Reland ^2 "[async] Expose async hooks to d8"

This is a reland of 8e0f67be3f

Previously landed as: 3c4d0316e4 / 1065818
Previously landed as: 8e0f67be3f / 1088890

Original change's description:
> [async] Expose async hooks to d8
>
> This implementation follows the Node.js API as a guideline.

Bug: chromium:850530
Change-Id: I8ba22b11c80328108b197d687826ce0198420c9c
Reviewed-on: https://chromium-review.googlesource.com/1125679
Reviewed-by: Benedikt Meurer <bmeurer@chromium.org>
Commit-Queue: Maya Lekova <mslekova@chromium.org>
Cr-Commit-Position: refs/heads/master@{#54191}

BUILD.gn

@@ -3330,6 +3330,8 @@ if (is_component_build) {
 v8_executable("d8") {
   sources = [
     "$target_gen_dir/d8-js.cc",
+    "src/async-hooks-wrapper.cc",
+    "src/async-hooks-wrapper.h",
     "src/d8-console.cc",
     "src/d8-console.h",
     "src/d8.cc",

src/async-hooks-wrapper.cc

@@ -0,0 +1,245 @@
+// Copyright 2018 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/async-hooks-wrapper.h"
+#include "src/d8.h"
+
+namespace v8 {
+
+void AsyncHooksWrap::Enable() { enabled_ = true; }
+
+void AsyncHooksWrap::Disable() { enabled_ = false; }
+
+v8::Local<v8::Function> AsyncHooksWrap::init_function() const {
+  return init_function_.Get(isolate_);
+}
+void AsyncHooksWrap::set_init_function(v8::Local<v8::Function> value) {
+  init_function_.Reset(isolate_, value);
+}
+v8::Local<v8::Function> AsyncHooksWrap::before_function() const {
+  return before_function_.Get(isolate_);
+}
+void AsyncHooksWrap::set_before_function(v8::Local<v8::Function> value) {
+  before_function_.Reset(isolate_, value);
+}
+v8::Local<v8::Function> AsyncHooksWrap::after_function() const {
+  return after_function_.Get(isolate_);
+}
+void AsyncHooksWrap::set_after_function(v8::Local<v8::Function> value) {
+  after_function_.Reset(isolate_, value);
+}
+v8::Local<v8::Function> AsyncHooksWrap::promiseResolve_function() const {
+  return promiseResolve_function_.Get(isolate_);
+}
+void AsyncHooksWrap::set_promiseResolve_function(
+    v8::Local<v8::Function> value) {
+  promiseResolve_function_.Reset(isolate_, value);
+}
+
+static AsyncHooksWrap* UnwrapHook(
+    const v8::FunctionCallbackInfo<v8::Value>& args) {
+  Isolate* isolate = args.GetIsolate();
+  HandleScope scope(isolate);
+  Local<Object> hook = args.This();
+  Local<External> wrap = Local<External>::Cast(hook->GetInternalField(0));
+  void* ptr = wrap->Value();
+  return static_cast<AsyncHooksWrap*>(ptr);
+}
+
+static void EnableHook(const v8::FunctionCallbackInfo<v8::Value>& args) {
+  AsyncHooksWrap* wrap = UnwrapHook(args);
+  wrap->Enable();
+}
+
+static void DisableHook(const v8::FunctionCallbackInfo<v8::Value>& args) {
+  AsyncHooksWrap* wrap = UnwrapHook(args);
+  wrap->Disable();
+}
+
+async_id_t AsyncHooks::GetExecutionAsyncId() const {
+  return asyncContexts.top().execution_async_id;
+}
+
+async_id_t AsyncHooks::GetTriggerAsyncId() const {
+  return asyncContexts.top().trigger_async_id;
+}
+
+Local<Object> AsyncHooks::CreateHook(
+    const v8::FunctionCallbackInfo<v8::Value>& args) {
+  Isolate* isolate = args.GetIsolate();
+  EscapableHandleScope handle_scope(isolate);
+
+  Local<Context> currentContext = isolate->GetCurrentContext();
