[promises] Move CreateResolvingFunctions to c++

src/js/promise.js

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 (function(global, utils, extrasUtils) {
 
 "use strict";
 
 %CheckIsBootstrapping();
 
@@ skipping 31 matching lines @@
 });
 
 // -------------------------------------------------------------------
 
 // [[PromiseState]] values:
 // These values should be kept in sync with PromiseStatus in globals.h
 const kPending = 0;
 const kFulfilled = +1;
 const kRejected = +2;
 
-// ES#sec-createresolvingfunctions
-// CreateResolvingFunctions ( promise )
-function CreateResolvingFunctions(promise, debugEvent) {
-  var alreadyResolved = false;
-
-  // ES#sec-promise-resolve-functions
-  // Promise Resolve Functions
-  var resolve = value => {
-    if (alreadyResolved === true) return;
-    alreadyResolved = true;
-    ResolvePromise(promise, value);
-  };
-
-  // ES#sec-promise-reject-functions
-  // Promise Reject Functions
-  var reject = reason => {
-    if (alreadyResolved === true) return;
-    alreadyResolved = true;
-    %PromiseReject(promise, reason, debugEvent);
-    PromiseSet(promise, kRejected, reason);
-  };
-
-  return {
-    __proto__: null,
-    resolve: resolve,
-    reject: reject
-  };
-}
-
+const kResolveCallback = 0;
+const kRejectCallback = 1;
 
 // ES#sec-promise-executor
 // Promise ( executor )
 var GlobalPromise = function Promise(executor) {
   if (executor === promiseRawSymbol) {
     return %_NewObject(GlobalPromise, new.target);
   }
   if (IS_UNDEFINED(new.target)) throw %make_type_error(kNotAPromise, this);
   if (!IS_CALLABLE(executor)) {
     throw %make_type_error(kResolverNotAFunction, executor);
   }
 
   var promise = PromiseInit(%_NewObject(GlobalPromise, new.target));
   // Calling the reject function would be a new exception, so debugEvent = true
-  var callbacks = CreateResolvingFunctions(promise, true);
+  var callbacks = %create_resolving_functions(promise, true);

[Benedikt Meurer, 2016/11/09 05:14:30]

There seems to be no need to have the container object here at all. Can you
leave a TODO here, to cleanup this and only allocate the context plus the two
JSFunctions (ideally when this becomes a TF builtin)?

[gsathya, 2016/11/09 15:57:44]

Yeah this container exists only because of the piecemeal migration plan. it
should go away once we move all the callers to c++. Here's a CL that removes one
-- https://codereview.chromium.org/2487053002/ Rest will be moved shortly.

Added TODO for now.

   var debug_is_active = DEBUG_IS_ACTIVE;
   try {
     if (debug_is_active) %DebugPushPromise(promise);
-    executor(callbacks.resolve, callbacks.reject);
+    executor(callbacks[kResolveCallback], callbacks[kRejectCallback]);
   } %catch (e) {  // Natives syntax to mark this catch block.
-    %_Call(callbacks.reject, UNDEFINED, e);
+    %_Call(callbacks[kRejectCallback], UNDEFINED, e);
   } finally {
     if (debug_is_active) %DebugPopPromise();
   }
 
   return promise;
 }
 
 // Core functionality.
 
 function PromiseSet(promise, status, value) {
@@ skipping 172 matching lines @@
         }
         // Don't cause a debug event as this case is forwarding a rejection
         %PromiseReject(promise, thenableValue, false);
         PromiseSet(promise, kRejected, thenableValue);
         SET_PRIVATE(resolution, promiseHasHandlerSymbol, true);
         return;
       }
     }
 
     if (IS_CALLABLE(then)) {
-      var callbacks = CreateResolvingFunctions(promise, false);
+      var callbacks = %create_resolving_functions(promise, false);

[Benedikt Meurer, 2016/11/09 05:14:30]

Same here.

