Add UUID cache to new db backend

src/calibre/db/backend.py

@@ -29,7 +29,7 @@ from calibre.utils.magick.draw import save_cover_data_to
 from calibre.utils.recycle_bin import delete_tree
 from calibre.db.tables import (OneToOneTable, ManyToOneTable, ManyToManyTable,
         SizeTable, FormatsTable, AuthorsTable, IdentifiersTable, PathTable,
-        CompositeTable, LanguagesTable)
+        CompositeTable, LanguagesTable, UUIDTable)
 # }}}
 
 '''
@@ -701,7 +701,7 @@ class DB(object):
                         if col == 'cover' else col)
             if not metadata['column']:
                 metadata['column'] = col
-            tables[col] = (PathTable if col == 'path' else OneToOneTable)(col, metadata)
+            tables[col] = (PathTable if col == 'path' else UUIDTable if col == 'uuid' else OneToOneTable)(col, metadata)
 
         for col in ('series', 'publisher', 'rating'):
             tables[col] = ManyToOneTable(col, self.field_metadata[col].copy())

src/calibre/db/tables.py

@@ -98,6 +98,17 @@ class SizeTable(OneToOneTable):
                 'WHERE data.book=books.id) FROM books'):
             self.book_col_map[row[0]] = self.unserialize(row[1])
 
+class UUIDTable(OneToOneTable):
+
+    def read(self, db):
+        OneToOneTable.read(self, db)
+        self.uuid_to_id_map = {v:k for k, v in self.book_col_map.iteritems()}
+
+    def update_uuid_cache(self, book_id_val_map):
+        for book_id, uuid in book_id_val_map.iteritems():
+            self.uuid_to_id_map.pop(self.book_col_map[book_id], None)  # discard old uuid
+            self.uuid_to_id_map[uuid] = book_id
+
 class CompositeTable(OneToOneTable):
 
     def read(self, db):

src/calibre/db/write.py

@@ -174,12 +174,19 @@ def one_one_in_books(book_id_val_map, db, field, *args):
         db.conn.executemany(
             'UPDATE books SET %s=? WHERE id=?'%field.metadata['column'], sequence)
         field.table.book_col_map.update(book_id_val_map)
-    if field.name == 'title':
-        # Set the title sort field
-        field.title_sort_field.writer.set_books(
-            {k:title_sort(v) for k, v in book_id_val_map.iteritems()}, db)
     return set(book_id_val_map)
 
+def set_uuid(book_id_val_map, db, field, *args):
+    field.table.update_uuid_cache(book_id_val_map)
+    return one_one_in_books(book_id_val_map, db, field, *args)
+
+def set_title(book_id_val_map, db, field, *args):
+    ans = one_one_in_books(book_id_val_map, db, field, *args)
+    # Set the title sort field
+    field.title_sort_field.writer.set_books(
+        {k:title_sort(v) for k, v in book_id_val_map.iteritems()}, db)
+    return ans
+
 def one_one_in_other(book_id_val_map, db, field, *args):
     'Set a one-one field in the non-books table, like comments'
     deleted = tuple((k,) for k, v in book_id_val_map.iteritems() if v is None)
@@ -460,6 +467,10 @@ class Writer(object):
             self.set_books_func = custom_series_index
         elif self.name == 'identifiers':
             self.set_books_func = identifiers
+        elif self.name == 'uuid':
+            self.set_books_func = set_uuid
+        elif self.name == 'title':
+            self.set_books_func = set_title
         elif field.is_many_many:
             self.set_books_func = many_many
         elif field.is_many: