Inline createResolvingFunctions().

This avoids creating a result object and saves some memory for a boolean in the non-chaining case.
cscott · Dec 8, 2015 · ed96b47 · ed96b47
1 parent 93ff998
commit ed96b47
Showing 1 changed file with 42 additions and 30 deletions.
diff --git a/lib/promise.js b/lib/promise.js
@@ -162,8 +162,9 @@ var enqueue = useAsap ? require('asap/raw') : IsCallable(global.setImmediate) ?
 var PROMISE_IDENTITY = (function(v) { return v; });
 var PROMISE_THROWER = (function(t) { throw t; });
 var PROMISE_PENDING = 0;
-var PROMISE_FULFILLED = 1;
-var PROMISE_REJECTED = 2;
+var PROMISE_RESOLVING = 1; // PROMISE_PENDING combined with alreadyResolved
+var PROMISE_FULFILLED = 2;
+var PROMISE_REJECTED = 3;
 
 var promiseReactionJob = function(handler, promiseCapability, argument) {
   var handlerResult, resolve, reject;
@@ -257,41 +258,38 @@ var rejectPromise = function(promise, reason) {
   promise._promise_state = PROMISE_REJECTED;
 };
 
-var createResolvingFunctions = function(promise) {
+var resolvePromise = function(promise, resolution) {
+  if (resolution === promise) {
+    return rejectPromise(promise, new TypeError('Self resolution'));
+  }
+  if (!TypeIsObject(resolution)) {
+    return fulfillPromise(promise, resolution);
+  }
+  var then = tryCatch1(function(r) { return r.then; }, resolution);
+  if (then === errorObj) {
+    return rejectPromise(promise, then.e);
+  }
+  if (!IsCallable(then)) {
+    return fulfillPromise(promise, resolution);
+  }
+  enqueue(function() {
+    promiseResolveThenableJob(promise, resolution, then);
+  });
+};
+
+var promiseResolveThenableJob = function(promise, thenable, then) {
+  // Inlined copy of createResolvingFunctions(promise)
   var alreadyResolved = false;
   var resolve = function(resolution) {
-    var then;
     if (alreadyResolved) { return; }
     alreadyResolved = true;
-    if (resolution === promise) {
-      return rejectPromise(promise, new TypeError('Self resolution'));
-    }
-    if (!TypeIsObject(resolution)) {
-      return fulfillPromise(promise, resolution);
-    }
-    then = tryCatch1(function(r) { return r.then; }, resolution);
-    if (then === errorObj) {
-      return rejectPromise(promise, then.e);
-    }
-    if (!IsCallable(then)) {
-      return fulfillPromise(promise, resolution);
-    }
-    enqueue(function() {
-      promiseResolveThenableJob(promise, resolution, then);
-    });
+    resolvePromise(promise, resolution);
   };
   var reject = function(reason) {
     if (alreadyResolved) { return; }
     alreadyResolved = true;
     return rejectPromise(promise, reason);
   };
-  return { resolve: resolve, reject: reject };
-};
-
-var promiseResolveThenableJob = function(promise, thenable, then) {
-  var resolvingFunctions = createResolvingFunctions(promise);
-  var resolve = resolvingFunctions.resolve;
-  var reject = resolvingFunctions.reject;
   var value = tryCatch2r(then, thenable, resolve, reject);
   if (value === errorObj) {
     reject(value.e);
@@ -319,9 +317,22 @@ var Promise = function Promise(resolver) {
   this._promise_fulfillReactions0 = void 0;
   this._promise_rejectReactions0 = void 0;
   this._promise_reactionCapability0 = void 0;
-  var resolvingFunctions = createResolvingFunctions(this);
-  var reject = resolvingFunctions.reject;
-  var value = tryCatch2(resolver, resolvingFunctions.resolve, reject);
+  // Inlined copy of createResolvingFunctions(this), using _promise_state
+  // to track the `alreadyResolved` boolean.
+  var promise = this;
+  var resolve = function(resolution) {
+    /* jshint bitwise: false */
+    if ((promise._promise_state & 3) !== PROMISE_PENDING) { return; }
+    promise._promise_state++; // Sets state to PROMISE_RESOLVING
+    resolvePromise(promise, resolution);
+  };
+  var reject = function(reason) {
+    /* jshint bitwise: false */
+    if ((promise._promise_state & 3) !== PROMISE_PENDING) { return; }
+    promise._promise_state++; // Sets state to PROMISE_RESOLVING
+    rejectPromise(promise, reason);
+  };
+  var value = tryCatch2(resolver, resolve, reject);
   if (value === errorObj) {
     reject(value.e);
   }
@@ -379,6 +390,7 @@ defineProperties(Promise$prototype, {
     var length;
     switch (promise._promise_state & 3) {
     case PROMISE_PENDING:
+    case PROMISE_RESOLVING:
       length = promise._promise_state >>> 2;
       if (length === 0) {
         promise._promise_fulfillReactions0 = onFulfilled;