+
+  AsyncHooksWrap* wrap = new AsyncHooksWrap(isolate);
+
+  CHECK(args[0]->IsObject());
+
+  Local<Object> fn_obj = args[0].As<Object>();
+
+#define SET_HOOK_FN(name)                                                   \
+  Local<Value> name##_v =                                                   \
+      fn_obj                                                                \
+          ->Get(currentContext,                                             \
+                String::NewFromUtf8(isolate, #name, NewStringType::kNormal) \
+                    .ToLocalChecked())                                      \
+          .ToLocalChecked();                                                \
+  if (name##_v->IsFunction()) {                                             \
+    wrap->set_##name##_function(name##_v.As<Function>());                   \
+  }
+
+  SET_HOOK_FN(init);
+  SET_HOOK_FN(before);
+  SET_HOOK_FN(after);
+  SET_HOOK_FN(promiseResolve);
+#undef SET_HOOK_FN
+
+  async_wraps_.push_back(wrap);
+
+  Local<Object> obj = async_hooks_templ.Get(isolate)
+                          ->NewInstance(currentContext)
+                          .ToLocalChecked();
+  obj->SetInternalField(0, External::New(isolate, wrap));
+
+  return handle_scope.Escape(obj);
+}
+
+void AsyncHooks::ShellPromiseHook(PromiseHookType type, Local<Promise> promise,
+                                  Local<Value> parent) {
+  AsyncHooks* hooks = Shell::GetAsyncHooks();
+
+  HandleScope handle_scope(hooks->isolate_);
+
+  Local<Context> currentContext = hooks->isolate_->GetCurrentContext();
+
+  if (type == PromiseHookType::kInit) {
+    ++hooks->current_async_id;
+    Local<Integer> async_id =
+        Integer::New(hooks->isolate_, hooks->current_async_id);
+
+    promise->SetPrivate(currentContext,
+                        hooks->async_id_smb.Get(hooks->isolate_), async_id);
+    if (parent->IsPromise()) {
+      Local<Promise> parent_promise = parent.As<Promise>();
+      Local<Value> parent_async_id =
+          parent_promise
+              ->GetPrivate(hooks->isolate_->GetCurrentContext(),
+                           hooks->async_id_smb.Get(hooks->isolate_))
+              .ToLocalChecked();
+      promise->SetPrivate(currentContext,
+                          hooks->trigger_id_smb.Get(hooks->isolate_),
+                          parent_async_id);
+    } else {
+      CHECK(parent->IsUndefined());
+      Local<Integer> trigger_id = Integer::New(hooks->isolate_, 0);
+      promise->SetPrivate(currentContext,
+                          hooks->trigger_id_smb.Get(hooks->isolate_),
+                          trigger_id);
+    }
+  } else if (type == PromiseHookType::kBefore) {
+    AsyncContext ctx;
+    ctx.execution_async_id =
+        promise
+            ->GetPrivate(hooks->isolate_->GetCurrentContext(),
+                         hooks->async_id_smb.Get(hooks->isolate_))
+            .ToLocalChecked()
+            .As<Integer>()
+            ->Value();
+    ctx.trigger_async_id =
+        promise
+            ->GetPrivate(hooks->isolate_->GetCurrentContext(),
+                         hooks->trigger_id_smb.Get(hooks->isolate_))
