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Sample

futures-util 0.3.34: Polling an empty FuturesUnordered returns None without terminating the collection so new futures can be pushed and polled dynamically, whereas wrapping it in Fuse permanently latches is_terminated on the first None and ignores subsequent pushed tasks

Verified sample for cargo futures-util 0.3.34: Polling an empty FuturesUnordered returns None without terminating the collection so new futures can be pushed…

sha256:2336755e4371002b1fe77659a664fa05c66c674b78f48b4f45d6cad20aa9c8f0

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Execution evidence

The declared environment and the signed runs are kept apart, so you can see exactly what this sample ran and where.

Evidence basis
Signed contract pass
Verification receipts
2
Signing keys that built it
2
Declared environment rust linux x64 rust rust cargo

Verification-run environments

Environment Contract Stages Run
rust 1 · linux alpine/x64 · docker ed25519:d91480838ac982c9 PASS compile:SKIPPED · contract:PASS · load:PASS · resolve:PASS
CONTAINER_RUN · cargo@1
2026-08-16
rust 1 · linux alpine/x64 · docker ed25519:2175b912ea1c23b1 PASS compile:SKIPPED · contract:PASS · load:PASS · resolve:PASS
CONTAINER_RUN · cargo@1
2026-08-18

Case

HOW
Goal
Polling an empty FuturesUnordered returns None without terminating the collection so new futures can be pushed and polled dynamically, whereas wrapping it in Fuse permanently latches is_terminated on the first None and ignores subsequent pushed tasks
Packages
Symbols
  • futures_util::stream::FuturesUnordered
  • futures_util::stream::StreamExt
  • futures_util::sink::SinkExt
  • futures_util::sink::Sink
Environment
rust
Created
2026-08-16T09:35:31Z

Contract

  1. assert polling an empty FuturesUnordered returns Ready(None) without preventing subsequent push calls from yielding new items on future polls
  2. assert wrapping FuturesUnordered in Fuse permanently latches is_terminated on the first None and returns Ready(None) forever even when new items are pushed to the inner queue
  3. assert buffer_unordered with zero capacity returns Poll::Pending unconditionally without draining available items from the upstream stream
  4. assert polling select_next_some on an already terminated fused stream panics at runtime while next returns Ready(None)
  5. assert ready_chunks yields all currently available elements immediately in a single poll batch without waiting for the full capacity buffer or stream EOF
  6. assert SplitSink::reunite only succeeds when paired with the SplitStream from the same split invocation and fails on cross-split pairs
  7. assert stream select exhausts both constituent streams completely before returning Ready(None)

Files

  • .gitignore
  • Cargo.lock
  • Cargo.toml
  • NOTES.md
  • csx.json
  • src/lib.rs

Download the source artifact (tar.gz)

Origin Seeder

csx-seed