gecko-dev/dom/workers/RuntimeService.cpp

/* -*- 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 "RuntimeService.h"

#include "nsAutoPtr.h"
#include "nsIChannel.h"
#include "nsIContentSecurityPolicy.h"
#include "nsIDocument.h"
#include "nsIDOMChromeWindow.h"
#include "nsIEffectiveTLDService.h"
#include "nsIObserverService.h"
#include "nsIPrincipal.h"
#include "nsIScriptContext.h"
#include "nsIScriptError.h"
#include "nsIScriptSecurityManager.h"
#include "nsISupportsPriority.h"
#include "nsITimer.h"
#include "nsIURI.h"
#include "nsPIDOMWindow.h"

#include <algorithm>
#include "BackgroundChild.h"
#include "GeckoProfiler.h"
#include "jsfriendapi.h"
#include "mozilla/ArrayUtils.h"
#include "mozilla/AsyncEventDispatcher.h"
#include "mozilla/Atomics.h"
#include "mozilla/CycleCollectedJSContext.h"
#include "mozilla/Telemetry.h"
#include "mozilla/TimeStamp.h"
#include "mozilla/dom/asmjscache/AsmJSCache.h"
#include "mozilla/dom/AtomList.h"
#include "mozilla/dom/BindingUtils.h"
#include "mozilla/dom/ErrorEventBinding.h"
#include "mozilla/dom/EventTargetBinding.h"
#include "mozilla/dom/MessageChannel.h"
#include "mozilla/dom/MessageEventBinding.h"
#include "mozilla/dom/WorkerBinding.h"
#include "mozilla/dom/ScriptSettings.h"
#include "mozilla/dom/IndexedDatabaseManager.h"
#include "mozilla/ipc/BackgroundChild.h"
#include "mozilla/DebugOnly.h"
#include "mozilla/Preferences.h"
#include "mozilla/dom/Navigator.h"
#include "nsContentUtils.h"
#include "nsCycleCollector.h"
#include "nsDOMJSUtils.h"
#include "nsIIPCBackgroundChildCreateCallback.h"
#include "nsISupportsImpl.h"
#include "nsLayoutStatics.h"
#include "nsNetUtil.h"
#include "nsServiceManagerUtils.h"
#include "nsThreadUtils.h"
#include "nsXPCOM.h"
#include "nsXPCOMPrivate.h"
#include "OSFileConstants.h"
#include "xpcpublic.h"

#include "Principal.h"
#include "SharedWorker.h"
#include "WorkerDebuggerManager.h"
#include "WorkerPrivate.h"
#include "WorkerRunnable.h"
#include "WorkerScope.h"
#include "WorkerThread.h"
#include "prsystem.h"

using namespace mozilla;
using namespace mozilla::dom;
using namespace mozilla::ipc;

USING_WORKERS_NAMESPACE

using mozilla::MutexAutoLock;
using mozilla::MutexAutoUnlock;
using mozilla::Preferences;

// The size of the worker runtime heaps in bytes. May be changed via pref.
#define WORKER_DEFAULT_RUNTIME_HEAPSIZE 32 * 1024 * 1024

// The size of the generational GC nursery for workers, in bytes.
#define WORKER_DEFAULT_NURSERY_SIZE 1 * 1024 * 1024

// The size of the worker JS allocation threshold in MB. May be changed via pref.
#define WORKER_DEFAULT_ALLOCATION_THRESHOLD 30

// Half the size of the actual C stack, to be safe.
#define WORKER_CONTEXT_NATIVE_STACK_LIMIT 128 * sizeof(size_t) * 1024

// The maximum number of hardware concurrency, overridable via pref.
#define MAX_HARDWARE_CONCURRENCY 8

// The maximum number of threads to use for workers, overridable via pref.
#define MAX_WORKERS_PER_DOMAIN 512

static_assert(MAX_WORKERS_PER_DOMAIN >= 1,
              "We should allow at least one worker per domain.");

// The default number of seconds that close handlers will be allowed to run for
// content workers.
#define MAX_SCRIPT_RUN_TIME_SEC 10

