Changes as discussed. Tests improved to check that the cache is cleared and that ProxyMetadata returns the link map

src/calibre/db/cache.py

@@ -291,7 +291,14 @@ class Cache:
             self.format_metadata_cache.clear()
         if search_cache:
             self._clear_search_caches(book_ids)
-        self.link_maps_cache = {}
+        self.clear_link_map_cache(book_ids)
+
+    def clear_link_map_cache(self, book_ids=None):
+        if book_ids is None:
+            self.link_maps_cache = {}
+        else:
+            for book in book_ids:
+                self.link_maps_cache.pop(book, None)
 
     @write_api
     def reload_from_db(self, clear_caches=True):
@@ -1487,6 +1494,7 @@ class Cache:
             if update_path and do_path_update:
                 self._update_path(dirtied, mark_as_dirtied=False)
             self._mark_as_dirty(dirtied)
+            self.clear_link_map_cache(dirtied)
             self.event_dispatcher(EventType.metadata_changed, name, dirtied)
         return dirtied
 
@@ -1502,6 +1510,7 @@ class Cache:
             self.format_metadata_cache.pop(book_id, None)
             if mark_as_dirtied:
                 self._mark_as_dirty(book_ids)
+            self.clear_link_map_cache(book_ids)
 
     @read_api
     def get_a_dirtied_book(self):
@@ -2161,6 +2170,7 @@ class Cache:
                 for book_id in moved_books:
                     self._set_field(f.index_field.name, {book_id:self._get_next_series_num_for(self._fast_field_for(f, book_id), field=field)})
             self._mark_as_dirty(affected_books)
+            self.clear_link_map_cache(affected_books)
         self.event_dispatcher(EventType.items_renamed, field, affected_books, id_map)
         return affected_books, id_map
 
@@ -2180,6 +2190,7 @@ class Cache:
                 self._set_field(field.index_field.name, {bid:1.0 for bid in affected_books})
             else:
                 self._mark_as_dirty(affected_books)
+            self.clear_link_map_cache(affected_books)
         self.event_dispatcher(EventType.items_removed, field, affected_books, item_ids)
         return affected_books
 
@@ -2314,6 +2325,7 @@ class Cache:
                 self._set_field('author_sort', val_map)
         if changed_books:
             self._mark_as_dirty(changed_books)
+            self.clear_link_map_cache(changed_books)
         return changed_books
 
     @write_api
@@ -2324,6 +2336,7 @@ class Cache:
             changed_books |= self._books_for_field('authors', author_id)
         if changed_books:
             self._mark_as_dirty(changed_books)
+            self.clear_link_map_cache(changed_books)
         return changed_books
 
     @read_api
@@ -2416,6 +2429,7 @@ class Cache:
             changed_books |= self._books_for_field(field, id_)
         if changed_books:
             self._mark_as_dirty(changed_books)
+            self.clear_link_map_cache(changed_books)
         return changed_books
 
     @read_api

src/calibre/db/lazy.py

@@ -330,9 +330,6 @@ class ProxyMetadata(Metadata):
         sa(self, '_user_metadata', db.field_metadata)
 
     def __getattribute__(self, field):
-        if field == 'link_maps':
-            db = ga(self, '_db')()
-            return db.get_all_link_maps_for_book(ga(self, '_book_id'))
         getter = getters.get(field, None)
         if getter is not None:
             return getter(ga(self, '_db'), ga(self, '_book_id'), ga(self, '_cache'))
@@ -354,6 +351,10 @@ class ProxyMetadata(Metadata):
                 return custom_getter(field, ga(self, '_db'), ga(self, '_book_id'), ga(self, '_cache'))
             return composite_getter(self, field, ga(self, '_db'), ga(self, '_book_id'), ga(self, '_cache'), ga(self, 'formatter'), ga(self, 'template_cache'))
 
