When `update()` is called while another update (typically the automatic
updater thread) is already running, the Rust updater previously bailed
with `UpdateError::UpdateAlreadyInProgress`, which surfaced in Dart as
`UpdateException: Update already in progress (unknown)`. This is the
single highest-volume `UpdateException` in customer telemetry, yet the
underlying situation is benign — the in-flight update continues on its
own, the caller simply did not start a new one.
Add a new `UpdateStatus::UpdateInProgress` variant and matching C
status code `SHOREBIRD_UPDATE_IN_PROGRESS = 4`. `updater::update()`
catches the `UpdateAlreadyInProgress` error from the lock helper and
maps it to `Ok(UpdateStatus::UpdateInProgress)`. The Dart wrapper
treats the new status as a successful return alongside
`SHOREBIRD_UPDATE_INSTALLED`, so `update()` no longer throws for this
case.
Update the existing `usage_during_hung_update` c_api test to assert the
new contract, and add a Dart test covering the in-progress return path.
Version skew: new Dart on an old engine still sees the legacy
`SHOREBIRD_UPDATE_ERROR` + "Update already in progress" message and
will still throw. The fix lands once both sides ship.
Partially addresses shorebirdtech/shorebird#3682 — does not resolve the
broader asymmetry of `update()` semantics (it still does not wait for
someone else's in-flight update to finish), which remains as v2 design
work in shorebirdtech/shorebird#3684.
Eric Seidel
563f1b773a