ci: cache the pinned Turnip archive and retry its download (#2276)

* ci: cache the pinned Turnip archive and retry its download

"Prepare graphics driver variants" fetched the same checksum-pinned Banners-Turnip
zip from GitHub on every run with a single 120 s attempt, so a 502 or a read
timeout failed whole PR builds three times today. The archive is now cached
between runs (it is still checked against its SHA-256 after a restore), and a
cold download is retried on timeouts, 429 and 5xx with a growing pause.

* ci: keep PowerVR's verified downloads between runs

tools/powervr/fetch.py already keeps checksum-verified downloads in
~/.cache/droiddeck-build, but CI never saved that folder, so every run fetched
the PowerVR components again and a read timeout failed "Build the add-on
packs". The folder joins the existing pack-inputs cache, keyed on
release.json too.

.github/workflows/build.yml

@@ -313,6 +313,11 @@ jobs:
       - name: Build the DiRT 3 / DiRT Showdown ws2_32 stand-in
         run: python3 tools/components/prepare.py dirt-ws2
 
+      - name: Cache graphics driver inputs
+        uses: actions/cache@v4
+        with:
+          path: app/build/quest-inputs
+          key: quest-inputs-${{ hashFiles('tools/quest/build-driver.py') }}
       - name: Prepare graphics driver variants
         run: python3 tools/quest/build-driver.py "$ANDROID_HOME/ndk/$NDK_VERSION"
       - name: Record and pack prepared components
@@ -558,9 +563,11 @@ jobs:
       - name: Cache checksum-pinned pack inputs
         uses: actions/cache@v4
         with:
-          path: ~/.cache/droiddeck-pack-inputs
-          key: pack-inputs-v1-${{ hashFiles('tools/packs/build.sh', 'tools/packs/fetch-verified.sh', 'tools/packs/tracking/release.env') }}
-          restore-keys: pack-inputs-v1-
+          path: |
+            ~/.cache/droiddeck-pack-inputs
+            ~/.cache/droiddeck-build
+          key: pack-inputs-v2-${{ hashFiles('tools/packs/build.sh', 'tools/packs/fetch-verified.sh', 'tools/packs/tracking/release.env', 'tools/powervr/release.json') }}
+          restore-keys: pack-inputs-v2-
       - name: Build the add-on packs
         run: |
           python3 tools/powervr/fetch.py

tools/quest/build-driver.py

@@ -7,6 +7,9 @@ import sys
 import tarfile
 import tempfile
 import hashlib
+import http.client
+import time
+import urllib.error
 import urllib.request
 import zipfile
 
@@ -32,11 +35,23 @@ def pack(entries, output):
     print(output)
 
 
+def download(url, attempts=4):
+    for attempt in range(1, attempts + 1):
+        try:
+            with urllib.request.urlopen(url, timeout=120) as response:
+                return response.read()
+        except (OSError, http.client.HTTPException) as error:
+            if attempt == attempts or isinstance(error, urllib.error.HTTPError) and error.code < 500 and error.code != 429:
+                raise
+            print(f'Download failed ({error}); retrying in {attempt * 15} s')
+            time.sleep(attempt * 15)
+
+
 def build_a6xx(ndk, output_dir=OUTPUT.parent, archive_path=None):
     cached = archive_path or ROOT / 'app/build/quest-inputs' / f'Turnip-{A6XX_TAG}.zip'
     if not cached.exists():
         cached.parent.mkdir(parents=True, exist_ok=True)
-        data = urllib.request.urlopen(A6XX_URL, timeout=120).read()
+        data = download(A6XX_URL)
         if hashlib.sha256(data).hexdigest() != A6XX_SHA256:
             raise ValueError('A6xx archive checksum mismatch')
         cached.write_bytes(data)

tools/tests/test_quest_driver_download.py

@@ -0,0 +1,56 @@
+import importlib.util
+import io
+import unittest
+import urllib.error
+from pathlib import Path
+from unittest import mock
+
+SCRIPT = Path(__file__).resolve().parents[1] / "quest/build-driver.py"
+spec = importlib.util.spec_from_file_location("build_driver", SCRIPT)
+driver = importlib.util.module_from_spec(spec)
+spec.loader.exec_module(driver)
+
+
+def http_error(code):
+    return urllib.error.HTTPError("https://example.invalid/a.zip", code, "error", {}, io.BytesIO())
+
+
+class Response(io.BytesIO):
+    def __enter__(self):
+        return self
+
+    def __exit__(self, *args):
+        self.close()
+
+
+class DriverDownloadTest(unittest.TestCase):
+    def fetch(self, *outcomes):
+        calls = []
+
+        def urlopen(url, timeout):
+            calls.append(url)
+            outcome = outcomes[len(calls) - 1]
+            if isinstance(outcome, Exception):
+                raise outcome
+            return Response(outcome)
+
+        with mock.patch.object(driver.urllib.request, "urlopen", urlopen), mock.patch.object(driver.time, "sleep") as sleep:
+            try:
+                return driver.download("https://example.invalid/a.zip"), len(calls), sleep.call_count
+            except Exception as error:
+                return error, len(calls), sleep.call_count
+
+    def test_a_timeout_or_server_error_is_retried(self):
+        self.assertEqual((b"zip", 3, 2), self.fetch(TimeoutError("read timed out"), http_error(502), b"zip"))
+
+    def test_a_missing_file_fails_at_once(self):
+        error, calls, sleeps = self.fetch(http_error(404))
+        self.assertEqual((404, 1, 0), (error.code, calls, sleeps))
+
+    def test_it_gives_up_after_the_last_attempt(self):
+        error, calls, sleeps = self.fetch(*[http_error(504)] * 4)
+        self.assertEqual((504, 4, 3), (error.code, calls, sleeps))
+
+
+if __name__ == "__main__":
+    unittest.main()