DXR is a code search and navigation tool aimed at making sense of large projects. It supports full-text and regex searches as well as structural queries.

Header

Mercurial (b6d82b1a6b02)

VCS Links

Line Code
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 647 648 649 650 651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 666 667 668 669 670 671 672 673 674 675 676 677 678 679 680 681 682 683 684 685 686 687 688 689 690 691 692 693 694 695 696 697 698 699 700 701 702 703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720 721 722 723 724 725 726 727 728 729 730 731 732 733 734 735 736 737 738 739 740 741 742 743 744 745 746 747 748 749 750 751 752 753 754 755 756 757 758 759 760 761 762 763 764 765 766 767 768 769 770
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#include "mozilla/CycleCollectedJSContext.h"
#include <algorithm>
#include "mozilla/ArrayUtils.h"
#include "mozilla/AsyncEventDispatcher.h"
#include "mozilla/AutoRestore.h"
#include "mozilla/CycleCollectedJSRuntime.h"
#include "mozilla/EventStateManager.h"
#include "mozilla/Move.h"
#include "mozilla/MemoryReporting.h"
#include "mozilla/Sprintf.h"
#include "mozilla/StaticPrefs_dom.h"
#include "mozilla/Telemetry.h"
#include "mozilla/TimelineConsumers.h"
#include "mozilla/TimelineMarker.h"
#include "mozilla/Unused.h"
#include "mozilla/DebuggerOnGCRunnable.h"
#include "mozilla/dom/DOMJSClass.h"
#include "mozilla/dom/DOMException.h"
#include "mozilla/dom/ProfileTimelineMarkerBinding.h"
#include "mozilla/dom/PromiseBinding.h"
#include "mozilla/dom/PromiseDebugging.h"
#include "mozilla/dom/PromiseRejectionEvent.h"
#include "mozilla/dom/PromiseRejectionEventBinding.h"
#include "mozilla/dom/ScriptSettings.h"
#include "jsapi.h"
#include "js/Debug.h"
#include "js/GCAPI.h"
#include "js/Utility.h"
#include "nsContentUtils.h"
#include "nsCycleCollectionNoteRootCallback.h"
#include "nsCycleCollectionParticipant.h"
#include "nsCycleCollector.h"
#include "nsDOMJSUtils.h"
#include "nsDOMMutationObserver.h"
#include "nsJSUtils.h"
#include "nsPIDOMWindow.h"
#include "nsWrapperCache.h"
#include "nsStringBuffer.h"

#include "nsThread.h"
#include "nsThreadUtils.h"
#include "xpcpublic.h"

using namespace mozilla;
using namespace mozilla::dom;

namespace mozilla {

CycleCollectedJSContext::CycleCollectedJSContext()
    : mIsPrimaryContext(true),
      mRuntime(nullptr),
      mJSContext(nullptr),
      mDoingStableStates(false),
      mTargetedMicroTaskRecursionDepth(0),
      mMicroTaskLevel(0),
      mDebuggerRecursionDepth(0),
      mMicroTaskRecursionDepth(0) {
  MOZ_COUNT_CTOR(CycleCollectedJSContext);

  // Reinitialize PerThreadAtomCache because dom/bindings/Codegen.py compares
  // against zero rather than JSID_VOID to detect uninitialized jsid members.
  memset(static_cast<PerThreadAtomCache*>(this), 0, sizeof(PerThreadAtomCache));

  nsCOMPtr<nsIThread> thread = do_GetCurrentThread();
  mOwningThread = thread.forget().downcast<nsThread>().take();
  MOZ_RELEASE_ASSERT(mOwningThread);
}

CycleCollectedJSContext::~CycleCollectedJSContext() {
  MOZ_COUNT_DTOR(CycleCollectedJSContext);
  // If the allocation failed, here we are.
  if (!mJSContext) {
    return;
  }

