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//! I/O conveniences when working with primitives in `tokio-core`
//!
//! Contains various combinators to work with I/O objects and type definitions
//! as well.
//!
//! A description of the high-level I/O combinators can be [found online] in
//! addition to a description of the [low level details].
//!
//! [found online]: https://tokio.rs/docs/getting-started/core/
//! [low level details]: https://tokio.rs/docs/going-deeper-tokio/core-low-level/
#![deprecated(note = "moved to the `tokio-io` crate")]
#![allow(deprecated)]
use std::io;
use futures::{Async, Poll};
use futures::future::BoxFuture;
use futures::stream::BoxStream;
use iovec::IoVec;
/// A convenience typedef around a `Future` whose error component is `io::Error`
pub type IoFuture<T> = BoxFuture<T, io::Error>;
/// A convenience typedef around a `Stream` whose error component is `io::Error`
pub type IoStream<T> = BoxStream<T, io::Error>;
/// A convenience macro for working with `io::Result<T>` from the `Read` and
/// `Write` traits.
///
/// This macro takes `io::Result<T>` as input, and returns `T` as the output. If
/// the input type is of the `Err` variant, then `Poll::NotReady` is returned if
/// it indicates `WouldBlock` or otherwise `Err` is returned.
#[macro_export]
macro_rules! try_nb {
($e:expr) => (match $e {
Ok(t) => t,
Err(ref e) if e.kind() == ::std::io::ErrorKind::WouldBlock => {
return Ok(::futures::Async::NotReady)
}
Err(e) => return Err(e.into()),
})
}
mod copy;
mod frame;
mod flush;
mod read_exact;
mod read_to_end;
mod read;
mod read_until;
mod split;
mod window;
mod write_all;
pub use self::copy::{copy, Copy};
pub use self::frame::{EasyBuf, EasyBufMut, Framed, Codec};
pub use self::flush::{flush, Flush};
pub use self::read_exact::{read_exact, ReadExact};
pub use self::read_to_end::{read_to_end, ReadToEnd};
pub use self::read::{read, Read};
pub use self::read_until::{read_until, ReadUntil};
pub use self::split::{ReadHalf, WriteHalf};
pub use self::window::Window;
pub use self::write_all::{write_all, WriteAll};
/// A trait for read/write I/O objects
///
/// This trait represents I/O objects which are readable and writable.
/// Additionally, they're associated with the ability to test whether they're
/// readable or writable.
///
/// Importantly, the methods of this trait are intended to be used in conjunction
/// with the current task of a future. Namely whenever any of them return a
/// value that indicates "would block" the current future's task is arranged to
/// receive a notification when the method would otherwise not indicate that it
/// would block.
pub trait Io: io::Read + io::Write {
/// Tests to see if this I/O object may be readable.
///
/// This method returns an `Async<()>` indicating whether the object
/// **might** be readable. It is possible that even if this method returns
/// `Async::Ready` that a call to `read` would return a `WouldBlock` error.
///
/// There is a default implementation for this function which always
/// indicates that an I/O object is readable, but objects which can
/// implement a finer grained version of this are recommended to do so.
///
/// If this function returns `Async::NotReady` then the current future's
/// task is arranged to receive a notification when it might not return
/// `NotReady`.
///
/// # Panics
///
/// This method is likely to panic if called from outside the context of a
/// future's task.
fn poll_read(&mut self) -> Async<()> {
Async::Ready(())
}
/// Tests to see if this I/O object may be writable.
///
/// This method returns an `Async<()>` indicating whether the object
/// **might** be writable. It is possible that even if this method returns
/// `Async::Ready` that a call to `write` would return a `WouldBlock` error.
///
/// There is a default implementation for this function which always
/// indicates that an I/O object is writable, but objects which can
/// implement a finer grained version of this are recommended to do so.
///
/// If this function returns `Async::NotReady` then the current future's
/// task is arranged to receive a notification when it might not return
/// `NotReady`.
///
/// # Panics
///
/// This method is likely to panic if called from outside the context of a
/// future's task.
fn poll_write(&mut self) -> Async<()> {
Async::Ready(())
}
/// Read in a list of buffers all at once.
///
/// This operation will attempt to read bytes from this socket and place
/// them into the list of buffers provided. Note that each buffer is an
/// `IoVec` which can be created from a byte slice.
///
/// The buffers provided will be filled in sequentially. A buffer will be
/// entirely filled up before the next is written to.
