Add "triggers" to quickly decide when to not run builders. #4084

davidmorgan · 2025-07-08T11:00:33Z

Before/after incremental builds with a locally-configured annotation trigger for built_value, this with the --mostly-no-codegen option so most files should not run the builder.

before

5s built_value_generator:built_value on 1001 inputs: 2 same, 999 no-op; spent 3s analyzing                                                                                                                                                                   
1s source_gen:combining_builder on 1001 inputs: 999 skipped, 2 same; spent 1s tracking                                                                                                                                                                       
                                                                                                                                                                                                                                                             
Built with build_runner in 8s; wrote 4 outputs.

after

2s built_value_generator:built_value on 1001 inputs: 999 skipped, 1 not triggered, 1 same; spent 1s analyzing                                                                                                                                                
1s source_gen:combining_builder on 1001 inputs: 1000 skipped, 1 same; spent 1s tracking                                                                                                                                                                      
                                                                                                                                                                                                                                                             
Built with build_runner in 5s; wrote 2 outputs.

999 have changed from no-op to skipped: previously the builder would run and analyze all files, now build_runner has noticed that only a primary input change can affect triggering for 999 files and so they are skipped.

github-actions · 2025-07-08T11:02:36Z

PR Health

Changelog Entry ✔️

Package	Changed Files

Changes to files need to be accounted for in their respective changelogs.

jensjoha

This seems like an awful lot of manual config that's bound to go wrong at some point.
We can't do something similar without manual config?

jensjoha · 2025-08-11T06:40:01Z

build_runner_core/lib/src/package_graph/build_triggers.dart

+
+  @override
+  bool triggersOnPrimaryInput(String source) {
+    return source.contains('package:$import');


Technically an import string can be split into multiple lines, e.g.

import 'd' /* hello */ 'a' //there 'r' // I'm 't' // a ':' // perfectly 'i' // valid 'o' // import '' // ! ;

(and I have seen than --- not as absurdly as I did above but as I recall to make it fit on lines or something)

I was hesitant to do full parsing simply because there is no convenient place to dedupe the parsing work; but I do think it's better and the way to go in the end.

Filed #4128 to figure out a way to save parsing multiple times, and changed the code to do parsing so annotation + import checks are both (hopefully) now correct.

jensjoha · 2025-08-11T06:43:15Z

build_runner_core/lib/src/package_graph/build_triggers.dart

+
+  @override
+  bool triggersOnPrimaryInput(String source) {
+    return source.contains('@$annotation');


I believe @ myAnnotation is valid too.

Addressed by switch to parsing.

Also, I realized that annotations should be checked for in all compilation units, it's not like imports where they can only be in the main library. So, I added finding and loading all the parts for the check, and test coverage for that.

jensjoha · 2025-08-11T06:45:19Z

build_runner_core/lib/src/package_graph/build_triggers.dart

+      for (final entry in triggersByBuilder.entries) {
+        final builderName = entry.key;
+
+        if (!builderName.contains(_builderNamePattern)) {


Won't this be found below?

No, the checks below are just on the triggers, not the builder names.

jensjoha · 2025-08-11T06:46:47Z

build_runner_core/lib/src/package_graph/build_triggers.dart

+  /// message.
+  ///
+  /// The only supported trigger is [ImportBuildTrigger].
+  static (BuildTrigger?, String?) tryParse(String trigger) {


Could this be private?
If it has to be public I think I'd prefer a "proper return type" rather than a record.

Thanks; made private.

davidmorgan

Thanks, please take another look.

Re: config-based: the fact that it's config based rather than code means that the builder package, the user package and any additional package in the build can all contribute triggers.

Usually, only the builder package will want to define triggers, which would work in code; but then if you want to add a new way to trigger, e.g. to re-export an annotation, you're stuck.

My expectation is that for most builders, just a trigger defined with the builder works 95% of the time, and then a small number of advanced users defining new ways to run the builder can do what they want for the remaining 5%. One important case is one builder that triggers another, as freezed does with json_serializable ... that should work.

