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nimble_pool 1.1.0: Check a resource out of a NimblePool and survive the failure paths: what the checkout function must return, which failures the pool recovers from, and which one silently leaks a worker

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sha256:b9a321085b5992dc0c641045e8b697e67dbb23c7f9958ea2d4e0b145d1a2f486

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実行証拠

宣言された環境と署名済みの実行を分けてあります。このサンプルが何をどこで実行したかをそのまま確認できます。

証拠の基準
署名済みコントラクト合格
検証レシート
1
ビルドした署名鍵
1
宣言された環境 elixir 1 linux x64 elixir 1 elixir mix

検証実行環境

環境 コントラクト ステージ 実行日
elixir 1 · linux alpine/x64 · docker ed25519:a2ec939a4c60e243 PASS compile:PASS · contract:PASS · load:PASS · resolve:PASS
CONTAINER_RUN · hex@1
2026-08-14

ケース

HOW
ゴール
Check a resource out of a NimblePool and survive the failure paths: what the checkout function must return, which failures the pool recovers from, and which one silently leaks a worker
パッケージ
シンボル
  • NimblePool.start_link
  • NimblePool.checkout!
  • NimblePool.update
  • NimblePool.child_spec
  • NimblePool.init_pool
  • NimblePool.init_worker
  • NimblePool.handle_checkout
  • NimblePool.handle_checkin
  • NimblePool.handle_update
  • NimblePool.handle_cancelled
  • NimblePool.terminate_worker
環境
elixir 1
作成日
2026-08-14T20:12:13Z

コントラクト

  1. assert :pool_size defaults to 10 rather than System.schedulers_online(), by counting exactly ten init_worker callbacks at start_link and no eleventh
  2. assert lazy: true starts no workers at all and builds exactly one on the first checkout
  3. assert the checkout! function body runs in the CLIENT process, and that the from it receives is {pool_pid, ref} carrying the POOL's pid, unlike GenServer.handle_call/3 where from carries the caller's
  4. assert checkout! returns the first element of the two-tuple and only handle_checkin/4 ever sees the second
  5. assert the asynchronous check-in does not race a re-checkout: twenty-five sequential checkouts against a one-worker pool all succeed
  6. assert raising inside the checkout! function is the recoverable failure: handle_cancelled(:checked_out) then terminate_worker(:error, ...) then a replacement init_worker, with handle_checkin skipped
  7. assert returning a value that is not a two-tuple raises {:try_clause, value} and silently leaks the worker: no handle_cancelled, no terminate_worker, no replacement, and every later checkout on that pool exits :timeout
  8. assert the leaked worker is reclaimed only when the calling process itself dies, which is when the pool's monitor fires handle_cancelled(:checked_out) and terminate_worker(:DOWN, ...)
  9. assert {:skip, exception, pool_state} from handle_checkout/4 raises that exception in the client while leaving the worker checked in and serving the next call, terminating nothing
  10. assert {:remove, reason, pool_state} from handle_checkout/4 retries the same checkout against another worker, so a remove keyed on the command destroys and rebuilds more workers than the pool size and the caller only ever sees its own checkout timeout
  11. assert a caller that times out while still queued cancels as :queued and tears down nothing, while a caller killed holding a worker cancels as :checked_out with terminate_worker reason :DOWN
  12. assert NimblePool.update/2 is called from inside the checkout! function with from, routes to handle_update/3, and replaces the worker_state that handle_checkin/4 later receives while the client_state passes through unchanged

ファイル

  • csx.json
  • lib/csx_nimble_pool/churn_worker.ex
  • lib/csx_nimble_pool/instrumented_worker.ex
  • mix.exs
  • mix.lock
  • test/contract_test.exs
  • test/test_helper.exs

ソースアーティファクトをダウンロード (tar.gz)

オリジンシーダー

anonymous