1 files changed, 23 insertions, 24 deletions

diff --git a/hypervideo_dl/cache.py b/hypervideo_dl/cache.py
index 24acb1b..2e9c1ef 100644
--- a/hypervideo_dl/cache.py
+++ b/hypervideo_dl/cache.py
@@ -1,28 +1,23 @@
-from __future__ import unicode_literals
-
+import contextlib
 import errno
-import io
 import json
 import os
 import re
 import shutil
 import traceback
 
-from .compat import compat_getenv
-from .utils import (
-    expand_path,
-    write_json_file,
-)
+from .utils import expand_path, traverse_obj, version_tuple, write_json_file
+from .version import __version__
 
 
-class Cache(object):
+class Cache:
     def __init__(self, ydl):
         self._ydl = ydl
 
     def _get_root_dir(self):
         res = self._ydl.params.get('cachedir')
         if res is None:
-            cache_root = compat_getenv('XDG_CACHE_HOME', '~/.cache')
+            cache_root = os.getenv('XDG_CACHE_HOME', '~/.cache')
             res = os.path.join(cache_root, 'hypervideo')
         return expand_path(res)
 
@@ -31,7 +26,7 @@ class Cache(object):
             'invalid section %r' % section
         assert re.match(r'^[a-zA-Z0-9_.-]+$', key), 'invalid key %r' % key
         return os.path.join(
-            self._get_root_dir(), section, '%s.%s' % (key, dtype))
+            self._get_root_dir(), section, f'{key}.{dtype}')
 
     @property
     def enabled(self):
@@ -51,33 +46,37 @@ class Cache(object):
                 if ose.errno != errno.EEXIST:
                     raise
             self._ydl.write_debug(f'Saving {section}.{key} to cache')
-            write_json_file(data, fn)
+            write_json_file({'hypervideo_version': __version__, 'data': data}, fn)
         except Exception:
             tb = traceback.format_exc()
-            self._ydl.report_warning(
-                'Writing cache to %r failed: %s' % (fn, tb))
+            self._ydl.report_warning(f'Writing cache to {fn!r} failed: {tb}')
+
+    def _validate(self, data, min_ver):
+        version = traverse_obj(data, 'hypervideo_version')
+        if not version:  # Backward compatibility
+            data, version = {'data': data}, '2022.08.19'
+        if not min_ver or version_tuple(version) >= version_tuple(min_ver):
+            return data['data']
+        self._ydl.write_debug(f'Discarding old cache from version {version} (needs {min_ver})')
 
-    def load(self, section, key, dtype='json', default=None):
+    def load(self, section, key, dtype='json', default=None, *, min_ver=None):
         assert dtype in ('json',)
 
         if not self.enabled:
             return default
 
         cache_fn = self._get_cache_fn(section, key, dtype)
-        try:
+        with contextlib.suppress(OSError):
             try:
-                with io.open(cache_fn, 'r', encoding='utf-8') as cachef:
+                with open(cache_fn, encoding='utf-8') as cachef:
                     self._ydl.write_debug(f'Loading {section}.{key} from cache')
-                    return json.load(cachef)
-            except ValueError:
+                    return self._validate(json.load(cachef), min_ver)
+            except (ValueError, KeyError):
                 try:
                     file_size = os.path.getsize(cache_fn)
-                except (OSError, IOError) as oe:
+                except OSError as oe:
                     file_size = str(oe)
-                self._ydl.report_warning(
-                    'Cache retrieval from %s failed (%s)' % (cache_fn, file_size))
-        except IOError:
-            pass  # No cache available
+                self._ydl.report_warning(f'Cache retrieval from {cache_fn} failed ({file_size})')
 
         return default