  JS_SetContextPrivate(mJSContext, nullptr);

  mRuntime->RemoveContext(this);

  if (mIsPrimaryContext) {
    mRuntime->Shutdown(mJSContext);
  }

  // Last chance to process any events.
  CleanupIDBTransactions(mBaseRecursionDepth);
  MOZ_ASSERT(mPendingIDBTransactions.IsEmpty());

  ProcessStableStateQueue();
  MOZ_ASSERT(mStableStateEvents.IsEmpty());

  // Clear mPendingException first, since it might be cycle collected.
  mPendingException = nullptr;

  MOZ_ASSERT(mDebuggerMicroTaskQueue.empty());
  MOZ_ASSERT(mPendingMicroTaskRunnables.empty());

  mUncaughtRejections.reset();
  mConsumedRejections.reset();

  mAboutToBeNotifiedRejectedPromises.Clear();
  mPendingUnhandledRejections.Clear();

  JS_DestroyContext(mJSContext);
  mJSContext = nullptr;

  if (mIsPrimaryContext) {
    nsCycleCollector_forgetJSContext();
  } else {
    nsCycleCollector_forgetNonPrimaryContext();
  }

  mozilla::dom::DestroyScriptSettings();

  mOwningThread->SetScriptObserver(nullptr);
  NS_RELEASE(mOwningThread);

  if (mIsPrimaryContext) {
    delete mRuntime;
  }
  mRuntime = nullptr;
}

void CycleCollectedJSContext::InitializeCommon() {
  mRuntime->AddContext(this);

  mOwningThread->SetScriptObserver(this);
  // The main thread has a base recursion depth of 0, workers of 1.
  mBaseRecursionDepth = RecursionDepth();

  NS_GetCurrentThread()->SetCanInvokeJS(true);

  JS::SetJobQueue(mJSContext, this);
  JS::SetPromiseRejectionTrackerCallback(mJSContext,
                                         PromiseRejectionTrackerCallback, this);
  mUncaughtRejections.init(mJSContext,
                           JS::GCVector<JSObject*, 0, js::SystemAllocPolicy>(
                               js::SystemAllocPolicy()));
  mConsumedRejections.init(mJSContext,
                           JS::GCVector<JSObject*, 0, js::SystemAllocPolicy>(
                               js::SystemAllocPolicy()));

  // Cast to PerThreadAtomCache for dom::GetAtomCache(JSContext*).
  JS_SetContextPrivate(mJSContext, static_cast<PerThreadAtomCache*>(this));
}

nsresult CycleCollectedJSContext::Initialize(JSRuntime* aParentRuntime,
                                             uint32_t aMaxBytes,
                                             uint32_t aMaxNurseryBytes) {
  MOZ_ASSERT(!mJSContext);

  mozilla::dom::InitScriptSettings();
  mJSContext = JS_NewContext(aMaxBytes, aMaxNurseryBytes, aParentRuntime);
  if (!mJSContext) {
    return NS_ERROR_OUT_OF_MEMORY;
  }

  mRuntime = CreateRuntime(mJSContext);

  InitializeCommon();

  nsCycleCollector_registerJSContext(this);

  return NS_OK;
}

nsresult CycleCollectedJSContext::InitializeNonPrimary(
    CycleCollectedJSContext* aPrimaryContext) {
  MOZ_ASSERT(!mJSContext);

  mIsPrimaryContext = false;

  mozilla::dom::InitScriptSettings();
  mJSContext = JS_NewCooperativeContext(aPrimaryContext->mJSContext);
  if (!mJSContext) {
    return NS_ERROR_OUT_OF_MEMORY;
  }

  mRuntime = aPrimaryContext->mRuntime;

