lowlet 0.1.2

Low-latency IPC library using shared memory and lock-free structures
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
133
134
135
136

use std::sync::atomic::{AtomicBool, Ordering};
use std::sync::Arc;

use crate::buf::RingBuffer;
use crate::err::{Error, Result};

pub struct Sender<T, const N: usize> {
    buf: Arc<RingBuffer<T, N>>,
    closed: Arc<AtomicBool>,
}

impl<T, const N: usize> Sender<T, N> {
    #[allow(dead_code)]
    pub(crate) fn new(buf: Arc<RingBuffer<T, N>>) -> Self {
        Self {
            buf,
            closed: Arc::new(AtomicBool::new(false)),
        }
    }

    pub(crate) fn new_with_closed(buf: Arc<RingBuffer<T, N>>, closed: Arc<AtomicBool>) -> Self {
        Self { buf, closed }
    }

    #[allow(dead_code)]
    pub(crate) fn closed_flag(&self) -> Arc<AtomicBool> {
        self.closed.clone()
    }

    #[inline]
    pub fn send(&self, value: T) -> Result<()> {
        if self.closed.load(Ordering::Acquire) {
            return Err(Error::ChannelClosed);
        }
        self.buf.send(value)
    }

    #[inline]
    pub fn try_send(&self, value: T) -> Result<()> {
        self.send(value)
    }

    pub fn send_spin(&self, value: T) -> Result<()>
    where
        T: Copy,
    {
        loop {
            if self.closed.load(Ordering::Acquire) {
                return Err(Error::ChannelClosed);
            }
            match self.buf.send(value) {
                Ok(()) => return Ok(()),
                Err(Error::QueueFull) => std::hint::spin_loop(),
                Err(e) => return Err(e),
            }
        }
    }

    #[inline]
    pub fn capacity(&self) -> usize {
        N
    }

    #[inline]
    pub fn is_full(&self) -> bool {
        self.buf.len() >= N
    }

    #[inline]
    pub fn is_closed(&self) -> bool {
        self.closed.load(Ordering::Acquire)
    }

    pub fn close(&self) {
        self.closed.store(true, Ordering::Release);
    }

    pub fn send_batch(&self, items: &[T]) -> Result<usize>
    where
        T: Copy,
    {
        if self.closed.load(Ordering::Acquire) {
            return Err(Error::ChannelClosed);
        }

        let mut sent = 0;

        for item in items {
            match self.buf.send(*item) {
                Ok(()) => sent += 1,
                Err(e) => {
                    if sent == 0 {
                        return Err(e);
                    }
                    break;
                }
            }
        }

        Ok(sent)
    }

    pub fn send_timeout(&self, value: T, timeout: std::time::Duration) -> Result<()>
    where
        T: Copy,
    {
        let start = std::time::Instant::now();

        loop {
            if self.closed.load(Ordering::Acquire) {
                return Err(Error::ChannelClosed);
            }
            match self.buf.send(value) {
                Ok(()) => return Ok(()),
                Err(e) => {
                    if start.elapsed() >= timeout {
                        return Err(e);
                    }
                    std::hint::spin_loop();
                }
            }
        }
    }
}

impl<T, const N: usize> Clone for Sender<T, N> {
    fn clone(&self) -> Self {
        Self {
            buf: self.buf.clone(),
            closed: self.closed.clone(),
        }
    }
}

unsafe impl<T: Send, const N: usize> Send for Sender<T, N> {}
unsafe impl<T: Send, const N: usize> Sync for Sender<T, N> {}