Struct futures_lite::io::BlockOn

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pub struct BlockOn<T>(/* private fields */);
Expand description

Blocks on all async I/O operations and implements std::io traits.

Sometimes async I/O needs to be used in a blocking manner. If calling future::block_on() manually all the time becomes too tedious, use this type for more convenient blocking on async I/O operations.

This type implements traits Read, Write, or Seek if the inner type implements AsyncRead, AsyncWrite, or AsyncSeek, respectively.

If writing data through the Write trait, make sure to flush before dropping the BlockOn handle or some buffered data might get lost.

Examples

use futures_lite::io::BlockOn;
use futures_lite::pin;
use std::io::Read;

let reader: &[u8] = b"hello";
pin!(reader);

let mut blocking_reader = BlockOn::new(reader);
let mut contents = String::new();

// This line blocks - note that there is no await:
blocking_reader.read_to_string(&mut contents)?;

Implementations§

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impl<T> BlockOn<T>

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pub fn new(io: T) -> BlockOn<T>

Wraps an async I/O handle into a blocking interface.

Examples
use futures_lite::io::BlockOn;
use futures_lite::pin;

let reader: &[u8] = b"hello";
pin!(reader);

let blocking_reader = BlockOn::new(reader);
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pub fn get_ref(&self) -> &T

Gets a reference to the async I/O handle.

Examples
use futures_lite::io::BlockOn;
use futures_lite::pin;

let reader: &[u8] = b"hello";
pin!(reader);

let blocking_reader = BlockOn::new(reader);
let r = blocking_reader.get_ref();
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pub fn get_mut(&mut self) -> &mut T

Gets a mutable reference to the async I/O handle.

Examples
use futures_lite::io::BlockOn;
use futures_lite::pin;

let reader: &[u8] = b"hello";
pin!(reader);

let mut blocking_reader = BlockOn::new(reader);
let r = blocking_reader.get_mut();
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pub fn into_inner(self) -> T

Extracts the inner async I/O handle.

Examples
use futures_lite::io::BlockOn;
use futures_lite::pin;

let reader: &[u8] = b"hello";
pin!(reader);

let blocking_reader = BlockOn::new(reader);
let inner = blocking_reader.into_inner();

Trait Implementations§

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impl<T: AsyncBufRead + Unpin> BufRead for BlockOn<T>

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fn fill_buf(&mut self) -> Result<&[u8]>

Returns the contents of the internal buffer, filling it with more data from the inner reader if it is empty. Read more
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fn consume(&mut self, amt: usize)

Tells this buffer that amt bytes have been consumed from the buffer, so they should no longer be returned in calls to read. Read more
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fn has_data_left(&mut self) -> Result<bool, Error>

🔬This is a nightly-only experimental API. (buf_read_has_data_left)
Check if the underlying Read has any data left to be read. Read more
1.0.0 · source§

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

Read all bytes into buf until the delimiter byte or EOF is reached. Read more
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fn skip_until(&mut self, byte: u8) -> Result<usize, Error>

🔬This is a nightly-only experimental API. (bufread_skip_until)
Skip all bytes until the delimiter byte or EOF is reached. Read more
1.0.0 · source§

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

Read all bytes until a newline (the 0xA byte) is reached, and append them to the provided String buffer. Read more
1.0.0 · source§

fn split(self, byte: u8) -> Split<Self>
where Self: Sized,

Returns an iterator over the contents of this reader split on the byte byte. Read more
1.0.0 · source§

fn lines(self) -> Lines<Self>
where Self: Sized,

Returns an iterator over the lines of this reader. Read more
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impl<T: Debug> Debug for BlockOn<T>

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

Formats the value using the given formatter. Read more
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impl<T: AsyncRead + Unpin> Read for BlockOn<T>

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

Pull some bytes from this source into the specified buffer, returning how many bytes were read. Read more
1.36.0 · source§

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

Like read, except that it reads into a slice of buffers. Read more
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fn is_read_vectored(&self) -> bool

🔬This is a nightly-only experimental API. (can_vector)
Determines if this Reader has an efficient read_vectored implementation. Read more
1.0.0 · source§

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. Read more
1.0.0 · source§

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

Read all bytes until EOF in this source, appending them to buf. Read more
1.6.0 · source§

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

Read the exact number of bytes required to fill buf. Read more
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fn read_buf(&mut self, buf: BorrowedCursor<'_>) -> Result<(), Error>