+            .ToLocalChecked()
+            .As<Integer>()
+            ->Value();
+    hooks->asyncContexts.push(ctx);
+  } else if (type == PromiseHookType::kAfter) {
+    hooks->asyncContexts.pop();
+  }
+
+  for (AsyncHooksWrap* wrap : hooks->async_wraps_) {
+    PromiseHookDispatch(type, promise, parent, wrap, hooks);
+  }
+}
+
+void AsyncHooks::Initialize() {
+  HandleScope handle_scope(isolate_);
+
+  async_hook_ctor.Reset(isolate_, FunctionTemplate::New(isolate_));
+  async_hook_ctor.Get(isolate_)->SetClassName(
+      String::NewFromUtf8(isolate_, "AsyncHook", NewStringType::kNormal)
+          .ToLocalChecked());
+
+  async_hooks_templ.Reset(isolate_,
+                          async_hook_ctor.Get(isolate_)->InstanceTemplate());
+  async_hooks_templ.Get(isolate_)->SetInternalFieldCount(1);
+  async_hooks_templ.Get(isolate_)->Set(
+      String::NewFromUtf8(isolate_, "enable"),
+      FunctionTemplate::New(isolate_, EnableHook));
+  async_hooks_templ.Get(isolate_)->Set(
+      String::NewFromUtf8(isolate_, "disable"),
+      FunctionTemplate::New(isolate_, DisableHook));
+
+  async_id_smb.Reset(isolate_, Private::New(isolate_));
+  trigger_id_smb.Reset(isolate_, Private::New(isolate_));
+
+  isolate_->SetPromiseHook(ShellPromiseHook);
+}
+
+void AsyncHooks::Deinitialize() {
+  isolate_->SetPromiseHook(nullptr);
+  for (AsyncHooksWrap* wrap : async_wraps_) {
+    delete wrap;
+  }
+}
+
+void AsyncHooks::PromiseHookDispatch(PromiseHookType type,
+                                     Local<Promise> promise,
+                                     Local<Value> parent, AsyncHooksWrap* wrap,
+                                     AsyncHooks* hooks) {
+  if (!wrap->IsEnabled()) {
+    return;
+  }
+
+  HandleScope handle_scope(hooks->isolate_);
+
+  Local<Value> rcv = Undefined(hooks->isolate_);
+  Local<Value> async_id =
+      promise
+          ->GetPrivate(hooks->isolate_->GetCurrentContext(),
+                       hooks->async_id_smb.Get(hooks->isolate_))
+          .ToLocalChecked();
+  Local<Value> args[1] = {async_id};
+
+  // Sacrifice the brevity for readability and debugfulness
+  if (type == PromiseHookType::kInit) {
+    if (!wrap->init_function().IsEmpty()) {
+      Local<Value> initArgs[4] = {
+          async_id,
+          String::NewFromUtf8(hooks->isolate_, "PROMISE",
+                              NewStringType::kNormal)
+              .ToLocalChecked(),
+          promise
+              ->GetPrivate(hooks->isolate_->GetCurrentContext(),
+                           hooks->trigger_id_smb.Get(hooks->isolate_))
+              .ToLocalChecked(),
+          promise};
+      wrap->init_function()->Call(rcv, 4, initArgs);
+    }
+  } else if (type == PromiseHookType::kBefore) {
+    if (!wrap->before_function().IsEmpty()) {
+      wrap->before_function()->Call(rcv, 1, args);
+    }
+  } else if (type == PromiseHookType::kAfter) {
+    if (!wrap->after_function().IsEmpty()) {
+      wrap->after_function()->Call(rcv, 1, args);
+    }
+  } else if (type == PromiseHookType::kResolve) {
+    if (!wrap->promiseResolve_function().IsEmpty()) {
+      wrap->promiseResolve_function()->Call(rcv, 1, args);
+    }
+  }
+}
+
+}  // namespace v8

