http2: improve http2 code a bit

Multiple general improvements to http2 internals for
readability and efficiency

[This backport applied to v10.x cleanly but had several
merge conflicts on v8.x.]

PR-URL: #23984
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Trivikram Kamat <trivikr.dev@gmail.com>
Reviewed-By: Ujjwal Sharma <usharma1998@gmail.com>
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>

benchmark/http2/headers.js

@@ -42,8 +42,7 @@ function main(conf) {
 
     function doRequest(remaining) {
       const req = client.request(headersObject);
-      req.end();
-      req.on('data', () => {});
+      req.resume();
       req.on('end', () => {
         if (remaining > 0) {
           doRequest(remaining - 1);

benchmark/http2/respond-with-fd.js

@@ -8,9 +8,9 @@ const fs = require('fs');
 const file = path.join(path.resolve(__dirname, '../fixtures'), 'alice.html');
 
 const bench = common.createBenchmark(main, {
-  requests: [100, 1000, 10000, 100000, 1000000],
-  streams: [100, 200, 1000],
-  clients: [1, 2],
+  requests: [100, 1000, 5000],
+  streams: [1, 10, 20, 40, 100, 200],
+  clients: [2],
   benchmarker: ['h2load']
 }, { flags: ['--no-warnings', '--expose-http2'] });
 

benchmark/http2/simple.js

@@ -9,9 +9,9 @@ const fs = require('fs');
 const file = path.join(path.resolve(__dirname, '../fixtures'), 'alice.html');
 
 const bench = common.createBenchmark(main, {
-  requests: [100, 1000, 10000, 100000],
-  streams: [100, 200, 1000],
-  clients: [1, 2],
+  requests: [100, 1000, 5000],
+  streams: [1, 10, 20, 40, 100, 200],
+  clients: [2],
   benchmarker: ['h2load']
 }, { flags: ['--no-warnings', '--expose-http2'] });
 

lib/internal/http2/util.js

@@ -408,14 +408,20 @@ function mapToHeaders(map,
   let count = 0;
   const keys = Object.keys(map);
   const singles = new Set();
-  for (var i = 0; i < keys.length; i++) {
-    let key = keys[i];
-    let value = map[key];
+  let i;
+  let isArray;
+  let key;
+  let value;
+  let isSingleValueHeader;
+  let err;
+  for (i = 0; i < keys.length; i++) {
+    key = keys[i];
+    value = map[key];
     if (value === undefined || key === '')
       continue;
     key = key.toLowerCase();
-    const isSingleValueHeader = kSingleValueHeaders.has(key);
-    let isArray = Array.isArray(value);
+    isSingleValueHeader = kSingleValueHeaders.has(key);
+    isArray = Array.isArray(value);
     if (isArray) {
       switch (value.length) {
         case 0:
@@ -437,26 +443,26 @@ function mapToHeaders(map,
       singles.add(key);
     }
     if (key[0] === ':') {
-      const err = assertValuePseudoHeader(key);
+      err = assertValuePseudoHeader(key);
       if (err !== undefined)
         return err;
       ret = `${key}\0${value}\0${ret}`;
       count++;
-    } else {
-      if (isIllegalConnectionSpecificHeader(key, value)) {
-        return new errors.Error('ERR_HTTP2_INVALID_CONNECTION_HEADERS', key);
-      }
-      if (isArray) {
-        for (var k = 0; k < value.length; k++) {
-          const val = String(value[k]);
-          ret += `${key}\0${val}\0`;
-        }
-        count += value.length;
-      } else {
-        ret += `${key}\0${value}\0`;
-        count++;
+      continue;
+    }
+    if (isIllegalConnectionSpecificHeader(key, value)) {
+      return new errors.Error('ERR_HTTP2_INVALID_CONNECTION_HEADERS', key);
+    }
+    if (isArray) {
+      for (var k = 0; k < value.length; k++) {
+        const val = String(value[k]);
+        ret += `${key}\0${val}\0`;
       }
+      count += value.length;
+      continue;
     }
+    ret += `${key}\0${value}\0`;
+    count++;
   }
 
   return [ret, count];