// The number of seconds that idle threads can hang around before being killed.
#define IDLE_THREAD_TIMEOUT_SEC 30

// The maximum number of threads that can be idle at one time.
#define MAX_IDLE_THREADS 20

#define PREF_WORKERS_PREFIX "dom.workers."
#define PREF_WORKERS_MAX_PER_DOMAIN PREF_WORKERS_PREFIX "maxPerDomain"
#define PREF_WORKERS_MAX_HARDWARE_CONCURRENCY "dom.maxHardwareConcurrency"

#define PREF_MAX_SCRIPT_RUN_TIME_CONTENT "dom.max_script_run_time"
#define PREF_MAX_SCRIPT_RUN_TIME_CHROME "dom.max_chrome_script_run_time"

#define GC_REQUEST_OBSERVER_TOPIC "child-gc-request"
#define CC_REQUEST_OBSERVER_TOPIC "child-cc-request"
#define MEMORY_PRESSURE_OBSERVER_TOPIC "memory-pressure"

#define BROADCAST_ALL_WORKERS(_func, ...)                                      \
  PR_BEGIN_MACRO                                                               \
    AssertIsOnMainThread();                                                    \
                                                                               \
    AutoTArray<WorkerPrivate*, 100> workers;                                 \
    {                                                                          \
      MutexAutoLock lock(mMutex);                                              \
                                                                               \
      AddAllTopLevelWorkersToArray(workers);                                   \
    }                                                                          \
                                                                               \
    if (!workers.IsEmpty()) {                                                  \
      for (uint32_t index = 0; index < workers.Length(); index++) {            \
        workers[index]-> _func (__VA_ARGS__);                                  \
      }                                                                        \
    }                                                                          \
  PR_END_MACRO

// Prefixes for observing preference changes.
#define PREF_JS_OPTIONS_PREFIX "javascript.options."
#define PREF_WORKERS_OPTIONS_PREFIX PREF_WORKERS_PREFIX "options."
#define PREF_MEM_OPTIONS_PREFIX "mem."
#define PREF_GCZEAL "gcZeal"

namespace {

const uint32_t kNoIndex = uint32_t(-1);

uint32_t gMaxWorkersPerDomain = MAX_WORKERS_PER_DOMAIN;
uint32_t gMaxHardwareConcurrency = MAX_HARDWARE_CONCURRENCY;

// Does not hold an owning reference.
RuntimeService* gRuntimeService = nullptr;

// Only true during the call to Init.
bool gRuntimeServiceDuringInit = false;

class LiteralRebindingCString : public nsDependentCString
{
public:
  template<int N>
  void RebindLiteral(const char (&aStr)[N])
  {
    Rebind(aStr, N-1);
  }
};

template <typename T>
struct PrefTraits;

template <>
struct PrefTraits<bool>
{
  typedef bool PrefValueType;

  static const PrefValueType kDefaultValue = false;

  static inline PrefValueType
  Get(const char* aPref)
  {
    AssertIsOnMainThread();
    return Preferences::GetBool(aPref);
  }

  static inline bool
  Exists(const char* aPref)
  {
    AssertIsOnMainThread();
    return Preferences::GetType(aPref) == nsIPrefBranch::PREF_BOOL;
  }
};

template <>
struct PrefTraits<int32_t>
{
  typedef int32_t PrefValueType;

  static inline PrefValueType
  Get(const char* aPref)
  {
    AssertIsOnMainThread();
    return Preferences::GetInt(aPref);
  }

  static inline bool
  Exists(const char* aPref)
  {
    AssertIsOnMainThread();
    return Preferences::GetType(aPref) == nsIPrefBranch::PREF_INT;
  }
};

template <typename T>
T
GetWorkerPref(const nsACString& aPref,
              const T aDefault = PrefTraits<T>::kDefaultValue)
{
  AssertIsOnMainThread();

  typedef PrefTraits<T> PrefHelper;

