[promises] Move PromiseReactionJob to c++

src/isolate.cc

 // 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.
 
 #include "src/isolate.h"
 
 #include <stdlib.h>
 
 #include <fstream>  // NOLINT(readability/streams)
 #include <sstream>
 
 #include "src/ast/context-slot-cache.h"
 #include "src/base/hashmap.h"
 #include "src/base/platform/platform.h"
 #include "src/base/sys-info.h"
 #include "src/base/utils/random-number-generator.h"
 #include "src/basic-block-profiler.h"
 #include "src/bootstrapper.h"
 #include "src/cancelable-task.h"
 #include "src/codegen.h"
 #include "src/compilation-cache.h"
 #include "src/compilation-statistics.h"
 #include "src/compiler-dispatcher/optimizing-compile-dispatcher.h"
 #include "src/crankshaft/hydrogen.h"
 #include "src/debug/debug.h"
 #include "src/deoptimizer.h"
+#include "src/elements.h"
 #include "src/external-reference-table.h"
 #include "src/frames-inl.h"
 #include "src/ic/access-compiler-data.h"
 #include "src/ic/stub-cache.h"
 #include "src/interface-descriptors.h"
 #include "src/interpreter/interpreter.h"
 #include "src/isolate-inl.h"
 #include "src/libsampler/sampler.h"
 #include "src/log.h"
 #include "src/messages.h"
@@ skipping 2964 matching lines @@
   if (promise_reject_callback_ == NULL) return;
   Handle<JSArray> stack_trace;
   if (event == v8::kPromiseRejectWithNoHandler && value->IsJSObject()) {
     stack_trace = GetDetailedStackTrace(Handle<JSObject>::cast(value));
   }
   promise_reject_callback_(v8::PromiseRejectMessage(
       v8::Utils::PromiseToLocal(promise), event, v8::Utils::ToLocal(value),
       v8::Utils::StackTraceToLocal(stack_trace)));
 }
 
+namespace {
+class PromiseDebugEventHelper {

[adamk, 2016/10/12 16:18:11]

We often name these things scopes, so how about PromiseDebugEventScope?

[gsathya, 2016/10/12 20:08:53]

Done.

+ public:
+  PromiseDebugEventHelper(Isolate* isolate, Handle<Object> before,

[adamk, 2016/10/12 16:18:11]

You could reduce the lines-of-code (or at least encapsulate more of the logic)
by taking Object* as before/after and constructing the handles 1) only if debug
is active and 2) after checking debug_is_active

[gsathya, 2016/10/12 20:08:53]

Done.

+                          Handle<Object> after)
+      : isolate_(isolate), before_(before), after_(after) {
+    if (isolate_->debug()->is_active() && before_->IsJSObject()) {
+      isolate_->debug()->OnAsyncTaskEvent(Handle<JSObject>::cast(before_));
+    }
+  }
+
+  ~PromiseDebugEventHelper() {
+    if (isolate_->debug()->is_active() && after_->IsJSObject()) {
+      isolate_->debug()->OnAsyncTaskEvent(Handle<JSObject>::cast(after_));
+    }
+  }
+
+ private:
+  Isolate* isolate_;
+  Handle<Object> before_;
+  Handle<Object> after_;
+};
+}  // namespace
+
+void Isolate::PromiseReactionJob(
+    Handle<PromiseReactionJobInfo> promise_reaction_job_info,
+    MaybeHandle<Object>* result, MaybeHandle<Object>* maybe_exception) {
+  Handle<Object> before(promise_reaction_job_info->before_debug_event(), this);
+  Handle<Object> after(promise_reaction_job_info->after_debug_event(), this);
+  PromiseDebugEventHelper helper(this, before, after);
+
+  Handle<Object> value(promise_reaction_job_info->value(), this);
+  Handle<Object> tasks(promise_reaction_job_info->tasks(), this);
+  Handle<JSFunction> promise_handle_fn = promise_handle();
+  Handle<Object> undefined = factory()->undefined_value();
+
+  // If tasks is an array we have multiple onFulfilled/onRejected callbacks
+  // associated with the promise. The deferred object for each callback
+  // is attached to this array as well.
+  // Otherwise, there is a single callback and the deferred object is attached
+  // directly to PromiseReactionJobInfo.
+  if (tasks->IsJSArray()) {
+    Handle<JSArray> array = Handle<JSArray>::cast(tasks);
+    DCHECK(array->length()->IsSmi());
+    int length = Smi::cast(array->length())->value();
+    ElementsAccessor* accessor = array->GetElementsAccessor();
+    DCHECK(length % 2 == 0);
+    for (int i = 0; i < length; i += 2) {
+      DCHECK(accessor->HasElement(array, i));
+      DCHECK(accessor->HasElement(array, i + 1));
+      Handle<Object> argv[] = {value, accessor->Get(array, i),
+                               accessor->Get(array, i + 1)};
+      *result = Execution::TryCall(this, promise_handle_fn, undefined,
+                                   arraysize(argv), argv, maybe_exception);
+      if (result->is_null() && maybe_exception->is_null()) {

[adamk, 2016/10/12 16:18:11]

Copy and paste a comment with this, too:

// If execution is terminating, just bail out.

[gsathya, 2016/10/12 20:08:53]

Done.

+        return;
+      }
+    }
+  } else {
+    Handle<Object> deferred(promise_reaction_job_info->deferred(), this);
+    Handle<Object> argv[] = {value, tasks, deferred};
+    *result =
+        Execution::TryCall(this, promise_handle(), factory()->undefined_value(),

[adamk, 2016/10/12 16:18:11]

You can pass promise_handle_fn and undefined here

[gsathya, 2016/10/12 20:08:53]

Done.

