bedrock-kv / bedrock / 20dbbd67d7c8cd7946fbdd8cca5976107f6a136b

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github

Clean up distributor placeholder on Livebook reevaluation (#313)

Fixes bedrock-tah.

A distributor exits normally when its director dies, which does not
propagate across its link to the registered placeholder. On
Livebook/Kino child reevaluation, that left the old placeholder alive,
so the replacement distributor took the lock but failed its startup
sweep with `{:already_started, old_placeholder_pid}` and retried every
second.

The distributor now synchronously stops its placeholder from
`terminate/2`, treating an already-dead placeholder as benign. The
regression starts a real distributor and named linked placeholder,
terminates the director, proves both exit, then starts a replacement
distributor with the same placeholder name.

Verification:
- Red regression before implementation: placeholder did not exit after
distributor normal termination.
- Focused distributor server tests (50 tests).
- Livebook-style same-VM terminate/restart harness: one epoch-2 lock
acquisition over 7 seconds; no startup-sweep failure.
- Full suite: 17 doctests, 158 properties, 2927 tests, 0 failures.
- `mix compile --warnings-as-errors`, `mix credo --strict`, and `mix
dialyzer`.

Adversarial review completed before push: checked normal-link semantics,
already-dead placeholder handling, synchronous name release, and
replacement-name collision coverage.

2 of 4 new or added lines in 1 file covered. (50.0%)

7108 of 8790 relevant lines covered (80.86%)

1164.29 hits per line