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

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This commit is contained in:
Sean McArthur
2018-05-05 14:14:19 -07:00
parent fdcd2a4b17
commit 325b7e519a
1 changed files with 10 additions and 10 deletions
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20
src/proto/h1/role.rs
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@@ -1,4 +1,5 @@
use std::fmt::{self, Write}; use std::fmt::{self, Write};
use std::mem;
use bytes::{BytesMut, Bytes}; use bytes::{BytesMut, Bytes};
use http::header::{CONTENT_LENGTH, DATE, Entry, HeaderName, HeaderValue, TRANSFER_ENCODING}; use http::header::{CONTENT_LENGTH, DATE, Entry, HeaderName, HeaderValue, TRANSFER_ENCODING};
@@ -32,12 +33,13 @@ where
if buf.len() == 0 { if buf.len() == 0 {
return Ok(None); return Ok(None);
} }
let mut headers_indices = [HeaderIndices { // Unsafe: both headers_indices and headers are using unitialized memory,
name: (0, 0), // but we *never* read any of it until after httparse has assigned
value: (0, 0) // values into it. By not zeroing out the stack memory, this saves
}; MAX_HEADERS]; // a good ~5% on pipeline benchmarks.
let mut headers_indices: [HeaderIndices; MAX_HEADERS] = unsafe { mem::uninitialized() };
let (len, method, path, version, headers_len) = { 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()); trace!("Request.parse([Header; {}], [u8; {}])", headers.len(), buf.len());
let mut req = httparse::Request::new(&mut headers); let mut req = httparse::Request::new(&mut headers);
match req.parse(&buf)? { match req.parse(&buf)? {
@@ -262,12 +264,10 @@ where
if buf.len() == 0 { if buf.len() == 0 {
return Ok(None); return Ok(None);
} }
let mut headers_indices = [HeaderIndices { // Unsafe: see comment in Server Http1Transaction, above.
name: (0, 0), let mut headers_indices: [HeaderIndices; MAX_HEADERS] = unsafe { mem::uninitialized() };
value: (0, 0)
}; MAX_HEADERS];
let (len, status, version, headers_len) = { 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()); trace!("Response.parse([Header; {}], [u8; {}])", headers.len(), buf.len());
let mut res = httparse::Response::new(&mut headers); let mut res = httparse::Response::new(&mut headers);
let bytes = buf.as_ref(); let bytes = buf.as_ref();