  InitializeCommon();

  nsCycleCollector_registerNonPrimaryContext(this);

  return NS_OK;
}

/* static */
CycleCollectedJSContext* CycleCollectedJSContext::GetFor(JSContext* aCx) {
  // Cast from void* matching JS_SetContextPrivate.
  auto atomCache = static_cast<PerThreadAtomCache*>(JS_GetContextPrivate(aCx));
  // Down cast.
  return static_cast<CycleCollectedJSContext*>(atomCache);
}

size_t CycleCollectedJSContext::SizeOfExcludingThis(
    MallocSizeOf aMallocSizeOf) const {
  return 0;
}

class PromiseJobRunnable final : public MicroTaskRunnable {
 public:
  PromiseJobRunnable(JS::HandleObject aPromise, JS::HandleObject aCallback,
                     JS::HandleObject aCallbackGlobal,
                     JS::HandleObject aAllocationSite,
                     nsIGlobalObject* aIncumbentGlobal)
      : mCallback(new PromiseJobCallback(aCallback, aCallbackGlobal,
                                         aAllocationSite, aIncumbentGlobal)),
        mPropagateUserInputEventHandling(false) {
    MOZ_ASSERT(js::IsFunctionObject(aCallback));

    if (aPromise) {
      JS::PromiseUserInputEventHandlingState state =
          JS::GetPromiseUserInputEventHandlingState(aPromise);
      mPropagateUserInputEventHandling =
          state ==
          JS::PromiseUserInputEventHandlingState::HadUserInteractionAtCreation;
    }
  }

  virtual ~PromiseJobRunnable() {}

 protected:
  MOZ_CAN_RUN_SCRIPT
  virtual void Run(AutoSlowOperation& aAso) override {
    JSObject* callback = mCallback->CallbackPreserveColor();
    nsIGlobalObject* global = callback ? xpc::NativeGlobal(callback) : nullptr;
    if (global && !global->IsDying()) {
      // Propagate the user input event handling bit if needed.
      nsCOMPtr<nsPIDOMWindowInner> win = do_QueryInterface(global);
      RefPtr<Document> doc;
      if (win) {
        doc = win->GetExtantDoc();
      }
      AutoHandlingUserInputStatePusher userInpStatePusher(
          mPropagateUserInputEventHandling);

      mCallback->Call("promise callback");
      aAso.CheckForInterrupt();
    }
    // Now that mCallback is no longer needed, clear any pointers it contains to
    // JS GC things. This removes any storebuffer entries associated with those
    // pointers, which can cause problems by taking up memory and by triggering
    // minor GCs. This otherwise would not happen until the next minor GC or
    // cycle collection.
    mCallback->Reset();
  }

  virtual bool Suppressed() override {
    nsIGlobalObject* global =
        xpc::NativeGlobal(mCallback->CallbackPreserveColor());
    return global && global->IsInSyncOperation();
  }

 private:
  const RefPtr<PromiseJobCallback> mCallback;
  bool mPropagateUserInputEventHandling;
};

JSObject* CycleCollectedJSContext::getIncumbentGlobal(JSContext* aCx) {
  nsIGlobalObject* global = mozilla::dom::GetIncumbentGlobal();
  if (global) {
    return global->GetGlobalJSObject();
  }
  return nullptr;
}

bool CycleCollectedJSContext::enqueuePromiseJob(
    JSContext* aCx, JS::HandleObject aPromise, JS::HandleObject aJob,
    JS::HandleObject aAllocationSite, JS::HandleObject aIncumbentGlobal) {
  MOZ_ASSERT(aCx == Context());
  MOZ_ASSERT(Get() == this);

  nsIGlobalObject* global = nullptr;
  if (aIncumbentGlobal) {
    global = xpc::NativeGlobal(aIncumbentGlobal);
  }
  JS::RootedObject jobGlobal(aCx, JS::CurrentGlobalOrNull(aCx));
  RefPtr<PromiseJobRunnable> runnable = new PromiseJobRunnable(
      aPromise, aJob, jobGlobal, aAllocationSite, global);
  DispatchToMicroTask(runnable.forget());
  return true;
}

