perf(lib): improve parsing by using uninitialized httparse header array

This commit is contained in:
Sean McArthur
2018-05-05 14:14:19 -07:00
parent fdcd2a4b17
commit 325b7e519a

View File

@@ -1,4 +1,5 @@
use std::fmt::{self, Write};
use std::mem;
use bytes::{BytesMut, Bytes};
use http::header::{CONTENT_LENGTH, DATE, Entry, HeaderName, HeaderValue, TRANSFER_ENCODING};
@@ -32,12 +33,13 @@ where
if buf.len() == 0 {
return Ok(None);
}
let mut headers_indices = [HeaderIndices {
name: (0, 0),
value: (0, 0)
}; MAX_HEADERS];
// Unsafe: both headers_indices and headers are using unitialized memory,
// but we *never* read any of it until after httparse has assigned
// values into it. By not zeroing out the stack memory, this saves
// a good ~5% on pipeline benchmarks.
let mut headers_indices: [HeaderIndices; MAX_HEADERS] = unsafe { mem::uninitialized() };
let (len, method, path, version, headers_len) = {
let mut headers = [httparse::EMPTY_HEADER; MAX_HEADERS];
let mut headers: [httparse::Header; MAX_HEADERS] = unsafe { mem::uninitialized() };
trace!("Request.parse([Header; {}], [u8; {}])", headers.len(), buf.len());
let mut req = httparse::Request::new(&mut headers);
match req.parse(&buf)? {
@@ -262,12 +264,10 @@ where
if buf.len() == 0 {
return Ok(None);
}
let mut headers_indices = [HeaderIndices {
name: (0, 0),
value: (0, 0)
}; MAX_HEADERS];
// Unsafe: see comment in Server Http1Transaction, above.
let mut headers_indices: [HeaderIndices; MAX_HEADERS] = unsafe { mem::uninitialized() };
let (len, status, version, headers_len) = {
let mut headers = [httparse::EMPTY_HEADER; MAX_HEADERS];
let mut headers: [httparse::Header; MAX_HEADERS] = unsafe { mem::uninitialized() };
trace!("Response.parse([Header; {}], [u8; {}])", headers.len(), buf.len());
let mut res = httparse::Response::new(&mut headers);
let bytes = buf.as_ref();