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.
23const AIO: u8 = 0b0100;
24const LIO: u8 = 0b1000;
25const PRIORITY: u8 = 0b10000;
26
27impl Interest {
28 /// Returns a `Interest` set representing readable interests.
29 pub const READABLE: Interest = Interest(unsafe { NonZeroU8::new_unchecked(READABLE) });
30
31 /// Returns a `Interest` set representing writable interests.
32 pub const WRITABLE: Interest = Interest(unsafe { NonZeroU8::new_unchecked(WRITABLE) });
33
34 /// Returns a `Interest` set representing AIO completion interests.
35 #[cfg(any(
36 target_os = "dragonfly",
37 target_os = "freebsd",
38 target_os = "ios",
39 target_os = "macos",
40 target_os = "tvos",
41 target_os = "watchos",
42 ))]
43 pub const AIO: Interest = Interest(unsafe { NonZeroU8::new_unchecked(AIO) });
44
45 /// Returns a `Interest` set representing LIO completion interests.
46 #[cfg(target_os = "freebsd")]
47 pub const LIO: Interest = Interest(unsafe { NonZeroU8::new_unchecked(LIO) });
48
49 /// Returns a `Interest` set representing priority completion interests.
50 #[cfg(any(target_os = "linux", target_os = "android"))]
51 pub const PRIORITY: Interest = Interest(unsafe { NonZeroU8::new_unchecked(PRIORITY) });
52
53 /// Add together two `Interest`.
54 ///
55 /// This does the same thing as the `BitOr` implementation, but is a
56 /// constant function.
57 ///
58 /// ```
59 /// use mio::Interest;
60 ///
61 /// const INTERESTS: Interest = Interest::READABLE.add(Interest::WRITABLE);
62 /// # fn silent_dead_code_warning(_: Interest) { }
63 /// # silent_dead_code_warning(INTERESTS)
64 /// ```
65 #[allow(clippy::should_implement_trait)]
66 #[must_use = "this returns the result of the operation, without modifying the original"]
67 pub const fn add(self, other: Interest) -> Interest {
68 Interest(unsafe { NonZeroU8::new_unchecked(self.0.get() | other.0.get()) })
69 }
70
71 /// Removes `other` `Interest` from `self`.
72 ///
73 /// Returns `None` if the set would be empty after removing `other`.
74 ///
75 /// ```
76 /// use mio::Interest;
77 ///
78 /// const RW_INTERESTS: Interest = Interest::READABLE.add(Interest::WRITABLE);
79 ///
80 /// // As long a one interest remain this will return `Some`.
81 /// let w_interest = RW_INTERESTS.remove(Interest::READABLE).unwrap();
82 /// assert!(!w_interest.is_readable());
83 /// assert!(w_interest.is_writable());
84 ///
85 /// // Removing all interests from the set will return `None`.
86 /// assert_eq!(w_interest.remove(Interest::WRITABLE), None);
87 ///
88 /// // Its also possible to remove multiple interests at once.
89 /// assert_eq!(RW_INTERESTS.remove(RW_INTERESTS), None);
90 /// ```
91 #[must_use = "this returns the result of the operation, without modifying the original"]
92 pub fn remove(self, other: Interest) -> Option<Interest> {
93 NonZeroU8::new(self.0.get() & !other.0.get()).map(Interest)
94 }
95
96 /// Returns true if the value includes readable readiness.
97 #[must_use]
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 #[must_use]
104 pub const fn is_writable(self) -> bool {
105 (self.0.get() & WRITABLE) != 0
106 }
107
108 /// Returns true if `Interest` contains AIO readiness.
109 #[must_use]
110 pub const fn is_aio(self) -> bool {
111 (self.0.get() & AIO) != 0
112 }
113
114 /// Returns true if `Interest` contains LIO readiness.
115 #[must_use]
116 pub const fn is_lio(self) -> bool {
117 (self.0.get() & LIO) != 0
118 }
119
120 /// Returns true if `Interest` contains priority readiness.
121 #[must_use]
122 pub const fn is_priority(self) -> bool {
123 (self.0.get() & PRIORITY) != 0
124 }
125}
126
127impl ops::BitOr for Interest {
128 type Output = Self;
129
130 #[inline]
131 fn bitor(self, other: Self) -> Self {
132 self.add(other)
133 }
134}
135
136impl ops::BitOrAssign for Interest {
137 #[inline]
138 fn bitor_assign(&mut self, other: Self) {
139 self.0 = (*self | other).0;
140 }
141}
142
143impl fmt::Debug for Interest {
144 fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
145 let mut one = false;
146 if self.is_readable() {
147 if one {
148 write!(fmt, " | ")?
149 }
150 write!(fmt, "READABLE")?;
151 one = true
152 }
153 if self.is_writable() {
154 if one {
155 write!(fmt, " | ")?
156 }
157 write!(fmt, "WRITABLE")?;
158 one = true
159 }
160 #[cfg(any(
161 target_os = "dragonfly",
162 target_os = "freebsd",
163 target_os = "ios",
164 target_os = "macos",
165 target_os = "tvos",
166 target_os = "watchos",
167 ))]
168 {
169 if self.is_aio() {
170 if one {
171 write!(fmt, " | ")?
172 }
173 write!(fmt, "AIO")?;
174 one = true
175 }
176 }
177 #[cfg(target_os = "freebsd")]
178 {
179 if self.is_lio() {
180 if one {
181 write!(fmt, " | ")?
182 }
183 write!(fmt, "LIO")?;
184 one = true
185 }
186 }
187 #[cfg(any(target_os = "linux", target_os = "android"))]
188 {
189 if self.is_priority() {
190 if one {
191 write!(fmt, " | ")?
192 }
193 write!(fmt, "PRIORITY")?;
194 one = true
195 }
196 }
197 debug_assert!(one, "printing empty interests");
198 Ok(())
199 }
200}
201