///
/// The number of bytes read is returned, if successful, or an error is
/// returned otherwise. If no bytes are available to be read yet then
/// a "would block" error is returned. This operation should not block.
///
/// There is a default implementation for this function which treats this
/// as a single read using the first buffer in the list, but objects which
/// can implement this as an atomic read using all the buffers are
/// recommended to do so. For example, `TcpStream` can implement this
/// using the `readv` syscall.
fn read_vec(&mut self, bufs: &mut [&mut IoVec]) -> io::Result<usize> {
if bufs.is_empty() {
Ok(0)
} else {
self.read(&mut bufs[0])
}
}
/// Write a list of buffers all at once.
///
/// This operation will attempt to write a list of byte buffers to this
/// socket. Note that each buffer is an `IoVec` which can be created from a
/// byte slice.
///
/// The buffers provided will be written sequentially. A buffer will be
/// entirely written before the next is written.
///
/// The number of bytes written is returned, if successful, or an error is
/// returned otherwise. If the socket is not currently writable then a
/// "would block" error is returned. This operation should not block.
///
/// There is a default implementation for this function which writes the
/// first buffer only, but objects which can implement this as an atomic
/// write using all the buffers are recommended to do so. For example,
/// `TcpStream` can implement this using the `writev` syscall.
fn write_vec(&mut self, bufs: &[&IoVec]) -> io::Result<usize> {
if bufs.is_empty() {
Ok(0)
} else {
self.write(&bufs[0])
}
}
/// Provides a `Stream` and `Sink` interface for reading and writing to this
/// `Io` object, using `Decode` and `Encode` to read and write the raw data.
///
/// Raw I/O objects work with byte sequences, but higher-level code usually
/// wants to batch these into meaningful chunks, called "frames". This
/// method layers framing on top of an I/O object, by using the `Codec`
/// traits to handle encoding and decoding of messages frames. Note that
/// the incoming and outgoing frame types may be distinct.
///
/// This function returns a *single* object that is both `Stream` and
/// `Sink`; grouping this into a single object is often useful for layering
/// things like gzip or TLS, which require both read and write access to the
/// underlying object.
///
/// If you want to work more directly with the streams and sink, consider
/// calling `split` on the `Framed` returned by this method, which will
/// break them into separate objects, allowing them to interact more easily.
fn framed<C: Codec>(self, codec: C) -> Framed<Self, C>
where Self: Sized,
{
frame::framed(self, codec)
}
/// Helper method for splitting this read/write object into two halves.
///
/// The two halves returned implement the `Read` and `Write` traits,
/// respectively.
fn split(self) -> (ReadHalf<Self>, WriteHalf<Self>)
where Self: Sized
{
split::split(self)
}
}
/// A trait for framed reading and writing.
///
/// Most implementations of `FramedIo` are for doing protocol level
/// serialization and deserialization.
///
/// Importantly, the methods of this trait are intended to be used in conjunction
/// with the current task of a future. Namely whenever any of them return a
/// value that indicates "would block" the current future's task is arranged to
/// receive a notification when the method would otherwise not indicate that it
/// would block.
//
/// For a sample implementation of `FramedIo` you can take a look at the
/// `Framed` type in the `frame` module of this crate.
#[doc(hidden)]
#[deprecated(since = "0.1.1", note = "replaced by Sink + Stream")]
pub trait FramedIo {
/// Messages written
type In;
/// Messages read
type Out;
/// Tests to see if this `FramedIo` may be readable.
fn poll_read(&mut self) -> Async<()>;
/// Read a message frame from the `FramedIo`
fn read(&mut self) -> Poll<Self::Out, io::Error>;
/// Tests to see if this `FramedIo` may be writable.
///
/// Unlike most other calls to poll readiness, it is important that when
/// `FramedIo::poll_write` returns `Async::Ready` that a write will
/// succeed.
fn poll_write(&mut self) -> Async<()>;
/// Write a message frame to the `FramedIo`
fn write(&mut self, req: Self::In) -> Poll<(), io::Error>;
/// Flush pending writes or do any other work not driven by reading /
/// writing.
///
/// Since the backing source is non-blocking, there is no guarantee that a
/// call to `FramedIo::write` is able to write the full message to the
/// backing source immediately. In this case, the `FramedIo` will need to
/// buffer the remaining data to write. Calls to `FramedIo:flush` attempt
/// to write any remaining data in the write buffer to the underlying
/// source.
fn flush(&mut self) -> Poll<(), io::Error>;
}