From 45ef3c91c2348560a9a282b44f4b7b8b28929b6f Mon Sep 17 00:00:00 2001
From: Aaron O'Mullan <aaron.omullan@gmail.com>
Date: Mon, 21 Mar 2022 12:56:30 +0100
Subject: [PATCH] perf(http): avoid per header alloc (#14051)

---
 ext/http/lib.rs | 62 +++++++++++++++++++------------------------------
 1 file changed, 24 insertions(+), 38 deletions(-)

diff --git a/ext/http/lib.rs b/ext/http/lib.rs
index 48a58067e8..d636e206cb 100644
--- a/ext/http/lib.rs
+++ b/ext/http/lib.rs
@@ -517,50 +517,36 @@ async fn op_http_write_headers(
 
   builder.headers_mut().unwrap().reserve(headers.len());
   for (key, value) in &headers {
-    match &*key.to_ascii_lowercase() {
-      b"cache-control" => {
-        if let Ok(value) = std::str::from_utf8(value) {
-          if let Some(cache_control) = CacheControl::from_value(value) {
-            // We skip compression if the cache-control header value is set to
-            // "no-transform"
-            if cache_control.no_transform {
-              headers_allow_compression = false;
-            }
+    if key.eq_ignore_ascii_case(b"cache-control") {
+      if let Ok(value) = std::str::from_utf8(value) {
+        if let Some(cache_control) = CacheControl::from_value(value) {
+          // We skip compression if the cache-control header value is set to
+          // "no-transform"
+          if cache_control.no_transform {
+            headers_allow_compression = false;
           }
-        } else {
-          headers_allow_compression = false;
         }
-      }
-      b"content-range" => {
-        // we skip compression if the `content-range` header value is set, as it
-        // indicates the contents of the body were negotiated based directly
-        // with the user code and we can't compress the response
-        headers_allow_compression = false;
-      }
-      b"content-type" => {
-        if !value.is_empty() {
-          content_type_header = Some(value);
-        }
-      }
-      b"content-encoding" => {
-        // we don't compress if a content-encoding header was provided
+      } else {
         headers_allow_compression = false;
       }
+    } else if key.eq_ignore_ascii_case(b"content-range") {
+      // we skip compression if the `content-range` header value is set, as it
+      // indicates the contents of the body were negotiated based directly
+      // with the user code and we can't compress the response
+      headers_allow_compression = false;
+    } else if key.eq_ignore_ascii_case(b"content-type") && !value.is_empty() {
+      content_type_header = Some(value);
+    } else if key.eq_ignore_ascii_case(b"content-encoding") {
+      // we don't compress if a content-encoding header was provided
+      headers_allow_compression = false;
+    } else if key.eq_ignore_ascii_case(b"etag") && !value.is_empty() {
       // we store the values of ETag and Vary and skip adding them for now, as
       // we may need to modify or change.
-      b"etag" => {
-        if !value.is_empty() {
-          etag_header = Some(value);
-          continue;
-        }
-      }
-      b"vary" => {
-        if !value.is_empty() {
-          vary_header = Some(value);
-          continue;
-        }
-      }
-      _ => {}
+      etag_header = Some(value);
+      continue;
+    } else if key.eq_ignore_ascii_case(b"vary") && !value.is_empty() {
+      vary_header = Some(value);
+      continue;
     }
     builder = builder.header(key.as_ref(), value.as_ref());
   }