fix(dfir_pipes): forward size_hint from pull to push in SendPush pivot [ci-bench]#2881
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fix(dfir_pipes): forward size_hint from pull to push in SendPush pivot [ci-bench]#2881MingweiSamuel wants to merge 1 commit into
size_hint from pull to push in SendPush pivot [ci-bench]#2881MingweiSamuel wants to merge 1 commit into
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…ot [ci-bench] Before starting the pull loop, forward the pull's `size_hint` to the push side so terminal operators like `VecPush` can pre-allocate capacity via `Vec::reserve`. This avoids repeated doubling reallocations when the input size is known (e.g., draining a handoff buffer with known length). The hint is forwarded once per `SendPush` future (guarded by a bool flag) to avoid redundant reserve calls on subsequent polls. `Vec::reserve` is when allocation actually happens (not `Vec::new`), so this might hurt performance if it messes up re-allocation order for growing vecs somehow, but probably ok. Co-authored-by: Infinity 🤖 <infinity@hydro.run> PR: #2881
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size_hint from pull to push in SendPush pivot [ci-bench]size_hint from pull to push in SendPush pivot [ci-bench]
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📊 Benchmark Results✅ Benchmark completed! You can download the results from the links below. Run History:
Last updated: 2026-05-20T23:44:40.286Z |
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Pull request overview
This PR improves dfir_pipes pull→push bridging by forwarding the upstream Pull::size_hint() into the downstream Push::size_hint() once per SendPush future, enabling terminal pushes (e.g., VecPush) to pre-reserve capacity and reduce reallocations.
Changes:
- Added a
size_hintedflag toSendPushto ensure the hint is forwarded at most once. - Forwarded
Pull::size_hint()to the push side before entering the pull loop inSendPush::poll.
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| // Forward size hint from pull to push once, so the push side | ||
| // can pre-allocate capacity (e.g., Vec::reserve). | ||
| if !core::mem::replace(this.size_hinted, true) { | ||
| let hint = Pull::size_hint(&*this.pull); | ||
| this.push.as_mut().size_hint(hint); | ||
| } |
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luckyworkama
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May 22, 2026
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Before starting the pull loop, forward the pull's
size_hintto the pushside so terminal operators like
VecPushcan pre-allocate capacity viaVec::reserve. This avoids repeated doubling reallocations when the inputsize is known (e.g., draining a handoff buffer with known length).
The hint is forwarded once per
SendPushfuture (guarded by a bool flag)to avoid redundant reserve calls on subsequent polls.
Vec::reserveis when allocation actually happens (notVec::new), so this might hurt performanceif it messes up re-allocation order for growing vecs somehow, but probably ok.
Co-authored-by: Infinity 🤖 infinity@hydro.run