Defer execution of main until resume for hot restart with DDC library bundle format #2623
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… bundle format pause_isolates_on_start tells DWDS and the client that during a hot restart or a hot reload, the VM service will pause and is actively waiting for the client to remove existing breakpoints, reregister them, and then resume. It lets the client know by sending a kPausePostRequest event. In order to do this in DWDS, we need to defer the execution of main until that resume. So, like we do with the require restarter, we wait for a completer to finish before we call main after a hot restart. This completer is only provided when the flag is enabled. Fixes existing code that marks the completer as completed before running main. The previous code canceled the subscription in an unawaited Future. This may result in us recalling main because the event stream could still have a listener. An example is if we hit a breakpoint immediately after main and call resume. Also fixes an issue where metadata information isn't recomputed on a hot restart. This is needed when new files are added. Adds tests for: - Modifying a line with a breakpoint and restarting. - Adding a line before a breakpoint and restarting. - Removing a line before a breakpoint and restarting. - Adding a file and putting a breakpoint in it before restarting.
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I believe this should be ready for review - the test failures seem to be tied to existing failures which require investigation. |
nshahan
reviewed
May 27, 2025
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@bkonyi Whenever you get a chance, can I have you review this as well? |
nshahan
approved these changes
May 29, 2025
bkonyi
approved these changes
May 30, 2025
…ns of console logs after resume to use a future instead
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Thanks! I added logic to check that there are no breakpoints in the isolate after a hot restart but before we process a |
- Recompile is needed for the frontend server even when no edits are made - Also use expectAll in hot_restart_breakpoints_test
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Revisions updated by `dart tools/rev_sdk_deps.dart`. ai (https://github.com/dart-lang/ai/compare/1d9d60c..f2b48c6): f2b48c6 2025-06-09 Nate Bosch Retain compatibility with 3.7 SDKs (dart-lang/ai#163) 52adf08 2025-06-06 Jacob MacDonald add homepage, repository, and documentation links to the pub result (dart-lang/ai#155) fa1c2be 2025-06-06 Nate Bosch Always use the failures-only reporter for testing (dart-lang/ai#160) 66a152f 2025-06-06 Nate Bosch Instruct clients to prefer MCP (dart-lang/ai#161) 55ad850 2025-06-05 Jacob MacDonald Add a retroactive changelog (dart-lang/ai#157) b08a610 2025-06-05 Jacob MacDonald Update instructions, add cursor install link (dart-lang/ai#159) web (https://github.com/dart-lang/web/compare/f1becf0..de6b3e4): de6b3e4 2025-06-06 Srujan Gaddam Add missing copyrights and delete empty files (dart-lang/web#371) 74a33ba 2025-06-06 Kevin Moore Add in a missing library directive, missing new line (dart-lang/web#370) 4d24eb5 2025-06-06 nikeokoronkwo [web_generator] Setting up `web_generator` for Dart JS Interop Gen (dart-lang/web#368) webdev (https://github.com/dart-lang/webdev/compare/55941b0..661dafd): 661dafd4 2025-06-08 Srujan Gaddam Defer execution of main until resume for hot restart with DDC library bundle format (dart-lang/webdev#2623) 01a3b9d7 2025-06-06 Nicholas Shahan Remove skip from chrome proxy service test Change-Id: If3d4326d0bacf47a4d95520dbd0aac5fb58de439 Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/433363 Commit-Queue: Devon Carew <devoncarew@google.com> Reviewed-by: Konstantin Shcheglov <scheglov@google.com>
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pause_isolates_on_start tells DWDS and the client that during a hot restart or a hot reload, the VM service will pause and is actively waiting for the client to remove existing breakpoints, reregister them, and then resume. It lets the client know by sending a PausePostRequest event.
In order to do this in DWDS, we need to defer the execution of main until that resume. So, like we do with the require restarter, we wait for a completer to finish before we call main after a hot restart. This completer is only provided when the flag is enabled.
Fixes existing code that marks the completer as completed before running main. The previous code canceled the subscription in an unawaited Future. This may result in us recalling main because the event stream could still have a listener. An example is if we hit a breakpoint immediately after main and call resume.
Also fixes an issue where metadata information isn't recomputed on a hot restart. This is needed when new files are added.
Adds tests for: