Struct fixed_buffer_tokio::AsyncFixedBuf

pub struct AsyncFixedBuf<T>(_);

A newtime that wraps FixedBuf and implements tokio::io::AsyncRead and tokio::io::AsyncWrite.

It also has async versions of FixedBuf's io functions.

Implementations

impl<T> AsyncFixedBuf<T>

pub const fn new(mem: T) -> Self

Creates a new FixedBuf and wraps it in an AsyncFixedBuf.

See FixedBuf::new for details.

pub fn into_inner(self) -> FixedBuf<T>

Drops the struct and returns its internal FixedBuf.

impl<T: AsRef<[u8]>> AsyncFixedBuf<T>

pub fn filled(mem: T) -> Self

Creates a new FixedBuf and wraps it in an AsyncFixedBuf.

Reading the buffer will return the bytes in mem.

See FixedBuf::filled for details.

impl<T: AsMut<[u8]>> AsyncFixedBuf<T>

pub async fn copy_once_from<R: AsyncRead + Unpin + Send, '_, '_>(
    &'_ mut self,
    reader: &'_ mut R
) -> Result<usize, Error>

Reads from reader once and writes the data into the buffer.

Returns InvalidData if there is no empty space in the buffer. See shift.

impl<T: AsRef<[u8]> + AsMut<[u8]>> AsyncFixedBuf<T>

pub async fn read_frame<R, F, '_, '_, '_>(
    &'_ mut self,
    reader: &'_ mut R,
    deframer_fn: F
) -> Result<Option<&'_ [u8]>, Error> where
    R: AsyncRead + Unpin + Send,
    F: Fn(&[u8]) -> Result<Option<(Range<usize>, usize)>, MalformedInputError>, 

Async version of FixedBuf::read_frame.

Methods from Deref<Target = FixedBuf<T>>

pub fn len(&self) -> usize

Returns the number of unread bytes in the buffer.

Example:

let mut buf: FixedBuf<[u8; 16]> = FixedBuf::new([0u8; 16]);
assert_eq!(0, buf.len());
buf.write_str("abc");
assert_eq!(3, buf.len());
buf.read_bytes(2);
assert_eq!(1, buf.len());
buf.shift();
assert_eq!(1, buf.len());
buf.read_all();
assert_eq!(0, buf.len());

pub fn is_empty(&self) -> bool

Returns true if there are unread bytes in the buffer.

Example:

let mut buf: FixedBuf<[u8; 16]> = FixedBuf::new([0u8; 16]);
assert!(buf.is_empty());
buf.write_str("abc").unwrap();
assert!(!buf.is_empty());
buf.read_all();
assert!(buf.is_empty());

pub fn clear(&mut self)

Discards all data in the buffer.

pub fn capacity(&self) -> usize

Returns the maximum number of bytes that can be stored in the buffer.

Example:

let mut buf: FixedBuf<[u8; 16]> = FixedBuf::new([0u8; 16]);
assert_eq!(16, buf.capacity());
buf.write_str("abc").unwrap();
assert_eq!(16, buf.capacity());

pub fn escape_ascii(&self) -> String

Copies all readable bytes to a string. Includes printable ASCII characters as-is. Converts non-printable characters to strings like "\n" and "\x19".

Leaves the buffer unchanged.

Uses core::ascii::escape_default(https://doc.rust-lang.org/core/ascii/fn.escape_default.html internally to escape each byte.

This function is useful for printing byte slices to logs and comparing byte slices in tests.

Example test:

use fixed_buffer::FixedBuf;
let mut buf = FixedBuf::new([0u8; 16]);
buf.write_str("abc");
buf.write_str("€");
assert_eq!("abc\\xe2\\x82\\xac", buf.escape_ascii());

pub fn mem(&self) -> &[u8]

This is a low-level function.

Borrows the entire internal memory buffer.

pub fn readable(&self) -> &[u8]

Returns the slice of readable bytes in the buffer. After processing some bytes from the front of the slice, call read to consume the bytes.

This is a low-level method. You probably want to use std::io::Read::read or tokio::io::AsyncReadExt::read , implemented for FixedBuffer in fixed_buffer_tokio::AsyncReadExt.

pub fn read_bytes(&mut self, num_bytes: usize) -> &[u8]

Reads bytes from the buffer.

Panics if the buffer does not contain enough bytes.

pub fn read_all(&mut self) -> &[u8]

Reads all the bytes from the buffer.

