Reland "Implement v8::internal::MicrotaskQueue::EnqueueMicrotask"

This is a reland of 836773c0

Original change's description:
> Implement v8::internal::MicrotaskQueue::EnqueueMicrotask
> 
> This adds `queue` and `pending_microtask_count` as members of
> v8::internal::MicrotaskQueue, and implements its EnqueueMicrotask.
> The implementation itself is similar to Isolate::EnqueueMicrotask.
> 
> Bug: v8:8124
> Change-Id: Idb5c50b2add96b72cbe9e36aeec7cb568072f0cb
> Reviewed-on: https://chromium-review.googlesource.com/1205430
> Commit-Queue: Taiju Tsuiki <tzik@chromium.org>
> Reviewed-by: Adam Klein <adamk@chromium.org>
> Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#55884}

Bug: v8:8124
Change-Id: Ibd32aec28c8fd9eab88904e62ba97a715295765d
Reviewed-on: https://chromium-review.googlesource.com/1226577Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Reviewed-by: Adam Klein <adamk@chromium.org>
Commit-Queue: Taiju Tsuiki <tzik@chromium.org>
Cr-Commit-Position: refs/heads/master@{#55924}

src/heap/factory.cc

@@ -27,6 +27,7 @@
 #include "src/objects/js-regexp-inl.h"
 #include "src/objects/literal-objects-inl.h"
 #include "src/objects/microtask-inl.h"
+#include "src/objects/microtask-queue-inl.h"
 #include "src/objects/module-inl.h"
 #include "src/objects/promise-inl.h"
 #include "src/objects/scope-info.h"
@@ -1621,6 +1622,16 @@ Handle<PromiseResolveThenableJobTask> Factory::NewPromiseResolveThenableJobTask(
   return microtask;
 }
 
+Handle<MicrotaskQueue> Factory::NewMicrotaskQueue() {
+  // MicrotaskQueue should be TENURED, as it outlives Context, and is mostly
+  // as long-living as Context is.
+  Handle<MicrotaskQueue> microtask_queue =
+      Handle<MicrotaskQueue>::cast(NewStruct(MICROTASK_QUEUE_TYPE, TENURED));
+  microtask_queue->set_queue(*empty_fixed_array());
+  microtask_queue->set_pending_microtask_count(0);
+  return microtask_queue;
+}
+
 Handle<Foreign> Factory::NewForeign(Address addr, PretenureFlag pretenure) {
   // Statically ensure that it is safe to allocate foreigns in paged spaces.
   STATIC_ASSERT(Foreign::kSize <= kMaxRegularHeapObjectSize);

src/heap/factory.h

@@ -439,6 +439,8 @@ class V8_EXPORT_PRIVATE Factory {
       Handle<JSPromise> promise_to_resolve, Handle<JSReceiver> then,
       Handle<JSReceiver> thenable, Handle<Context> context);
 
+  Handle<MicrotaskQueue> NewMicrotaskQueue();
+
   // Foreign objects are pretenured when allocated by the bootstrapper.
   Handle<Foreign> NewForeign(Address addr,
                              PretenureFlag pretenure = NOT_TENURED);

src/objects-debug.cc

@@ -1284,7 +1284,12 @@ void PromiseReactionJobTask::PromiseReactionJobTaskVerify(Isolate* isolate) {
         promise_or_capability()->IsPromiseCapability());
 }
 
-void MicrotaskQueue::MicrotaskQueueVerify(Isolate* isolate) { UNIMPLEMENTED(); }
+void MicrotaskQueue::MicrotaskQueueVerify(Isolate* isolate) {
+  CHECK(IsMicrotaskQueue());
+  VerifyHeapPointer(isolate, queue());
+  VerifySmiField(kPendingMicrotaskCountOffset);
+  CHECK_LE(pending_microtask_count(), queue()->length());
+}
 
 void PromiseFulfillReactionJobTask::PromiseFulfillReactionJobTaskVerify(
     Isolate* isolate) {

src/objects-printer.cc

@@ -2198,7 +2198,10 @@ void UncompiledDataWithPreParsedScope::UncompiledDataWithPreParsedScopePrint(
 }
 
 void MicrotaskQueue::MicrotaskQueuePrint(std::ostream& os) {  // NOLINT
-  UNIMPLEMENTED();
+  HeapObject::PrintHeader(os, "MicrotaskQueue");
+  os << "\n - pending_microtask_count: " << pending_microtask_count();
+  os << "\n - queue: " << Brief(queue());
+  os << "\n";
 }
 
 void InterpreterData::InterpreterDataPrint(std::ostream& os) {  // NOLINT

src/objects/microtask-queue-inl.h

@@ -16,6 +16,9 @@ namespace v8 {
 namespace internal {
 
 CAST_ACCESSOR(MicrotaskQueue)
+ACCESSORS(MicrotaskQueue, queue, FixedArray, kQueueOffset)
+SMI_ACCESSORS(MicrotaskQueue, pending_microtask_count,
+              kPendingMicrotaskCountOffset)
 