  T result;

  nsAutoCString prefName;
  prefName.AssignLiteral(PREF_WORKERS_OPTIONS_PREFIX);
  prefName.Append(aPref);

  if (PrefHelper::Exists(prefName.get())) {
    result = PrefHelper::Get(prefName.get());
  }
  else {
    prefName.AssignLiteral(PREF_JS_OPTIONS_PREFIX);
    prefName.Append(aPref);

    if (PrefHelper::Exists(prefName.get())) {
      result = PrefHelper::Get(prefName.get());
    }
    else {
      result = aDefault;
    }
  }

  return result;
}

// This fn creates a key for a SharedWorker that contains the name, script
// spec, and the serialized origin attributes:
// "name|scriptSpec^key1=val1&key2=val2&key3=val3"
void
GenerateSharedWorkerKey(const nsACString& aScriptSpec,
                        const nsACString& aName,
                        const OriginAttributes& aAttrs,
                        nsCString& aKey)
{
  nsAutoCString suffix;
  aAttrs.CreateSuffix(suffix);

  aKey.Truncate();
  aKey.SetCapacity(aName.Length() + aScriptSpec.Length() + suffix.Length() + 2);
  aKey.Append(aName);
  aKey.Append('|');
  aKey.Append(aScriptSpec);
  aKey.Append(suffix);
}

void
LoadContextOptions(const char* aPrefName, void* /* aClosure */)
{
  AssertIsOnMainThread();

  RuntimeService* rts = RuntimeService::GetService();
  if (!rts) {
    // May be shutting down, just bail.
    return;
  }

  const nsDependentCString prefName(aPrefName);

  // Several other pref branches will get included here so bail out if there is
  // another callback that will handle this change.
  if (StringBeginsWith(prefName,
                       NS_LITERAL_CSTRING(PREF_JS_OPTIONS_PREFIX
                                          PREF_MEM_OPTIONS_PREFIX)) ||
      StringBeginsWith(prefName,
                       NS_LITERAL_CSTRING(PREF_WORKERS_OPTIONS_PREFIX
                                          PREF_MEM_OPTIONS_PREFIX))) {
    return;
  }

#ifdef JS_GC_ZEAL
  if (prefName.EqualsLiteral(PREF_JS_OPTIONS_PREFIX PREF_GCZEAL) ||
      prefName.EqualsLiteral(PREF_WORKERS_OPTIONS_PREFIX PREF_GCZEAL)) {
    return;
  }
#endif

  // Context options.
  JS::ContextOptions contextOptions;
  contextOptions.setAsmJS(GetWorkerPref<bool>(NS_LITERAL_CSTRING("asmjs")))
                .setWasm(GetWorkerPref<bool>(NS_LITERAL_CSTRING("wasm")))
                .setThrowOnAsmJSValidationFailure(GetWorkerPref<bool>(
                      NS_LITERAL_CSTRING("throw_on_asmjs_validation_failure")))
                .setBaseline(GetWorkerPref<bool>(NS_LITERAL_CSTRING("baselinejit")))
                .setIon(GetWorkerPref<bool>(NS_LITERAL_CSTRING("ion")))
                .setNativeRegExp(GetWorkerPref<bool>(NS_LITERAL_CSTRING("native_regexp")))
                .setAsyncStack(GetWorkerPref<bool>(NS_LITERAL_CSTRING("asyncstack")))
                .setWerror(GetWorkerPref<bool>(NS_LITERAL_CSTRING("werror")))
                .setExtraWarnings(GetWorkerPref<bool>(NS_LITERAL_CSTRING("strict")));

  RuntimeService::SetDefaultContextOptions(contextOptions);

  if (rts) {
    rts->UpdateAllWorkerContextOptions();
  }
}

#ifdef JS_GC_ZEAL
void
LoadGCZealOptions(const char* /* aPrefName */, void* /* aClosure */)
{
  AssertIsOnMainThread();

  RuntimeService* rts = RuntimeService::GetService();
  if (!rts) {
    // May be shutting down, just bail.
    return;
  }

  int32_t gczeal = GetWorkerPref<int32_t>(NS_LITERAL_CSTRING(PREF_GCZEAL), -1);
  if (gczeal < 0) {
    gczeal = 0;
  }

  int32_t frequency =
    GetWorkerPref<int32_t>(NS_LITERAL_CSTRING("gcZeal.frequency"), -1);
  if (frequency < 0) {
    frequency = JS_DEFAULT_ZEAL_FREQ;
  }

