async_hooks: add missing async_hooks destroys in AsyncReset

This adds missing async_hooks destroy calls for sockets (in
_http_agent.js) and HTTP parsers. We need to emit a destroy in
AsyncWrap#AsyncReset before assigning a new async_id when the instance
has already been in use and is being recycled, because in that case, we
have already emitted an init for the "old" async_id.

This also removes a duplicated init call for HTTP parser: Each time a
new parser was created, AsyncReset was being called via the C++ Parser
class constructor (super constructor AsyncWrap) and also via
Parser::Reinitialize.

PR-URL: https://github.com/nodejs/node/pull/23272
Fixes: https://github.com/nodejs/node/issues/19859
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: James M Snell <jasnell@gmail.com>

test/parallel/test-async-hooks-http-parser-destroy.js

@@ -0,0 +1,61 @@
+'use strict';
+const common = require('../common');
+const Countdown = require('../common/countdown');
+const assert = require('assert');
+const async_hooks = require('async_hooks');
+const http = require('http');
+
+// Regression test for https://github.com/nodejs/node/issues/19859.
+// Checks that matching destroys are emitted when creating new/reusing old http
+// parser instances.
+
+const N = 50;
+const KEEP_ALIVE = 100;
+
+const createdIds = [];
+const destroyedIds = [];
+async_hooks.createHook({
+  init: common.mustCallAtLeast((asyncId, type) => {
+    if (type === 'HTTPPARSER') {
+      createdIds.push(asyncId);
+    }
+  }, N),
+  destroy: (asyncId) => {
+    destroyedIds.push(asyncId);
+  }
+}).enable();
+
+const server = http.createServer(function(req, res) {
+  res.end('Hello');
+});
+
+const keepAliveAgent = new http.Agent({
+  keepAlive: true,
+  keepAliveMsecs: KEEP_ALIVE,
+});
+
+const countdown = new Countdown(N, () => {
+  server.close(() => {
+    // give the server sockets time to close (which will also free their
+    // associated parser objects) after the server has been closed.
+    setTimeout(() => {
+      createdIds.forEach((createdAsyncId) => {
+        assert.ok(destroyedIds.indexOf(createdAsyncId) >= 0);
+      });
+    }, KEEP_ALIVE * 2);
+  });
+});
+
+server.listen(0, function() {
+  for (let i = 0; i < N; ++i) {
+    (function makeRequest() {
+      http.get({
+        port: server.address().port,
+        agent: keepAliveAgent
+      }, function(res) {
+        countdown.dec();
+        res.resume();
+      });
+    })();
+  }
+});