src/async-hooks-wrapper.h

@@ -0,0 +1,95 @@
+// Copyright 2018 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.
+
+#ifndef V8_ASYNC_HOOKS_WRAPPER_H_
+#define V8_ASYNC_HOOKS_WRAPPER_H_
+
+#include <stack>
+
+#include "include/v8.h"
+#include "src/objects.h"
+
+namespace v8 {
+
+typedef double async_id_t;
+
+struct AsyncContext {
+  async_id_t execution_async_id;
+  async_id_t trigger_async_id;
+};
+
+class AsyncHooksWrap {
+ public:
+  explicit AsyncHooksWrap(Isolate* isolate) {
+    enabled_ = false;
+    isolate_ = isolate;
+  }
+  void Enable();
+  void Disable();
+  bool IsEnabled() const { return enabled_; }
+
+  inline v8::Local<v8::Function> init_function() const;
+  inline void set_init_function(v8::Local<v8::Function> value);
+  inline v8::Local<v8::Function> before_function() const;
+  inline void set_before_function(v8::Local<v8::Function> value);
+  inline v8::Local<v8::Function> after_function() const;
+  inline void set_after_function(v8::Local<v8::Function> value);
+  inline v8::Local<v8::Function> promiseResolve_function() const;
+  inline void set_promiseResolve_function(v8::Local<v8::Function> value);
+
+ private:
+  Isolate* isolate_;
+
+  Persistent<v8::Function> init_function_;
+  Persistent<v8::Function> before_function_;
+  Persistent<v8::Function> after_function_;
+  Persistent<v8::Function> promiseResolve_function_;
+
+  bool enabled_;
+};
+
+class AsyncHooks {
+ public:
+  explicit AsyncHooks(Isolate* isolate) {
+    isolate_ = isolate;
+
+    AsyncContext ctx;
+    ctx.execution_async_id = 1;
+    ctx.trigger_async_id = 0;
+    asyncContexts.push(ctx);
+    current_async_id = 1;
+
+    Initialize();
+  }
+  ~AsyncHooks() { Deinitialize(); }
+
+  async_id_t GetExecutionAsyncId() const;
+  async_id_t GetTriggerAsyncId() const;
+
+  Local<Object> CreateHook(const v8::FunctionCallbackInfo<v8::Value>& args);
+
+ private:
+  std::vector<AsyncHooksWrap*> async_wraps_;
+  Isolate* isolate_;
+  Persistent<FunctionTemplate> async_hook_ctor;
+  Persistent<ObjectTemplate> async_hooks_templ;
+  Persistent<Private> async_id_smb;
+  Persistent<Private> trigger_id_smb;
+
+  void Initialize();
+  void Deinitialize();
+
+  static void ShellPromiseHook(PromiseHookType type, Local<Promise> promise,
+                               Local<Value> parent);
+  static void PromiseHookDispatch(PromiseHookType type, Local<Promise> promise,
+                                  Local<Value> parent, AsyncHooksWrap* wrap,
+                                  AsyncHooks* hooks);
+
+  std::stack<AsyncContext> asyncContexts;
+  async_id_t current_async_id;
+};
+
+}  // namespace v8
+
+#endif  // V8_ASYNC_HOOKS_WRAPPER_H_

src/d8.cc

@@ -469,6 +469,7 @@ base::LazyMutex Shell::workers_mutex_;
 bool Shell::allow_new_workers_ = true;
 std::vector<Worker*> Shell::workers_;
 std::vector<ExternalizedContents> Shell::externalized_contents_;
+AsyncHooks* Shell::async_hooks_wrapper_;
 base::LazyMutex Shell::isolate_status_lock_;
 std::map<v8::Isolate*, bool> Shell::isolate_status_;
 base::LazyMutex Shell::cached_code_mutex_;
@@ -1244,6 +1245,32 @@ void Shell::RealmSharedSet(Local<String> property,
   data->realm_shared_.Reset(isolate, value);
 }
 