 }  // namespace internal
 }  // namespace v8

src/objects/microtask-queue.cc

@@ -9,10 +9,26 @@
 namespace v8 {
 namespace internal {
 
+// DCHECK requires this for taking the reference of it.
+constexpr int MicrotaskQueue::kMinimumQueueCapacity;
+
 // static
-void MicrotaskQueue::EnqueueMicrotask(Handle<MicrotaskQueue> microtask_queue,
+void MicrotaskQueue::EnqueueMicrotask(Isolate* isolate,
+                                      Handle<MicrotaskQueue> microtask_queue,
                                       Handle<Microtask> microtask) {
-  UNIMPLEMENTED();
+  Handle<FixedArray> queue(microtask_queue->queue(), isolate);
+  int num_tasks = microtask_queue->pending_microtask_count();
+  DCHECK_LE(num_tasks, queue->length());
+  if (num_tasks == queue->length()) {
+    queue = isolate->factory()->CopyFixedArrayAndGrow(
+        queue, std::max(num_tasks, kMinimumQueueCapacity));
+    microtask_queue->set_queue(*queue);
+  }
+  DCHECK_LE(kMinimumQueueCapacity, queue->length());
+  DCHECK_LT(num_tasks, queue->length());
+  DCHECK(queue->get(num_tasks)->IsUndefined(isolate));
+  queue->set(num_tasks, *microtask);
+  microtask_queue->set_pending_microtask_count(num_tasks + 1);
 }
 
 // static

src/objects/microtask-queue.h

@@ -14,17 +14,34 @@
 namespace v8 {
 namespace internal {
 
-class MicrotaskQueue : public Struct {
+class V8_EXPORT_PRIVATE MicrotaskQueue : public Struct {
  public:
   DECL_CAST(MicrotaskQueue)
   DECL_VERIFIER(MicrotaskQueue)
   DECL_PRINTER(MicrotaskQueue)
 
-  static void EnqueueMicrotask(Handle<MicrotaskQueue> microtask_queue,
+  // A FixedArray that the queued microtasks are stored.
+  // The first |pending_microtask_count| slots contains Microtask instance
+  // for each, and followings are undefined_value if any.
+  DECL_ACCESSORS(queue, FixedArray)
+
+  // The number of microtasks queued in |queue|. This must be less or equal to
+  // the length of |queue|.
+  DECL_INT_ACCESSORS(pending_microtask_count)
+
+  // Enqueues |microtask| to |microtask_queue|.
+  static void EnqueueMicrotask(Isolate* isolate,
+                               Handle<MicrotaskQueue> microtask_queue,
                                Handle<Microtask> microtask);
+
+  // Runs all enqueued microtasks.
   static void RunMicrotasks(Handle<MicrotaskQueue> microtask_queue);
 
-  static const int kSize = HeapObject::kHeaderSize;
+  static constexpr int kMinimumQueueCapacity = 8;
+
+  static const int kQueueOffset = HeapObject::kHeaderSize;
+  static const int kPendingMicrotaskCountOffset = kQueueOffset + kPointerSize;
+  static const int kSize = kPendingMicrotaskCountOffset + kPointerSize;
 
  private:
   DISALLOW_IMPLICIT_CONSTRUCTORS(MicrotaskQueue);

test/unittests/BUILD.gn

@@ -183,6 +183,7 @@ v8_source_set("unittests_sources") {
     "libplatform/worker-thread-unittest.cc",
     "locked-queue-unittest.cc",
     "object-unittest.cc",
+    "objects/microtask-queue-unittest.cc",
     "parser/ast-value-unittest.cc",
     "parser/preparser-unittest.cc",
     "register-configuration-unittest.cc",

test/unittests/objects/microtask-queue-unittest.cc

+// 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/objects/microtask-queue.h"
+
+#include "test/unittests/test-utils.h"
+
+namespace v8 {
+namespace internal {
+
+void NoopCallback(void*) {}
+
+class MicrotaskQueueTest : public TestWithIsolate {
+ public:
+  Handle<Microtask> NewMicrotask() {
+    MicrotaskCallback callback = &NoopCallback;
+    void* data = nullptr;
+    return factory()->NewCallbackTask(
+        factory()->NewForeign(reinterpret_cast<Address>(callback)),
+        factory()->NewForeign(reinterpret_cast<Address>(data)));
+  }
+};
+
+TEST_F(MicrotaskQueueTest, EnqueueMicrotask) {
+  Handle<MicrotaskQueue> microtask_queue = factory()->NewMicrotaskQueue();
+  Handle<Microtask> microtask = NewMicrotask();
+
+  EXPECT_EQ(0, microtask_queue->pending_microtask_count());
+  MicrotaskQueue::EnqueueMicrotask(isolate(), microtask_queue, microtask);
+  EXPECT_EQ(1, microtask_queue->pending_microtask_count());
+  ASSERT_LE(1, microtask_queue->queue()->length());
+  EXPECT_EQ(*microtask, microtask_queue->queue()->get(0));
+
+  std::vector<Handle<Microtask>> microtasks;
+  microtasks.push_back(microtask);
+
+  // Queue microtasks until the reallocation.
+  int queue_capacity = microtask_queue->queue()->length();
+  for (int i = 0; i < queue_capacity; ++i) {
+    microtask = NewMicrotask();
+    MicrotaskQueue::EnqueueMicrotask(isolate(), microtask_queue, microtask);
+    microtasks.push_back(microtask);
+  }
+
+  int num_tasks = static_cast<int>(microtasks.size());
+  EXPECT_EQ(num_tasks, microtask_queue->pending_microtask_count());
+  ASSERT_LE(num_tasks, microtask_queue->queue()->length());
+  for (int i = 0; i < num_tasks; ++i) {
+    EXPECT_EQ(*microtasks[i], microtask_queue->queue()->get(i));
+  }
+}
+
+}  // namespace internal
+}  // namespace v8