* io_uring: ring mapped buffers
Ring mapped buffers are newer implementation of ring provided buffers, supported
since kernel 5.19. Best described in Jens Axboe [post](https://github.com/axboe/liburing/wiki/io_uring-and-networking-in-2023#provided-buffers)
This commit implements low level io_uring_*_buf_ring_* functions as mostly
direct translation from liburing. It also adds BufferGroup abstraction over those
low level functions.
* io_uring: add multishot recv to BufferGroup
Once we have ring mapped provided buffers functionality it is possible to use
multishot recv operation. Multishot receive is submitted once, and completions
are posted whenever data arrives on the socket. Received data are placed in a
new buffer from buffer group.
Reference: [io_uring and networking in 2023](https://github.com/axboe/liburing/wiki/io_uring-and-networking-in-2023#multi-shot)
Getting NOENT for cancel completion result, meaning:
-ENOENT
The request identified by user_data could not be located.
This could be because it completed before the cancelation
request was issued, or if an invalid identifier is used.
https://man7.org/linux/man-pages/man3/io_uring_prep_cancel.3.htmlhttps://github.com/ziglang/zig/actions/runs/6801394000/job/18492139893?pr=17806
Result in cancel/recv cqes are different depending on the kernel.
on older kernel (tested with v6.0.16, v6.1.57, v6.2.12, v6.4.16)
cqe_cancel.err() == .NOENT
cqe_crecv.err() == .NOBUFS
on kernel (tested with v6.5.0, v6.5.7)
cqe_cancel.err() == .SUCCESS
cqe_crecv.err() == .CANCELED
* `linux.IO_Uring` -> `linux.IoUring` to align with naming conventions.
* All functions `io_uring_prep_foo` are now methods `prep_foo` on `io_uring_sqe`, which is in a file of its own.
* `SubmissionQueue` and `CompletionQueue` are namespaced under `IoUring`.
This is a breaking change.
The new file and namespace layouts are more idiomatic, and allow us to
eliminate one more usage of `usingnamespace` from the standard library.
2 remain.
* std.c: consolidate some definitions, making them share code. For
example, freebsd, dragonfly, and openbsd can all share the same
`pthread_mutex_t` definition.
* add type safety to std.c.O
- this caught a bug where mode flags were incorrectly passed as the
open flags.
* 3 fewer uses of usingnamespace keyword
* as per convention, remove purposeless field prefixes from struct field
names even if they have those prefixes in the corresponding C code.
* fix incorrect wasi libc Stat definition
* remove C definitions from incorrectly being in std.os.wasi
* make std.os.wasi definitions type safe
* go through wasi native APIs even when linking libc because the libc
APIs are problematic and wasteful
* don't expose WASI definitions in std.posix
* remove std.os.wasi.rights_t.ALL: this is a footgun. should it be all
future rights too? or only all current rights known? both are
the wrong answer.
This syscall was added to simplify the the libc implementations of
fchmodat, as the original syscall does not take a `flags` argument.
Another syscall, `map_shadow_stack`, was also added for x86_64.
Getting this error in ci:
run test std-arm-linux-none-generic-Debug: error: 'test.accept/connect/send_zc/recv' failed: /home/ci/actions-runner1/_work/zig/zig/lib/std/os/linux/io_uring.zig:60:23: 0x70b06b in init_params (test)
.NOSYS => return error.SystemOutdated,
^
/home/ci/actions-runner1/_work/zig/zig/lib/std/os/linux/io_uring.zig:27:16: 0x70b6b7 in init (test)
return try IO_Uring.init_params(entries, ¶ms);
^
/home/ci/actions-runner1/_work/zig/zig/lib/std/os/linux/io_uring.zig:3807:16: 0x72405b in test.accept/connect/send_zc/recv (test)
var ring = try IO_Uring.init(16, 0);
https://github.com/ziglang/zig/actions/runs/6909813408/job/18801841015?pr=18025
Reverting previous change.
I'm building test bin and then running it in virtual machines with different
kernels. So Linux kernel checks has to be runtime instead of comptime.
So far we relied on getting EINVAL in CQE for operations that kernel don't
support. The problem with that approach is that there are many other reasons
(like wrong params) to get EINVAL. The other problem is when we have an
operation that existed before and gets new behavior via different attributes,
like accept and accept_direct. Older kernels can fall back to non direct
operation although we set attributes for direct operation. Operation completes
successfully in both cases but with different results.
This commit introduces kernel version check at the start of the test. Making
body of the test free of checking for various kernel version differences.
Feature availability references:
* https://manpages.debian.org/unstable/liburing-dev/io_uring_enter.2.en.html
* https://kernel.dk/axboe-kr2022.pdf
* 5acf7969bc/lib/std/os/linux.zig (L3727)
* 5acf7969bc/lib/std/os/linux.zig (L3993)
`send_zc` tries to avoid making intermediate copies of data. Zerocopy execution
is not guaranteed and may fall back to copying.
The flags field of the first struct io_uring_cqe may likely contain
IORING_CQE_F_MORE , which means that there will be a second completion event /
notification for the request, with the user_data field set to the same value.
The user must not modify the data buffer until the notification is posted. The
first cqe follows the usual rules and so its res field will contain the number
of bytes sent or a negative error code. The notification's res field will be set
to zero and the flags field will contain IORING_CQE_F_NOTIF. The two step model
is needed because the kernel may hold on to buffers for a long time, e.g.
waiting for a TCP ACK, and having a separate cqe for request completions allows
userspace to push more data without extra delays. Note, notifications are only
responsible for controlling the lifetime of the buffers, and as such don't mean
anything about whether the data has atually been sent out or received by the
other end. Even errored requests may generate a notification, and the user must
check for IORING_CQE_F_MORE rather than relying on the result.
Available since kernel 6.0.
References:
https://man7.org/linux/man-pages/man3/io_uring_prep_send_zc.3.htmlhttps://man7.org/linux/man-pages/man2/io_uring_enter.2.html
There is no grantee that `copy_cqes` will return exactly wait_nr number of cqes.
If there are ready cqes it can return > 0 but < wait_nr number of cqes.
Server networking application typically accept multiple connections. Multishot
accept simplifies handling these situations. Applications submits once and
receives CQE whenever a new connection request comes in.
Multishot is active until it is canceled or experience error. While active, and
further notification are expected CQE completion will have IORING_CQE_F_MORE set
in the flags. If this flag isn't set, the application must re-arm this request
by submitting a new one.
Reference: [io_uring and networking in 2023](https://github.com/axboe/liburing/wiki/io_uring-and-networking-in-2023#multi-shot)
* 128-bit integer multiplication with overflow
* more instruction encodings used by std inline asm
* implement the `try_ptr` air instruction
* follow correct stack frame abi
* enable full panic handler
* enable stack traces
This reverts commit 0c99ba1eab63865592bb084feb271cd4e4b0357e, reversing
changes made to 5f92b070bf284f1493b1b5d433dd3adde2f46727.
This caused a CI failure when it landed in master branch due to a
128-bit `@byteSwap` in std.mem.
Insn.st() can be used with dynamic size just like Insn.stx(), which is
relevant in a code generation context.
using ImmOrReg caused an error as its fields were ordered differently than
Source.
After fixing some issues with inline assembly in the C backend, the std
cleanups have the side effect of making these functions compatible with
the backend, allowing it to be used on linux without linking libc.
