http: add server.keepAliveTimeoutBuffer option

PR-URL: https://github.com/nodejs/node/pull/59243
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
Reviewed-By: Jason Zhang <xzha4350@gmail.com>

test/parallel/test-http-keep-alive-timeout-buffer.js

@@ -0,0 +1,39 @@
+'use strict';
+
+const common = require('../common');
+const http = require('http');
+const assert = require('assert');
+
+const server = http.createServer(common.mustCall((req, res) => {
+  const body = 'buffer test\n';
+
+  res.writeHead(200, { 'Content-Length': body.length });
+  res.write(body);
+  res.end();
+}));
+
+server.keepAliveTimeout = 100;
+
+if (server.keepAliveTimeoutBuffer === undefined) {
+  server.keepAliveTimeoutBuffer = 1000;
+}
+assert.strictEqual(server.keepAliveTimeoutBuffer, 1000);
+
+server.listen(0, () => {
+  http.get({
+    port: server.address().port,
+    path: '/',
+  }, (res) => {
+    res.resume();
+    server.close();
+  });
+});
+
+{
+  const customBuffer = 3000;
+  const server = http.createServer(() => {});
+  server.keepAliveTimeout = 200;
+  server.keepAliveTimeoutBuffer = customBuffer;
+  assert.strictEqual(server.keepAliveTimeoutBuffer, customBuffer);
+  server.close();
+}