emscripten: Add epoll support - #5427
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Emscripten restored the `sys/epoll.h` header in 6.0.2 and implements `epoll_create`, `epoll_create1`, `epoll_ctl`, `epoll_wait` and `epoll_pwait` in the JS filesystem as of 6.0.8. Version detection in libc-test now also tracks the tiny version component so that point releases can be distinguished, and parses the uppercase `__EMSCRIPTEN_MAJOR__` macro forms used since Emscripten 5.0.1, where the lowercase names became non-integer aliases. Link: https://github.com/emscripten-core/emscripten/blob/4483d70a78098ed5d860dff2dc21f3025b2da2ee/system/lib/libc/musl/include/sys/epoll.h#L17 Link: https://github.com/emscripten-core/emscripten/blob/4483d70a78098ed5d860dff2dc21f3025b2da2ee/system/lib/libc/musl/include/sys/epoll.h#L70-L74 Link: emscripten-core/emscripten#27206 Link: emscripten-core/emscripten#27207
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This PR was rebased onto a different main commit. Here's a range-diff highlighting what actually changed. Rebasing is a normal part of keeping PRs up to date, so no action is needed—this note is just to help reviewers. |
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Emscripten restored the `sys/epoll.h` header in 6.0.2 and implements `epoll_create`, `epoll_create1`, `epoll_ctl`, `epoll_wait` and `epoll_pwait` in the JS filesystem as of 6.0.8. Version detection in libc-test now also tracks the tiny version component so that point releases can be distinguished, and parses the uppercase `__EMSCRIPTEN_MAJOR__` macro forms used since Emscripten 5.0.1, where the lowercase names became non-integer aliases. Link: https://github.com/emscripten-core/emscripten/blob/4483d70a78098ed5d860dff2dc21f3025b2da2ee/system/lib/libc/musl/include/sys/epoll.h#L17 Link: https://github.com/emscripten-core/emscripten/blob/4483d70a78098ed5d860dff2dc21f3025b2da2ee/system/lib/libc/musl/include/sys/epoll.h#L70-L74 Link: emscripten-core/emscripten#27206 Link: emscripten-core/emscripten#27207 (backport <rust-lang#5427>) (cherry picked from commit 04c162b)
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Emscripten restored the `sys/epoll.h` header in 6.0.2 and implements `epoll_create`, `epoll_create1`, `epoll_ctl`, `epoll_wait` and `epoll_pwait` in the JS filesystem as of 6.0.8. Version detection in libc-test now also tracks the tiny version component so that point releases can be distinguished, and parses the uppercase `__EMSCRIPTEN_MAJOR__` macro forms used since Emscripten 5.0.1, where the lowercase names became non-integer aliases. Link: https://github.com/emscripten-core/emscripten/blob/4483d70a78098ed5d860dff2dc21f3025b2da2ee/system/lib/libc/musl/include/sys/epoll.h#L17 Link: https://github.com/emscripten-core/emscripten/blob/4483d70a78098ed5d860dff2dc21f3025b2da2ee/system/lib/libc/musl/include/sys/epoll.h#L70-L74 Link: emscripten-core/emscripten#27206 Link: emscripten-core/emscripten#27207 (backport <rust-lang#5427>) (cherry picked from commit 04c162b)
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Follow-on to tokio-rs#8285, enabling `tokio::net` on Emscripten over mio's epoll selector and Node's raw sockets (`-sNODERAWSOCKETS`). The I/O driver is the native one. Under JSPI, Emscripten's `epoll_wait` is a blocking wait that suspends on the host event loop, resuming on readiness (or the mio waker pipe) or the deadline, so `park` and `park_timeout` need nothing target-specific. The one addition is for the scheduler's zero-duration maintenance park: a zero-timeout `epoll_wait` is a synchronous probe, and the host loop is the only producer of readiness, so the driver yields one host turn first, as the zero-duration `ParkThread` park already does. Without JSPI a real wait panics rather than spinning, matching the existing park semantics. Under pthreads with `-sPROXY_TO_PTHREAD` the wait blocks on the worker as on native, with no target-specific code at all. TcpStream/TcpListener/UdpSocket, stream `AF_UNIX` sockets, `lookup_host` and `AsyncFd` work as on native. Gated where Node lacks the primitive: datagram `AF_UNIX` (`UnixDatagram`, `UnixSocket::new_datagram`), `socketpair(2)` (`UnixStream::pair`), and `SO_PEERCRED` (`peer_cred` reports unsupported). Name resolution goes through Emscripten's synchronous `getaddrinfo`, which maps hostnames to synthetic addresses, so the `localhost` tests are ignored on this target. CI adds `net` to both emscripten test runs on the released emsdk: JSPI (815 passed, 0 failed, 19 ignored) and pthreads, which regains `-sPROXY_TO_PTHREAD` (818 passed, 0 failed, 19 ignored). The JSPI run uses Rust beta until 1.99 is stable, which is where `OwnedFd::try_clone` (mio's registry handle) gains Emscripten support. TEMPORARY: `mio` comes from tokio-rs/mio#1969 until released, which in turn takes `libc` from the `libc-0.2` branch for its emscripten epoll bindings (rust-lang/libc#5427).