+// async_hooks.createHook() registers functions to be called for different
+// lifetime events of each async operation.
+void Shell::AsyncHooksCreateHook(
+    const v8::FunctionCallbackInfo<v8::Value>& args) {
+  Local<Object> wrap = async_hooks_wrapper_->CreateHook(args);
+  args.GetReturnValue().Set(wrap);
+}
+
+// async_hooks.executionAsyncId() returns the asyncId of the current execution
+// context.
+void Shell::AsyncHooksExecutionAsyncId(
+    const v8::FunctionCallbackInfo<v8::Value>& args) {
+  Isolate* isolate = args.GetIsolate();
+  HandleScope handle_scope(isolate);
+  args.GetReturnValue().Set(
+      v8::Number::New(isolate, async_hooks_wrapper_->GetExecutionAsyncId()));
+}
+
+void Shell::AsyncHooksTriggerAsyncId(
+    const v8::FunctionCallbackInfo<v8::Value>& args) {
+  Isolate* isolate = args.GetIsolate();
+  HandleScope handle_scope(isolate);
+  args.GetReturnValue().Set(
+      v8::Number::New(isolate, async_hooks_wrapper_->GetTriggerAsyncId()));
+}
+
 void WriteToFile(FILE* file, const v8::FunctionCallbackInfo<v8::Value>& args) {
   for (int i = 0; i < args.Length(); i++) {
     HandleScope handle_scope(args.GetIsolate());
@@ -1857,6 +1884,26 @@ Local<ObjectTemplate> Shell::CreateGlobalTemplate(Isolate* isolate) {
           .ToLocalChecked(),
       os_templ);
 
+  if (i::FLAG_expose_async_hooks) {
+    Local<ObjectTemplate> async_hooks_templ = ObjectTemplate::New(isolate);
+    async_hooks_templ->Set(
+        String::NewFromUtf8(isolate, "createHook", NewStringType::kNormal)
+            .ToLocalChecked(),
+        FunctionTemplate::New(isolate, AsyncHooksCreateHook));
+    async_hooks_templ->Set(
+        String::NewFromUtf8(isolate, "executionAsyncId", NewStringType::kNormal)
+            .ToLocalChecked(),
+        FunctionTemplate::New(isolate, AsyncHooksExecutionAsyncId));
+    async_hooks_templ->Set(
+        String::NewFromUtf8(isolate, "triggerAsyncId", NewStringType::kNormal)
+            .ToLocalChecked(),
+        FunctionTemplate::New(isolate, AsyncHooksTriggerAsyncId));
+    global_template->Set(
+        String::NewFromUtf8(isolate, "async_hooks", NewStringType::kNormal)
+            .ToLocalChecked(),
+        async_hooks_templ);
+  }
+
   return global_template;
 }
 
@@ -1910,6 +1957,10 @@ void Shell::Initialize(Isolate* isolate) {
       v8::Isolate::kMessageError | v8::Isolate::kMessageWarning |
           v8::Isolate::kMessageInfo | v8::Isolate::kMessageDebug |
           v8::Isolate::kMessageLog);
+
+  if (i::FLAG_expose_async_hooks) {
+    async_hooks_wrapper_ = new AsyncHooks(isolate);
+  }
 }
 
 
@@ -2058,6 +2109,10 @@ void Shell::WriteLcovData(v8::Isolate* isolate, const char* file) {
 }
 
 void Shell::OnExit(v8::Isolate* isolate) {
+  if (i::FLAG_expose_async_hooks) {
+    delete async_hooks_wrapper_;  // This uses the isolate
+  }
+
   // Dump basic block profiling data.
   if (i::BasicBlockProfiler* profiler =
           reinterpret_cast<i::Isolate*>(isolate)->basic_block_profiler()) {

src/d8.h

@@ -13,6 +13,7 @@
 #include <vector>
 
 #include "src/allocation.h"
+#include "src/async-hooks-wrapper.h"
 #include "src/base/platform/time.h"
 #include "src/string-hasher.h"
 #include "src/utils.h"
@@ -400,6 +401,14 @@ class Shell : public i::AllStatic {
                              Local<Value> value,
                              const  PropertyCallbackInfo<void>& info);
 
+  static void AsyncHooksCreateHook(
+      const v8::FunctionCallbackInfo<v8::Value>& args);
+  static void AsyncHooksExecutionAsyncId(
+      const v8::FunctionCallbackInfo<v8::Value>& args);
+  static void AsyncHooksTriggerAsyncId(
+      const v8::FunctionCallbackInfo<v8::Value>& args);
+  static AsyncHooks* GetAsyncHooks() { return async_hooks_wrapper_; }
+
   static void Print(const v8::FunctionCallbackInfo<v8::Value>& args);
   static void PrintErr(const v8::FunctionCallbackInfo<v8::Value>& args);
   static void Write(const v8::FunctionCallbackInfo<v8::Value>& args);
@@ -494,6 +503,8 @@ class Shell : public i::AllStatic {
   static std::vector<Worker*> workers_;
   static std::vector<ExternalizedContents> externalized_contents_;
 
