Speed up deleting of large numbers of books and show progress while doing so

src/calibre/gui2/actions/delete.py

@@ -5,13 +5,65 @@ __license__   = 'GPL v3'
 __copyright__ = '2010, Kovid Goyal <kovid@kovidgoyal.net>'
 __docformat__ = 'restructuredtext en'
 
-from PyQt4.Qt import QMenu
+from functools import partial
+
+from PyQt4.Qt import QMenu, QObject, QTimer
 
 from calibre.gui2 import error_dialog
 from calibre.gui2.dialogs.delete_matching_from_device import DeleteMatchingFromDeviceDialog
 from calibre.gui2.dialogs.confirm_delete import confirm
 from calibre.gui2.actions import InterfaceAction
 
+single_shot = partial(QTimer.singleShot, 10)
+
+class MultiDeleter(QObject):
+
+    def __init__(self, gui, rows, callback):
+        from calibre.gui2.dialogs.progress import ProgressDialog
+        QObject.__init__(self, gui)
+        self.model = gui.library_view.model()
+        self.ids = list(map(self.model.id, rows))
+        self.gui = gui
+        self.failures = []
+        self.deleted_ids = []
+        self.callback = callback
+        single_shot(self.delete_one)
+        self.pd = ProgressDialog(_('Deleting...'), parent=gui,
+                cancelable=False, min=0, max=len(self.ids))
+        self.pd.setModal(True)
+        self.pd.show()
+
+    def delete_one(self):
+        if not self.ids:
+            self.cleanup()
+            return
+        id_ = self.ids.pop()
+        title = 'id%d'%id_
+        try:
+            title = self.model.db.title(id_, index_is_id=True)
+            self.model.db.delete_book(id_, notify=False, commit=False)
+            self.deleted_ids.append(id_)
+        except:
+            import traceback
+            self.failures.append((id_, title, traceback.format_exc()))
+        single_shot(self.delete_one)
+        self.pd.value += 1
+        self.pd.set_msg(_('Deleted') + ' ' + title)
+
+    def cleanup(self):
+        self.pd.hide()
+        self.pd = None
+        self.model.db.commit()
+        self.model.db.clean()
+        self.model.books_deleted()
+        self.gui.tags_view.recount()
+        self.callback(self.deleted_ids)
+        if self.failures:
+            msg = ['==>'+x[1]+'\n'+x[2] for x in self.failures]
+            error_dialog(self.gui, _('Failed to delete'),
+                    _('Failed to delete some books, click the Show Details button'
+                    ' for details.'), det_msg='\n\n'.join(msg), show=True)
+
 class DeleteAction(InterfaceAction):
 
     name = 'Remove Books'
@@ -179,8 +231,13 @@ class DeleteAction(InterfaceAction):
             row = None
             if ci.isValid():
                 row = ci.row()
-            ids_deleted = view.model().delete_books(rows)
-            self.library_ids_deleted(ids_deleted, row)
+            if len(rows) < 5:
+                ids_deleted = view.model().delete_books(rows)
+                self.library_ids_deleted(ids_deleted, row)
+            else:
+                self.__md = MultiDeleter(self.gui, rows,
+                        partial(self.library_ids_deleted, current_row=row))
+
         else:
             if not confirm('<p>'+_('The selected books will be '
                                    '<b>permanently deleted</b> '

src/calibre/gui2/library/models.py

@@ -223,21 +223,22 @@ class BooksModel(QAbstractTableModel): # {{{
     def by_author(self):
         return self.sorted_on[0] == 'authors'
 
+    def books_deleted(self):
+        self.count_changed()
+        self.clear_caches()
+        self.reset()
+
     def delete_books(self, indices):
         ids = map(self.id, indices)
         for id in ids:
             self.db.delete_book(id, notify=False)
-        self.count_changed()
-        self.clear_caches()
-        self.reset()
+        self.books_deleted()
         return ids
 
     def delete_books_by_id(self, ids):
         for id in ids:
             self.db.delete_book(id)
-        self.count_changed()
-        self.clear_caches()
-        self.reset()
+        self.books_deleted()
 
     def books_added(self, num):
         if num > 0:

src/calibre/library/database2.py

@@ -953,23 +953,24 @@ class LibraryDatabase2(LibraryDatabase, SchemaUpgrade, CustomColumns):
             self.notify('metadata', [id])
         return True
 
-    def delete_book(self, id, notify=True):
+    def delete_book(self, id, notify=True, commit=True):
         '''
         Removes book from the result cache and the underlying database.
+        If you set commit to False, you must call clean() manually afterwards
         '''
         try:
             path = os.path.join(self.library_path, self.path(id, index_is_id=True))
         except:
             path = None
-        self.data.remove(id)
         if path and os.path.exists(path):
             self.rmtree(path)
             parent = os.path.dirname(path)
             if len(os.listdir(parent)) == 0:
                 self.rmtree(parent)
         self.conn.execute('DELETE FROM books WHERE id=?', (id,))
-        self.conn.commit()
-        self.clean()
+        if commit:
+            self.conn.commit()
+            self.clean()
         self.data.books_deleted([id])
         if notify:
             self.notify('delete', [id])