Struct Signal

pub struct Signal { /* private fields */ }

An implementation of Stream for receiving a particular type of signal.

This structure implements the Stream trait and represents notifications of the current process receiving a particular signal. The signal being listened for is passed to Signal::new, and the same signal number is then yielded as each element for the stream.

In general signal handling on Unix is a pretty tricky topic, and this structure is no exception! There are some important limitations to keep in mind when using Signal streams:

• Signals handling in Unix already necessitates coalescing signals together sometimes. This Signal stream is also no exception here in that it will also coalesce signals. That is, even if the signal handler for this process runs multiple times, the Signal stream may only return one signal notification. Specifically, before poll is called, all signal notifications are coalesced into one item returned from poll. Once poll has been called, however, a further signal is guaranteed to be yielded as an item.

  Put another way, any element pulled off the returned stream corresponds to at least one signal, but possibly more.

• Signal handling in general is relatively inefficient. Although some improvements are possible in this crate, it’s recommended to not plan on having millions of signal channels open.

• Currently the “driver task” to process incoming signals never exits. This driver task runs in the background of the event loop provided, and in general you shouldn’t need to worry about it.

If you’ve got any questions about this feel free to open an issue on the repo, though, as I’d love to chat about this! In other words, I’d love to alleviate some of these limitations if possible!

Implementations

impl Signal

pub fn new(signal: c_int) -> IoFuture<Signal>

Creates a new stream which will receive notifications when the current process receives the signal signal.

This function will create a new stream which binds to the default event loop. This function returns a future which will then resolve to the signal stream, if successful.

The Signal stream is an infinite stream which will receive notifications whenever a signal is received. More documentation can be found on Signal itself, but to reiterate:

• Signals may be coalesced beyond what the kernel already does.
• Once a signal handler is registered with the process the underlying libc signal handler is never unregistered.

A Signal stream can be created for a particular signal number multiple times. When a signal is received then all the associated channels will receive the signal notification.

Errors

• If the lower-level C functions fail for some reason.
• If the previous initialization of this specific signal failed.
• If the signal is one of signal_hook::FORBIDDEN

pub fn with_handle(signal: c_int, handle: &Handle) -> IoFuture<Signal>

Creates a new stream which will receive notifications when the current process receives the signal signal.

This function will create a new stream which may be based on the event loop handle provided. This function returns a future which will then resolve to the signal stream, if successful.

The Signal stream is an infinite stream which will receive notifications whenever a signal is received. More documentation can be found on Signal itself, but to reiterate:

• Signals may be coalesced beyond what the kernel already does.
• Once a signal handler is registered with the process the underlying libc signal handler is never unregistered.

A Signal stream can be created for a particular signal number multiple times. When a signal is received then all the associated channels will receive the signal notification.

Trait Implementations

impl Drop for Signal

fn drop(&mut self)

Executes the destructor for this type.

impl Stream for Signal

type Item = i32

The type of item this stream will yield on success.

type Error = Error

The type of error this stream may generate.

fn poll(&mut self) -> Poll<Option<c_int>, Error>

Attempt to pull out the next value of this stream, returning None if the stream is finished.

fn wait(self) -> Wait<Self>

where Self: Sized,

Creates an iterator which blocks the current thread until each item of this stream is resolved.

fn into_future(self) -> StreamFuture<Self>

where Self: Sized,

Converts this stream into a Future.

fn map<U, F>(self, f: F) -> Map<Self, F>

where F: FnMut(Self::Item) -> U, Self: Sized,

Converts a stream of type T to a stream of type U.

fn map_err<U, F>(self, f: F) -> MapErr<Self, F>

where F: FnMut(Self::Error) -> U, Self: Sized,

Converts a stream of error type T to a stream of error type U.

fn filter<F>(self, f: F) -> Filter<Self, F>

where F: FnMut(&Self::Item) -> bool, Self: Sized,

Filters the values produced by this stream according to the provided predicate.

fn filter_map<F, B>(self, f: F) -> FilterMap<Self, F>

where F: FnMut(Self::Item) -> Option<B>, Self: Sized,

Filters the values produced by this stream while simultaneously mapping them to a different type.

fn then<F, U>(self, f: F) -> Then<Self, F, U>

where F: FnMut(Result<Self::Item, Self::Error>) -> U, U: IntoFuture, Self: Sized,

Chain on a computation for when a value is ready, passing the resulting item to the provided closure f.

fn and_then<F, U>(self, f: F) -> AndThen<Self, F, U>

where F: FnMut(Self::Item) -> U, U: IntoFuture<Error = Self::Error>, Self: Sized,

Chain on a computation for when a value is ready, passing the successful results to the provided closure f.

fn or_else<F, U>(self, f: F) -> OrElse<Self, F, U>

where F: FnMut(Self::Error) -> U, U: IntoFuture<Item = Self::Item>, Self: Sized,

Chain on a computation for when an error happens, passing the erroneous result to the provided closure f.