+        if field == 'link_maps':
+            db = ga(self, '_db')()
+            return db.get_all_link_maps_for_book(ga(self, '_book_id'))
+
         try:
             return ga(self, '_cache')[field]
         except KeyError:

src/calibre/db/schema_upgrades.py

@@ -795,6 +795,7 @@ CREATE TRIGGER fkc_annot_update
         self.db.reindex_annotations()
 
     def upgrade_version_25(self):
+        alters = []
         for record in self.db.execute(
                 'SELECT label,name,datatype,editable,display,normalized,id,is_multiple FROM custom_columns'):
             data = {
@@ -809,12 +810,14 @@ CREATE TRIGGER fkc_annot_update
                     }
             if data['normalized']:
                 tn = 'custom_column_{}'.format(data['num'])
-                self.db.execute(f'ALTER TABLE {tn} ADD COLUMN link TEXT NOT NULL DEFAULT "";')
+                alters.append(f'ALTER TABLE {tn} ADD COLUMN link TEXT NOT NULL DEFAULT "";')
-        self.db.execute('ALTER TABLE publishers ADD COLUMN link TEXT NOT NULL DEFAULT "";')
+
-        self.db.execute('ALTER TABLE series ADD COLUMN link TEXT NOT NULL DEFAULT "";')
+        alters.append('ALTER TABLE publishers ADD COLUMN link TEXT NOT NULL DEFAULT "";')
-        self.db.execute('ALTER TABLE tags ADD COLUMN link TEXT NOT NULL DEFAULT "";')
+        alters.append('ALTER TABLE series ADD COLUMN link TEXT NOT NULL DEFAULT "";')
+        alters.append('ALTER TABLE tags ADD COLUMN link TEXT NOT NULL DEFAULT "";')
         # These aren't necessary in that there is no UI to set links, but having them
         # makes the code uniform
-        self.db.execute('ALTER TABLE languages ADD COLUMN link TEXT NOT NULL DEFAULT "";')
+        alters.append('ALTER TABLE languages ADD COLUMN link TEXT NOT NULL DEFAULT "";')
-        self.db.execute('ALTER TABLE ratings ADD COLUMN link TEXT NOT NULL DEFAULT "";')
+        alters.append('ALTER TABLE ratings ADD COLUMN link TEXT NOT NULL DEFAULT "";')
+        self.db.execute('\n'.join(alters))
 

src/calibre/db/tests/writing.py

@@ -946,6 +946,25 @@ class WritingTest(BaseTest):
         self.assertEqual('url', links['tags']['foo'], 'link for tag foo is wrong')
         self.assertEqual('url2', links['publisher']['random'], 'link for publisher random is wrong')
 
+        # Check that renaming a tag keeps the link and clears the link map cache for the book
+        self.assertTrue(1 in cache.link_maps_cache, "book not in link_map_cache")
+        tag_id = cache.get_item_id('tags', 'foo')
+        cache.rename_items('tags', {tag_id: 'foobar'})
+        self.assertTrue(1 not in cache.link_maps_cache, "book still in link_map_cache")
+        links = cache.get_link_map('tags')
+        self.assertTrue('foobar' in links, "rename foo lost the link")
+        self.assertEqual(links['foobar'], 'url', "The link changed contents")
+        links = cache.get_all_link_maps_for_book(1)
+        self.assertTrue(1 in cache.link_maps_cache, "book not put back into link_map_cache")
+        self.assertDictEqual({'publisher': {'random': 'url2'}, 'tags': {'foobar': 'url'}},
+                             links, "book links incorrect after tag rename")
+
+        # Check ProxyMetadata
+        mi = cache.get_proxy_metadata(1)
+        self.assertDictEqual({'publisher': {'random': 'url2'}, 'tags': {'foobar': 'url'}},
+                             mi.link_maps, "ProxyMetadata didn't return the right link map")
+
+
         # Now test deleting the links.
         links = cache.get_link_map('tags')
         to_del = {l:'' for l in links.keys()}