Maintaining the POSIX `stat` bits for Zig is a pain. The order and
bit-length of members differ between all architectures, and int types
can be signed or unsigned. The libcs deal with this by introducing the
own version of `struct stat` and copying the kernel structure members to
it. In the case of glibc, they did it twice thanks to the largefile
transition!
In practice, the project needs to maintain three versions of `struct
stat`:
- What the kernel defines.
- What musl wants for `struct stat`.
- What glibc wants for `struct stat64`. Make sure to use `fstatat64`!
This isn't as simple as running `zig translate-c`. In #21440 I had to:
- Compile toolchains for each arch+glibc/musl combo.
- Create a test `fstat` program with/without `FILE_OFFSET_BITS=64`.
- Dump the value for `struct stat`.
- Stare at `std.os.linux`/`std.c` and cry.
- Add some missing padding.
The fact that so many target checks in the `linux` and `posix` tests
exist is most likely due to writing to padding bits and failing later.
The solution to this madness is `statx(2)`:
- It takes a single structure that is the same for all arches AND libcs.
- It uses a custom timestamp format, but it is 64-bit ready.
- It gives the same info as `fstatat(2)` and more!
- Unlike `fstatat(2)`, you can request a subset of the info required
based on passing a mask.
It's so good that modern Linux arches (e.g. riscv) don't even implement
`stat`, with the libcs using a generic `struct stat` and copying from
`struct statx`.
Therefore, this commit rips out all the `stat` bits from `std.os.linux`
and `std.c`. `std.posix.Stat` is now `void`, and calling
`std.posix.*stat` is an compile-time error. A wrapper around `statx` has
been added to `std.os.linux`, and callers have been upgraded to use it.
Tests have also been updated to use `statx` where possible.
While I was here, I converted the mask and file attributes to be packed
struct bitfields. A nice side effect is checking that you actually
recieved the members you asked for via `Statx.mask`, which I have used
by adding `assert`s at specific callsites.
[Incremental provided buffer
consumption](https://github.com/axboe/liburing/wiki/What's-new-with-io_uring-in-6.11-and-6.12#incremental-provided-buffer-consumption)
support is added in kernel 6.12.
IoUring.BufferGroup will now use incremental consumption whenever
kernel supports it.
Before, provided buffers are wholly consumed when picked. Each cqe
points to the different buffer. With this, cqe points to the part of the
buffer. Multiple cqe's can reuse same buffer.
Appropriate sizing of buffers becomes less important.
There are slight changes in BufferGroup interface (it now needs to track
current receive point for each buffer). Init requires allocator
instead of buffers slice, it will allocate buffers slice and head
pointers slice. Get and put now requires cqe becasue there we have
information will the buffer be reused.
ring.cmd_sock is generic socket operation. Two most common uses are
setsockopt and getsockopt. This provides same interface as posix
versions of this methods.
libring has also [sqe_set_flags](https://man7.org/linux/man-pages/man3/io_uring_sqe_set_flags.3.html)
method. Adding that in our io_uring_sqe. Adding sqe.link_next method for setting most common flag.
* fix merge conflicts
* rename the declarations
* reword documentation
* extract FixedBufferAllocator to separate file
* take advantage of locals
* remove the assertion about max alignment in Allocator API, leaving it
Allocator implementation defined
* fix non-inline function call in start logic
The GeneralPurposeAllocator implementation is totally broken because it
uses global state but I didn't address that in this commit.
heap.zig: define new default page sizes
heap.zig: add min/max_page_size and their options
lib/std/c: add miscellaneous declarations
heap.zig: add pageSize() and its options
switch to new page sizes, especially in GPA/stdlib
mem.zig: remove page_size
It is now composed of these main sections:
* Declarations that are shared among all operating systems.
* Declarations that have the same name, but different type signatures
depending on the operating system. Often multiple operating systems
share the same type signatures however.
* Declarations that are specific to a single operating system.
- These are imported one per line so you can see where they come from,
protected by a comptime block to prevent accessing the wrong one.
Closes#19352 by changing the convention to making types `void` and
functions `{}`, so that it becomes possible to update `@hasDecl` sites
to use `@TypeOf(f) != void` or `T != void`. Happily, this ended up
removing some duplicate logic and update some bitrotted feature
detection checks.
A handful of types have been modified to gain namespacing and type
safety. This is a breaking change.
Oh, and the last usage of `usingnamespace` site is eliminated.
In my first [try](https://github.com/ziglang/zig/pull/20224) to fix
20212 I didn't reproduce bug on required kernel (6.9.2) and wrongly
concluded that first two completions have different order on newer
kernel.
On my current kernel (6.5.0) order of completions is: send1, recv,
send2. On 6.9.2 order is send1, send2, recv. This fix allows second two
completions to arrive in any order.
Tested on both kernels.
Fixes: #20212
Deprecated aliases that are now compile errors:
- `std.fs.MAX_PATH_BYTES` (renamed to `std.fs.max_path_bytes`)
- `std.mem.tokenize` (split into `tokenizeAny`, `tokenizeSequence`, `tokenizeScalar`)
- `std.mem.split` (split into `splitSequence`, `splitAny`, `splitScalar`)
- `std.mem.splitBackwards` (split into `splitBackwardsSequence`, `splitBackwardsAny`, `splitBackwardsScalar`)
- `std.unicode`
+ `utf16leToUtf8Alloc`, `utf16leToUtf8AllocZ`, `utf16leToUtf8`, `fmtUtf16le` (all renamed to have capitalized `Le`)
+ `utf8ToUtf16LeWithNull` (renamed to `utf8ToUtf16LeAllocZ`)
- `std.zig.CrossTarget` (moved to `std.Target.Query`)
Deprecated `lib/std/std.zig` decls were deleted instead of made a `@compileError` because the `refAllDecls` in the test block would trigger the `@compileError`. The deleted top-level `std` namespaces are:
- `std.rand` (renamed to `std.Random`)
- `std.TailQueue` (renamed to `std.DoublyLinkedList`)
- `std.ChildProcess` (renamed/moved to `std.process.Child`)
This is not exhaustive. Deprecated aliases that I didn't touch:
+ `std.io.*`
+ `std.Build.*`
+ `std.builtin.Mode`
+ `std.zig.c_translation.CIntLiteralRadix`
+ anything in `src/`
We are posting two submission (zero copy send and receive) and then
reading two completions. There is no guarantee that those completions
will be in the order of submissions.
This test was expecting fist send completion then receive.
Fix is allowing them to come other way too.
* 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.
Andrew Kelley