fix(session): cap Retry-After on the requests retry policies

A server-sent Retry-After could park a run for up to six hours.

tests/core/test_retry_after.py

@@ -6,7 +6,9 @@ from types import SimpleNamespace
 
 import pytest
 
-from unshackle.core.session import RnetSession
+from unshackle.core.providers.imdb import IMDBProvider
+from unshackle.core.service import Service
+from unshackle.core.session import MAX_BACKOFF, RnetSession
 
 
 @pytest.fixture
@@ -67,3 +69,15 @@ def test_exponential_backoff_without_retry_after(session):
 
 def test_no_response_still_backs_off(session):
     assert session.get_sleep_time(None, 30) == session.max_backoff
+
+
+def test_service_session_caps_retry_after():
+    retry = Service.get_session().get_adapter("https://example.invalid/").max_retries
+    assert retry.respect_retry_after_header
+    assert retry.retry_after_max == MAX_BACKOFF
+
+
+def test_provider_session_gives_up_on_a_rate_limit():
+    retry = IMDBProvider().session.get_adapter("https://example.invalid/").max_retries
+    assert not retry.respect_retry_after_header
+    assert 429 not in retry.status_forcelist

unshackle/core/providers/_base.py

@@ -61,7 +61,7 @@ class MetadataProvider(metaclass=ABCMeta):
             retry = Retry(
                 total=3,
                 backoff_factor=1,
-                status_forcelist=[429, 500, 502, 503, 504],
+                status_forcelist=[500, 502, 503, 504],
                 allowed_methods=["GET", "POST"],
                 respect_retry_after_header=False,
             )

unshackle/core/remote_service.py

@@ -38,6 +38,7 @@ from unshackle.core.console import console, prompt_user
 from unshackle.core.constants import AnyTrack
 from unshackle.core.credential import Credential
 from unshackle.core.proxies.resolve import is_loopback
+from unshackle.core.session import MAX_BACKOFF
 from unshackle.core.titles import Title_T, Titles_T, remap_titles
 from unshackle.core.titles.episode import Episode, Series
 from unshackle.core.titles.movie import Movie, Movies
@@ -921,7 +922,12 @@ class RemoteService:
         self._session.mount(
             "https://",
             HTTPAdapter(
-                max_retries=Retry(total=5, backoff_factor=0.2, status_forcelist=[429, 500, 502, 503, 504]),
+                max_retries=Retry(
+                    total=5,
+                    backoff_factor=0.2,
+                    status_forcelist=[429, 500, 502, 503, 504],
+                    retry_after_max=MAX_BACKOFF,
+                ),
                 pool_maxsize=64,
                 pool_block=True,
             ),

unshackle/core/service.py

@@ -431,6 +431,7 @@ class Service(metaclass=ABCMeta):
                     status_forcelist=STATUS_FORCELIST,
                     allowed_methods=RETRY_METHODS,
                     respect_retry_after_header=True,
+                    retry_after_max=MAX_BACKOFF,
                 ),
                 pool_connections=POOL_MAX_SIZE,
                 pool_maxsize=POOL_MAX_SIZE,

unshackle/core/tracks/track.py

@@ -31,7 +31,7 @@ from unshackle.core.downloaders import requests
 from unshackle.core.drm import DRM_T, ClearKeyCENC, PlayReady, Widevine
 from unshackle.core.drm.verify import decrypt_track
 from unshackle.core.events import events
-from unshackle.core.session import RnetSession, utf8_text
+from unshackle.core.session import MAX_BACKOFF, RnetSession, utf8_text
 from unshackle.core.tracks import resume
 from unshackle.core.utilities import get_boxes, log_event, try_ensure_utf8
 from unshackle.core.utils.subprocess import ffprobe
@@ -78,7 +78,12 @@ def direct_session(session: Union[Session, "RnetSession"], proxy: Optional[str]
     new.mount(
         "https://",
         HTTPAdapter(
-            max_retries=Retry(total=5, backoff_factor=0.2, status_forcelist=[429, 500, 502, 503, 504]),
+            max_retries=Retry(
+                total=5,
+                backoff_factor=0.2,
+                status_forcelist=[429, 500, 502, 503, 504],
+                retry_after_max=MAX_BACKOFF,
+            ),
             pool_maxsize=64,
             pool_block=True,
         ),