// Used only by the SpiderMonkey Debugger API, and even then only via
// JS::AutoDebuggerJobQueueInterruption, to ensure that the debuggee's queue is
// not affected; see comments in js/public/Promise.h.
void CycleCollectedJSContext::runJobs(JSContext* aCx) {
  MOZ_ASSERT(aCx == Context());
  MOZ_ASSERT(Get() == this);
  PerformMicroTaskCheckPoint();
}

bool CycleCollectedJSContext::empty() const {
  // This is our override of JS::JobQueue::empty. Since that interface is only
  // concerned with the ordinary microtask queue, not the debugger microtask
  // queue, we only report on the former.
  return mPendingMicroTaskRunnables.empty();
}

// Preserve a debuggee's microtask queue while it is interrupted by the
// debugger. See the comments for JS::AutoDebuggerJobQueueInterruption.
class CycleCollectedJSContext::SavedMicroTaskQueue
    : public JS::JobQueue::SavedJobQueue {
 public:
  explicit SavedMicroTaskQueue(CycleCollectedJSContext* ccjs) : ccjs(ccjs) {
    ccjs->mDebuggerRecursionDepth++;
    ccjs->mPendingMicroTaskRunnables.swap(mQueue);
  }

  ~SavedMicroTaskQueue() {
    MOZ_RELEASE_ASSERT(ccjs->mPendingMicroTaskRunnables.empty());
    MOZ_RELEASE_ASSERT(ccjs->mDebuggerRecursionDepth);
    ccjs->mDebuggerRecursionDepth--;
    ccjs->mPendingMicroTaskRunnables.swap(mQueue);
  }

 private:
  CycleCollectedJSContext* ccjs;
  std::queue<RefPtr<MicroTaskRunnable>> mQueue;
};

js::UniquePtr<JS::JobQueue::SavedJobQueue>
CycleCollectedJSContext::saveJobQueue(JSContext* cx) {
  auto saved = js::MakeUnique<SavedMicroTaskQueue>(this);
  if (!saved) {
    // When MakeUnique's allocation fails, the SavedMicroTaskQueue constructor
    // is never called, so mPendingMicroTaskRunnables is still initialized.
    JS_ReportOutOfMemory(cx);
    return nullptr;
  }

  return saved;
}

/* static */
void CycleCollectedJSContext::PromiseRejectionTrackerCallback(
    JSContext* aCx, bool aMutedErrors, JS::HandleObject aPromise,
    JS::PromiseRejectionHandlingState state, void* aData) {
  CycleCollectedJSContext* self = static_cast<CycleCollectedJSContext*>(aData);

  MOZ_ASSERT(aCx == self->Context());
  MOZ_ASSERT(Get() == self);

  // TODO: Bug 1549351 - Promise rejection event should not be sent for
  // cross-origin scripts

  PromiseArray& aboutToBeNotified = self->mAboutToBeNotifiedRejectedPromises;
  PromiseHashtable& unhandled = self->mPendingUnhandledRejections;
  uint64_t promiseID = JS::GetPromiseID(aPromise);

  if (state == JS::PromiseRejectionHandlingState::Unhandled) {
    PromiseDebugging::AddUncaughtRejection(aPromise);
    if (mozilla::StaticPrefs::dom_promise_rejection_events_enabled() &&
        !aMutedErrors) {
      RefPtr<Promise> promise =
          Promise::CreateFromExisting(xpc::NativeGlobal(aPromise), aPromise);
      aboutToBeNotified.AppendElement(promise);
      unhandled.Put(promiseID, promise);
    }
  } else {
    PromiseDebugging::AddConsumedRejection(aPromise);
    if (mozilla::StaticPrefs::dom_promise_rejection_events_enabled() &&
        !aMutedErrors) {
      for (size_t i = 0; i < aboutToBeNotified.Length(); i++) {
        if (aboutToBeNotified[i] &&
            aboutToBeNotified[i]->PromiseObj() == aPromise) {
          // To avoid large amounts of memmoves, we don't shrink the vector
          // here. Instead, we filter out nullptrs when iterating over the
          // vector later.
          aboutToBeNotified[i] = nullptr;
          DebugOnly<bool> isFound = unhandled.Remove(promiseID);
          MOZ_ASSERT(isFound);
          return;
        }
      }
      RefPtr<Promise> promise;
      unhandled.Remove(promiseID, getter_AddRefs(promise));
      if (!promise) {
        nsIGlobalObject* global = xpc::NativeGlobal(aPromise);
        if (nsCOMPtr<EventTarget> owner = do_QueryInterface(global)) {
          RootedDictionary<PromiseRejectionEventInit> init(aCx);
          init.mPromise = Promise::CreateFromExisting(global, aPromise);
          init.mReason = JS::GetPromiseResult(aPromise);

