lib: implement aysnc_hooks API in core

Implement async_hooks support in the following:

* fatalException handler
* process.nextTick
* Timers
* net/dgram/http

lib/_http_agent.js

@@ -25,6 +25,8 @@ const net = require('net');
 const util = require('util');
 const EventEmitter = require('events');
 const debug = util.debuglog('http');
+const async_id_symbol = process.binding('async_wrap').async_id_symbol;
+const nextTick = require('internal/process/next_tick').nextTick;
 
 // New Agent code.
 
@@ -93,6 +95,7 @@ function Agent(options) {
           self.freeSockets[name] = freeSockets;
           socket.setKeepAlive(true, self.keepAliveMsecs);
           socket.unref();
+          socket[async_id_symbol] = -1;
           socket._httpMessage = null;
           self.removeSocket(socket, options);
           freeSockets.push(socket);
@@ -162,6 +165,8 @@ Agent.prototype.addRequest = function addRequest(req, options) {
   if (freeLen) {
     // we have a free socket, so use that.
     var socket = this.freeSockets[name].shift();
+    // Assign the handle a new asyncId and run any init() hooks.
+    socket._handle.asyncReset();
     debug('have free socket');
 
     // don't leak
@@ -176,7 +181,7 @@ Agent.prototype.addRequest = function addRequest(req, options) {
     // If we are under maxSockets create a new one.
     this.createSocket(req, options, function(err, newSocket) {
       if (err) {
-        process.nextTick(function() {
+        nextTick(newSocket._handle.getAsyncId(), function() {
           req.emit('error', err);
         });
         return;
@@ -289,7 +294,7 @@ Agent.prototype.removeSocket = function removeSocket(s, options) {
     // If we have pending requests and a socket gets closed make a new one
     this.createSocket(req, options, function(err, newSocket) {
       if (err) {
-        process.nextTick(function() {
+        nextTick(newSocket._handle.getAsyncId(), function() {
           req.emit('error', err);
         });
         return;

lib/_http_client.js

@@ -36,6 +36,7 @@ const Agent = require('_http_agent');
 const Buffer = require('buffer').Buffer;
 const urlToOptions = require('internal/url').urlToOptions;
 const outHeadersKey = require('internal/http').outHeadersKey;
+const nextTick = require('internal/process/next_tick').nextTick;
 
 // The actual list of disallowed characters in regexp form is more like:
 //    /[^A-Za-z0-9\-._~!$&'()*+,;=/:@]/
@@ -577,9 +578,12 @@ function responseKeepAlive(res, req) {
     socket.removeListener('close', socketCloseListener);
     socket.removeListener('error', socketErrorListener);
     socket.once('error', freeSocketErrorListener);
+    // There are cases where _handle === null. Avoid those. Passing null to
+    // nextTick() will call initTriggerId() to retrieve the id.
+    const asyncId = socket._handle ? socket._handle.getAsyncId() : null;
     // Mark this socket as available, AFTER user-added end
     // handlers have a chance to run.
-    process.nextTick(emitFreeNT, socket);
+    nextTick(asyncId, emitFreeNT, socket);
   }
 }
 

lib/_http_common.js

@@ -28,6 +28,7 @@ const HTTPParser = binding.HTTPParser;
 const FreeList = require('internal/freelist').FreeList;
 const ondrain = require('internal/http').ondrain;
 const incoming = require('_http_incoming');
+const emitDestroy = require('async_hooks').emitDestroy;
 const IncomingMessage = incoming.IncomingMessage;
 const readStart = incoming.readStart;
 const readStop = incoming.readStop;
@@ -211,8 +212,13 @@ function freeParser(parser, req, socket) {
     parser.incoming = null;
     parser.outgoing = null;
     parser[kOnExecute] = null;
-    if (parsers.free(parser) === false)
+    if (parsers.free(parser) === false) {
       parser.close();
+    } else {
+      // Since the Parser destructor isn't going to run the destroy() callbacks
+      // it needs to be triggered manually.
+      emitDestroy(parser.getAsyncId());
+    }
   }
   if (req) {
     req.parser = null;

lib/_http_outgoing.js

@@ -31,6 +31,8 @@ const common = require('_http_common');
 const checkIsHttpToken = common._checkIsHttpToken;
 const checkInvalidHeaderChar = common._checkInvalidHeaderChar;
 const outHeadersKey = require('internal/http').outHeadersKey;
+const async_id_symbol = process.binding('async_wrap').async_id_symbol;
+const nextTick = require('internal/process/next_tick').nextTick;
 
 const CRLF = common.CRLF;
 const debug = common.debug;
@@ -265,8 +267,9 @@ function _writeRaw(data, encoding, callback) {
     if (this.output.length) {
       this._flushOutput(conn);
     } else if (!data.length) {
-      if (typeof callback === 'function')
-        process.nextTick(callback);
+      if (typeof callback === 'function') {
+        nextTick(this.socket[async_id_symbol], callback);
+      }
       return true;
     }
     // Directly write to socket.
@@ -624,7 +627,10 @@ const crlf_buf = Buffer.from('\r\n');
 OutgoingMessage.prototype.write = function write(chunk, encoding, callback) {
   if (this.finished) {
     var err = new Error('write after end');
-    process.nextTick(writeAfterEndNT.bind(this), err, callback);
+    nextTick(this.socket[async_id_symbol],
+             writeAfterEndNT.bind(this),
+             err,
+             callback);
 
     return true;
   }

lib/async_hooks.js

@@ -32,7 +32,7 @@ var processing_hook = false;
 // Use to temporarily store and updated active_hooks_array if the user enables
 // or disables a hook while hooks are being processed.
 var tmp_active_hooks_array = null;
-// Keep track of the field counds held in tmp_active_hooks_array.
+// Keep track of the field counts held in tmp_active_hooks_array.
 var tmp_async_hook_fields = null;
 
