[async] Optimize poll_uring_ with stack allocation and fix cq_ready bug #1836
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Use boost::container::small_vector to allocate up to 64 completion entries on the stack, avoiding heap allocation in the common case. Fix bug where io_uring_sq_ready() was incorrectly used instead of io_uring_cq_ready() when reserving capacity for the completions vector. The code processes completion queue entries, not submission queue entries, so it should check completion queue readiness. - Add COMPLETIONS_STACK_CAPACITY constant (64) for stack capacity - Replace std::vector with small_vector for stack allocation - Fix io_uring_sq_ready() → io_uring_cq_ready() in reserve() call This code was generated using Claude Sonnet 4.5
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Pull Request Overview
This PR optimizes memory allocation in the io_uring polling function and fixes a critical bug in completion queue size estimation. The changes improve performance by avoiding heap allocations for common cases while correcting the logic for determining the number of pending completions.
- Replace heap-allocated vector with stack-allocated small_vector for up to 64 completion entries
- Fix incorrect use of submission queue ready count instead of completion queue ready count
- Add COMPLETIONS_STACK_CAPACITY constant for maintainability
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Chen-Yifan
approved these changes
Oct 28, 2025
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Use boost::container::small_vector to allocate up to 64 completion entries on the stack, avoiding heap allocation in the common case.
Fix bug where io_uring_sq_ready() was incorrectly used instead of io_uring_cq_ready() when reserving capacity for the completions vector. The code processes completion queue entries, not submission queue entries, so it should check completion queue readiness.
This code was generated using Claude Sonnet 4.5