There's a suggestion to add a lint to point out cases where a trigger should be defined #4086

davidmorgan · 2025-08-11T07:44:24Z

build_runner_core/lib/src/package_graph/build_triggers.dart

+      for (final entry in triggersByBuilder.entries) {
+        final builderName = entry.key;
+
+        if (!builderName.contains(_builderNamePattern)) {


No, the checks below are just on the triggers, not the builder names.

davidmorgan · 2025-08-11T07:45:22Z

build_runner_core/lib/src/package_graph/build_triggers.dart

+  /// message.
+  ///
+  /// The only supported trigger is [ImportBuildTrigger].
+  static (BuildTrigger?, String?) tryParse(String trigger) {


Thanks; made private.

davidmorgan · 2025-08-11T11:44:58Z

build_runner_core/lib/src/package_graph/build_triggers.dart

+
+  @override
+  bool triggersOnPrimaryInput(String source) {
+    return source.contains('package:$import');


I was hesitant to do full parsing simply because there is no convenient place to dedupe the parsing work; but I do think it's better and the way to go in the end.

Filed #4128 to figure out a way to save parsing multiple times, and changed the code to do parsing so annotation + import checks are both (hopefully) now correct.

davidmorgan · 2025-08-11T11:45:56Z

build_runner_core/lib/src/package_graph/build_triggers.dart

+
+  @override
+  bool triggersOnPrimaryInput(String source) {
+    return source.contains('@$annotation');


Addressed by switch to parsing.

Also, I realized that annotations should be checked for in all compilation units, it's not like imports where they can only be in the main library. So, I added finding and loading all the parts for the check, and test coverage for that.

jensjoha · 2025-08-11T12:24:59Z

build_runner_core/lib/src/package_graph/build_triggers.dart

+            name = '$name.${metadata.constructorName}';
+          }
+          if (annotation == name) return true;
+          final periodIndex = name.indexOf('.');


Do we end up comparing to metadata.constructorName or could name (before line 216) have dots in it where we want to remove the first part? Could there be a comment explaining? (and either compare directly to metadata.constructorName or make sure we don't depending on what we're actually trying to achieve)

Thanks, added comment + a bit of test coverage on the awkward case. (Import prefixes and class names can't actually be distinguished).

davidmorgan mentioned this pull request Jul 8, 2025

Faster skip when annotation is not imported #4083

Open

davidmorgan force-pushed the run-heuristics branch 3 times, most recently from 466580e to 5deeaae Compare July 14, 2025 08:47

davidmorgan mentioned this pull request Jul 18, 2025

Support testing builder factories. #4102

Draft

davidmorgan force-pushed the run-heuristics branch 6 times, most recently from b575b09 to 0551fa2 Compare July 21, 2025 07:53

davidmorgan marked this pull request as ready for review July 21, 2025 07:58

davidmorgan mentioned this pull request Jul 23, 2025

Allow outputting to any subdirectory with $lib$ and $bin$ targets #4107

Open

davidmorgan force-pushed the run-heuristics branch 3 times, most recently from b7baf18 to 48f8008 Compare August 8, 2025 15:38

Add option to skip based on primary input content.

1329b6e

davidmorgan force-pushed the run-heuristics branch from 48f8008 to 1329b6e Compare August 8, 2025 15:53

davidmorgan changed the title ~~Add option to skip based on primary input content.~~ Add "triggers" to quickly decide when to not run builders. Aug 8, 2025

davidmorgan requested a review from jensjoha August 8, 2025 16:12

jensjoha reviewed Aug 11, 2025

View reviewed changes

davidmorgan mentioned this pull request Aug 11, 2025

Dedupe parse work #4128

Open

Address review comments.

9e3fff3

davidmorgan force-pushed the run-heuristics branch from f58f003 to 9e3fff3 Compare August 11, 2025 11:43

davidmorgan commented Aug 11, 2025

View reviewed changes

davidmorgan requested a review from jensjoha August 11, 2025 11:57

jensjoha approved these changes Aug 11, 2025

View reviewed changes

Address review comments.

55bef9f

davidmorgan merged commit f0a289e into dart-lang:master Aug 12, 2025
75 checks passed

davidmorgan deleted the run-heuristics branch August 12, 2025 06:17

Add "triggers" to quickly decide when to not run builders. #4084

Add "triggers" to quickly decide when to not run builders. #4084

Conversation

davidmorgan commented Jul 8, 2025 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Uh oh!

github-actions bot commented Jul 8, 2025 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

PR Health

Uh oh!

jensjoha left a comment

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

davidmorgan left a comment

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Uh oh!

Uh oh!

davidmorgan commented Jul 8, 2025 •

edited

Loading

github-actions bot commented Jul 8, 2025 •

edited

Loading