+  static AsyncHooks* async_hooks_wrapper_;
+
   static void WriteIgnitionDispatchCountersFile(v8::Isolate* isolate);
   // Append LCOV coverage data to file.
   static void WriteLcovData(v8::Isolate* isolate, const char* file);

src/flag-definitions.h

@@ -863,6 +863,7 @@ DEFINE_BOOL(enable_experimental_builtins, false,
             "enable new csa-based experimental builtins")
 DEFINE_BOOL(disallow_code_generation_from_strings, false,
             "disallow eval and friends")
+DEFINE_BOOL(expose_async_hooks, false, "expose async_hooks object")
 
 // builtins.cc
 DEFINE_BOOL(allow_unsafe_function_constructor, false,

test/mjsunit/allocation-site-info.js

@@ -258,6 +258,12 @@ assertKind(elements_kind.fast, obj);
 obj = newarraycase_list_smiobj(2);
 assertKind(elements_kind.fast, obj);
 
+// Perform a gc because without it the test below can experience an
+// allocation failure at an inconvenient point. Allocation mementos get
+// cleared on gc, and they can't deliver elements kind feedback when that
+// happens.
+gc();
+
 // Case: array constructor calls with out of date feedback.
 // The boilerplate should incorporate all feedback, but the input array
 // should be minimally transitioned based on immediate need.

test/mjsunit/async-hooks/api-methods.js

@@ -0,0 +1,68 @@
+// Copyright 2018 the V8 project authors. All rights reserved.
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+//       notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+//       copyright notice, this list of conditions and the following
+//       disclaimer in the documentation and/or other materials provided
+//       with the distribution.
+//     * Neither the name of Google Inc. nor the names of its
+//       contributors may be used to endorse or promote products derived
+//       from this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+// Flags: --expose-async-hooks
+
+// Check for correct API methods
+(function() {
+  assertTrue(async_hooks.hasOwnProperty('createHook'),
+    'Async hooks missing createHook method');
+  assertTrue(async_hooks.hasOwnProperty('executionAsyncId'),
+    'Async hooks missing executionAsyncId method');
+  assertTrue(async_hooks.hasOwnProperty('triggerAsyncId'),
+    'Async hooks missing triggerAsyncId method');
+
+  let ah = async_hooks.createHook({});
+  assertTrue(ah.hasOwnProperty('enable'), 'Async hooks missing enable method');
+  assertTrue(ah.hasOwnProperty('disable'),
+    'Async hooks missing disable method');
+})();
+
+// Check for correct enabling/disabling of async hooks
+(function() {
+  let storedPromise;
+  let ah = async_hooks.createHook({
+    init(asyncId, type, triggerAsyncId, resource) {
+      storedPromise = resource.promise || resource;
+    }
+  });
+  ah.enable();
+
+  let createdPromise = new Promise(function(resolve) {
+    resolve(42);
+  });
+  assertSame(storedPromise, createdPromise,
+    "Async hooks weren't enabled correctly");
+  ah.disable();
+  createdPromise = Promise.resolve(52);
+  assertNotSame(storedPromise, createdPromise,
+    "Async hooks weren't disabled correctly");
+  ah.enable();
+  createdPromise = Promise.resolve(62);
+  assertSame(storedPromise, createdPromise,
+    "Async hooks weren't enabled correctly");
+})();

