Struct corona::io::BlockingWrapper

pub struct BlockingWrapper<T>(_);

A wrapper to turn async IO streams into sync ones.

This can be used to wrap an asynchronous stream ‒ anything that is AsyncRead or AsyncWrite (like tokio's TcpStream) into a sync one. When performing IO, the current coroutine is suspended, but the thread isn't blocked.

This makes it possible to use blocking API (for example serde_json::from_reader) on asynchronous primitives.

Note that if T is AsyncRead (or AsyncWrite), &mut T is too. Therefore, it is possible both to turn the stream into a sync one permanently (or, until the wrapper is unwrapped with into_inner), or just temporarily.

Examples

use std::io::{Read, Result as IoResult};
use corona::io::BlockingWrapper;
use tokio::net::TcpStream;

fn blocking_read(connection: &mut TcpStream) -> IoResult<()> {
    let mut connection = BlockingWrapper::new(connection);
    let mut buf = [0u8; 64];
    // This will block the coroutine, but not the thread
    connection.read_exact(&mut buf)
}

Panics

Using the wrapped object may panic in these circumstances:

• If it is used outside of a coroutine (as there's nothing to suspend at that time).
• If the tokio core is dropped while waiting for data.

Methods

impl<T> BlockingWrapper<T>

pub fn new(stream: T) -> Self

Wraps the stream and turns it to synchronous one.

pub fn inner(&self) -> &T

Accesses the inner stream.

pub fn inner_mut(&mut self) -> &mut T

Accesses the inner stream mutably.

pub fn into_inner(self) -> T

Consumes the wrapper and produces the original stream.

Trait Implementations

impl<T: Clone> Clone for BlockingWrapper<T>

Important traits for BlockingWrapper<T>

impl<T: AsyncRead> Read for BlockingWrapper<T>impl<T: AsyncWrite> Write for BlockingWrapper<T>

fn clone(&self) -> BlockingWrapper<T>

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl<T: Debug> Debug for BlockingWrapper<T>

fn fmt(&self, f: &mut Formatter) -> Result

Formats the value using the given formatter.

impl<T: Eq> Eq for BlockingWrapper<T>

impl<T> From<T> for BlockingWrapper<T>

fn from(stream: T) -> Self

Performs the conversion.

impl<T: Hash> Hash for BlockingWrapper<T>

fn hash<__H: Hasher>(&self, state: &mut __H)

Feeds this value into the given [Hasher].

fn hash_slice<H>(data: &[Self], state: &mut H) where
    H: Hasher, 

Feeds a slice of this type into the given [Hasher].

impl<T: Ord> Ord for BlockingWrapper<T>

fn cmp(&self, other: &BlockingWrapper<T>) -> Ordering

This method returns an [Ordering] between self and other.

#[must_use] fn max(self, other: Self) -> Self

Compares and returns the maximum of two values.

#[must_use] fn min(self, other: Self) -> Self

Compares and returns the minimum of two values.

#[must_use] fn clamp(self, min: Self, max: Self) -> Self

🔬 This is a nightly-only experimental API. (clamp)

Restrict a value to a certain interval.

impl<T: PartialEq> PartialEq<BlockingWrapper<T>> for BlockingWrapper<T>

fn eq(&self, other: &BlockingWrapper<T>) -> bool

This method tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &BlockingWrapper<T>) -> bool

This method tests for !=.

impl<T: PartialOrd> PartialOrd<BlockingWrapper<T>> for BlockingWrapper<T>

fn partial_cmp(&self, other: &BlockingWrapper<T>) -> Option<Ordering>

This method returns an ordering between self and other values if one exists.

fn lt(&self, other: &BlockingWrapper<T>) -> bool

This method tests less than (for self and other) and is used by the < operator.

fn le(&self, other: &BlockingWrapper<T>) -> bool

This method tests less than or equal to (for self and other) and is used by the <= operator.

fn gt(&self, other: &BlockingWrapper<T>) -> bool

This method tests greater than (for self and other) and is used by the > operator.

fn ge(&self, other: &BlockingWrapper<T>) -> bool

This method tests greater than or equal to (for self and other) and is used by the >= operator.

impl<T: AsyncRead> Read for BlockingWrapper<T>

fn read(&mut self, buf: &mut [u8]) -> IoResult<usize>

Pull some bytes from this source into the specified buffer, returning how many bytes were read.

fn read_vectored(&mut self, bufs: &mut [IoSliceMut]) -> Result<usize, Error>

Like read, except that it reads into a slice of buffers.

unsafe fn initializer(&self) -> Initializer

🔬 This is a nightly-only experimental API. (read_initializer)

Determines if this Reader can work with buffers of uninitialized memory.

fn read_to_end(&mut self, buf: &mut Vec<u8>) -> Result<usize, Error>

Read all bytes until EOF in this source, placing them into buf.

fn read_to_string(&mut self, buf: &mut String) -> Result<usize, Error>

Read all bytes until EOF in this source, appending them to buf.

fn read_exact(&mut self, buf: &mut [u8]) -> Result<(), Error>

Read the exact number of bytes required to fill buf.

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

Creates a "by reference" adaptor for this instance of Read.

fn bytes(self) -> Bytes<Self>

Transforms this Read instance to an [Iterator] over its bytes.

fn chain<R>(self, next: R) -> Chain<Self, R> where
    R: Read, 

Creates an adaptor which will chain this stream with another.

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

Creates an adaptor which will read at most limit bytes from it.

impl<T> StructuralEq for BlockingWrapper<T>

impl<T> StructuralPartialEq for BlockingWrapper<T>

impl<T: AsyncWrite> Write for BlockingWrapper<T>

fn write(&mut self, buf: &[u8]) -> IoResult<usize>

Write a buffer into this writer, returning how many bytes were written.

fn flush(&mut self) -> IoResult<()>

Flush this output stream, ensuring that all intermediately buffered contents reach their destination.

fn write_vectored(&mut self, bufs: &[IoSlice]) -> Result<usize, Error>

Like write, except that it writes from a slice of buffers.

fn write_all(&mut self, buf: &[u8]) -> Result<(), Error>

Attempts to write an entire buffer into this writer.

fn write_fmt(&mut self, fmt: Arguments) -> Result<(), Error>

Writes a formatted string into this writer, returning any error encountered.

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

Creates a "by reference" adaptor for this instance of Write.