commit 5f75bb8ba25c963664d1d4be9cd07fd4c7141fac
author Brian Wilkerson <brianwilkerson@google.com> Thu May 15 10:12:20 2025 -0700
committer Commit Queue <dart-scoped@luci-project-accounts.iam.gserviceaccount.com> Thu May 15 10:12:20 2025 -0700
tree dca05ecc1ba6a7c515183b7e063a1e9dfb9ab94f
parent e6784e05800509b7407061815813bd4665bded3a

Replace change builder copying with a transactional model

Copying change builders in order to enable reverting changes from a
single correction producer when there's an exception is expensive.

This CL replaces that implementation with a transactional model.
Clients are not required to start a transaction (that happens
automatically), but are required to signal the end of a transaction by
invoking either `commit` or `revert`. (Actually, `commit` is assumed
if neither method is invoked before computing the `SourceChange`.)

There is some information in the Dart file edit builder related to
imports that isn't correctly handled. The reason for this is that too
much of the import computation is done up-front. I don't think this
will be a problem in practice (or at least not often), but we should
come back at some point to change the implementation so that we retain
abstract data longer and perform more processing at the very end (where
we'll have complete information and probably be able to do a better
job anyway).

This CL improved the performance of the benchmark that adds and applies
fixes for 10,000 lint violations.

  Before it took an average of 11216.0 ms.
  After it took an average of 4200.2 ms.

Which is about a 62% improvement.

Change-Id: I12710606455a04e34a82308ede5d9fba1c68b972
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/428060
Reviewed-by: Samuel Rawlins <srawlins@google.com>
Commit-Queue: Brian Wilkerson <brianwilkerson@google.com>