 // Each constant tracks how many callbacks there are for any given step of
@@ -41,9 +41,9 @@ var tmp_async_hook_fields = null;
 const { kInit, kBefore, kAfter, kDestroy, kCurrentAsyncId, kCurrentTriggerId,
     kAsyncUidCntr, kInitTriggerId } = async_wrap.constants;
 
+const { async_id_symbol, trigger_id_symbol } = async_wrap;
+
 // Used in AsyncHook and AsyncEvent.
-const async_id_symbol = Symbol('_asyncId');
-const trigger_id_symbol = Symbol('_triggerId');
 const init_symbol = Symbol('init');
 const before_symbol = Symbol('before');
 const after_symbol = Symbol('after');

lib/dgram.js

@@ -25,7 +25,10 @@ const assert = require('assert');
 const Buffer = require('buffer').Buffer;
 const util = require('util');
 const EventEmitter = require('events');
+const setInitTriggerId = require('async_hooks').setInitTriggerId;
 const UV_UDP_REUSEADDR = process.binding('constants').os.UV_UDP_REUSEADDR;
+const async_id_symbol = process.binding('async_wrap').async_id_symbol;
+const nextTick = require('internal/process/next_tick').nextTick;
 
 const UDP = process.binding('udp_wrap').UDP;
 const SendWrap = process.binding('udp_wrap').SendWrap;
@@ -111,6 +114,7 @@ function Socket(type, listener) {
   this._handle = handle;
   this._receiving = false;
   this._bindState = BIND_STATE_UNBOUND;
+  this[async_id_symbol] = this._handle.getAsyncId();
   this.type = type;
   this.fd = null; // compatibility hack
 
@@ -433,6 +437,10 @@ function doSend(ex, self, ip, list, address, port, callback) {
     req.callback = callback;
     req.oncomplete = afterSend;
   }
+  // node::SendWrap isn't instantiated and attached to the JS instance of
+  // SendWrap above until send() is called. So don't set the init trigger id
+  // until now.
+  setInitTriggerId(self[async_id_symbol]);
   var err = self._handle.send(req,
                               list,
                               list.length,
@@ -442,7 +450,7 @@ function doSend(ex, self, ip, list, address, port, callback) {
   if (err && callback) {
     // don't emit as error, dgram_legacy.js compatibility
     const ex = exceptionWithHostPort(err, 'send', address, port);
-    process.nextTick(callback, ex);
+    nextTick(self[async_id_symbol], callback, ex);
   }
 }
 
@@ -469,7 +477,7 @@ Socket.prototype.close = function(callback) {
   this._stopReceiving();
   this._handle.close();
   this._handle = null;
-  process.nextTick(socketCloseNT, this);
+  nextTick(this[async_id_symbol], socketCloseNT, this);
 
   return this;
 };

lib/internal/bootstrap_node.js

@@ -305,10 +305,20 @@
   }
 
   function setupProcessFatal() {
+    const async_wrap = process.binding('async_wrap');
+    // Arrays containing hook flags and ids for async_hook calls.
+    const { async_hook_fields, async_uid_fields } = async_wrap;
+    // Internal functions needed to manipulate the stack.
+    const { clearIdStack, popAsyncIds } = async_wrap;
+    const { kAfter, kCurrentAsyncId, kInitTriggerId } = async_wrap.constants;
 
     process._fatalException = function(er) {
       var caught;
 
+      // It's possible that kInitTriggerId was set for a constructor call that
+      // threw and was never cleared. So clear it now.
+      async_uid_fields[kInitTriggerId] = 0;
+
       if (process.domain && process.domain._errorHandler)
         caught = process.domain._errorHandler(er) || caught;
 
@@ -327,9 +337,21 @@
           // nothing to be done about it at this point.
         }
 
-      // if we handled an error, then make sure any ticks get processed
       } else {
+        // If we handled an error, then make sure any ticks get processed
         NativeModule.require('timers').setImmediate(process._tickCallback);
+
+        // Emit the after() hooks now that the exception has been handled.
+        if (async_hook_fields[kAfter] > 0) {
+          do {
+            NativeModule.require('async_hooks').emitAfter(
+                async_uid_fields[kCurrentAsyncId]);
+          // popAsyncIds() returns true if there are more ids on the stack.
+          } while (popAsyncIds(async_uid_fields[kCurrentAsyncId]));
+        // Or completely empty the id stack.
+        } else {
+          clearIdStack();
+        }
       }
 
       return caught;