From 0fa0de10ced93fbebf7c8309948a2a85f9023ae1 Mon Sep 17 00:00:00 2001
From: Wez Furlong <wez@wezfurlong.org>
Date: Wed, 14 Jun 2023 09:56:34 -0700
Subject: [PATCH] replace bytes::find with memchr::memmem::find

This is a much more efficient implementation with ~20% improved
throughput and latency with the simple signing benchmark.

signing/sign            time:   [1.3024 ms 1.3050 ms 1.3076 ms]
                        thrpt:  [2.2886 MiB/s 2.2933 MiB/s 2.2978 MiB/s]
                 change:
                        time:   [-19.016% -18.855% -18.691%] (p = 0.00 < 0.05)
                        thrpt:  [+22.987% +23.237% +23.482%]
                        Performance has improved.
---
 Cargo.lock   | 1 +
 Cargo.toml   | 1 +
 src/bytes.rs | 8 +-------
 3 files changed, 3 insertions(+), 7 deletions(-)

diff --git a/Cargo.lock b/Cargo.lock
index 7227bb12..6c757e08 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -131,6 +131,7 @@ dependencies = [
  "futures",
  "indexmap",
  "mailparse",
+ "memchr",
  "nom",
  "quick-error 2.0.1",
  "regex",
diff --git a/Cargo.toml b/Cargo.toml
index c3d7fb86..83d913a7 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -14,6 +14,7 @@ license = "MIT"
 [dependencies]
 ed25519-dalek = "1.0.1"
 mailparse = "0.14"
+memchr = "2.5"
 quick-error = "2.0.1"
 nom = "7.1.0"
 chrono = { version = "0.4.19", default-features = false, features = ["clock", "std"] }
diff --git a/src/bytes.rs b/src/bytes.rs
index ec82e3a7..b00a65a5 100644
--- a/src/bytes.rs
+++ b/src/bytes.rs
@@ -1,4 +1,5 @@
 ///! Various utility functions to operate on bytes
+pub(crate) use memchr::memmem::find;
 
 pub(crate) fn get_all_after<'a>(bytes: &'a [u8], end: &[u8]) -> &'a [u8] {
     if let Some(mut end_index) = find(bytes, end) {
@@ -9,13 +10,6 @@ pub(crate) fn get_all_after<'a>(bytes: &'a [u8], end: &[u8]) -> &'a [u8] {
     }
 }
 
-/// Find the offset of specific bytes in bytes
-pub(crate) fn find(bytes: &[u8], search: &[u8]) -> Option<usize> {
-    bytes
-        .windows(search.len())
-        .position(|window| window == search)
-}
-
 pub(crate) fn replace(bytes: &mut [u8], from: char, to: char) {
     for byte in bytes.iter_mut() {
         if *byte == from as u8 {