  RuntimeService::SetDefaultGCZeal(uint8_t(gczeal), uint32_t(frequency));

  if (rts) {
    rts->UpdateAllWorkerGCZeal();
  }
}
#endif

void
UpdateCommonJSGCMemoryOption(RuntimeService* aRuntimeService,
                             const nsACString& aPrefName, JSGCParamKey aKey)
{
  AssertIsOnMainThread();
  NS_ASSERTION(!aPrefName.IsEmpty(), "Empty pref name!");

  int32_t prefValue = GetWorkerPref(aPrefName, -1);
  uint32_t value =
    (prefValue < 0 || prefValue >= 10000) ? 0 : uint32_t(prefValue);

  RuntimeService::SetDefaultJSGCSettings(aKey, value);

  if (aRuntimeService) {
    aRuntimeService->UpdateAllWorkerMemoryParameter(aKey, value);
  }
}

void
UpdateOtherJSGCMemoryOption(RuntimeService* aRuntimeService,
                            JSGCParamKey aKey, uint32_t aValue)
{
  AssertIsOnMainThread();

  RuntimeService::SetDefaultJSGCSettings(aKey, aValue);

  if (aRuntimeService) {
    aRuntimeService->UpdateAllWorkerMemoryParameter(aKey, aValue);
  }
}


void
LoadJSGCMemoryOptions(const char* aPrefName, void* /* aClosure */)
{
  AssertIsOnMainThread();

  RuntimeService* rts = RuntimeService::GetService();

  if (!rts) {
    // May be shutting down, just bail.
    return;
  }

  NS_NAMED_LITERAL_CSTRING(jsPrefix, PREF_JS_OPTIONS_PREFIX);
  NS_NAMED_LITERAL_CSTRING(workersPrefix, PREF_WORKERS_OPTIONS_PREFIX);

  const nsDependentCString fullPrefName(aPrefName);

  // Pull out the string that actually distinguishes the parameter we need to
  // change.
  nsDependentCSubstring memPrefName;
  if (StringBeginsWith(fullPrefName, jsPrefix)) {
    memPrefName.Rebind(fullPrefName, jsPrefix.Length());
  }
  else if (StringBeginsWith(fullPrefName, workersPrefix)) {
    memPrefName.Rebind(fullPrefName, workersPrefix.Length());
  }
  else {
    NS_ERROR("Unknown pref name!");
    return;
  }

#ifdef DEBUG
  // During Init() we get called back with a branch string here, so there should
  // be no just a "mem." pref here.
  if (!rts) {
    NS_ASSERTION(memPrefName.EqualsLiteral(PREF_MEM_OPTIONS_PREFIX), "Huh?!");
  }
#endif

  // If we're running in Init() then do this for every pref we care about.
  // Otherwise we just want to update the parameter that changed.
  for (uint32_t index = !gRuntimeServiceDuringInit
                          ? JSSettings::kGCSettingsArraySize - 1 : 0;
       index < JSSettings::kGCSettingsArraySize;
       index++) {
    LiteralRebindingCString matchName;

    matchName.RebindLiteral(PREF_MEM_OPTIONS_PREFIX "max");
    if (memPrefName == matchName || (gRuntimeServiceDuringInit && index == 0)) {
      int32_t prefValue = GetWorkerPref(matchName, -1);
      uint32_t value = (prefValue <= 0 || prefValue >= 0x1000) ?
                       uint32_t(-1) :
                       uint32_t(prefValue) * 1024 * 1024;
      UpdateOtherJSGCMemoryOption(rts, JSGC_MAX_BYTES, value);
      continue;
    }

    matchName.RebindLiteral(PREF_MEM_OPTIONS_PREFIX "high_water_mark");
    if (memPrefName == matchName || (gRuntimeServiceDuringInit && index == 1)) {
      int32_t prefValue = GetWorkerPref(matchName, 128);
      UpdateOtherJSGCMemoryOption(rts, JSGC_MAX_MALLOC_BYTES,
                                 uint32_t(prefValue) * 1024 * 1024);
      continue;
    }