          RefPtr<PromiseRejectionEvent> event =
              PromiseRejectionEvent::Constructor(
                  owner, NS_LITERAL_STRING("rejectionhandled"), init);

          RefPtr<AsyncEventDispatcher> asyncDispatcher =
              new AsyncEventDispatcher(owner, event);
          asyncDispatcher->PostDOMEvent();
        }
      }
    }
  }
}

already_AddRefed<Exception> CycleCollectedJSContext::GetPendingException()
    const {
  MOZ_ASSERT(mJSContext);

  nsCOMPtr<Exception> out = mPendingException;
  return out.forget();
}

void CycleCollectedJSContext::SetPendingException(Exception* aException) {
  MOZ_ASSERT(mJSContext);
  mPendingException = aException;
}

std::queue<RefPtr<MicroTaskRunnable>>&
CycleCollectedJSContext::GetMicroTaskQueue() {
  MOZ_ASSERT(mJSContext);
  return mPendingMicroTaskRunnables;
}

std::queue<RefPtr<MicroTaskRunnable>>&
CycleCollectedJSContext::GetDebuggerMicroTaskQueue() {
  MOZ_ASSERT(mJSContext);
  return mDebuggerMicroTaskQueue;
}

void CycleCollectedJSContext::ProcessStableStateQueue() {
  MOZ_ASSERT(mJSContext);
  MOZ_RELEASE_ASSERT(!mDoingStableStates);
  mDoingStableStates = true;

  // When run, one event can add another event to the mStableStateEvents, as
  // such you can't use iterators here.
  for (uint32_t i = 0; i < mStableStateEvents.Length(); ++i) {
    nsCOMPtr<nsIRunnable> event = mStableStateEvents[i].forget();
    event->Run();
  }

  mStableStateEvents.Clear();
  mDoingStableStates = false;
}

void CycleCollectedJSContext::CleanupIDBTransactions(uint32_t aRecursionDepth) {
  MOZ_ASSERT(mJSContext);
  MOZ_RELEASE_ASSERT(!mDoingStableStates);
  mDoingStableStates = true;

  nsTArray<PendingIDBTransactionData> localQueue =
      std::move(mPendingIDBTransactions);

  for (uint32_t i = 0; i < localQueue.Length(); ++i) {
    PendingIDBTransactionData& data = localQueue[i];
    if (data.mRecursionDepth != aRecursionDepth) {
      continue;
    }

    {
      nsCOMPtr<nsIRunnable> transaction = data.mTransaction.forget();
      transaction->Run();
    }

    localQueue.RemoveElementAt(i--);
  }

  // If the queue has events in it now, they were added from something we
  // called, so they belong at the end of the queue.
  localQueue.AppendElements(mPendingIDBTransactions);
  localQueue.SwapElements(mPendingIDBTransactions);
  mDoingStableStates = false;
}

