http2: avoid copying the options in respond()

respond() copied the user-provided options object on every call just
so it could normalize and locally flip options.endStream, and
prepareResponseHeadersObject() then looked the :status and date
fields up again on the dictionary-mode null-prototype headers copy
it had just built. Use a local variable for endStream and pick up
:status/date while copying the headers instead.
No measurable throughput change on its own; this removes an object
clone and several dictionary-mode property lookups per response.
Signed-off-by: Matteo Collina <hello@matteocollina.com>
PR-URL: #64265
Backport-PR-URL: #64663
Reviewed-By: Antoine du Hamel <duhamelantoine1995@gmail.com>
Reviewed-By: Tim Perry <pimterry@gmail.com>
Reviewed-By: Ethan Arrowood <ethan@arrowood.dev>

Author: mcollina

lib/internal/http2/core.js

@@ -2654,31 +2654,35 @@ function prepareResponseHeaders(stream, headersParam, options) {
 functionprepareResponseHeadersObject(oldHeaders,options){
 assertIsObject(oldHeaders,'headers',['Object','Array']);
 constheaders={__proto__: null};
+letstatusCode;
+lethasDate=false;
 
 if(oldHeaders!==null&&oldHeaders!==undefined){
 // This loop is here for performance reason. Do not change.
+// The :status and date fields are picked up while copying so they do
+// not have to be looked up again on the null-prototype copy.
 for(constkeyinoldHeaders){
 if(ObjectHasOwn(oldHeaders,key)){
-headers[key]=oldHeaders[key];
+constvalue=oldHeaders[key];
+headers[key]=value;
+if(key===HTTP2_HEADER_STATUS)
+statusCode=value;
+elseif(key===HTTP2_HEADER_DATE)
+hasDate=value!=null;
 }
 }
 headers[kSensitiveHeaders]=oldHeaders[kSensitiveHeaders];
 }
 
-conststatusCode=
-headers[HTTP2_HEADER_STATUS]=
-headers[HTTP2_HEADER_STATUS]|0||HTTP_STATUS_OK;
+statusCode=headers[HTTP2_HEADER_STATUS]=statusCode|0||HTTP_STATUS_OK;
 
-if(options.sendDate==null||options.sendDate){
-headers[HTTP2_HEADER_DATE]??=utcDate();
+if(!hasDate&&(options.sendDate==null||options.sendDate)){
+headers[HTTP2_HEADER_DATE]=utcDate();
 }
 
 validatePreparedResponseHeaders(headers,statusCode);
 
-return{
- headers,
-statusCode: headers[HTTP2_HEADER_STATUS],
-};
+return{ headers, statusCode };
 }
 
 functionprepareResponseHeadersArray(headers,options){
@@ -3047,15 +3051,17 @@ class ServerHttp2Stream extends Http2Stream {
 conststate=this[kState];
 
 assertIsObject(options,'options');
-options={ ...options};
+// The options are only read, never mutated, so the user-provided object
+// can be used directly instead of copying it.
+options??=kEmptyObject;
 
 debugStreamObj(this,'initiating response');
 this[kUpdateTimer]();
 
-options.endStream=!!options.endStream;
+constendStream=!!options.endStream;
 
 letstreamOptions=0;
-if(options.endStream)
+if(endStream)
 streamOptions|=STREAM_OPTION_EMPTY_PAYLOAD;
 
 if(options.waitForTrailers){
@@ -3073,12 +3079,11 @@ class ServerHttp2Stream extends Http2Stream {
 
 // Close the writable side if the endStream option is set or status
 // is one of known codes with no payload, or it's a head request
-if(!!options.endStream||
+if(endStream||
 statusCode===HTTP_STATUS_NO_CONTENT||
 statusCode===HTTP_STATUS_RESET_CONTENT||
 statusCode===HTTP_STATUS_NOT_MODIFIED||
 this.headRequest===true){
-options.endStream=true;
 this.end();
 }