🔬This is a nightly-only experimental API. (read_buf)
Pull some bytes from this source into the specified buffer. Read more
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fn read_buf_exact(&mut self, cursor: BorrowedCursor<'_>) -> Result<(), Error>

🔬This is a nightly-only experimental API. (read_buf)
Read the exact number of bytes required to fill cursor. Read more
1.0.0 · source§

fn by_ref(&mut self) -> &mut Self
where Self: Sized,

Creates a “by reference” adaptor for this instance of Read. Read more
1.0.0 · source§

fn bytes(self) -> Bytes<Self>
where Self: Sized,

Transforms this Read instance to an Iterator over its bytes. Read more
1.0.0 · source§

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

Creates an adapter which will chain this stream with another. Read more
1.0.0 · source§

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

Creates an adapter which will read at most limit bytes from it. Read more
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impl<T: AsyncSeek + Unpin> Seek for BlockOn<T>

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fn seek(&mut self, pos: SeekFrom) -> Result<u64>

Seek to an offset, in bytes, in a stream. Read more
1.55.0 · source§

fn rewind(&mut self) -> Result<(), Error>

Rewind to the beginning of a stream. Read more
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fn stream_len(&mut self) -> Result<u64, Error>

🔬This is a nightly-only experimental API. (seek_stream_len)
Returns the length of this stream (in bytes). Read more
1.51.0 · source§

fn stream_position(&mut self) -> Result<u64, Error>

Returns the current seek position from the start of the stream. Read more
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fn seek_relative(&mut self, offset: i64) -> Result<(), Error>

🔬This is a nightly-only experimental API. (seek_seek_relative)
Seeks relative to the current position. Read more
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impl<T: AsyncWrite + Unpin> Write for BlockOn<T>

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

Write a buffer into this writer, returning how many bytes were written. Read more
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fn flush(&mut self) -> Result<()>

Flush this output stream, ensuring that all intermediately buffered contents reach their destination. Read more
1.36.0 · source§

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

Like write, except that it writes from a slice of buffers. Read more
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fn is_write_vectored(&self) -> bool

🔬This is a nightly-only experimental API. (can_vector)
Determines if this Writer has an efficient write_vectored implementation. Read more
1.0.0 · source§

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

Attempts to write an entire buffer into this writer. Read more
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fn write_all_vectored(&mut self, bufs: &mut [IoSlice<'_>]) -> Result<(), Error>

🔬This is a nightly-only experimental API. (write_all_vectored)
Attempts to write multiple buffers into this writer. Read more
1.0.0 · source§

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

Writes a formatted string into this writer, returning any error encountered. Read more
1.0.0 · source§

fn by_ref(&mut self) -> &mut Self
where Self: Sized,

Creates a “by reference” adapter for this instance of Write. Read more

Auto Trait Implementations§

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impl<T> RefUnwindSafe for BlockOn<T>
where T: RefUnwindSafe,

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impl<T> Send for BlockOn<T>
where T: Send,

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impl<T> Sync for BlockOn<T>
where T: Sync,

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impl<T> Unpin for BlockOn<T>
where T: Unpin,

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impl<T> UnwindSafe for BlockOn<T>
where T: UnwindSafe,

Blanket Implementations§

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impl<T> Any for T
where T: 'static + ?Sized,

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fn type_id(&self) -> TypeId

Gets the TypeId of self. Read more
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impl<T> Borrow<T> for T
where T: ?Sized,

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fn borrow(&self) -> &T

Immutably borrows from an owned value. Read more
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impl<T> BorrowMut<T> for T
where T: ?Sized,

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fn borrow_mut(&mut self) -> &mut T

Mutably borrows from an owned value. Read more
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impl<T> From<T> for T

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fn from(t: T) -> T

Returns the argument unchanged.

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impl<T, U> Into<U> for T
where U: From<T>,

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fn into(self) -> U

Calls U::from(self).

That is, this conversion is whatever the implementation of From<T> for U chooses to do.

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impl<T, U> TryFrom<U> for T
where U: Into<T>,

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type Error = Infallible

The type returned in the event of a conversion error.
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fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>

Performs the conversion.
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impl<T, U> TryInto<U> for T
where U: TryFrom<T>,

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type Error = <U as TryFrom<T>>::Error

The type returned in the event of a conversion error.
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fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>

Performs the conversion.