +21,7 @@ from lnbits.helpers import (
     version_parse,
 )
 from lnbits.settings import settings
+from lnbits.utils.cache import cache
 
 
 class ExplicitRelease(BaseModel):
@@ -606,6 +608,37 @@ class InstallableExtension(BaseModel):
 
     @classmethod
     async def get_installable_extensions(
+        cls, post_refresh_cache: bool = False
+    ) -> list[InstallableExtension]:
+        extension_list: list[InstallableExtension] = []
+
+        cache_key = "extensions:installable"
+        cache_value = cache.value(cache_key)
+        if not cache_value:
+            extension_list = await cls._get_installable_extensions()
+            cache.set(cache_key, extension_list, expiry=3600)  # one hour
+            return extension_list
+
+        if cache_value.older_than(10 * 60) or post_refresh_cache:
+            # refresh cache in background if older than 10 minutes or requested
+            create_task(cls._refresh_installable_extensions_cache())
+
+        extension_list = cache_value.value  # type: ignore
+        return extension_list
+
+    @classmethod
+    async def _refresh_installable_extensions_cache(
+        cls,
+    ) -> None:
+        cache_key = "extensions:installable"
+        extension_list: list[InstallableExtension] = (
+            await cls._get_installable_extensions()
+        )
+
+        cache.set(cache_key, extension_list, expiry=3600)
+
+    @classmethod
+    async def _get_installable_extensions(
         cls,
     ) -> list[InstallableExtension]:
         extension_list: list[InstallableExtension] = []

lnbits/core/tasks.py

@@ -57,7 +57,9 @@ async def run_by_the_minute_tasks() -> None:
         if minute_counter % 60 == 0:
             try:
                 # initialize the list of all extensions
-                await InstallableExtension.get_installable_extensions()
+                await InstallableExtension.get_installable_extensions(
+                    post_refresh_cache=True
+                )
             except Exception as ex:
                 logger.error(ex)
 

lnbits/core/views/extension_api.py

@@ -508,7 +508,9 @@ async def extensions(account_id: AccountId = Depends(check_account_id_exists)):
     installed_exts: list[InstallableExtension] = await get_installed_extensions()
     installed_exts_ids = [e.id for e in installed_exts]
 
-    installable_exts = await InstallableExtension.get_installable_extensions()
+    installable_exts = await InstallableExtension.get_installable_extensions(
+        post_refresh_cache=account_id.is_admin_id
+    )
     installable_exts_ids = [e.id for e in installable_exts]
     installable_exts += [e for e in installed_exts if e.id not in installable_exts_ids]
 

lnbits/utils/cache.py

@@ -13,6 +13,9 @@ class Cached(NamedTuple):
     value: Any
     expiry: float
 
+    def older_than(self, seconds: float) -> bool:
+        return time() - self.expiry > seconds
+
 
 class Cache:
     """
@@ -23,6 +26,9 @@ class Cache:
         self.interval = interval
         self._values: dict[Any, Cached] = {}
 
+    def value(self, key: str) -> Cached | None:
+        return self._values.get(key)
+
     def get(self, key: str, default=None) -> Any | None:
         cached = self._values.get(key)
         if cached is not None: