cover_last_modified()

src/calibre/db/backend.py

@@ -963,6 +963,13 @@ class DB(object):
                 import traceback
                 traceback.print_exc()
 
+    def cover_last_modified(self, path):
+        path = os.path.abspath(os.path.join(self.library_path, path, 'cover.jpg'))
+        try:
+            return utcfromtimestamp(os.stat(path).st_mtime)
+        except EnvironmentError:
+            pass  # Cover doesn't exist
+
     def copy_cover_to(self, path, dest, windows_atomic_move=None, use_hardlink=False):
         path = os.path.abspath(os.path.join(self.library_path, path, 'cover.jpg'))
         if windows_atomic_move is not None:

src/calibre/db/cache.py

@@ -526,6 +526,14 @@ class Cache(object):
                 ret = i
         return ret
 
+    @read_api
+    def cover_last_modified(self, book_id):
+        try:
+            path = self._field_for('path', book_id).replace('/', os.sep)
+        except AttributeError:
+            return
+        return self.backend.cover_last_modified(path)
+
     @read_api
     def copy_cover_to(self, book_id, dest, use_hardlink=False):
         '''

src/calibre/db/legacy.py

@@ -290,6 +290,10 @@ class LibraryDatabase(object):
         mi = self.new_api.get_metadata(book_id, get_cover=key == 'cover')
         return mi.get(key, default)
 
+    def cover_last_modified(self, index, index_is_id=False):
+        book_id = index if index_is_id else self.id(index)
+        return self.new_api.cover_last_modified(book_id) or self.last_modified()
+
     def authors_sort_strings(self, index, index_is_id=False):
         book_id = index if index_is_id else self.id(index)
         return list(self.new_api.author_sort_strings_for_books((book_id,))[book_id])