void CycleCollectedJSContext::BeforeProcessTask(bool aMightBlock) {
  // If ProcessNextEvent was called during a microtask callback, we
  // must process any pending microtasks before blocking in the event loop,
  // otherwise we may deadlock until an event enters the queue later.
  if (aMightBlock && PerformMicroTaskCheckPoint()) {
    // If any microtask was processed, we post a dummy event in order to
    // force the ProcessNextEvent call not to block.  This is required
    // to support nested event loops implemented using a pattern like
    // "while (condition) thread.processNextEvent(true)", in case the
    // condition is triggered here by a Promise "then" callback.
    NS_DispatchToMainThread(new Runnable("BeforeProcessTask"));
  }
}

void CycleCollectedJSContext::AfterProcessTask(uint32_t aRecursionDepth) {
  MOZ_ASSERT(mJSContext);

  // See HTML 6.1.4.2 Processing model

  // Step 4.1: Execute microtasks.
  PerformMicroTaskCheckPoint();

  // Step 4.2 Execute any events that were waiting for a stable state.
  ProcessStableStateQueue();

  // This should be a fast test so that it won't affect the next task
  // processing.
  IsIdleGCTaskNeeded();
}

void CycleCollectedJSContext::AfterProcessMicrotasks() {
  MOZ_ASSERT(mJSContext);
  // Notify unhandled promise rejections:
  // https://html.spec.whatwg.org/multipage/webappapis.html#notify-about-rejected-promises
  if (mAboutToBeNotifiedRejectedPromises.Length()) {
    RefPtr<NotifyUnhandledRejections> runnable = new NotifyUnhandledRejections(
        this, std::move(mAboutToBeNotifiedRejectedPromises));
    NS_DispatchToCurrentThread(runnable);
  }
  // Cleanup Indexed Database transactions:
  // https://html.spec.whatwg.org/multipage/webappapis.html#perform-a-microtask-checkpoint
  CleanupIDBTransactions(RecursionDepth());
}

void CycleCollectedJSContext::IsIdleGCTaskNeeded() const {
  class IdleTimeGCTaskRunnable : public mozilla::IdleRunnable {
   public:
    using mozilla::IdleRunnable::IdleRunnable;

   public:
    NS_IMETHOD Run() override {
      CycleCollectedJSRuntime* ccrt = CycleCollectedJSRuntime::Get();
      if (ccrt) {
        ccrt->RunIdleTimeGCTask();
      }
      return NS_OK;
    }

    nsresult Cancel() override { return NS_OK; }
  };

  if (Runtime()->IsIdleGCTaskNeeded()) {
    nsCOMPtr<nsIRunnable> gc_task = new IdleTimeGCTaskRunnable();
    NS_DispatchToCurrentThreadQueue(gc_task.forget(), EventQueuePriority::Idle);
    Runtime()->SetPendingIdleGCTask();
  }
}

uint32_t CycleCollectedJSContext::RecursionDepth() const {
  // Debugger interruptions are included in the recursion depth so that debugger
  // microtask checkpoints do not run IDB transactions which were initiated
  // before the interruption.
  return mOwningThread->RecursionDepth() + mDebuggerRecursionDepth;
}

void CycleCollectedJSContext::RunInStableState(
    already_AddRefed<nsIRunnable>&& aRunnable) {
  MOZ_ASSERT(mJSContext);
  mStableStateEvents.AppendElement(std::move(aRunnable));
}

void CycleCollectedJSContext::AddPendingIDBTransaction(
    already_AddRefed<nsIRunnable>&& aTransaction) {
  MOZ_ASSERT(mJSContext);

  PendingIDBTransactionData data;
  data.mTransaction = aTransaction;

  MOZ_ASSERT(mOwningThread);
  data.mRecursionDepth = RecursionDepth();