    matchName.RebindLiteral(PREF_MEM_OPTIONS_PREFIX
                            "gc_high_frequency_time_limit_ms");
    if (memPrefName == matchName || (gRuntimeServiceDuringInit && index == 2)) {
      UpdateCommonJSGCMemoryOption(rts, matchName,
                                   JSGC_HIGH_FREQUENCY_TIME_LIMIT);
      continue;
    }

    matchName.RebindLiteral(PREF_MEM_OPTIONS_PREFIX
                            "gc_low_frequency_heap_growth");
    if (memPrefName == matchName || (gRuntimeServiceDuringInit && index == 3)) {
      UpdateCommonJSGCMemoryOption(rts, matchName,
                                   JSGC_LOW_FREQUENCY_HEAP_GROWTH);
      continue;
    }

    matchName.RebindLiteral(PREF_MEM_OPTIONS_PREFIX
                            "gc_high_frequency_heap_growth_min");
    if (memPrefName == matchName || (gRuntimeServiceDuringInit && index == 4)) {
      UpdateCommonJSGCMemoryOption(rts, matchName,
                                   JSGC_HIGH_FREQUENCY_HEAP_GROWTH_MIN);
      continue;
    }

    matchName.RebindLiteral(PREF_MEM_OPTIONS_PREFIX
                            "gc_high_frequency_heap_growth_max");
    if (memPrefName == matchName || (gRuntimeServiceDuringInit && index == 5)) {
      UpdateCommonJSGCMemoryOption(rts, matchName,
                                   JSGC_HIGH_FREQUENCY_HEAP_GROWTH_MAX);
      continue;
    }

    matchName.RebindLiteral(PREF_MEM_OPTIONS_PREFIX
                            "gc_high_frequency_low_limit_mb");
    if (memPrefName == matchName || (gRuntimeServiceDuringInit && index == 6)) {
      UpdateCommonJSGCMemoryOption(rts, matchName,
                                   JSGC_HIGH_FREQUENCY_LOW_LIMIT);
      continue;
    }

    matchName.RebindLiteral(PREF_MEM_OPTIONS_PREFIX
                            "gc_high_frequency_high_limit_mb");
    if (memPrefName == matchName || (gRuntimeServiceDuringInit && index == 7)) {
      UpdateCommonJSGCMemoryOption(rts, matchName,
                                   JSGC_HIGH_FREQUENCY_HIGH_LIMIT);
      continue;
    }

    matchName.RebindLiteral(PREF_MEM_OPTIONS_PREFIX
                            "gc_allocation_threshold_mb");
    if (memPrefName == matchName || (gRuntimeServiceDuringInit && index == 8)) {
      UpdateCommonJSGCMemoryOption(rts, matchName, JSGC_ALLOCATION_THRESHOLD);
      continue;
    }

    matchName.RebindLiteral(PREF_MEM_OPTIONS_PREFIX "gc_incremental_slice_ms");
    if (memPrefName == matchName || (gRuntimeServiceDuringInit && index == 9)) {
      int32_t prefValue = GetWorkerPref(matchName, -1);
      uint32_t value =
        (prefValue <= 0 || prefValue >= 100000) ? 0 : uint32_t(prefValue);
      UpdateOtherJSGCMemoryOption(rts, JSGC_SLICE_TIME_BUDGET, value);
      continue;
    }

    matchName.RebindLiteral(PREF_MEM_OPTIONS_PREFIX "gc_dynamic_heap_growth");
    if (memPrefName == matchName ||
        (gRuntimeServiceDuringInit && index == 10)) {
      bool prefValue = GetWorkerPref(matchName, false);
      UpdateOtherJSGCMemoryOption(rts, JSGC_DYNAMIC_HEAP_GROWTH,
                                 prefValue ? 0 : 1);
      continue;
    }

    matchName.RebindLiteral(PREF_MEM_OPTIONS_PREFIX "gc_dynamic_mark_slice");
    if (memPrefName == matchName ||
        (gRuntimeServiceDuringInit && index == 11)) {
      bool prefValue = GetWorkerPref(matchName, false);
      UpdateOtherJSGCMemoryOption(rts, JSGC_DYNAMIC_MARK_SLICE,
                                 prefValue ? 0 : 1);
      continue;
    }