The buffer becomes empty and subsequent writes can fill the whole buffer.

pub fn read_and_copy_bytes(&mut self, dest: &mut [u8]) -> usize

Reads byte from the buffer and copies them into dest.

Returns the number of bytes copied.

Returns 0 when the buffer is empty or dest is zero-length.

pub fn copy_once_from<R>(&mut self, reader: &mut R) -> Result<usize, Error> where
    R: Read, 

Reads from reader once and writes the data into the buffer.

Returns InvalidData if there is no empty space in the buffer. See shift.

pub fn write_str(&mut self, s: &str) -> Result<(), NotEnoughSpaceError>

Writes s into the buffer, after any unread bytes.

Returns Err if the buffer doesn't have enough free space at the end for the whole string.

See shift.

Example:

let mut buf: FixedBuf<[u8; 8]> = FixedBuf::new([0u8; 8]);
buf.write_str("123").unwrap();
buf.write_str("456").unwrap();
assert_eq!("1234", escape_ascii(buf.read_bytes(4)));
buf.write_str("78").unwrap();
buf.write_str("9").unwrap_err();  // End of buffer is full.

pub fn write_bytes(&mut self, data: &[u8]) -> Result<usize, NotEnoughSpaceError>

Tries to write data into the buffer, after any unread bytes.

Returns Ok(data.len()) if it wrote all of the bytes.

Returns NotEnoughSpaceError if the buffer doesn't have enough free space at the end for all of the bytes.

See shift.

Example:

let mut buf: FixedBuf<[u8; 8]> = FixedBuf::new([0u8; 8]);
assert_eq!(3 as usize, buf.write_bytes("123".as_bytes()).unwrap());
assert_eq!(3 as usize, buf.write_bytes("456".as_bytes()).unwrap());
assert_eq!("1234", escape_ascii(buf.read_bytes(4)));
assert_eq!(2 as usize, buf.write_bytes("78".as_bytes()).unwrap());  // Fills buffer.
buf.write_bytes("9".as_bytes()).unwrap_err();  // Error, buffer is full.

pub fn writable(&mut self) -> Option<&mut [u8]>

Returns the writable part of the buffer.

To use this, first modify bytes at the beginning of the slice. Then call wrote(usize) to commit those bytes into the buffer and make them available for reading.

Returns None when the end of the buffer is full. See shift.

This is a low-level method. You probably want to use std::io::Write::write or tokio::io::AsyncWriteExt::write, implemented for FixedBuffer in fixed_buffer_tokio::AsyncWriteExt.

Example:

let mut buf: FixedBuf<[u8; 8]> = FixedBuf::new([0u8; 8]);
buf.writable().unwrap()[0] = 'a' as u8;
buf.writable().unwrap()[1] = 'b' as u8;
buf.writable().unwrap()[2] = 'c' as u8;
buf.wrote(3);
assert_eq!("abc", escape_ascii(buf.read_bytes(3)));

pub fn wrote(&mut self, num_bytes: usize)

Commits bytes into the buffer. Call this after writing to the front of the writable slice.

This is a low-level method.

Panics when there is not num_bytes free at the end of the buffer.

See writable().

pub fn shift(&mut self)

Recovers buffer space.

The buffer is not circular. After you read bytes, the space at the beginning of the buffer is unused. Call this method to move unread data to the beginning of the buffer and recover the space. This makes the free space available for writes, which go at the end of the buffer.

pub fn deframe<F>(
    &mut self,
    deframer_fn: F
) -> Result<Option<Range<usize>>, Error> where
    F: Fn(&[u8]) -> Result<Option<(Range<usize>, usize)>, MalformedInputError>, 

This is a low-level function. Use read_frame instead.

Calls deframer_fn to check if the buffer contains a complete frame. Consumes the frame bytes from the buffer and returns the range of the frame's contents in the internal memory. Use mem to immutably borrow the internal memory and construct the slice with &mem()[range]. This is necessary because deframe borrows self mutably but read_frame needs to borrow it immutably and return a slice.

Returns None if the buffer is empty or contains an incomplete frame.

Returns InvalidData when deframer_fn returns an error.

pub fn read_frame<R, F>(
    &mut self,
    reader: &mut R,
    deframer_fn: F
) -> Result<Option<&[u8]>, Error> where
    F: Fn(&[u8]) -> Result<Option<(Range<usize>, usize)>, MalformedInputError>,
    R: Read, 

Reads from reader into the buffer.

