From d602c7a2ed80c978f94bd63f76b54d0843bea6cf Mon Sep 17 00:00:00 2001
From: James Ide <ide@expo.io>
Date: Fri, 20 Jul 2018 17:25:02 -0700
Subject: [PATCH] http2: release request()'s "connect" event listener after it
 runs
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The `Http2Session#request()` method internally listens to the "connect"
event if the session has not yet established a connection so that the
actual request can be sent after the connection has been established.

This commit removes the event listener after it runs and carries out
the request and is no longer needed. In practice this shouldn't affect
the behavior of the session object since the "connect" event fires only
once anyway, but removing the listener releases its references. The
rest of this class subscribes to the "connect" event with `once`
instead of `on` as well.

Tested by adding a new test that ensures `Http2Session#request()` is
called before the connection is established, indicated by a "connect"
listener that is run. The test also ensures all "connect" listeners are
removed after the connection is established.

Backport-PR-URL: https://github.com/nodejs/node/pull/22850
PR-URL: https://github.com/nodejs/node/pull/21916
Reviewed-By: Michaël Zasso <targos@protonmail.com>
Reviewed-By: Trivikram Kamat <trivikr.dev@gmail.com>
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Anatoli Papirovski <apapirovski@mac.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
---
 lib/internal/http2/core.js                    |  2 +-
 ...t-http2-request-remove-connect-listener.js | 28 +++++++++++++++++++
 2 files changed, 29 insertions(+), 1 deletion(-)
 create mode 100644 test/parallel/test-http2-request-remove-connect-listener.js

diff --git a/lib/internal/http2/core.js b/lib/internal/http2/core.js
index 9beb8833a297fb..e496c3a87fd3ee 100644
--- a/lib/internal/http2/core.js
+++ b/lib/internal/http2/core.js
@@ -1384,7 +1384,7 @@ class ClientHttp2Session extends Http2Session {
 
     const onConnect = requestOnConnect.bind(stream, headersList, options);
     if (this.connecting) {
-      this.on('connect', onConnect);
+      this.once('connect', onConnect);
     } else {
       onConnect();
     }
diff --git a/test/parallel/test-http2-request-remove-connect-listener.js b/test/parallel/test-http2-request-remove-connect-listener.js
new file mode 100644
index 00000000000000..61de140c225144
--- /dev/null
+++ b/test/parallel/test-http2-request-remove-connect-listener.js
@@ -0,0 +1,28 @@
+'use strict';
+
+const common = require('../common');
+if (!common.hasCrypto)
+  common.skip('missing crypto');
+const assert = require('assert');
+const http2 = require('http2');
+
+
+const server = http2.createServer();
+server.on('stream', common.mustCall((stream) => {
+  stream.respond();
+  stream.end();
+}));
+
+server.listen(0, common.mustCall(() => {
+  const client = http2.connect(`http://localhost:${server.address().port}`);
+  const req = client.request();
+  client.once('connect', common.mustCall());
+
+  req.on('response', common.mustCall(() => {
+    assert.strictEqual(client.listenerCount('connect'), 0);
+  }));
+  req.on('close', common.mustCall(() => {
+    server.close();
+    client.close();
+  }));
+}));