+                           arraysize(argv), argv, maybe_exception);
+    if (result->is_null() && maybe_exception->is_null()) {

[adamk, 2016/10/12 16:18:11]

No need to do anything special in this case, right? We're about to return
anyway.

[gsathya, 2016/10/12 20:08:53]

Done.

+      return;
+    }
+  }
+}
+
 void Isolate::PromiseResolveThenableJob(Handle<PromiseContainer> container,
                                         MaybeHandle<Object>* result,
                                         MaybeHandle<Object>* maybe_exception) {
-  if (debug()->is_active()) {
-    Handle<Object> before_debug_event(container->before_debug_event(), this);
-    if (before_debug_event->IsJSObject()) {
-      debug()->OnAsyncTaskEvent(Handle<JSObject>::cast(before_debug_event));
-    }
-  }
+  Handle<Object> before(container->before_debug_event(), this);
+  Handle<Object> after(container->after_debug_event(), this);
+  PromiseDebugEventHelper helper(this, before, after);
 
   Handle<JSReceiver> thenable(container->thenable(), this);
   Handle<JSFunction> resolve(container->resolve(), this);
   Handle<JSFunction> reject(container->reject(), this);
   Handle<JSReceiver> then(container->then(), this);
   Handle<Object> argv[] = {resolve, reject};
   *result = Execution::TryCall(this, then, thenable, arraysize(argv), argv,
                                maybe_exception);
 
   Handle<Object> reason;
   if (maybe_exception->ToHandle(&reason)) {
     DCHECK(result->is_null());
     Handle<Object> reason_arg[] = {reason};
     *result =
         Execution::TryCall(this, reject, factory()->undefined_value(),
                            arraysize(reason_arg), reason_arg, maybe_exception);
   }
-
-  if (debug()->is_active()) {
-    Handle<Object> after_debug_event(container->after_debug_event(), this);
-    if (after_debug_event->IsJSObject()) {
-      debug()->OnAsyncTaskEvent(Handle<JSObject>::cast(after_debug_event));
-    }
-  }
 }
 
 void Isolate::EnqueueMicrotask(Handle<Object> microtask) {
   DCHECK(microtask->IsJSFunction() || microtask->IsCallHandlerInfo() ||
-         microtask->IsPromiseContainer());
+         microtask->IsPromiseContainer() ||
+         microtask->IsPromiseReactionJobInfo());
   Handle<FixedArray> queue(heap()->microtask_queue(), this);
   int num_tasks = pending_microtask_count();
   DCHECK(num_tasks <= queue->length());
   if (num_tasks == 0) {
     queue = factory()->NewFixedArray(8);
     heap()->set_microtask_queue(*queue);
   } else if (num_tasks == queue->length()) {
     queue = factory()->CopyFixedArrayAndGrow(queue, num_tasks);
     heap()->set_microtask_queue(*queue);
   }
@@ skipping 31 matching lines @@
 
       if (microtask->IsCallHandlerInfo()) {
         Handle<CallHandlerInfo> callback_info =
             Handle<CallHandlerInfo>::cast(microtask);
         v8::MicrotaskCallback callback =
             v8::ToCData<v8::MicrotaskCallback>(callback_info->callback());
         void* data = v8::ToCData<void*>(callback_info->data());
         callback(data);
       } else {
         SaveContext save(this);
-        Context* context = microtask->IsJSFunction()
-                               ? Handle<JSFunction>::cast(microtask)->context()
-                               : Handle<PromiseContainer>::cast(microtask)
-                                     ->resolve()
-                                     ->context();
+        Context* context;
+        if (microtask->IsJSFunction()) {
+          context = Handle<JSFunction>::cast(microtask)->context();
+        } else if (microtask->IsPromiseContainer()) {
+          context =
+              Handle<PromiseContainer>::cast(microtask)->resolve()->context();
+        } else {
+          context = Handle<PromiseReactionJobInfo>::cast(microtask)->context();
+        }
+
         set_context(context->native_context());
         handle_scope_implementer_->EnterMicrotaskContext(
             Handle<Context>(context, this));
 
         MaybeHandle<Object> result;
         MaybeHandle<Object> maybe_exception;
 
         if (microtask->IsJSFunction()) {
           Handle<JSFunction> microtask_function =
               Handle<JSFunction>::cast(microtask);
           result = Execution::TryCall(this, microtask_function,
                                       factory()->undefined_value(), 0, NULL,
                                       &maybe_exception);
-        } else {
+        } else if (microtask->IsPromiseContainer()) {
           PromiseResolveThenableJob(Handle<PromiseContainer>::cast(microtask),
                                     &result, &maybe_exception);
+        } else {
+          PromiseReactionJob(Handle<PromiseReactionJobInfo>::cast(microtask),
+                             &result, &maybe_exception);
         }
 
         handle_scope_implementer_->LeaveMicrotaskContext();
 
         // If execution is terminating, just bail out.
         if (result.is_null() && maybe_exception.is_null()) {
           // Clear out any remaining callbacks in the queue.
           heap()->set_microtask_queue(heap()->empty_fixed_array());
           set_pending_microtask_count(0);
           return;
@@ skipping 192 matching lines @@
   // Then check whether this scope intercepts.
   if ((flag & intercept_mask_)) {
     intercepted_flags_ |= flag;
     return true;
   }
   return false;
 }
 
 }  // namespace internal
 }  // namespace v8