Add library/modules/std/net/epoll.sx — raw epoll bindings, the linux twin of
std/net/kqueue.sx — and branch std.event.Loop on `inline if OS` so the
OS-neutral readiness Loop runs on linux (epoll) as well as darwin (kqueue);
callers never see the backend.
epoll_event has no packed-struct primitive in sx, so it is modelled as an
arch-branched struct of u32 fields — { events, data_lo, data_hi } → 12 bytes on
x86_64 (matching __attribute__((packed))), { events, pad, data_lo, data_hi } →
16 bytes on aarch64 — every field 4-aligned, so the layout is byte-exact for the
kernel ABI with no packed attribute and no unaligned access. The fd is stashed
in data_lo (epoll echoes one data word, not the fd separately).
epoll.sx is self-contained (libc only, no build.sx): the `inline if ARCH`
selecting the struct is resolved by the compiler's flatten pre-pass, so the
module's IR stays small. The epoll backend is imported INSIDE event.sx's
`inline if OS == .linux` branch (not top level): event.sx rides the std.sx
barrel, so a top-level import would register epoll's types into every std
program's type table on darwin and drift every .ir snapshot.
The epoll Loop keeps a small per-fd registration table (combined EPOLLIN/OUT
mask via EPOLL_CTL_ADD/MOD/DEL), maps the fd back to the caller's udata, arms
EPOLLRDHUP so a peer half-close surfaces as Event.eof (matching kqueue EV_EOF),
and uses an eventfd as the cross-thread wake channel (kqueue's EVFILT_USER).
Validation: the kqueue path runs end-to-end on the macOS host (1632 unchanged);
the epoll bindings + ABI layout are corpus-locked ir-only by
examples/event/1633 (x86_64-linux, both arches probe-verified). The epoll Loop
is verified to lower clean for both linux arches and self-reviewed, but is not
corpus-snapshotted (a Loop example drags the std barrel → ~18k-line brittle IR);
runtime behavior validates on a linux runner.
Replace the bare-paren tuple grammar with explicit, position-unambiguous
forms, mirroring how structs work:
type `(A, B)` -> `Tuple(A, B)` (named keeps `:`)
value `(a, b)` -> `.(a, b)` (named uses `=`)
typed (new) -> `Tuple(A, B).(a, b)` (like `Point.{...}`)
failable `-> (T, !)` -> `-> T !`
`-> (T1, T2, !)`-> `-> Tuple(T1, T2) !` (channel outside Tuple)
Bare `(...)` is now grouping only, everywhere; a comma in bare parens is a
hard error with a migration hint. Grouping, function types `(A, B) -> R`,
param lists, lambdas, and match bindings are unaffected.
`Tuple(...)` is strictly a TYPE in every position (including `size_of` /
`type_info` args); a tuple VALUE comes only from `.(...)` (anonymous) or
`Tuple(...).(...)` (explicitly typed). A bare `Tuple(1, 2)` is a tuple
type with non-type elements -> rejected.
The ~110 tuple-bearing corpus files were migrated with a one-shot
AST-aware migrator (the `sx migrate` tool from the prior commit, removed
here). New examples: 0130 (new syntax), 0131 (typed construction), 1060
(named-tuple failable return). 1116 golden updated for the new hint text.
thread_pool_count = 0 (default) keeps handlers inline on the loop
thread — the measured fast path (BENCH-HTTPZ.md). N > 0 dispatches
each parsed request to a std.thread Pool of N workers, completing the
httpz two-pool shape: the connection freezes as CONN_HANDLING (no
reads, growth, eviction, or recycling — the worker borrows views into
its read buffer), the worker runs the handler under a per-job arena
and serializes into job-owned bytes, the completion queues under the
PoolState mutex, and the loop wakes through the new std.event wake
channel (kqueue EVFILT_USER + EV_CLEAR; the epoll twin maps to
eventfd), attaches the response, compacts the buffer, and resumes
keep-alive/pipeline handling. A full backlog sheds with 503. Stale
completions (generation mismatch after close) are dropped. Pool mode
requires the server's constructing allocator to be thread-safe
(GPA/malloc), documented on the knob.
PoolState lives behind a heap pointer (it embeds a Mutex and is shared
with workers; the Server struct itself is returned by value).
serialize_response/run_handler_job share one serialize_bytes.
examples/1633 gains the pooled section (GET, body echo, 404 across
worker threads) plus the loop-wake path exercised end to end; AOT run
five times. examples/1632 unchanged but the Event struct gains `user`.
Loop.init/close, add_read/del_read/add_write/del_write with a
per-registration udata word, and wait() normalizing backend events
into Event{fd, udata, readable, writable, eof, err, nbytes}. The epoll
twin (S4) slots in behind this surface when the linux target lands.
No timer registrations by design: request/keepalive eviction is
deadline math — deadline_in/expired/remaining_ms over std.time's
monotonic clock, with remaining_ms feeding wait's timeout. std.sx
barrel carries ; .ir snapshot regen is the usual mechanical
renumbering. examples/1632 pins idle timeout (and that it honors the
deadline), readable with fd/udata/nbytes, immediate writability on an
empty send buffer, and the eof flag on peer close; JIT + AOT.
