mio/sys/unix/selector/
epoll.rs

1use std::io;
2use std::os::fd::{AsFd, AsRawFd, BorrowedFd, FromRawFd, OwnedFd, RawFd};
3#[cfg(debug_assertions)]
4use std::sync::atomic::{AtomicUsize, Ordering};
5use std::time::Duration;
6
7use libc::{EPOLLET, EPOLLIN, EPOLLOUT, EPOLLPRI, EPOLLRDHUP};
8
9use crate::{Interest, Token};
10
11cfg_io_source! {
12    use std::ptr;
13}
14
15/// Unique id for use as `SelectorId`.
16#[cfg(debug_assertions)]
17static NEXT_ID: AtomicUsize = AtomicUsize::new(1);
18
19#[derive(Debug)]
20pub struct Selector {
21    #[cfg(debug_assertions)]
22    id: usize,
23    ep: OwnedFd,
24}
25
26impl Selector {
27    pub fn new() -> io::Result<Selector> {
28        // SAFETY: `epoll_create1(2)` ensures the fd is valid.
29        let ep = unsafe { OwnedFd::from_raw_fd(syscall!(epoll_create1(libc::EPOLL_CLOEXEC))?) };
30        Ok(Selector {
31            #[cfg(debug_assertions)]
32            id: NEXT_ID.fetch_add(1, Ordering::Relaxed),
33            ep,
34        })
35    }
36
37    pub fn try_clone(&self) -> io::Result<Selector> {
38        self.ep.try_clone().map(|ep| Selector {
39            // It's the same selector, so we use the same id.
40            #[cfg(debug_assertions)]
41            id: self.id,
42            ep,
43        })
44    }
45
46    pub fn select(&self, events: &mut Events, timeout: Option<Duration>) -> io::Result<()> {
47        let timeout = timeout
48            .map(|to| {
49                // `Duration::as_millis` truncates, so round up. This avoids
50                // turning sub-millisecond timeouts into a zero timeout, unless
51                // the caller explicitly requests that by specifying a zero
52                // timeout.
53                to.checked_add(Duration::from_nanos(999_999))
54                    .unwrap_or(to)
55                    .as_millis() as libc::c_int
56            })
57            .unwrap_or(-1);
58
59        events.clear();
60        syscall!(epoll_wait(
61            self.ep.as_raw_fd(),
62            events.as_mut_ptr(),
63            events.capacity() as i32,
64            timeout,
65        ))
66        .map(|n_events| {
67            // This is safe because `epoll_wait` ensures that `n_events` are
68            // assigned.
69            unsafe { events.set_len(n_events as usize) };
70        })
71    }
72
73    pub fn register(&self, fd: RawFd, token: Token, interests: Interest) -> io::Result<()> {
74        let mut event = libc::epoll_event {
75            events: interests_to_epoll(interests),
76            u64: usize::from(token) as u64,
77            #[cfg(target_os = "redox")]
78            _pad: 0,
79        };
80
81        let ep = self.ep.as_raw_fd();
82        syscall!(epoll_ctl(ep, libc::EPOLL_CTL_ADD, fd, &mut event)).map(|_| ())
83    }
84
85    cfg_any_os_ext! {
86    pub fn reregister(&self, fd: RawFd, token: Token, interests: Interest) -> io::Result<()> {
87        let mut event = libc::epoll_event {
88            events: interests_to_epoll(interests),
89            u64: usize::from(token) as u64,
90            #[cfg(target_os = "redox")]
91            _pad: 0,
92        };
93
94        let ep = self.ep.as_raw_fd();
95        syscall!(epoll_ctl(ep, libc::EPOLL_CTL_MOD, fd, &mut event)).map(|_| ())
96    }
97
98    pub fn deregister(&self, fd: RawFd) -> io::Result<()> {
99        let ep = self.ep.as_raw_fd();
100        syscall!(epoll_ctl(ep, libc::EPOLL_CTL_DEL, fd, ptr::null_mut())).map(|_| ())
101    }
102    }
103}
104
105cfg_io_source! {
106    impl Selector {
107        #[cfg(debug_assertions)]
108        pub fn id(&self) -> usize {
109            self.id
110        }
111    }
112}
113
114impl AsFd for Selector {
115    fn as_fd(&self) -> BorrowedFd<'_> {
116        self.ep.as_fd()
117    }
118}
119
120impl AsRawFd for Selector {
121    fn as_raw_fd(&self) -> RawFd {
122        self.ep.as_raw_fd()
