From 1f2af3a2909e1979d22834652e28662ba4db754b Mon Sep 17 00:00:00 2001
From: I-Al-Istannen <i-al-istannen@users.noreply.github.com>
Date: Tue, 13 Apr 2021 11:32:55 +0200
Subject: [PATCH] Retry on more I/O Errors

---
 PFERD/errors.py           | 18 ++++++++++++++++++
 PFERD/ilias/crawler.py    |  3 ++-
 PFERD/ilias/downloader.py | 24 +++++++++++-------------
 3 files changed, 31 insertions(+), 14 deletions(-)

diff --git a/PFERD/errors.py b/PFERD/errors.py
index d003314..d960e13 100644
--- a/PFERD/errors.py
+++ b/PFERD/errors.py
@@ -37,3 +37,21 @@ def swallow_and_print_errors(function: TFun) -> TFun:
             Console().print_exception()
             return None
     return cast(TFun, inner)
+
+
+def retry_on_io_exception(max_retries: int, message: str) -> Callable[[TFun], TFun]:
+    """
+    Decorates a function and retries it on any exception until the max retries count is hit.
+    """
+    def retry(function: TFun) -> TFun:
+        def inner(*args: Any, **kwargs: Any) -> Any:
+            for i in range(0, max_retries):
+                # pylint: disable=broad-except
+                try:
+                    return function(*args, **kwargs)
+                except IOError as error:
+                    PRETTY.warning(f"Error duing operation '{message}': {error}")
+                    PRETTY.warning(
+                        f"Retrying operation '{message}'. Remaining retries: {max_retries - 1 - i}")
+        return cast(TFun, inner)
+    return retry
diff --git a/PFERD/ilias/crawler.py b/PFERD/ilias/crawler.py
index 93b626e..edab284 100644
--- a/PFERD/ilias/crawler.py
+++ b/PFERD/ilias/crawler.py
@@ -15,7 +15,7 @@ from urllib.parse import (parse_qs, urlencode, urljoin, urlparse, urlsplit,
 import bs4
 import requests
 
-from ..errors import FatalException
+from ..errors import FatalException, retry_on_io_exception
 from ..logging import PrettyLogger
 from ..utils import soupify
 from .authenticators import IliasAuthenticator
@@ -625,6 +625,7 @@ class IliasCrawler:
 
         return results
 
+    @retry_on_io_exception(3, "fetching webpage")
     def _get_page(self, url: str, params: Dict[str, Any],
                   retry_count: int = 0) -> bs4.BeautifulSoup:
         """
diff --git a/PFERD/ilias/downloader.py b/PFERD/ilias/downloader.py
index 26e1f2d..f6132bf 100644
--- a/PFERD/ilias/downloader.py
+++ b/PFERD/ilias/downloader.py
@@ -10,6 +10,7 @@ from typing import Callable, List, Optional, Union
 import bs4
 import requests
 
+from ..errors import retry_on_io_exception
 from ..logging import PrettyLogger
 from ..organizer import Organizer
 from ..tmp_dir import TmpDir
@@ -116,26 +117,23 @@ class IliasDownloader:
         """
 
         LOGGER.debug("Downloading %r", info)
+
         if not self._strategy(self._organizer, info):
             self._organizer.mark(info.path)
             return
 
         tmp_file = self._tmp_dir.new_path()
 
-        download_successful = False
-        for _ in range(0, 3):
-            try:
-                if not self._try_download(info, tmp_file):
-                    LOGGER.info("Re-Authenticating due to download failure: %r", info)
-                    self._authenticator.authenticate(self._session)
-                else:
-                    download_successful = True
-                    break
-            except IOError as e:
-                PRETTY.warning(f"I/O Error when downloading ({e}). Retrying...",)
-            LOGGER.info("Retrying download for %s", info.path)
+        @retry_on_io_exception(3, "downloading file")
+        def download_impl() -> bool:
+            if not self._try_download(info, tmp_file):
+                LOGGER.info("Re-Authenticating due to download failure: %r", info)
+                self._authenticator.authenticate(self._session)
+                raise IOError("Scheduled retry")
+            else:
+                return True
 
-        if not download_successful:
+        if not download_impl():
             PRETTY.error(f"Download of file {info.path} failed too often! Skipping it...")
             return