http: don't cork noop .end()

lib/_http_outgoing.js

@@ -810,17 +810,18 @@ OutgoingMessage.prototype.end = function end(chunk, encoding, callback) {
     encoding = null;
   }
 
-  if (this.socket) {
-    this.socket.cork();
-  }
-
   if (chunk) {
     if (this.finished) {
       onError(this,
               new ERR_STREAM_WRITE_AFTER_END(),
               typeof callback !== 'function' ? nop : callback);
       return this;
     }
+
+    if (this.socket) {
+      this.socket.cork();
+    }
+
     write_(this, chunk, encoding, null, true);
   } else if (this.finished) {
     if (typeof callback === 'function') {
@@ -832,6 +833,10 @@ OutgoingMessage.prototype.end = function end(chunk, encoding, callback) {
     }
     return this;
   } else if (!this._header) {
+    if (this.socket) {
+      this.socket.cork();
+    }
+
     this._contentLength = 0;
     this._implicitHeader();
   }

test/parallel/test-http-outgoing-end-cork.js

@@ -0,0 +1,95 @@
+'use strict';
+const common = require('../common');
+const assert = require('assert');
+const http = require('http');
+
+const REQ_TIMEOUT = 500; // Set max ms of request time before abort
+
+// Set total allowed test timeout to avoid infinite loop
+// that will hang test suite
+const TOTAL_TEST_TIMEOUT = 1000;
+
+// Placeholder for sockets handled, to make sure that we
+// will reach a socket re-use case.
+const handledSockets = new Set();
+
+let metReusedSocket = false; // Flag for request loop termination.
+
+const doubleEndResponse = (res) => {
+  // First end the request while sending some normal data
+  res.end('regular end of request', 'utf8', common.mustCall());
+  // Make sure the response socket is uncorked after first call of end
+  assert.strictEqual(res.writableCorked, 0);
+  res.end(); // Double end the response to prep for next socket re-use.
+};
+
+const sendDrainNeedingData = (res) => {
+  // Send data to socket more than the high watermark so that
+  // it definitely needs drain
+  const highWaterMark = res.socket.writableHighWaterMark;
+  const bufferToSend = Buffer.alloc(highWaterMark + 100);
+  const ret = res.write(bufferToSend); // Write the request data.
+  // Make sure that we had back pressure on response stream.
+  assert.strictEqual(ret, false);
+  res.once('drain', () => res.end()); // End on drain.
+};
+
+const server = http.createServer((req, res) => {
+  const { socket: responseSocket } = res;
+  if (handledSockets.has(responseSocket)) { // re-used socket, send big data!
+    metReusedSocket = true; // stop request loop
+    console.debug('FOUND REUSED SOCKET!');
+    sendDrainNeedingData(res);
+  } else { // not used again
+    // add to make sure we recognise it when we meet socket again
+    handledSockets.add(responseSocket);
+    doubleEndResponse(res);
+  }
+});
+
+server.listen(0); // Start the server on a random port.
+
+const sendRequest = (agent) => new Promise((resolve, reject) => {
+  const timeout = setTimeout(common.mustNotCall(() => {
+    reject(new Error('Request timed out'));
+  }), REQ_TIMEOUT);
+  http.get({
+    port: server.address().port,
+    path: '/',
+    agent
+  }, common.mustCall((res) => {
+    const resData = [];
+    res.on('data', (data) => resData.push(data));
+    res.on('end', common.mustCall(() => {
+      const totalData = resData.reduce((total, elem) => total + elem.length, 0);
+      clearTimeout(timeout); // Cancel rejection timeout.
+      resolve(totalData); // fulfill promise
+    }));
+  }));
+});
+
+server.once('listening', async () => {
+  const testTimeout = setTimeout(common.mustNotCall(() => {
+    console.error('Test running for a while but could not met re-used socket');
+    process.exit(1);
+  }), TOTAL_TEST_TIMEOUT);
+  // Explicitly start agent to force socket reuse.
+  const agent = new http.Agent({ keepAlive: true });
+  // Start the request loop
+  let reqNo = 0;
+  while (!metReusedSocket) {
+    try {
+      console.log(`Sending req no ${++reqNo}`);
+      const totalData = await sendRequest(agent);
+      console.log(`${totalData} bytes were received for request ${reqNo}`);
+    } catch (err) {
+      console.error(err);
+      process.exit(1);
+    }
+  }
+  // Successfully tested conditions and ended loop
+  clearTimeout(testTimeout);
+  console.log('Closing server');
+  agent.destroy();
+  server.close();
+});

test/parallel/test-http-outgoing-end-multiple.js

@@ -9,10 +9,13 @@ const onWriteAfterEndError = common.mustCall((err) => {
 
 const server = http.createServer(common.mustCall(function(req, res) {
   res.end('testing ended state', common.mustCall());
+  assert.strictEqual(res.writableCorked, 0);
   res.end(common.mustCall((err) => {
     assert.strictEqual(err.code, 'ERR_STREAM_ALREADY_FINISHED');
   }));
+  assert.strictEqual(res.writableCorked, 0);
   res.end('end', onWriteAfterEndError);
+  assert.strictEqual(res.writableCorked, 0);
   res.on('error', onWriteAfterEndError);
   res.on('finish', common.mustCall(() => {
     res.end(common.mustCall((err) => {