123    }
124}
125
126fn interests_to_epoll(interests: Interest) -> u32 {
127    let mut kind = EPOLLET;
128
129    if interests.is_readable() {
130        kind = kind | EPOLLIN | EPOLLRDHUP;
131    }
132
133    if interests.is_writable() {
134        kind |= EPOLLOUT;
135    }
136
137    if interests.is_priority() {
138        kind |= EPOLLPRI;
139    }
140
141    kind as u32
142}
143
144pub type Event = libc::epoll_event;
145pub type Events = Vec<Event>;
146
147pub mod event {
148    use std::fmt;
149
150    use crate::sys::Event;
151    use crate::Token;
152
153    pub fn token(event: &Event) -> Token {
154        Token(event.u64 as usize)
155    }
156
157    pub fn is_readable(event: &Event) -> bool {
158        (event.events as libc::c_int & libc::EPOLLIN) != 0
159            || (event.events as libc::c_int & libc::EPOLLPRI) != 0
160    }
161
162    pub fn is_writable(event: &Event) -> bool {
163        (event.events as libc::c_int & libc::EPOLLOUT) != 0
164    }
165
166    pub fn is_error(event: &Event) -> bool {
167        (event.events as libc::c_int & libc::EPOLLERR) != 0
168    }
169
170    pub fn is_read_closed(event: &Event) -> bool {
171        // Both halves of the socket have closed
172        event.events as libc::c_int & libc::EPOLLHUP != 0
173            // Socket has received FIN or called shutdown(SHUT_RD)
174            || (event.events as libc::c_int & libc::EPOLLIN != 0
175                && event.events as libc::c_int & libc::EPOLLRDHUP != 0)
176    }
177
178    pub fn is_write_closed(event: &Event) -> bool {
179        // Both halves of the socket have closed
180        event.events as libc::c_int & libc::EPOLLHUP != 0
181            // Unix pipe write end has closed
182            || (event.events as libc::c_int & libc::EPOLLOUT != 0
183                && event.events as libc::c_int & libc::EPOLLERR != 0)
184            // The other side (read end) of a Unix pipe has closed.
185            || event.events as libc::c_int == libc::EPOLLERR
186    }
187
188    pub fn is_priority(event: &Event) -> bool {
189        (event.events as libc::c_int & libc::EPOLLPRI) != 0
190    }
191
192    pub fn is_aio(_: &Event) -> bool {
193        // Not supported in the kernel, only in libc.
194        false
195    }
196
197    pub fn is_lio(_: &Event) -> bool {
198        // Not supported.
199        false
200    }
201
202    pub fn debug_details(f: &mut fmt::Formatter<'_>, event: &Event) -> fmt::Result {
203        #[allow(clippy::trivially_copy_pass_by_ref)]
204        fn check_events(got: &u32, want: &libc::c_int) -> bool {
205            (*got as libc::c_int & want) != 0
206        }
207        debug_detail!(
208            EventsDetails(u32),
209            check_events,
210            libc::EPOLLIN,
211            libc::EPOLLPRI,
212            libc::EPOLLOUT,
213            libc::EPOLLRDNORM,
214            libc::EPOLLRDBAND,
215            libc::EPOLLWRNORM,
216            libc::EPOLLWRBAND,
217            libc::EPOLLMSG,
218            libc::EPOLLERR,
219            libc::EPOLLHUP,
220            libc::EPOLLET,
221            libc::EPOLLRDHUP,
222            libc::EPOLLONESHOT,
223            libc::EPOLLEXCLUSIVE,
224            libc::EPOLLWAKEUP,
225            libc::EPOLL_CLOEXEC,
226        );
227
228        // Can't reference fields in packed structures.
229        let e_u64 = event.u64;
230        f.debug_struct("epoll_event")
231            .field("events", &EventsDetails(event.events))
232            .field("u64", &e_u64)
233            .finish()
234    }
235}
236
237// No special requirement from the implementation around waking.
238pub(crate) use crate::sys::unix::waker::Waker;
239
240cfg_io_source! {
241    mod stateless_io_source;
242    pub(crate) use stateless_io_source::IoSourceState;
243}
mio/sys/unix/selector/epoll.rs

mio/sys/unix/selector/
epoll.rs