  // There must be an event running to get here.
#ifndef MOZ_WIDGET_COCOA
  MOZ_ASSERT(data.mRecursionDepth > mBaseRecursionDepth);
#else
  // XXX bug 1261143
  // Recursion depth should be greater than mBaseRecursionDepth,
  // or the runnable will stay in the queue forever.
  if (data.mRecursionDepth <= mBaseRecursionDepth) {
    data.mRecursionDepth = mBaseRecursionDepth + 1;
  }
#endif

  mPendingIDBTransactions.AppendElement(std::move(data));
}

void CycleCollectedJSContext::DispatchToMicroTask(
    already_AddRefed<MicroTaskRunnable> aRunnable) {
  RefPtr<MicroTaskRunnable> runnable(aRunnable);

  MOZ_ASSERT(NS_IsMainThread());
  MOZ_ASSERT(runnable);

  JS::JobQueueMayNotBeEmpty(Context());
  mPendingMicroTaskRunnables.push(runnable.forget());
}

class AsyncMutationHandler final : public mozilla::Runnable {
 public:
  AsyncMutationHandler() : mozilla::Runnable("AsyncMutationHandler") {}

  // MOZ_CAN_RUN_SCRIPT_BOUNDARY until Runnable::Run is MOZ_CAN_RUN_SCRIPT.  See
  // bug 1535398.
  MOZ_CAN_RUN_SCRIPT_BOUNDARY
  NS_IMETHOD Run() override {
    CycleCollectedJSContext* ccjs = CycleCollectedJSContext::Get();
    if (ccjs) {
      ccjs->PerformMicroTaskCheckPoint();
    }
    return NS_OK;
  }
};

bool CycleCollectedJSContext::PerformMicroTaskCheckPoint(bool aForce) {
  if (mPendingMicroTaskRunnables.empty() && mDebuggerMicroTaskQueue.empty()) {
    AfterProcessMicrotasks();
    // Nothing to do, return early.
    return false;
  }

  uint32_t currentDepth = RecursionDepth();
  if (mMicroTaskRecursionDepth >= currentDepth && !aForce) {
    // We are already executing microtasks for the current recursion depth.
    return false;
  }

  if (mTargetedMicroTaskRecursionDepth != 0 &&
      mTargetedMicroTaskRecursionDepth != currentDepth) {
    return false;
  }

  if (NS_IsMainThread() && !nsContentUtils::IsSafeToRunScript()) {
    // Special case for main thread where DOM mutations may happen when
    // it is not safe to run scripts.
    nsContentUtils::AddScriptRunner(new AsyncMutationHandler());
    return false;
  }

  mozilla::AutoRestore<uint32_t> restore(mMicroTaskRecursionDepth);
  MOZ_ASSERT(aForce ? currentDepth == 0 : currentDepth > 0);
  mMicroTaskRecursionDepth = currentDepth;

  bool didProcess = false;
  AutoSlowOperation aso;

  std::queue<RefPtr<MicroTaskRunnable>> suppressed;
  for (;;) {
    RefPtr<MicroTaskRunnable> runnable;
    if (!mDebuggerMicroTaskQueue.empty()) {
      runnable = mDebuggerMicroTaskQueue.front().forget();
      mDebuggerMicroTaskQueue.pop();
    } else if (!mPendingMicroTaskRunnables.empty()) {
      runnable = mPendingMicroTaskRunnables.front().forget();
      mPendingMicroTaskRunnables.pop();
    } else {
      break;
    }

    if (runnable->Suppressed()) {
      // Microtasks in worker shall never be suppressed.
      // Otherwise, mPendingMicroTaskRunnables will be replaced later with
      // all suppressed tasks in mDebuggerMicroTaskQueue unexpectedly.
      MOZ_ASSERT(NS_IsMainThread());
      JS::JobQueueMayNotBeEmpty(Context());
      suppressed.push(runnable);
    } else {
      if (mPendingMicroTaskRunnables.empty() &&
          mDebuggerMicroTaskQueue.empty() && suppressed.empty()) {
        JS::JobQueueIsEmpty(Context());
      }
      didProcess = true;
      runnable->Run(aso);
    }
  }

  // Put back the suppressed microtasks so that they will be run later.
  // Note, it is possible that we end up keeping these suppressed tasks around
  // for some time, but no longer than spinning the event loop nestedly
  // (sync XHR, alert, etc.)
  mPendingMicroTaskRunnables.swap(suppressed);

  AfterProcessMicrotasks();

  return didProcess;
}

void CycleCollectedJSContext::PerformDebuggerMicroTaskCheckpoint() {
  // Don't do normal microtask handling checks here, since whoever is calling
  // this method is supposed to know what they are doing.

