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mirror of https://github.com/fafhrd91/actix-web synced 2024-11-24 08:22:59 +01:00
actix-web/actix-files/src/chunked.rs
2020-09-20 23:18:25 +01:00

95 lines
2.5 KiB
Rust

use std::{
cmp, fmt,
fs::File,
future::Future,
io::{self, Read, Seek},
pin::Pin,
task::{Context, Poll},
};
use actix_web::{
error::{BlockingError, Error},
web,
};
use bytes::Bytes;
use futures_core::{ready, Stream};
use futures_util::future::{FutureExt, LocalBoxFuture};
use crate::handle_error;
type ChunkedBoxFuture =
LocalBoxFuture<'static, Result<(File, Bytes), BlockingError<io::Error>>>;
#[doc(hidden)]
/// A helper created from a `std::fs::File` which reads the file
/// chunk-by-chunk on a `ThreadPool`.
pub struct ChunkedReadFile {
pub(crate) size: u64,
pub(crate) offset: u64,
pub(crate) file: Option<File>,
pub(crate) fut: Option<ChunkedBoxFuture>,
pub(crate) counter: u64,
}
impl fmt::Debug for ChunkedReadFile {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
f.write_str("ChunkedReadFile")
}
}
impl Stream for ChunkedReadFile {
type Item = Result<Bytes, Error>;
fn poll_next(
mut self: Pin<&mut Self>,
cx: &mut Context<'_>,
) -> Poll<Option<Self::Item>> {
if let Some(ref mut fut) = self.fut {
return match ready!(Pin::new(fut).poll(cx)) {
Ok((file, bytes)) => {
self.fut.take();
self.file = Some(file);
self.offset += bytes.len() as u64;
self.counter += bytes.len() as u64;
Poll::Ready(Some(Ok(bytes)))
}
Err(e) => Poll::Ready(Some(Err(handle_error(e)))),
};
}
let size = self.size;
let offset = self.offset;
let counter = self.counter;
if size == counter {
Poll::Ready(None)
} else {
let mut file = self.file.take().expect("Use after completion");
self.fut = Some(
web::block(move || {
let max_bytes =
cmp::min(size.saturating_sub(counter), 65_536) as usize;
let mut buf = Vec::with_capacity(max_bytes);
file.seek(io::SeekFrom::Start(offset))?;
let n_bytes =
file.by_ref().take(max_bytes as u64).read_to_end(&mut buf)?;
if n_bytes == 0 {
return Err(io::ErrorKind::UnexpectedEof.into());
}
Ok((file, Bytes::from(buf)))
})
.boxed_local(),
);
self.poll_next(cx)
}
}
}