fn collect(self) -> Collect<Self>

where Self: Sized,

Collect all of the values of this stream into a vector, returning a future representing the result of that computation.

fn concat2(self) -> Concat2<Self>

where Self: Sized, Self::Item: Extend<<Self::Item as IntoIterator>::Item> + IntoIterator + Default,

Concatenate all results of a stream into a single extendable destination, returning a future representing the end result.

fn concat(self) -> Concat<Self>

where Self: Sized, Self::Item: Extend<<Self::Item as IntoIterator>::Item> + IntoIterator,

👎Deprecated since 0.1.14: please use Stream::concat2 instead

Concatenate all results of a stream into a single extendable destination, returning a future representing the end result.

fn fold<F, T, Fut>(self, init: T, f: F) -> Fold<Self, F, Fut, T>

where F: FnMut(T, Self::Item) -> Fut, Fut: IntoFuture<Item = T>, Self::Error: From<<Fut as IntoFuture>::Error>, Self: Sized,

Execute an accumulating computation over a stream, collecting all the values into one final result.

fn flatten(self) -> Flatten<Self>

where Self::Item: Stream, <Self::Item as Stream>::Error: From<Self::Error>, Self: Sized,

Flattens a stream of streams into just one continuous stream.

fn skip_while<P, R>(self, pred: P) -> SkipWhile<Self, P, R>

where P: FnMut(&Self::Item) -> R, R: IntoFuture<Item = bool, Error = Self::Error>, Self: Sized,

Skip elements on this stream while the predicate provided resolves to true.

fn take_while<P, R>(self, pred: P) -> TakeWhile<Self, P, R>

where P: FnMut(&Self::Item) -> R, R: IntoFuture<Item = bool, Error = Self::Error>, Self: Sized,

Take elements from this stream while the predicate provided resolves to true.

fn for_each<F, U>(self, f: F) -> ForEach<Self, F, U>

where F: FnMut(Self::Item) -> U, U: IntoFuture<Item = (), Error = Self::Error>, Self: Sized,

Runs this stream to completion, executing the provided closure for each element on the stream.

fn from_err<E>(self) -> FromErr<Self, E>

where E: From<Self::Error>, Self: Sized,

Map this stream’s error to any error implementing From for this stream’s Error, returning a new stream.

fn take(self, amt: u64) -> Take<Self>

where Self: Sized,

Creates a new stream of at most amt items of the underlying stream.

fn skip(self, amt: u64) -> Skip<Self>

where Self: Sized,

Creates a new stream which skips amt items of the underlying stream.

fn fuse(self) -> Fuse<Self>

where Self: Sized,

Fuse a stream such that poll will never again be called once it has finished.

fn by_ref(&mut self) -> &mut Self

where Self: Sized,

Borrows a stream, rather than consuming it.

fn catch_unwind(self) -> CatchUnwind<Self>

where Self: Sized + UnwindSafe,

Catches unwinding panics while polling the stream.

fn buffered(self, amt: usize) -> Buffered<Self>

where Self::Item: IntoFuture<Error = Self::Error>, Self: Sized,

An adaptor for creating a buffered list of pending futures.

fn buffer_unordered(self, amt: usize) -> BufferUnordered<Self>

where Self::Item: IntoFuture<Error = Self::Error>, Self: Sized,

An adaptor for creating a buffered list of pending futures (unordered).

fn merge<S>(self, other: S) -> Merge<Self, S>

where S: Stream<Error = Self::Error>, Self: Sized,

👎Deprecated: functionality provided by select now

An adapter for merging the output of two streams.

fn zip<S>(self, other: S) -> Zip<Self, S>

where S: Stream<Error = Self::Error>, Self: Sized,

An adapter for zipping two streams together.

fn chain<S>(self, other: S) -> Chain<Self, S>

where S: Stream<Item = Self::Item, Error = Self::Error>, Self: Sized,

Adapter for chaining two stream.

fn peekable(self) -> Peekable<Self>

where Self: Sized,

Creates a new stream which exposes a peek method.

fn chunks(self, capacity: usize) -> Chunks<Self>

where Self: Sized,

An adaptor for chunking up items of the stream inside a vector.

fn select<S>(self, other: S) -> Select<Self, S>

where S: Stream<Item = Self::Item, Error = Self::Error>, Self: Sized,

Creates a stream that selects the next element from either this stream or the provided one, whichever is ready first.

fn forward<S>(self, sink: S) -> Forward<Self, S>

where S: Sink<SinkItem = Self::Item>, Self::Error: From<<S as Sink>::SinkError>, Self: Sized,

A future that completes after the given stream has been fully processed into the sink, including flushing.

fn inspect<F>(self, f: F) -> Inspect<Self, F>

where F: FnMut(&Self::Item), Self: Sized,

Do something with each item of this stream, afterwards passing it on.

fn inspect_err<F>(self, f: F) -> InspectErr<Self, F>

where F: FnMut(&Self::Error), Self: Sized,

Do something with the error of this stream, afterwards passing it on.