  AutoSlowOperation aso;
  for (;;) {
    // For a debugger microtask checkpoint, we always use the debugger microtask
    // queue.
    std::queue<RefPtr<MicroTaskRunnable>>* microtaskQueue =
        &GetDebuggerMicroTaskQueue();

    if (microtaskQueue->empty()) {
      break;
    }

    RefPtr<MicroTaskRunnable> runnable = microtaskQueue->front().forget();
    MOZ_ASSERT(runnable);

    // This function can re-enter, so we remove the element before calling.
    microtaskQueue->pop();

    if (mPendingMicroTaskRunnables.empty() && mDebuggerMicroTaskQueue.empty()) {
      JS::JobQueueIsEmpty(Context());
    }
    runnable->Run(aso);
  }

  AfterProcessMicrotasks();
}

NS_IMETHODIMP CycleCollectedJSContext::NotifyUnhandledRejections::Run() {
  MOZ_ASSERT(mozilla::StaticPrefs::dom_promise_rejection_events_enabled());

  for (size_t i = 0; i < mUnhandledRejections.Length(); ++i) {
    RefPtr<Promise>& promise = mUnhandledRejections[i];
    if (!promise) {
      continue;
    }

    JS::RootingContext* cx = mCx->RootingCx();
    JS::RootedObject promiseObj(cx, promise->PromiseObj());
    MOZ_ASSERT(JS::IsPromiseObject(promiseObj));

    // Only fire unhandledrejection if the promise is still not handled;
    uint64_t promiseID = JS::GetPromiseID(promiseObj);
    if (!JS::GetPromiseIsHandled(promiseObj)) {
      if (nsCOMPtr<EventTarget> target =
              do_QueryInterface(promise->GetParentObject())) {
        RootedDictionary<PromiseRejectionEventInit> init(cx);
        init.mPromise = promise;
        init.mReason = JS::GetPromiseResult(promiseObj);
        init.mCancelable = true;

        RefPtr<PromiseRejectionEvent> event =
            PromiseRejectionEvent::Constructor(
                target, NS_LITERAL_STRING("unhandledrejection"), init);
        // We don't use the result of dispatching event here to check whether to
        // report the Promise to console.
        target->DispatchEvent(*event);
      }
    }

    if (!JS::GetPromiseIsHandled(promiseObj)) {
      DebugOnly<bool> isFound =
          mCx->mPendingUnhandledRejections.Remove(promiseID);
      MOZ_ASSERT(isFound);
    }

    // If a rejected promise is being handled in "unhandledrejection" event
    // handler, it should be removed from the table in
    // PromiseRejectionTrackerCallback.
    MOZ_ASSERT(!mCx->mPendingUnhandledRejections.Lookup(promiseID));
  }
  return NS_OK;
}

nsresult CycleCollectedJSContext::NotifyUnhandledRejections::Cancel() {
  MOZ_ASSERT(mozilla::StaticPrefs::dom_promise_rejection_events_enabled());

  for (size_t i = 0; i < mUnhandledRejections.Length(); ++i) {
    RefPtr<Promise>& promise = mUnhandledRejections[i];
    if (!promise) {
      continue;
    }

    JS::RootedObject promiseObj(mCx->RootingCx(), promise->PromiseObj());
    mCx->mPendingUnhandledRejections.Remove(JS::GetPromiseID(promiseObj));
  }
  return NS_OK;
}
}  // namespace mozilla