karmaio 0.1.0

A modern, fast, share-nothing asynchronous runtime for Rust
Documentation 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132

use std::io;

#[cfg(target_os = "linux")]
use crate::driver::backends::iouring::{Submission as UringSubmission, UringOperation};
#[cfg(any(
    target_os = "macos",
    target_os = "freebsd",
    target_os = "netbsd",
    target_os = "openbsd",
    target_os = "dragonfly"
))]
use crate::driver::backends::kqueue::{KqueueAttempt, KqueueOperation};

use crate::{
    buf::{BufResult, IoVectoredBufMut},
    driver::{
        helpers::io_handle::SharedIoHandle,
        ops::{Completion, Op},
    },
    runtime::local::CURRENT_DRIVER,
};

pub(crate) struct Readv<V: IoVectoredBufMut> {
    #[allow(unused)]
    io_handle: SharedIoHandle<std::fs::File>,
    pub(crate) bufs: V,
    #[cfg(unix)]
    iovs: Vec<libc::iovec>,
    offset: u64,
}

impl<V: IoVectoredBufMut> Op<Readv<V>> {
    pub(crate) fn readv(io_handle: &SharedIoHandle<std::fs::File>, bufs: V, offset: u64) -> io::Result<Op<Readv<V>>> {
        let data = Readv {
            io_handle: io_handle.clone(),
            bufs,
            #[cfg(unix)]
            iovs: Vec::new(),
            offset,
        };

        CURRENT_DRIVER.with(|handle| handle.upgrade().expect("Not in a runtime context").submit_op(data))
    }
}

impl<V: IoVectoredBufMut> Readv<V> {
    #[cfg(unix)]
    fn rebuild_iovs(&mut self) {
        self.iovs = self
            .bufs
            .iter_uninit_slice()
            .map(|buf| libc::iovec {
                iov_base: buf.as_mut_ptr().cast(),
                iov_len: buf.len(),
            })
            .collect();
    }

    fn finish(mut self, completion: Completion) -> BufResult<usize, V> {
        let capacity = self.bufs.total_capacity();
        match completion.bytes_transferred(capacity) {
            Ok(n) => {
                // Safety: bytes_transferred verified that the kernel-reported
                // initialized prefix fits within the aggregate capacity.
                unsafe { self.bufs.set_len(n) };
                BufResult(Ok(n), self.bufs)
            }
            Err(error) => BufResult(Err(error), self.bufs),
        }
    }
}

#[cfg(target_os = "linux")]
unsafe impl<V: IoVectoredBufMut> UringOperation for Readv<V> {
    type Output = BufResult<usize, V>;

    fn submit(&mut self) -> UringSubmission {
        use io_uring::{opcode, types};

        self.rebuild_iovs();
        opcode::Readv::new(
            types::Fd(self.io_handle.raw_fd()),
            self.iovs.as_ptr(),
            self.iovs.len() as u32,
        )
        .offset(self.offset as _)
        .build()
    }

    fn complete(self, completion: Completion) -> Self::Output {
        self.finish(completion)
    }
}

#[cfg(any(
    target_os = "macos",
    target_os = "freebsd",
    target_os = "netbsd",
    target_os = "openbsd",
    target_os = "dragonfly"
))]
impl<V: IoVectoredBufMut> KqueueOperation for Readv<V> {
    type Output = BufResult<usize, V>;

    fn attempt(&mut self) -> KqueueAttempt {
        self.rebuild_iovs();
        let fd = self.io_handle.raw_fd();
        let iovs = self.iovs.as_ptr() as usize;
        let iovcnt = self.iovs.len();
        let offset = self.offset;
        kqueue_syscall_blocking!({
            // Safety: the stable operation carrier retains the descriptor
            // array, buffers, and file until the blocking job completes.
            let fd = unsafe { std::os::fd::BorrowedFd::borrow_raw(fd) };
            let iovs = unsafe { std::slice::from_raw_parts(iovs as *const libc::iovec, iovcnt) };
            let mut bufs = iovs
                .iter()
                .map(|iov| {
                    let buf = unsafe { std::slice::from_raw_parts_mut(iov.iov_base.cast::<u8>(), iov.iov_len) };
                    std::io::IoSliceMut::new(buf)
                })
                .collect::<Vec<_>>();
            rustix::io::preadv(fd, &mut bufs, offset)
                .map(|n| n as u32)
                .map_err(std::io::Error::from)
        })
    }

    fn complete(self, completion: Completion) -> Self::Output {
        self.finish(completion)
    }
}