feat: improve translation propagation performance

Bulk update units and create changes instead of doing all the operations
manually. This should considerable reduce time needed for propagation,
but still there is some time to be spent on checks.

docs/admin/continuous.rst

@@ -468,6 +468,8 @@ Keeping translations same across components
 Once you have multiple translation components, you might want to ensure that
 the same strings have same translation. This can be achieved at several levels.
 
+.. _translation-propagation:
+
 Translation propagation
 +++++++++++++++++++++++
 

docs/changes.rst

@@ -17,6 +17,7 @@ Not yet released.
 * Editor in :ref:`zen-mode` is now stick to bottom of screen.
 * Added page navigation while :ref:`translating`.
 * :ref:`manage-appearance` now has distinct settings for dark mode.
+* Improved :ref:`translation-propagation` performance.
 
 **Bug fixes**
 * Using the `has:variant` field now correctly displays strings that have variant(s) in the search language, see :ref:`search-strings`.

weblate/trans/models/unit.py

@@ -1040,7 +1040,7 @@ def propagate(self, user: User, change_action=None, author=None, request=None):
         """Propagate current translation to all others."""
         from weblate.auth.permissions import PermissionResult
 
-        result = False
+        to_update: list[Unit] = []
         for unit in self.same_source_units:
             if unit.target == self.target and unit.state == self.state:
                 continue
@@ -1057,15 +1057,32 @@ def propagate(self, user: User, change_action=None, author=None, request=None):
                 continue
             unit.target = self.target
             unit.state = self.state
-            unit.save_backend(
-                user,
-                propagate=False,
-                change_action=change_action,
-                author=None,
-                run_checks=False,
-            )
-            result = True
-        return result
+            unit.commit_if_pending(user)
+            to_update.append(unit)
+
+        if not to_update:
+            return False
+
+        # Bulk update units
+        Unit.objects.filter(pk__in=(unit.pk for unit in to_update)).update(
+            target=self.target,
+            state=self.state,
+            last_updated=self.last_updated,
+        )
+
+        # Postprocess changes and generate change objects
+        changes = [
+            unit.post_save(user, user, None, check_new=False, save=False)
+            for unit in to_update
+        ]
+
+        # Bulk create changes
+        Change.objects.bulk_create(changes)
+
+        # Update user stats
+        user.profile.increase_count("translated", len(to_update))
+
+        return True
 
     def commit_if_pending(self, author: User) -> None:
         """Commit possible previous changes on this unit."""
@@ -1141,8 +1158,28 @@ def save_backend(
             propagate_checks=was_propagated or changed,
         )
 
+        # Generate change and process it
+        self.post_save(user or author, author, change_action)
+
+        # Update related source strings if working on a template
+        if self.translation.is_template and self.old_unit["target"] != self.target:
+            self.update_source_units(self.old_unit["target"], user or author, author)
+
+        return True
+
+    def post_save(
+        self,
+        user: User,
+        author: User | None,
+        change_action: int | None,
+        *,
+        save: bool = True,
+        check_new: bool = True,
+    ) -> Change:
         # Generate Change object for this change
-        change = self.generate_change(user or author, author, change_action)
+        change = self.generate_change(
+            user or author, author, change_action, save=save, check_new=check_new
+        )
 
         if change.action not in {
             Change.ACTION_UPLOAD,
@@ -1164,13 +1201,9 @@ def save_backend(
             )
 
             # Update user stats
-            change.author.profile.increase_count("translated")
-
-        # Update related source strings if working on a template
-        if self.translation.is_template and self.old_unit["target"] != self.target:
-            self.update_source_units(self.old_unit["target"], user or author, author)
-
-        return True
+            if save:
+                change.author.profile.increase_count("translated")
+        return change
 
     def update_source_units(
         self, previous_source: str, user: User, author: User | None
@@ -1229,7 +1262,7 @@ def generate_change(
         self,
         user: User | None,
         author: User | None,
-        change_action: int,
+        change_action: int | None,
         *,
         check_new: bool = True,
         save: bool = True,