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Follow-on to tokio-rs#8285, enabling `tokio::net` on Emscripten over mio's epoll selector and Node's raw sockets (`-sNODERAWSOCKETS`). The I/O driver is the native one. Under JSPI, Emscripten's `epoll_wait` is a blocking wait that suspends on the host event loop, resuming on readiness (or the mio waker pipe) or the deadline, so `park` and `park_timeout` need nothing target-specific beyond `jspi::io_wait`, which makes the wait a park in the JSPI sense: it leaves the runtime around the `epoll_wait` as the timer park does, so sibling activations may drive their own runtime while it is suspended. It also handles the scheduler's zero-duration maintenance park: a zero-timeout `epoll_wait` is a synchronous probe, and the host loop is the only producer of readiness, so the driver yields one host turn first, as the zero-duration `ParkThread` park already does. Without JSPI a real wait panics rather than spinning, matching the existing park semantics. Under pthreads with `-sPROXY_TO_PTHREAD` the wait blocks on the worker as on native, with no target-specific code at all. A wait with no deadline is a real `epoll_wait` that a socket could wake, so it suspends rather than panicking as the reactor-less park does; the `rt_emscripten_block_on` test of that panic is gated off `net`. TcpStream/TcpListener/UdpSocket, stream `AF_UNIX` sockets, `lookup_host` and `AsyncFd` work as on native. Gated where Node lacks the primitive: datagram `AF_UNIX` (`UnixDatagram`, `UnixSocket::new_datagram`), `socketpair(2)` (`UnixStream::pair`), and `SO_PEERCRED` (`peer_cred` reports unsupported). Name resolution goes through Emscripten's synchronous `getaddrinfo`, which maps hostnames to synthetic addresses, so the `localhost` tests are ignored on this target. CI adds `net` to both emscripten test runs on the released emsdk: JSPI (846 passed, 0 failed, 19 ignored) and pthreads, which regains `-sPROXY_TO_PTHREAD` (818 passed, 0 failed, 19 ignored). The JSPI lane links a `--pre-js` that fails a test binary whose `main` never returns: a park that suspends with no wake source leaves Node's event loop to drain and the process to exit 0, which cargo would otherwise take as success. The JSPI run uses Rust beta until 1.99 is stable, which is where `OwnedFd::try_clone` (mio's registry handle) gains Emscripten support. TEMPORARY: `mio` comes from tokio-rs/mio#1969 until released, which in turn takes `libc` from the `libc-0.2` branch for its emscripten epoll bindings (rust-lang/libc#5427).
guybedford
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Follow-on to tokio-rs#8285, enabling `tokio::net` on Emscripten over mio's epoll selector and Node's raw sockets (`-sNODERAWSOCKETS`). The I/O driver is the native one. Under JSPI, Emscripten's `epoll_wait` is a blocking wait that suspends on the host event loop, resuming on readiness (or the mio waker pipe) or the deadline, so `park` and `park_timeout` need nothing target-specific beyond `jspi::io_wait`, which makes the wait a park in the JSPI sense: it leaves the runtime around the `epoll_wait` as the timer park does, so sibling activations may drive their own runtime while it is suspended. It also handles the scheduler's zero-duration maintenance park: a zero-timeout `epoll_wait` is a synchronous probe, and the host loop is the only producer of readiness, so the driver yields one host turn first, as the zero-duration `ParkThread` park already does. Without JSPI a real wait panics rather than spinning, matching the existing park semantics. Under pthreads with `-sPROXY_TO_PTHREAD` the wait blocks on the worker as on native, with no target-specific code at all. A wait with no deadline is a real `epoll_wait` that a socket could wake, so it suspends rather than panicking as the reactor-less park does; the `rt_emscripten_block_on` test of that panic is gated off `net`. TcpStream/TcpListener/UdpSocket, stream `AF_UNIX` sockets, `lookup_host` and `AsyncFd` work as on native. Gated where Node lacks the primitive: datagram `AF_UNIX` (`UnixDatagram`, `UnixSocket::new_datagram`), `socketpair(2)` (`UnixStream::pair`), and `SO_PEERCRED` (`peer_cred` reports unsupported). Name resolution goes through Emscripten's synchronous `getaddrinfo`, which maps hostnames to synthetic addresses, so the `localhost` tests are ignored on this target. CI adds `net` to both emscripten test runs on the released emsdk: JSPI (846 passed, 0 failed, 19 ignored) and pthreads, which regains `-sPROXY_TO_PTHREAD` (818 passed, 0 failed, 19 ignored). The JSPI lane links a `--pre-js` that fails a test binary whose `main` never returns: a park that suspends with no wake source leaves Node's event loop to drain and the process to exit 0, which cargo would otherwise take as success. The JSPI run uses Rust beta until 1.99 is stable, which is where `OwnedFd::try_clone` (mio's registry handle) gains Emscripten support. TEMPORARY: `mio` comes from tokio-rs/mio#1969 until released, which in turn takes `libc` from the `libc-0.2` branch for its emscripten epoll bindings (rust-lang/libc#5427).
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This adds the epoll APIs for the
wasm32-unknown-emscriptentarget. Emscripten restored thesys/epoll.hheader in 6.0.2 (emscripten-core/emscripten#27206) and implements the epoll functions in the JS filesystem as of the upcoming 6.0.8 (emscripten-core/emscripten#27207).EPOLL_CLOEXECandepoll_create,epoll_create1,epoll_ctl,epoll_waitandepoll_pwaitfor Emscripten (theepoll_eventtype andEPOLL*constants were already defined for the target)test_emscripten, version-gated so that all currently released Emscripten versions (including the 3.1.68 CI pin) are unaffected__EMSCRIPTEN_major__macros are non-integer aliases of new uppercase forms, and the tiny version component is now tracked so that point releases can be distinguishedTested against Emscripten stable 6.0.7, where the header, type and constant tests run and pass, with the function link tests remaining version-gated until 6.0.8, and against the fully gated skip path.