[gsathya, 2016/11/09 15:57:45]

Done.

       if (DEBUG_IS_ACTIVE && IsPromise(resolution)) {
           // Mark the dependency of the new promise on the resolution
         SET_PRIVATE(resolution, promiseHandledBySymbol, promise);
       }
       %EnqueuePromiseResolveThenableJob(
-          resolution, then, callbacks.resolve, callbacks.reject);
+          resolution, then, callbacks[kResolveCallback],
+          callbacks[kRejectCallback]);
       return;
     }
   }
   %PromiseFulfill(promise, kFulfilled, resolution,
                   promiseFulfillReactionsSymbol);
   PromiseSet(promise, kFulfilled, resolution);
 }
 
 // Only used by async-await.js
-function RejectPromise(promise, reason) {
-  %PromiseReject(promise, reason, false);
+function RejectPromise(promise, reason, debugEvent) {
+  %PromiseReject(promise, reason, debugEvent);
   PromiseSet(promise, kRejected, reason);
 }
 
 // Export to bindings
 function DoRejectPromise(promise, reason) {
   %PromiseReject(promise, reason, true);
   PromiseSet(promise, kRejected, reason);
 }
 
 // ES#sec-newpromisecapability
 // NewPromiseCapability ( C )
 function NewPromiseCapability(C, debugEvent) {
   if (C === GlobalPromise) {
     // Optimized case, avoid extra closure.
     var promise = PromiseCreate();
-    var callbacks = CreateResolvingFunctions(promise, debugEvent);
+    var callbacks = %create_resolving_functions(promise, debugEvent);

[Benedikt Meurer, 2016/11/09 05:14:30]

And here.

[gsathya, 2016/11/09 15:57:44]

Done.

     return {
       promise: promise,
-      resolve: callbacks.resolve,
-      reject: callbacks.reject
+      resolve: callbacks[kResolveCallback],
+      reject: callbacks[kRejectCallback]
     };
   }
 
   var result = {promise: UNDEFINED, resolve: UNDEFINED, reject: UNDEFINED };
   result.promise = new C((resolve, reject) => {
     if (!IS_UNDEFINED(result.resolve) || !IS_UNDEFINED(result.reject))
         throw %make_type_error(kPromiseExecutorAlreadyInvoked);
     result.resolve = resolve;
     result.reject = reject;
   });
@@ skipping 294 matching lines @@
 utils.InstallFunctions(GlobalPromise.prototype, DONT_ENUM, [
   "then", PromiseThen,
   "catch", PromiseCatch
 ]);
 
 %InstallToContext([
   "promise_catch", PromiseCatch,
   "promise_create", PromiseCreate,
   "promise_has_user_defined_reject_handler", PromiseHasUserDefinedRejectHandler,
   "promise_reject", DoRejectPromise,
+  // TODO(gsathya): Remove this once we update the promise builtin.
+  "promise_internal_reject", RejectPromise,
   "promise_resolve", ResolvePromise,
   "promise_then", PromiseThen,
   "promise_handle", PromiseHandle,
   "promise_debug_get_info", PromiseDebugGetInfo
 ]);
 
 // This allows extras to create promises quickly without building extra
 // resolve/reject closures, and allows them to later resolve and reject any
 // promise without having to hold on to those closures forever.
 utils.InstallFunctions(extrasUtils, 0, [
   "createPromise", PromiseCreate,
   "resolvePromise", ResolvePromise,
   "rejectPromise", DoRejectPromise
 ]);
 
 utils.Export(function(to) {
   to.IsPromise = IsPromise;
   to.PromiseCreate = PromiseCreate;
   to.PromiseThen = PromiseThen;
 
   to.GlobalPromise = GlobalPromise;
   to.NewPromiseCapability = NewPromiseCapability;
   to.PerformPromiseThen = PerformPromiseThen;
   to.ResolvePromise = ResolvePromise;
   to.RejectPromise = RejectPromise;
 });
 
 })