node: add AsyncListener support

AsyncListener is a JS API that works in tandem with the AsyncWrap class
to allow the user to be alerted to key events in the life cycle of an
asynchronous event. The AsyncWrap class has its own MakeCallback
implementation that core will be migrated to use, and uses state sharing
techniques to allow quicker communication between JS and C++ whether the
async event callbacks need to be called.

lib/timers.js

@@ -30,6 +30,17 @@ var TIMEOUT_MAX = 2147483647; // 2^31-1
 
 var debug = require('util').debuglog('timer');
 
+var asyncFlags = process._asyncFlags;
+var runAsyncQueue = process._runAsyncQueue;
+var loadAsyncQueue = process._loadAsyncQueue;
+var unloadAsyncQueue = process._unloadAsyncQueue;
+
+// Do a little housekeeping.
+delete process._asyncFlags;
+delete process._runAsyncQueue;
+delete process._loadAsyncQueue;
+delete process._unloadAsyncQueue;
+
 
 // IDLE TIMEOUTS
 //
@@ -44,6 +55,9 @@ var debug = require('util').debuglog('timer');
 // value = list
 var lists = {};
 
+// Make Timer as monomorphic as possible.
+Timer.prototype._asyncQueue = undefined;
+
 // the main function - creates lists on demand and the watchers associated
 // with them.
 function insert(item, msecs) {
@@ -80,9 +94,9 @@ function listOnTimeout() {
   var now = Timer.now();
   debug('now: %s', now);
 
-  var first;
+  var diff, first, hasQueue, threw;
   while (first = L.peek(list)) {
-    var diff = now - first._idleStart;
+    diff = now - first._idleStart;
     if (diff < msecs) {
       list.start(msecs - diff, 0);
       debug('%d list wait because diff is %d', msecs, diff);
@@ -99,12 +113,20 @@ function listOnTimeout() {
       //
       // https://github.com/joyent/node/issues/2631
       var domain = first.domain;
-      if (domain && domain._disposed) continue;
+      if (domain && domain._disposed)
+        continue;
+
+      hasQueue = !!first._asyncQueue;
+
       try {
+        if (hasQueue)
+          loadAsyncQueue(first);
         if (domain)
           domain.enter();
-        var threw = true;
+        threw = true;
         first._onTimeout();
+        if (hasQueue)
+          unloadAsyncQueue(first);
         if (domain)
           domain.exit();
         threw = false;
@@ -162,7 +184,6 @@ exports.enroll = function(item, msecs) {
 exports.active = function(item) {
   var msecs = item._idleTimeout;
   if (msecs >= 0) {
-
     var list = lists[msecs];
     if (!list || L.isEmpty(list)) {
       insert(item, msecs);
@@ -171,6 +192,11 @@ exports.active = function(item) {
       L.append(list, item);
     }
   }
+  // Whether or not a new TimerWrap needed to be created, this should run
+  // for each item. This way each "item" (i.e. timer) can properly have
+  // their own domain assigned.
+  if (asyncFlags[0] > 0)
+    runAsyncQueue(item);
 };
 
 
@@ -316,16 +342,43 @@ L.init(immediateQueue);
 
 function processImmediate() {
   var queue = immediateQueue;
+  var domain, hasQueue, immediate;
 
   immediateQueue = {};
   L.init(immediateQueue);
 
   while (L.isEmpty(queue) === false) {
-    var immediate = L.shift(queue);
-    var domain = immediate.domain;
-    if (domain) domain.enter();
-    immediate._onImmediate();
-    if (domain) domain.exit();
+    immediate = L.shift(queue);
+    hasQueue = !!immediate._asyncQueue;
+    domain = immediate.domain;
+
+    if (hasQueue)
+      loadAsyncQueue(immediate);
+    if (domain)
+      domain.enter();
+
+    var threw = true;
+    try {
+      immediate._onImmediate();
+      threw = false;
+    } finally {
+      if (threw) {
+        if (!L.isEmpty(queue)) {
+          // Handle any remaining on next tick, assuming we're still
+          // alive to do so.
+          while (!L.isEmpty(immediateQueue)) {
+            L.append(queue, L.shift(immediateQueue));
+          }
+          immediateQueue = queue;
+          process.nextTick(processImmediate);
+        }
+      }
+    }
+
+    if (hasQueue)
+      unloadAsyncQueue(immediate);
+    if (domain)
+      domain.exit();
   }
 
   // Only round-trip to C++ land if we have to. Calling clearImmediate() on an
@@ -357,7 +410,11 @@ exports.setImmediate = function(callback) {
     process._immediateCallback = processImmediate;
   }
 
-  if (process.domain) immediate.domain = process.domain;
+  // setImmediates are handled more like nextTicks.
+  if (asyncFlags[0] > 0)
+    runAsyncQueue(immediate);
+  if (process.domain)
+    immediate.domain = process.domain;
 
   L.append(immediateQueue, immediate);
 
@@ -389,9 +446,10 @@ function unrefTimeout() {
 
   debug('unrefTimer fired');
 
-  var first;
+  var diff, domain, first, hasQueue, threw;
   while (first = L.peek(unrefList)) {
-    var diff = now - first._idleStart;
+    diff = now - first._idleStart;
+    hasQueue = !!first._asyncQueue;
 
     if (diff < first._idleTimeout) {
       diff = first._idleTimeout - diff;
@@ -403,17 +461,21 @@ function unrefTimeout() {
 
     L.remove(first);
 
-    var domain = first.domain;
+    domain = first.domain;
 
     if (!first._onTimeout) continue;
     if (domain && domain._disposed) continue;
 
     try {
+      if (hasQueue)
+        loadAsyncQueue(first);
       if (domain) domain.enter();
-      var threw = true;
+      threw = true;
       debug('unreftimer firing timeout');
       first._onTimeout();
       threw = false;
+      if (hasQueue)
+        unloadAsyncQueue(first);
       if (domain) domain.exit();
     } finally {
       if (threw) process.nextTick(unrefTimeout);

node.gyp

@@ -115,6 +115,8 @@
         'src/udp_wrap.cc',
         'src/uv.cc',
         # headers to make for a more pleasant IDE experience
+        'src/async-wrap.h',
+        'src/async-wrap-inl.h',
         'src/env.h',
         'src/env-inl.h',
         'src/handle_wrap.h',