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|
use snafu::ResultExt as _;
use std::convert::TryFrom as _;
#[derive(Debug, snafu::Snafu)]
pub enum Error {
#[snafu(display("failed to create ttyrec frame: got {} bytes of data, but ttyrec frames can be at most {} bytes", input, u32::max_value()))]
FrameTooBig { input: usize },
#[snafu(display("failed to create ttyrec frame: got {} seconds, but ttyrecs can be at most {} seconds", input, u32::max_value()))]
FrameTooLong { input: u64 },
#[snafu(display("failed to read from file: {}", source))]
ReadFile { source: tokio::io::Error },
#[snafu(display("failed to write to file: {}", source))]
WriteFile { source: tokio::io::Error },
}
pub type Result<T> = std::result::Result<T, Error>;
pub struct Frame {
pub time: std::time::Duration,
pub data: Vec<u8>,
}
impl std::convert::TryFrom<Frame> for Vec<u8> {
type Error = Error;
fn try_from(frame: Frame) -> Result<Self> {
let secs = u32::try_from(frame.time.as_secs()).map_err(|_| {
Error::FrameTooLong {
input: frame.time.as_secs(),
}
})?;
let micros = frame.time.subsec_micros();
let len = u32::try_from(frame.data.len()).map_err(|_| {
Error::FrameTooBig {
input: frame.data.len(),
}
})?;
let mut bytes = vec![];
bytes.extend(secs.to_le_bytes().iter());
bytes.extend(micros.to_le_bytes().iter());
bytes.extend(len.to_le_bytes().iter());
bytes.extend(frame.data.iter());
Ok(bytes)
}
}
#[repr(packed)]
struct Header {
secs: u32,
micros: u32,
len: u32,
}
impl Header {
fn time(&self) -> std::time::Duration {
std::time::Duration::from_micros(u64::from(
self.secs * 1_000_000 + self.micros,
))
}
fn len(&self) -> usize {
self.len as usize
}
}
pub struct Parser {
reading: std::collections::VecDeque<u8>,
read_state: Option<Header>,
}
impl Parser {
pub fn new() -> Self {
Default::default()
}
pub fn add_bytes(&mut self, bytes: &[u8]) {
self.reading.extend(bytes.iter());
}
pub fn next_frame(&mut self) -> Option<Frame> {
let header = if let Some(header) = &self.read_state {
header
} else {
if self.reading.len() < std::mem::size_of::<Header>() {
return None;
}
let secs1 = self.reading.pop_front().unwrap();
let secs2 = self.reading.pop_front().unwrap();
let secs3 = self.reading.pop_front().unwrap();
let secs4 = self.reading.pop_front().unwrap();
let secs = u32::from_le_bytes([secs1, secs2, secs3, secs4]);
let usecs1 = self.reading.pop_front().unwrap();
let usecs2 = self.reading.pop_front().unwrap();
let usecs3 = self.reading.pop_front().unwrap();
let usecs4 = self.reading.pop_front().unwrap();
let micros = u32::from_le_bytes([usecs1, usecs2, usecs3, usecs4]);
let len1 = self.reading.pop_front().unwrap();
let len2 = self.reading.pop_front().unwrap();
let len3 = self.reading.pop_front().unwrap();
let len4 = self.reading.pop_front().unwrap();
let len = u32::from_le_bytes([len1, len2, len3, len4]);
let header = Header { secs, micros, len };
self.read_state = Some(header);
self.read_state.as_ref().unwrap()
};
if self.reading.len() < header.len() {
return None;
}
let mut data = vec![];
for _ in 0..header.len() {
data.push(self.reading.pop_front().unwrap());
}
let time = header.time();
self.read_state = None;
Some(Frame { time, data })
}
}
impl Default for Parser {
fn default() -> Self {
Self {
reading: std::collections::VecDeque::new(),
read_state: None,
}
}
}
pub struct Creator {
base_time: Option<std::time::Instant>,
}
impl Creator {
pub fn new() -> Self {
Default::default()
}
pub fn frame(&mut self, data: &[u8]) -> Result<Vec<u8>> {
let cur_time = std::time::Instant::now();
let base_time = if let Some(base_time) = &self.base_time {
base_time
} else {
self.base_time = Some(cur_time);
self.base_time.as_ref().unwrap()
};
Vec::<u8>::try_from(Frame {
time: cur_time - *base_time,
data: data.to_vec(),
})
}
}
impl Default for Creator {
fn default() -> Self {
Self { base_time: None }
}
}
pub struct Reader<R> {
reader: R,
parser: Parser,
read_buf: [u8; 4096],
done_reading: bool,
}
impl<R: tokio::io::AsyncRead> Reader<R> {
pub fn new(reader: R) -> Self {
Self {
reader,
parser: Parser::new(),
read_buf: [0; 4096],
done_reading: false,
}
}
pub fn poll_read(&mut self) -> futures::Poll<Option<Frame>, Error> {
loop {
if let Some(frame) = self.parser.next_frame() {
return Ok(futures::Async::Ready(Some(frame)));
} else if self.done_reading {
return Ok(futures::Async::Ready(None));
}
let n = futures::try_ready!(self
.reader
.poll_read(&mut self.read_buf)
.context(ReadFile));
if n > 0 {
self.parser.add_bytes(&self.read_buf[..n]);
} else {
self.done_reading = true;
}
}
}
}
pub struct Writer<W> {
writer: W,
creator: Creator,
to_write: std::collections::VecDeque<u8>,
}
impl<W: tokio::io::AsyncWrite> Writer<W> {
pub fn new(writer: W) -> Self {
Self {
writer,
creator: Creator::new(),
to_write: std::collections::VecDeque::new(),
}
}
pub fn frame(&mut self, data: &[u8]) -> Result<()> {
let bytes = self.creator.frame(data)?;
self.to_write.extend(bytes.iter());
Ok(())
}
pub fn poll_write(&mut self) -> futures::Poll<(), Error> {
let (a, b) = self.to_write.as_slices();
let buf = if a.is_empty() { b } else { a };
let n = futures::try_ready!(self
.writer
.poll_write(buf)
.context(WriteFile));
for _ in 0..n {
self.to_write.pop_front();
}
Ok(futures::Async::Ready(()))
}
pub fn is_empty(&self) -> bool {
self.to_write.is_empty()
}
}
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