test/mjsunit/async-hooks/async-await-tree.js

@@ -0,0 +1,74 @@
+// Copyright 2018 the V8 project authors. All rights reserved.
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+//       notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+//       copyright notice, this list of conditions and the following
+//       disclaimer in the documentation and/or other materials provided
+//       with the distribution.
+//     * Neither the name of Google Inc. nor the names of its
+//       contributors may be used to endorse or promote products derived
+//       from this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+// Flags: --expose-async-hooks
+
+// Check for async/await asyncIds relation
+(function() {
+  let asyncIds = [], triggerIds = [];
+  let ah = async_hooks.createHook({
+    init(asyncId, type, triggerAsyncId, resource) {
+      if (type !== 'PROMISE') {
+        return;
+      }
+      asyncIds.push(asyncId);
+      triggerIds.push(triggerAsyncId);
+    },
+  });
+  ah.enable();
+
+  // Simplified version of Node.js util.promisify(setTimeout)
+  function sleep(callback, timeout) {
+    const promise = new Promise(function(resolve, reject) {
+      try {
+        setTimeout((err, ...values) => {
+          if (err) {
+            reject(err);
+          } else {
+            resolve(values[0]);
+          }
+        }, timeout);
+      } catch (err) {
+        reject(err);
+      }
+    });
+    return promise;
+  }
+
+  async function foo() {
+    await sleep(10);
+  }
+
+  foo().then(function() {
+    assertEquals(asyncIds.length, 6);
+    assertEquals(triggerIds.length, 6);
+    assertEquals(triggerIds[2], asyncIds[0]);
+    assertEquals(triggerIds[3], asyncIds[2]);
+    assertEquals(triggerIds[4], asyncIds[0]);
+    assertEquals(triggerIds[5], asyncIds[1]);
+  });
+})();

test/mjsunit/async-hooks/chained-promises.js

@@ -0,0 +1,48 @@
+// Copyright 2018 the V8 project authors. All rights reserved.
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+//       notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+//       copyright notice, this list of conditions and the following
+//       disclaimer in the documentation and/or other materials provided
+//       with the distribution.
+//     * Neither the name of Google Inc. nor the names of its
+//       contributors may be used to endorse or promote products derived
+//       from this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+// Flags: --expose-async-hooks
+
+// Check for chained promises asyncIds relation
+(function() {
+  let asyncIds = [], triggerIds = [];
+  let ah = async_hooks.createHook({
+    init(asyncId, type, triggerAsyncId, resource) {
+      asyncIds.push(asyncId);
+      triggerIds.push(triggerAsyncId);
+    },
+  });
+  ah.enable();
+  let createdPromise = new Promise(function(resolve) {
+    resolve(42);
+  }).then(function() {
+    assertEquals(asyncIds.length, 2, 'Exactly 2 promises should be inited');
+    assertEquals(triggerIds.length, 2, 'Exactly 2 promises should be inited');
+    assertEquals(triggerIds[1], asyncIds[0],
+      "Parent promise asyncId doesn't correspond to child triggerAsyncId");
+  });
+})();

test/mjsunit/async-hooks/execution-order.js

@@ -0,0 +1,65 @@
+// Copyright 2018 the V8 project authors. All rights reserved.
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+//       notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+//       copyright notice, this list of conditions and the following
+//       disclaimer in the documentation and/or other materials provided
+//       with the distribution.
+//     * Neither the name of Google Inc. nor the names of its
+//       contributors may be used to endorse or promote products derived
+//       from this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+// Flags: --expose-async-hooks
+
+// Check for correct execution of available hooks and asyncIds
+(function() {
+  let inited = false, resolved = false, before = false, after = false;
+  let storedAsyncId;
+  let ah = async_hooks.createHook({
+    init(asyncId, type, triggerAsyncId, resource) {
+      if (type !== 'PROMISE') {
+        return;
+      }
+      inited = true;
+      storedAsyncId = asyncId;
+    },
+    promiseResolve(asyncId) {
+      assertEquals(asyncId, storedAsyncId, 'AsyncId mismatch in resolve hook');
+      resolved = true;
+    },
+    before(asyncId) {
+      assertEquals(asyncId, storedAsyncId, 'AsyncId mismatch in before hook');
+      before = true;
+    },
+    after(asyncId) {
+      assertEquals(asyncId, storedAsyncId, 'AsyncId mismatch in after hook');
+      after = true;
+    },
+  });
+  ah.enable();
+
+  new Promise(function(resolve) {
+    resolve(42);
+  }).then(function() {
+    assertTrue(inited, "Didn't call init hook");
+    assertTrue(resolved, "Didn't call resolve hook");
+    assertTrue(before, "Didn't call before hook before the callback");
+    assertFalse(after, "Called after hook before the callback");
+  });
+})();