After each read, calls deframer_fn to check if the buffer now contains a complete frame. Consumes the frame bytes from the buffer and returns a slice with the frame contents.

Returns None when reader reaches EOF and the buffer is empty.

Returns UnexpectedEof when reader reaches EOF and the buffer contains an incomplete frame.

Returns InvalidData when deframer_fn returns an error or the buffer fills up.

Calls shift before reading.

Provided deframer functions:

• deframe_line
• deframe_crlf

Example

let mut buf: FixedBuf<[u8; 32]> = FixedBuf::new([0u8; 32]);
let mut input = std::io::Cursor::new(b"aaa\r\nbbb\n\nccc\n");
assert_eq!("aaa", escape_ascii(buf.read_frame(&mut input, deframe_line).unwrap().unwrap()));
assert_eq!("bbb", escape_ascii(buf.read_frame(&mut input, deframe_line).unwrap().unwrap()));
assert_eq!("", escape_ascii(buf.read_frame(&mut input, deframe_line).unwrap().unwrap()));
assert_eq!("ccc", escape_ascii(buf.read_frame(&mut input, deframe_line).unwrap().unwrap()));
assert_eq!(None, buf.read_frame(&mut input, deframe_line).unwrap());

Deframer Function deframe_fn

Checks if data contains an entire frame.

Never panics.

Returns Err(MalformedInputError) if data contains a malformed frame.

Returns Ok(None) if data contains an incomplete frame. The caller will read more data and call deframe again.

Returns Ok((range, len)) when data contains a complete well-formed frame of length len and contents &data[range].

A frame is a sequence of bytes containing a payload and metadata prefix or suffix bytes. The metadata define where the payload starts and ends. Popular frame protocols include line-delimiting (CSV), hexadecimal length prefix (HTTP chunked transfer encoding), and binary length prefix (TLS).

If the caller removes len bytes from the front of data, then data should start with the next frame, ready to call deframe again.

A line-delimited deframer returns range so that &data[range] contains the entire line without the final b'\n' or b"\r\n". It returns len that counts the bytes of the entire line and the final b'\n' or b"\r\n".

Example

A CRLF-terminated line deframer:

assert_eq!(Ok(None), deframe_crlf(b""));
assert_eq!(Ok(None), deframe_crlf(b"abc"));
assert_eq!(Ok(None), deframe_crlf(b"abc\r"));
assert_eq!(Ok(None), deframe_crlf(b"abc\n"));
assert_eq!(Ok(Some((0..3, 5))), deframe_crlf(b"abc\r\n"));
assert_eq!(Ok(Some((0..3, 5))), deframe_crlf(b"abc\r\nX"));

Trait Implementations

impl<T: AsRef<[u8]> + Unpin> AsyncRead for AsyncFixedBuf<T>

pub fn poll_read(
    self: Pin<&mut Self>,
    _cx: &mut Context<'_>,
    buf: &mut ReadBuf<'_>
) -> Poll<Result<(), Error>>

Attempts to read from the AsyncRead into buf.

impl<T: AsMut<[u8]>> AsyncWrite for AsyncFixedBuf<T>

pub fn poll_write(
    self: Pin<&mut Self>,
    _cx: &mut Context<'_>,
    buf: &[u8]
) -> Poll<Result<usize, Error>>

Attempt to write bytes from buf into the object.

pub fn poll_flush(
    self: Pin<&mut Self>,
    _cx: &mut Context<'_>
) -> Poll<Result<(), Error>>

Attempts to flush the object, ensuring that any buffered data reach their destination.

pub fn poll_shutdown(
    self: Pin<&mut Self>,
    _cx: &mut Context<'_>
) -> Poll<Result<(), Error>>

Initiates or attempts to shut down this writer, returning success when the I/O connection has completely shut down.

pub fn poll_write_vectored(
    self: Pin<&mut Self>,
    cx: &mut Context<'_>,
    bufs: &[IoSlice<'_>]
) -> Poll<Result<usize, Error>>

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

pub fn is_write_vectored(&self) -> bool

Determines if this writer has an efficient poll_write_vectored implementation.

impl<T> Deref for AsyncFixedBuf<T>

type Target = FixedBuf<T>

The resulting type after dereferencing.

pub fn deref(&self) -> &Self::Target

Dereferences the value.

impl<T> DerefMut for AsyncFixedBuf<T>

pub fn deref_mut(&mut self) -> &mut Self::Target

Mutably dereferences the value.

impl<T> Unpin for AsyncFixedBuf<T>