refactor: avoid http2 dynamic dispatch in socket handlers

Steps towards more clean separation between h1 and h2.

Refs: #2816

lib/core/symbols.js

@@ -59,5 +59,6 @@ module.exports = {
   kHTTP2CopyHeaders: Symbol('http2 copy headers'),
   kHTTPConnVersion: Symbol('http connection version'),
   kRetryHandlerDefaultRetry: Symbol('retry agent default retry'),
-  kConstruct: Symbol('constructable')
+  kConstruct: Symbol('constructable'),
+  kListeners: Symbol('listeners')
 }

lib/dispatcher/client.js

@@ -72,6 +72,7 @@ const {
   kLocalAddress,
   kMaxResponseSize,
   kHTTPConnVersion,
+  kListeners,
   // HTTP2
   kHost,
   kHTTP2Session,
@@ -111,6 +112,20 @@ const FastBuffer = Buffer[Symbol.species]
 
 const kClosedResolve = Symbol('kClosedResolve')
 
+function addListener (obj, name, listener) {
+  const listeners = (obj[kListeners] ??= [])
+  listeners.push([name, listener])
+  obj.on(name, listener)
+  return obj
+}
+
+function removeAllListeners (obj) {
+  for (const [name, listener] of obj[kListeners] ?? []) {
+    obj.removeListener(name, listener)
+  }
+  obj[kListeners] = null
+}
+
 /**
  * @type {import('../../types/client.js').default}
  */
@@ -803,11 +818,8 @@ class Parser {
 
     socket[kClient] = null
     socket[kError] = null
-    socket
-      .removeListener('error', onSocketError)
-      .removeListener('readable', onSocketReadable)
-      .removeListener('end', onSocketEnd)
-      .removeListener('close', onSocketClose)
+
+    removeAllListeners(socket)
 
     client[kSocket] = null
     client[kHTTP2Session] = null
@@ -1050,33 +1062,6 @@ function onParserTimeout (parser) {
   }
 }
 
-function onSocketReadable () {
-  const { [kParser]: parser } = this
-  if (parser) {
-    parser.readMore()
-  }
-}
-
-function onSocketError (err) {
-  const { [kClient]: client, [kParser]: parser } = this
-
-  assert(err.code !== 'ERR_TLS_CERT_ALTNAME_INVALID')
-
-  if (client[kHTTPConnVersion] !== 'h2') {
-    // On Mac OS, we get an ECONNRESET even if there is a full body to be forwarded
-    // to the user.
-    if (err.code === 'ECONNRESET' && parser.statusCode && !parser.shouldKeepAlive) {
-      // We treat all incoming data so for as a valid response.
-      parser.onMessageComplete()
-      return
-    }
-  }
-
-  this[kError] = err
-
-  onError(this[kClient], err)
-}
-
 function onError (client, err) {
   if (
     client[kRunning] === 0 &&
@@ -1097,32 +1082,8 @@ function onError (client, err) {
   }
 }
 
-function onSocketEnd () {
-  const { [kParser]: parser, [kClient]: client } = this
-
-  if (client[kHTTPConnVersion] !== 'h2') {
-    if (parser.statusCode && !parser.shouldKeepAlive) {
-      // We treat all incoming data so far as a valid response.
-      parser.onMessageComplete()
-      return
-    }
-  }
-
-  util.destroy(this, new SocketError('other side closed', util.getSocketInfo(this)))
-}
-
 function onSocketClose () {
-  const { [kClient]: client, [kParser]: parser } = this
-
-  if (client[kHTTPConnVersion] === 'h1' && parser) {
-    if (!this[kError] && parser.statusCode && !parser.shouldKeepAlive) {
-      // We treat all incoming data so far as a valid response.
-      parser.onMessageComplete()
-    }
-
-    this[kParser].destroy()
-    this[kParser] = null
-  }
+  const { [kClient]: client } = this
 
   const err = this[kError] || new SocketError('closed', util.getSocketInfo(this))
 
@@ -1241,6 +1202,18 @@ async function connect (client) {
 
       client[kHTTP2Session] = session
       socket[kHTTP2Session] = session
+
+      addListener(socket, 'error', function (err) {
+        assert(err.code !== 'ERR_TLS_CERT_ALTNAME_INVALID')
+
+        this[kError] = err
+
+        onError(this[kClient], err)
+      })
+      addListener(socket, 'end', function () {
+        util.destroy(this, new SocketError('other side closed', util.getSocketInfo(this)))
+      })
+      addListener(socket, 'close', onSocketClose)
     } else {
       if (!llhttpInstance) {
         llhttpInstance = await llhttpPromise
@@ -1252,19 +1225,63 @@ async function connect (client) {
       socket[kReset] = false
       socket[kBlocking] = false
       socket[kParser] = new Parser(client, socket, llhttpInstance)
+
+      addListener(socket, 'error', function (err) {
+        const { [kParser]: parser } = this
+
+        assert(err.code !== 'ERR_TLS_CERT_ALTNAME_INVALID')
+
+        // On Mac OS, we get an ECONNRESET even if there is a full body to be forwarded
+        // to the user.
+        if (err.code === 'ECONNRESET' && parser.statusCode && !parser.shouldKeepAlive) {
+          // We treat all incoming data so for as a valid response.
+          parser.onMessageComplete()
+          return
+        }
+
+        this[kError] = err
+
+        onError(this[kClient], err)
+      })
+      addListener(socket, 'readable', function () {
+        const { [kParser]: parser } = this
+        if (parser) {
+          parser.readMore()
+        }
+      })
+      addListener(socket, 'end', function () {
+        const { [kParser]: parser } = this
+
+        if (parser.statusCode && !parser.shouldKeepAlive) {
+          // We treat all incoming data so far as a valid response.
+          parser.onMessageComplete()
+          return
+        }
+
+        util.destroy(this, new SocketError('other side closed', util.getSocketInfo(this)))
+      })
+      addListener(socket, 'close', function () {
+        const { [kParser]: parser } = this
+
+        if (parser) {
+          if (!this[kError] && parser.statusCode && !parser.shouldKeepAlive) {
+            // We treat all incoming data so far as a valid response.
+            parser.onMessageComplete()
+          }
+
+          this[kParser].destroy()
+          this[kParser] = null
+        }
+
+        onSocketClose.call(this)
+      })
     }
 
     socket[kCounter] = 0
     socket[kMaxRequests] = client[kMaxRequests]
     socket[kClient] = client
     socket[kError] = null
 
-    socket
-      .on('error', onSocketError)
-      .on('readable', onSocketReadable)
-      .on('end', onSocketEnd)
-      .on('close', onSocketClose)
-
     client[kSocket] = socket
 
     if (channels.connected.hasSubscribers) {