test/mjsunit/async-hooks/promises-async-await.js

@@ -0,0 +1,70 @@
+// Copyright 2018 the V8 project authors. All rights reserved.
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+//       notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+//       copyright notice, this list of conditions and the following
+//       disclaimer in the documentation and/or other materials provided
+//       with the distribution.
+//     * Neither the name of Google Inc. nor the names of its
+//       contributors may be used to endorse or promote products derived
+//       from this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+// Flags: --expose-async-hooks
+
+// Check for executionAsyncId/triggerAsyncId when chained promises and
+// async/await are combined
+(function() {
+  let p;
+  let outerExecutionAsyncId = -1, outerTriggerAsyncId = -1;
+
+  function inIrrelevantContext(resolve) {
+    resolve(42);
+  }
+
+  function inContext1(foo) {
+    foo();
+  }
+
+  function inContext2(foo) {
+    foo();
+  }
+
+  outerExecutionAsyncId = async_hooks.executionAsyncId();
+  outerTriggerAsyncId = async_hooks.triggerAsyncId();
+
+  inContext1(() => {
+    p = new Promise(resolve => {
+      assertEquals(outerExecutionAsyncId, async_hooks.executionAsyncId());
+      assertEquals(outerTriggerAsyncId, async_hooks.triggerAsyncId());
+      inIrrelevantContext(resolve);
+    }).then(() => {
+      assertNotEquals(outerExecutionAsyncId, async_hooks.executionAsyncId());
+      assertNotEquals(outerTriggerAsyncId, async_hooks.triggerAsyncId());
+    });
+  });
+
+  inContext2(async () => {
+    assertEquals(outerExecutionAsyncId, async_hooks.executionAsyncId());
+    assertEquals(outerTriggerAsyncId, async_hooks.triggerAsyncId());
+    await p;
+    assertNotEquals(outerExecutionAsyncId, async_hooks.executionAsyncId());
+    assertNotEquals(outerTriggerAsyncId, async_hooks.triggerAsyncId());
+  });
+
+})();

test/mjsunit/es8/async-await-interleaved.js

@@ -0,0 +1,61 @@
+// Copyright 2018 the V8 project authors. All rights reserved.
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+//       notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+//       copyright notice, this list of conditions and the following
+//       disclaimer in the documentation and/or other materials provided
+//       with the distribution.
+//     * Neither the name of Google Inc. nor the names of its
+//       contributors may be used to endorse or promote products derived
+//       from this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+// Check for correct interleaving of Promises and async/await
+(function () {
+  const iterations = 10;
+  let promiseCounter = iterations;
+  let awaitCounter = 0;
+
+  async function check(v) {
+    awaitCounter = v;
+    // The following checks ensure that "await" takes 3 ticks on the
+    // microtask queue. Note: this will change in the future
+    if (awaitCounter === 0) {
+      assertEquals(iterations, promiseCounter);
+    } else if (awaitCounter <= Math.floor(iterations / 3)) {
+      assertEquals(iterations - awaitCounter * 3, promiseCounter);
+    } else {
+      assertEquals(0, promiseCounter);
+    }
+  }
+
+  async function f() {
+    for (let i = 0; i < iterations; i++) {
+      await check(i);
+    }
+    return 0;
+  }
+
+  function countdown(v) {
+    promiseCounter = v;
+    if (v > 0) Promise.resolve(v - 1).then(countdown);
+  }
+
+  countdown(iterations);
+  f();
+})();