Пример

Run at most N async operations at once in Dart with package:pool, keep the results lined up with the inputs, and know what the timeout actually guards

sha256:16a15d010dc0f1c9e1ee0824cafd5bd1ed1eb32530f108bc856e8cc348fa9179

Кейс

Цель

Run at most N async operations at once in Dart with package:pool, keep the results lined up with the inputs, and know what the timeout actually guards HOW

Пакеты

pool 1.5.2

Окружение

dart 3

Создан

2026-08-14T20:09:50Z

Контракт

• assert a Pool of two runs at most two bodies at once, and that a withResource body that throws still releases its slot, so the high-water mark afterwards is two and not one
• assert pool.forEach emits results in completion order rather than input order, so its list is a permutation of the inputs, while Future.wait over withResource keeps every result in position
• assert forEach holds every resource in the pool for the whole run, so an unrelated request on the same pool is blocked outright rather than throttled alongside it
• assert the default onError adds the error to the stream and carries on, and that returning false only drops the error, with all six elements processed either way
• assert toList on a forEach stream completes with the first error, discards the values already emitted and cancels the iteration, so the remaining elements are never attempted
• assert an error thrown while iterating the elements bypasses onError entirely and lands on the stream even when onError returns false
• assert the timeout is a pool-wide inactivity alarm that any request or release resets, so a starved caller waits nearly three times it, that it then fails every pending request at once with a TimeoutException carrying the configured duration, and that it never fires again for the life of the pool
• assert request() throws StateError synchronously on a closed pool while withResource puts the identical error into its returned future instead, and that close() is memoized to one future
• assert done completes only once the resources handed out before close are released
• assert allowRelease spends the resource token so a following release() throws StateError, that its callback runs only when the slot is wanted, and that a callback which throws completes the next caller's request() with that error and leaves the pool one usable resource short forever
• assert queued requests are answered in request order even when it is a later allowRelease callback that frees the slot
• assert Pool(0) and a negative limit throw ArgumentError from the constructor, and that queued waiters are served first in, first out

Файлы

• csx.json
• lib/throttle.dart
• pubspec.lock
• pubspec.yaml
• test/contract_test.dart

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Исходный сидер

anonymous

Квитанции проверки

• dart 3 · CONTAINER_RUN · compile:SKIPPED · contract:PASS · load:PASS · resolve:PASS · pub@1 · 2026-08-14 · ed25519:a2ec939a4c60e243