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use std::collections::VecDeque;
use std::io::IoSlice;
use bytes::{Buf, BufMut, Bytes, BytesMut};
pub(crate) struct BufList<T> {
bufs: VecDeque<T>,
}
impl<T: Buf> BufList<T> {
pub(crate) fn new() -> BufList<T> {
BufList {
bufs: VecDeque::new(),
}
}
#[inline]
pub(crate) fn push(&mut self, buf: T) {
debug_assert!(buf.has_remaining());
self.bufs.push_back(buf);
}
#[inline]
#[cfg(feature = "http1")]
pub(crate) fn bufs_cnt(&self) -> usize {
self.bufs.len()
}
}
impl<T: Buf> Buf for BufList<T> {
#[inline]
fn remaining(&self) -> usize {
self.bufs.iter().map(|buf| buf.remaining()).sum()
}
#[inline]
fn chunk(&self) -> &[u8] {
self.bufs.front().map(Buf::chunk).unwrap_or_default()
}
#[inline]
fn advance(&mut self, mut cnt: usize) {
while cnt > 0 {
{
let front = &mut self.bufs[0];
let rem = front.remaining();
if rem > cnt {
front.advance(cnt);
return;
} else {
front.advance(rem);
cnt -= rem;
}
}
self.bufs.pop_front();
}
}
#[inline]
fn chunks_vectored<'t>(&'t self, dst: &mut [IoSlice<'t>]) -> usize {
if dst.is_empty() {
return 0;
}
let mut vecs = 0;
for buf in &self.bufs {
vecs += buf.chunks_vectored(&mut dst[vecs..]);
if vecs == dst.len() {
break;
}
}
vecs
}
#[inline]
fn copy_to_bytes(&mut self, len: usize) -> Bytes {
// Our inner buffer may have an optimized version of copy_to_bytes, and if the whole
// request can be fulfilled by the front buffer, we can take advantage.
match self.bufs.front_mut() {
Some(front) if front.remaining() == len => {
let b = front.copy_to_bytes(len);
self.bufs.pop_front();
b
}
Some(front) if front.remaining() > len => front.copy_to_bytes(len),
_ => {
assert!(len <= self.remaining(), "`len` greater than remaining");
let mut bm = BytesMut::with_capacity(len);
bm.put(self.take(len));
bm.freeze()
}
}
}
}
#[cfg(test)]
mod tests {
use std::ptr;
use super::*;
fn hello_world_buf() -> BufList<Bytes> {
BufList {
bufs: vec![Bytes::from("Hello"), Bytes::from(" "), Bytes::from("World")].into(),
}
}
#[test]
fn to_bytes_shorter() {
let mut bufs = hello_world_buf();
let old_ptr = bufs.chunk().as_ptr();
let start = bufs.copy_to_bytes(4);
assert_eq!(start, "Hell");
assert!(ptr::eq(old_ptr, start.as_ptr()));
assert_eq!(bufs.chunk(), b"o");
assert!(ptr::eq(old_ptr.wrapping_add(4), bufs.chunk().as_ptr()));
assert_eq!(bufs.remaining(), 7);
}
#[test]
fn to_bytes_eq() {
let mut bufs = hello_world_buf();
let old_ptr = bufs.chunk().as_ptr();
let start = bufs.copy_to_bytes(5);
assert_eq!(start, "Hello");
assert!(ptr::eq(old_ptr, start.as_ptr()));
assert_eq!(bufs.chunk(), b" ");
assert_eq!(bufs.remaining(), 6);
}
#[test]
fn to_bytes_longer() {
let mut bufs = hello_world_buf();
let start = bufs.copy_to_bytes(7);
assert_eq!(start, "Hello W");
assert_eq!(bufs.remaining(), 4);
}
#[test]
fn one_long_buf_to_bytes() {
let mut buf = BufList::new();
buf.push(b"Hello World" as &[_]);
assert_eq!(buf.copy_to_bytes(5), "Hello");
assert_eq!(buf.chunk(), b" World");
}
#[test]
#[should_panic(expected = "`len` greater than remaining")]
fn buf_to_bytes_too_many() {
hello_world_buf().copy_to_bytes(42);
}
}