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|
use std::{
io,
pin::Pin,
task::{Context, Poll},
};
use futures_io::AsyncWrite;
use futures_lite::AsyncWriteExt;
use super::u16_to_hex;
use crate::{encode::Error, Channel, DELIMITER_LINE, ERR_PREFIX, FLUSH_LINE, MAX_DATA_LEN, RESPONSE_END_LINE};
pin_project_lite::pin_project! {
/// A way of writing packet lines asynchronously.
pub struct LineWriter<'a, W> {
#[pin]
pub(crate) writer: W,
pub(crate) prefix: &'a [u8],
pub(crate) suffix: &'a [u8],
state: State<'a>,
}
}
enum State<'a> {
Idle,
WriteHexLen([u8; 4], usize),
WritePrefix(&'a [u8]),
WriteData(usize),
WriteSuffix(&'a [u8]),
}
impl<'a, W: AsyncWrite + Unpin> LineWriter<'a, W> {
/// Create a new line writer writing data with a `prefix` and `suffix`.
///
/// Keep the additional `prefix` or `suffix` buffers empty if no prefix or suffix should be written.
pub fn new(writer: W, prefix: &'a [u8], suffix: &'a [u8]) -> Self {
LineWriter {
writer,
prefix,
suffix,
state: State::Idle,
}
}
/// Consume self and reveal the inner writer.
pub fn into_inner(self) -> W {
self.writer
}
}
fn into_io_err(err: Error) -> io::Error {
io::Error::new(io::ErrorKind::Other, err)
}
impl<W: AsyncWrite + Unpin> AsyncWrite for LineWriter<'_, W> {
fn poll_write(self: Pin<&mut Self>, cx: &mut Context<'_>, data: &[u8]) -> Poll<io::Result<usize>> {
use futures_lite::ready;
let mut this = self.project();
loop {
match &mut this.state {
State::Idle => {
let data_len = this.prefix.len() + data.len() + this.suffix.len();
if data_len > MAX_DATA_LEN {
return Poll::Ready(Err(into_io_err(Error::DataLengthLimitExceeded {
length_in_bytes: data_len,
})));
}
if data.is_empty() {
return Poll::Ready(Err(into_io_err(Error::DataIsEmpty)));
}
let data_len = data_len + 4;
let len_buf = u16_to_hex(data_len as u16);
*this.state = State::WriteHexLen(len_buf, 0)
}
State::WriteHexLen(hex_len, written) => {
while *written != hex_len.len() {
let n = ready!(this.writer.as_mut().poll_write(cx, &hex_len[*written..]))?;
if n == 0 {
return Poll::Ready(Err(io::ErrorKind::WriteZero.into()));
}
*written += n;
}
if this.prefix.is_empty() {
*this.state = State::WriteData(0)
} else {
*this.state = State::WritePrefix(this.prefix)
}
}
State::WritePrefix(buf) => {
while !buf.is_empty() {
let n = ready!(this.writer.as_mut().poll_write(cx, buf))?;
if n == 0 {
return Poll::Ready(Err(io::ErrorKind::WriteZero.into()));
}
let (_, rest) = std::mem::take(buf).split_at(n);
*buf = rest;
}
*this.state = State::WriteData(0)
}
State::WriteData(written) => {
while *written != data.len() {
let n = ready!(this.writer.as_mut().poll_write(cx, &data[*written..]))?;
if n == 0 {
return Poll::Ready(Err(io::ErrorKind::WriteZero.into()));
}
*written += n;
}
if this.suffix.is_empty() {
let written = 4 + this.prefix.len() + *written;
*this.state = State::Idle;
return Poll::Ready(Ok(written));
} else {
*this.state = State::WriteSuffix(this.suffix)
}
}
State::WriteSuffix(buf) => {
while !buf.is_empty() {
let n = ready!(this.writer.as_mut().poll_write(cx, buf))?;
if n == 0 {
return Poll::Ready(Err(io::ErrorKind::WriteZero.into()));
}
let (_, rest) = std::mem::take(buf).split_at(n);
*buf = rest;
}
*this.state = State::Idle;
return Poll::Ready(Ok(4 + this.prefix.len() + data.len() + this.suffix.len()));
}
}
}
}
fn poll_flush(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<io::Result<()>> {
let this = self.project();
this.writer.poll_flush(cx)
}
fn poll_close(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<io::Result<()>> {
let this = self.project();
this.writer.poll_close(cx)
}
}
async fn prefixed_and_suffixed_data_to_write(
prefix: &[u8],
data: &[u8],
suffix: &[u8],
mut out: impl AsyncWrite + Unpin,
) -> io::Result<usize> {
let data_len = prefix.len() + data.len() + suffix.len();
if data_len > MAX_DATA_LEN {
return Err(into_io_err(Error::DataLengthLimitExceeded {
length_in_bytes: data_len,
}));
}
if data.is_empty() {
return Err(into_io_err(Error::DataIsEmpty));
}
let data_len = data_len + 4;
let buf = u16_to_hex(data_len as u16);
out.write_all(&buf).await?;
if !prefix.is_empty() {
out.write_all(prefix).await?;
}
out.write_all(data).await?;
if !suffix.is_empty() {
out.write_all(suffix).await?;
}
Ok(data_len)
}
async fn prefixed_data_to_write(prefix: &[u8], data: &[u8], out: impl AsyncWrite + Unpin) -> io::Result<usize> {
prefixed_and_suffixed_data_to_write(prefix, data, &[], out).await
}
/// Write a `text` message to `out`, which is assured to end in a newline.
pub async fn text_to_write(text: &[u8], out: impl AsyncWrite + Unpin) -> io::Result<usize> {
prefixed_and_suffixed_data_to_write(&[], text, &[b'\n'], out).await
}
/// Write a `data` message to `out`.
pub async fn data_to_write(data: &[u8], out: impl AsyncWrite + Unpin) -> io::Result<usize> {
prefixed_data_to_write(&[], data, out).await
}
/// Write an error `message` to `out`.
pub async fn error_to_write(message: &[u8], out: impl AsyncWrite + Unpin) -> io::Result<usize> {
prefixed_data_to_write(ERR_PREFIX, message, out).await
}
/// Write a response-end message to `out`.
pub async fn response_end_to_write(mut out: impl AsyncWrite + Unpin) -> io::Result<usize> {
out.write_all(RESPONSE_END_LINE).await?;
Ok(4)
}
/// Write a delim message to `out`.
pub async fn delim_to_write(mut out: impl AsyncWrite + Unpin) -> io::Result<usize> {
out.write_all(DELIMITER_LINE).await?;
Ok(4)
}
/// Write a flush message to `out`.
pub async fn flush_to_write(mut out: impl AsyncWrite + Unpin) -> io::Result<usize> {
out.write_all(FLUSH_LINE).await?;
Ok(4)
}
/// Write `data` of `kind` to `out` using side-band encoding.
pub async fn band_to_write(kind: Channel, data: &[u8], out: impl AsyncWrite + Unpin) -> io::Result<usize> {
prefixed_data_to_write(&[kind as u8], data, out).await
}
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