[cache] Add cache validation by program version, based on yt-dlp

1 files changed, 23 insertions, 5 deletions

diff --git a/youtube_dl/cache.py b/youtube_dl/cache.py
index 7bdade1bd..4822439d0 100644
--- a/youtube_dl/cache.py
+++ b/youtube_dl/cache.py
@@ -10,12 +10,21 @@ import traceback
 
 from .compat import compat_getenv
 from .utils import (
+    error_to_compat_str,
     expand_path,
+    is_outdated_version,
+    try_get,
     write_json_file,
 )
+from .version import __version__
 
 
 class Cache(object):
+
+    _YTDL_DIR = 'youtube-dl'
+    _VERSION_KEY = _YTDL_DIR + '_version'
+    _DEFAULT_VERSION = '2021.12.17'
+
     def __init__(self, ydl):
         self._ydl = ydl
 
@@ -23,7 +32,7 @@ class Cache(object):
         res = self._ydl.params.get('cachedir')
         if res is None:
             cache_root = compat_getenv('XDG_CACHE_HOME', '~/.cache')
-            res = os.path.join(cache_root, 'youtube-dl')
+            res = os.path.join(cache_root, self._YTDL_DIR)
         return expand_path(res)
 
     def _get_cache_fn(self, section, key, dtype):
@@ -50,13 +59,22 @@ class Cache(object):
             except OSError as ose:
                 if ose.errno != errno.EEXIST:
                     raise
-            write_json_file(data, fn)
+            write_json_file({self._VERSION_KEY: __version__, 'data': data}, fn)
         except Exception:
             tb = traceback.format_exc()
             self._ydl.report_warning(
                 'Writing cache to %r failed: %s' % (fn, tb))
 
-    def load(self, section, key, dtype='json', default=None):
+    def _validate(self, data, min_ver):
+        version = try_get(data, lambda x: x[self._VERSION_KEY])
+        if not version:  # Backward compatibility
+            data, version = {'data': data}, self._DEFAULT_VERSION
+        if not is_outdated_version(version, min_ver or '0', assume_new=False):
+            return data['data']
+        self._ydl.to_screen(
+            'Discarding old cache from version {version} (needs {min_ver})'.format(**locals()))
+
+    def load(self, section, key, dtype='json', default=None, min_ver=None):
         assert dtype in ('json',)
 
         if not self.enabled:
@@ -66,12 +84,12 @@ class Cache(object):
         try:
             try:
                 with io.open(cache_fn, 'r', encoding='utf-8') as cachef:
-                    return json.load(cachef)
+                    return self._validate(json.load(cachef), min_ver)
             except ValueError:
                 try:
                     file_size = os.path.getsize(cache_fn)
                 except (OSError, IOError) as oe:
-                    file_size = str(oe)
+                    file_size = error_to_compat_str(oe)
                 self._ydl.report_warning(
                     'Cache retrieval from %s failed (%s)' % (cache_fn, file_size))
         except IOError: