Stream: git-wasmtime

Topic: wasmtime / PR #14987 wasi-sockets: Don't report a TCP inp...

Wasmtime GitHub notifications bot (Oct 25 2026 at 15:19):

libsmol opened PR #14987 from libsmol:tcp-read-readiness to bytecodealliance:main:

Fixes #14986.

TcpReceiveStream::poll_ready returned tokio's cached read readiness, which tokio only clears once an operation returns WouldBlock. Right after a connection is set up that readiness can already be set although nothing has been received, so a WASIp2 TCP input stream could report ready before any data arrived (details in the issue).

This makes poll_ready peek a single byte instead. poll_peek waits for data, the end of the stream or an error, and when there's nothing to read it clears tokio's readiness and registers the waker as before. poll_read is unchanged.

Testing

• p2_tcp_streams gains test_tcp_input_stream_should_not_be_ready_without_data, which checks that neither side of a fresh connection is ready, that the client becomes ready once the server writes, and that it's no longer ready after the data has been read. On main it fails in both p2::sync::p2_tcp_streams and p2::async_::p2_tcp_streams, and passes with this change.
• cargo test -p wasmtime-wasi passes except p3::p3_sockets_udp_connect, which fails the same way without this change in my environment (Linux aarch64 under OrbStack, where the loopback and public addresses end up on the same local interface).
• cargo clippy -p wasmtime-wasi --all-targets is clean.
• In an embedder using wasmtime_wasi::p2::add_to_linker_sync, wasi-libc's poll() on an idle accepted connection now waits for its timeout instead of returning 1 at once.

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This pull request was prepared by an AI coding assistant (Claude Code, running Anthropic's Claude Opus 5.5) on behalf of the libsmol project. We've tested it as described above, but we're happy to rework it if you'd prefer a different approach.

:robot: Generated with Claude Code

Wasmtime GitHub notifications bot (Oct 25 2026 at 15:19):

libsmol removed the review request for wasmtime-wasi-reviewers from PR #14987.

Wasmtime GitHub notifications bot (Oct 25 2026 at 15:19):

libsmol requested wasmtime-wasi-reviewers for a review on PR #14987.

Wasmtime GitHub notifications bot (Oct 25 2026 at 15:19):

libsmol requested rvolosatovs for a review on PR #14987.

Wasmtime GitHub notifications bot (Oct 25 2026 at 15:19):

libsmol removed the review request for wasmtime-core-reviewers from PR #14987.

Wasmtime GitHub notifications bot (Oct 25 2026 at 15:19):

libsmol requested cfallin for a review on PR #14987.

Wasmtime GitHub notifications bot (Oct 25 2026 at 15:19):

libsmol requested wasmtime-core-reviewers for a review on PR #14987.

Wasmtime GitHub notifications bot (Oct 25 2026 at 15:32):

tschneidereit commented on PR #14987:

Closing this for the same reason as the issue it's meant to close.

Wasmtime GitHub notifications bot (Oct 25 2026 at 15:32):

:cross_mark: tschneidereit closed without merge PR #14987.

Last updated: Oct 31 2026 at 23:03 UTC