From d4158e37fbef05954139d1e7a33f8042a14fccf0 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?J=C3=B6rn-Michael=20Miehe?=
 <40151420+ldericher@users.noreply.github.com>
Date: Wed, 31 Aug 2022 10:20:54 +0000
Subject: [PATCH] DavFile async download

---
 api/ovkiosk/dav_file.py | 29 +++++++++++++++++++++++++----
 1 file changed, 25 insertions(+), 4 deletions(-)

diff --git a/api/ovkiosk/dav_file.py b/api/ovkiosk/dav_file.py
index 1e80c2e..549f352 100644
--- a/api/ovkiosk/dav_file.py
+++ b/api/ovkiosk/dav_file.py
@@ -1,3 +1,5 @@
+import asyncio
+import functools
 import logging
 from io import BytesIO
 from threading import Lock
@@ -9,6 +11,20 @@ from webdav3.client import Resource
 _logger = logging.getLogger(__name__)
 
 
+def run_in_executor(f):
+    """
+    Decorator to make blocking function call asyncio compatible
+    https://stackoverflow.com/questions/41063331/how-to-use-asyncio-with-existing-blocking-library/
+    """
+
+    @functools.wraps(f)
+    def inner(*args, **kwargs):
+        loop = asyncio.get_running_loop()
+        return loop.run_in_executor(None, functools.partial(f, *args, **kwargs))
+
+    return inner
+
+
 class DavFile:
     __instances: Optional[list["DavFile"]] = None
     __scheduler = None
@@ -25,12 +41,17 @@ class DavFile:
         if refresh:
             DavFile.__instances.append(self)
 
-    def download(self) -> None:
+    async def download(self) -> None:
+
+        @run_in_executor
+        def download_inner() -> None:
+            self.__resource.write_to(self.__buffer)
+
         _logger.info(f"updating {self.__resource}")
         with self.__lock:
             self.__buffer.seek(0)
             self.__buffer.truncate(0)
-            self.__resource.write_to(self.__buffer)
+            await download_inner()
 
     @classmethod
     def refresh(cls, refresh_interval: int = 60) -> None:
@@ -42,9 +63,9 @@ class DavFile:
             )
             return
 
-        def tick() -> None:
+        async def tick() -> None:
             for davfile in DavFile.__instances:
-                davfile.download()
+                await davfile.download()
 
         cls.__scheduler = AsyncIOScheduler()
         cls.__scheduler.start()