Struct sys_util::EpollContext

pub struct EpollContext<T> { /* fields omitted */ }

EpollContext wraps linux epoll. It provides similar interface to PollContext. It is thread safe while PollContext is not. It requires user to pass in a reference of EpollEvents while PollContext does not. Always use PollContext if you don't need to access the same epoll from different threads.

Methods

impl<T: PollToken> EpollContext<T>

pub fn new() -> Result<EpollContext<T>>

Creates a new EpollContext.

pub fn add(&self, fd: &dyn AsRawFd, token: T) -> Result<()>

Adds the given fd to this context and associates the given token with the fd's readable events.

A fd can only be added once and does not need to be kept open. If the fd is dropped and there were no duplicated file descriptors (i.e. adding the same descriptor with a different FD number) added to this context, events will not be reported by wait anymore.

pub fn add_fd_with_events(
    &self,
    fd: &dyn AsRawFd,
    events: WatchingEvents,
    token: T
) -> Result<()>

Adds the given fd to this context, watching for the specified events and associates the given 'token' with those events.

A fd can only be added once and does not need to be kept open. If the fd is dropped and there were no duplicated file descriptors (i.e. adding the same descriptor with a different FD number) added to this context, events will not be reported by wait anymore.

pub fn modify(
    &self,
    fd: &dyn AsRawFd,
    events: WatchingEvents,
    token: T
) -> Result<()>

If fd was previously added to this context, the watched events will be replaced with events and the token associated with it will be replaced with the given token.

pub fn delete(&self, fd: &dyn AsRawFd) -> Result<()>

Deletes the given fd from this context.

If an fd's token shows up in the list of hangup events, it should be removed using this method or by closing/dropping (if and only if the fd was never dup()'d/fork()'d) the fd. Failure to do so will cause the wait method to always return immediately, causing ~100% CPU load.

pub fn wait<'a>(&self, events: &'a EpollEvents) -> Result<PollEvents<'a, T>>

Waits for any events to occur in FDs that were previously added to this context.

The events are level-triggered, meaning that if any events are unhandled (i.e. not reading for readable events and not closing for hungup events), subsequent calls to wait will return immediately. The consequence of not handling an event perpetually while calling wait is that the callers loop will degenerated to busy loop polling, pinning a CPU to ~100% usage.

pub fn wait_timeout<'a>(
    &self,
    events: &'a EpollEvents,
    timeout: Duration
) -> Result<PollEvents<'a, T>>

Like wait except will only block for a maximum of the given timeout.

This may return earlier than timeout with zero events if the duration indicated exceeds system limits.

Trait Implementations

impl<T: PollToken> IntoRawFd for EpollContext<T>

fn into_raw_fd(self) -> RawFd

Consumes this object, returning the raw underlying file descriptor.

impl<T: PollToken> AsRawFd for EpollContext<T>

fn as_raw_fd(&self) -> RawFd

Extracts the raw file descriptor.