Add limit iterator and context plumbing for --limit flag#4724
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Add limit iterator and context plumbing for --limit flag#4724simonfaltum wants to merge 3 commits intomainfrom
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Commit: 1fbc876
16 interesting tests: 7 SKIP, 6 RECOVERED, 3 flaky
Top 20 slowest tests (at least 2 minutes):
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Note: This review was posted by Claude (AI assistant). Shreyas will do a separate, more thorough review pass.
Priority: LOW — Clean, well-structured PR
MEDIUM: Next() doesn't guard against remaining <= 0
limitIterator.Next() unconditionally delegates to inner.Next() without checking remaining > 0. If Next() is called without first checking HasNext(), the limit won't be enforced (remaining goes negative). Low severity since all callers use the HasNext()/Next() pattern, but a guard would be cheap:
func (i *limitIterator[T]) Next(ctx context.Context) (T, error) {
if i.remaining <= 0 {
var zero T
return zero, fmt.Errorf("iterator exhausted")
}
// ...
}What looks good
WithLimit/GetLimitfollows standard Go context value patternApplyLimit(ctx, iter)keeps call sites cleanlimitIteratoris unexported (correct encapsulation)- Limit of 0 means "no limit" (common CLI convention)
- Thorough table-driven tests covering edge cases
- Lazy evaluation preserves iterator semantics
Overall excellent PR. The Next() guard is the only actionable item.
Return listing.ErrNoMoreItems when Next() is called with remaining <= 0, so the limit is enforced even if the caller skips HasNext().
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Why
The codegen template generates a --limit flag on every paginated list command. That generated code calls cmdio.WithLimit(ctx, n) to store the limit in context. RenderIterator then applies a limit iterator to cap total results. This PR adds the runtime plumbing that the generated code depends on.
Changes
Before: no mechanism to cap total results from list commands.
Now: libs/cmdio provides a limit iterator (wraps a listing.Iterator and stops after N items), WithLimit/GetLimit (context key for the limit value), and an ApplyLimit helper. All three RenderIterator functions call ApplyLimit before rendering.
Implementation:
Test plan