base_coroutine/event_loop/
interest.rs

1use std::num::NonZeroU8;
2use std::{fmt, ops};
3
4/// Interest used in registering.
5///
6/// Interest are used in [registering] [`event::Source`]s with [`Poll`], they
7/// indicate what readiness should be monitored for. For example if a socket is
8/// registered with [readable] interests and the socket becomes writable, no
9/// event will be returned from a call to [`poll`].
10///
11/// [registering]: struct.Registry.html#method.register
12/// [`event::Source`]: ./event/trait.Source.html
13/// [`Poll`]: struct.Poll.html
14/// [readable]: struct.Interest.html#associatedconstant.READABLE
15/// [`poll`]: struct.Poll.html#method.poll
16#[derive(Copy, PartialEq, Eq, Clone, PartialOrd, Ord)]
17pub struct Interest(NonZeroU8);
18
19// These must be unique.
20const READABLE: u8 = 0b0001;
21const WRITABLE: u8 = 0b0010;
22// The following are not available on all platforms.
23#[cfg_attr(
24    not(any(
25        target_os = "dragonfly",
26        target_os = "freebsd",
27        target_os = "ios",
28        target_os = "macos"
29    )),
30    allow(dead_code)
31)]
32const AIO: u8 = 0b0100;
33#[cfg_attr(not(target_os = "freebsd"), allow(dead_code))]
34const LIO: u8 = 0b1000;
35
36impl Interest {
37    /// Returns a `Interest` set representing readable interests.
38    pub const READABLE: Interest = Interest(unsafe { NonZeroU8::new_unchecked(READABLE) });
39
40    /// Returns a `Interest` set representing writable interests.
41    pub const WRITABLE: Interest = Interest(unsafe { NonZeroU8::new_unchecked(WRITABLE) });
42
43    /// Returns a `Interest` set representing AIO completion interests.
44    #[cfg(any(
45        target_os = "dragonfly",
46        target_os = "freebsd",
47        target_os = "ios",
48        target_os = "macos"
49    ))]
50    pub const AIO: Interest = Interest(unsafe { NonZeroU8::new_unchecked(AIO) });
51
52    /// Returns a `Interest` set representing LIO completion interests.
53    #[cfg(target_os = "freebsd")]
54    pub const LIO: Interest = Interest(unsafe { NonZeroU8::new_unchecked(LIO) });
55
56    /// Add together two `Interest`.
57    ///
58    /// This does the same thing as the `BitOr` implementation, but is a
59    /// constant function.
60    ///
61    /// ```
62    /// use base_coroutine::Interest;
63    ///
64    /// const INTERESTS: Interest = Interest::READABLE.add(Interest::WRITABLE);
65    /// # fn silent_dead_code_warning(_: Interest) { }
66    /// # silent_dead_code_warning(INTERESTS)
67    /// ```
68    #[allow(clippy::should_implement_trait)]
69    pub const fn add(self, other: Interest) -> Interest {
70        Interest(unsafe { NonZeroU8::new_unchecked(self.0.get() | other.0.get()) })
71    }
72
73    /// Removes `other` `Interest` from `self`.
74    ///
75    /// Returns `None` if the set would be empty after removing `other`.
76    ///
77    /// ```
78    /// use base_coroutine::Interest;
79    ///
80    /// const RW_INTERESTS: Interest = Interest::READABLE.add(Interest::WRITABLE);
81    ///
82    /// // As long a one interest remain this will return `Some`.
83    /// let w_interest = RW_INTERESTS.remove(Interest::READABLE).unwrap();
84    /// assert!(!w_interest.is_readable());
85    /// assert!(w_interest.is_writable());
86    ///
87    /// // Removing all interests from the set will return `None`.
88    /// assert_eq!(w_interest.remove(Interest::WRITABLE), None);
89    ///
90    /// // Its also possible to remove multiple interests at once.
91    /// assert_eq!(RW_INTERESTS.remove(RW_INTERESTS), None);
92    /// ```
93    pub fn remove(self, other: Interest) -> Option<Interest> {
94        NonZeroU8::new(self.0.get() & !other.0.get()).map(Interest)
95    }
96
97    /// Returns true if the value includes readable readiness.
98    pub const fn is_readable(self) -> bool {
99        (self.0.get() & READABLE) != 0
100    }
101
102    /// Returns true if the value includes writable readiness.
103    pub const fn is_writable(self) -> bool {
104        (self.0.get() & WRITABLE) != 0
105    }
106
107    /// Returns true if `Interest` contains AIO readiness
108    pub const fn is_aio(self) -> bool {
109        (self.0.get() & AIO) != 0
110    }
111
112    /// Returns true if `Interest` contains LIO readiness
113    pub const fn is_lio(self) -> bool {
114        (self.0.get() & LIO) != 0
115    }
116}
117
118impl ops::BitOr for Interest {
119    type Output = Self;
120
121    #[inline]
122    fn bitor(self, other: Self) -> Self {
123        self.add(other)
124    }
125}
126
127impl ops::BitOrAssign for Interest {
128    #[inline]
129    fn bitor_assign(&mut self, other: Self) {
130        self.0 = (*self | other).0;
131    }
132}
133
134impl fmt::Debug for Interest {
135    fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
136        let mut one = false;
137        if self.is_readable() {
138            if one {
139                write!(fmt, " | ")?
140            }
141            write!(fmt, "READABLE")?;
142            one = true
143        }
144        if self.is_writable() {
145            if one {
146                write!(fmt, " | ")?
147            }
148            write!(fmt, "WRITABLE")?;
149            one = true
150        }
151        #[cfg(any(
152            target_os = "dragonfly",
153            target_os = "freebsd",
154            target_os = "ios",
155            target_os = "macos"
156        ))]
157        {
158            if self.is_aio() {
159                if one {
160                    write!(fmt, " | ")?
161                }
162                write!(fmt, "AIO")?;
163                one = true
164            }
165        }
166        #[cfg(any(target_os = "freebsd"))]
167        {
168            if self.is_lio() {
169                if one {
170                    write!(fmt, " | ")?
171                }
172                write!(fmt, "LIO")?;
173                one = true
174            }
175        }
176        debug_assert!(one, "printing empty interests");
177        Ok(())
178    }
179}
base_coroutine/event_loop/interest.rs

base_coroutine/event_loop/
interest.rs