    matchName.RebindLiteral(PREF_MEM_OPTIONS_PREFIX "gc_min_empty_chunk_count");
    if (memPrefName == matchName ||
        (gRuntimeServiceDuringInit && index == 12)) {
      UpdateCommonJSGCMemoryOption(rts, matchName, JSGC_MIN_EMPTY_CHUNK_COUNT);
      continue;
    }

    matchName.RebindLiteral(PREF_MEM_OPTIONS_PREFIX "gc_max_empty_chunk_count");
    if (memPrefName == matchName ||
        (gRuntimeServiceDuringInit && index == 13)) {
      UpdateCommonJSGCMemoryOption(rts, matchName, JSGC_MAX_EMPTY_CHUNK_COUNT);
      continue;
    }

    matchName.RebindLiteral(PREF_MEM_OPTIONS_PREFIX "gc_compacting");
    if (memPrefName == matchName ||
        (gRuntimeServiceDuringInit && index == 14)) {
      bool prefValue = GetWorkerPref(matchName, false);
      UpdateOtherJSGCMemoryOption(rts, JSGC_COMPACTING_ENABLED,
                                 prefValue ? 0 : 1);
      continue;
    }

    matchName.RebindLiteral(PREF_MEM_OPTIONS_PREFIX "gc_refresh_frame_slices_enabled");
    if (memPrefName == matchName ||
        (gRuntimeServiceDuringInit && index == 15)) {
      bool prefValue = GetWorkerPref(matchName, false);
      UpdateOtherJSGCMemoryOption(rts, JSGC_REFRESH_FRAME_SLICES_ENABLED,
                                 prefValue ? 0 : 1);
      continue;
    }

#ifdef DEBUG
    nsAutoCString message("Workers don't support the 'mem.");
    message.Append(memPrefName);
    message.AppendLiteral("' preference!");
    NS_WARNING(message.get());
#endif
  }
}

bool
InterruptCallback(JSContext* aCx)
{
  WorkerPrivate* worker = GetWorkerPrivateFromContext(aCx);
  MOZ_ASSERT(worker);

  // Now is a good time to turn on profiling if it's pending.
  profiler_js_operation_callback();

  return worker->InterruptCallback(aCx);
}

class LogViolationDetailsRunnable final : public WorkerMainThreadRunnable
{
  nsString mFileName;
  uint32_t mLineNum;

public:
  LogViolationDetailsRunnable(WorkerPrivate* aWorker,
                              const nsString& aFileName,
                              uint32_t aLineNum)
    : WorkerMainThreadRunnable(aWorker,
                               NS_LITERAL_CSTRING("RuntimeService :: LogViolationDetails"))
    , mFileName(aFileName), mLineNum(aLineNum)
  {
    MOZ_ASSERT(aWorker);
  }

  virtual bool MainThreadRun() override;

private:
  ~LogViolationDetailsRunnable() {}
};

bool
ContentSecurityPolicyAllows(JSContext* aCx)
{
  WorkerPrivate* worker = GetWorkerPrivateFromContext(aCx);
  worker->AssertIsOnWorkerThread();

  if (worker->GetReportCSPViolations()) {
    nsString fileName;
    uint32_t lineNum = 0;

    JS::AutoFilename file;
    if (JS::DescribeScriptedCaller(aCx, &file, &lineNum) && file.get()) {
      fileName = NS_ConvertUTF8toUTF16(file.get());
    } else {
      MOZ_ASSERT(!JS_IsExceptionPending(aCx));
    }

    RefPtr<LogViolationDetailsRunnable> runnable =
        new LogViolationDetailsRunnable(worker, fileName, lineNum);

    ErrorResult rv;
    runnable->Dispatch(Killing, rv);
    if (NS_WARN_IF(rv.Failed())) {
      rv.SuppressException();
    }
  }

  return worker->IsEvalAllowed();
}

void
CTypesActivityCallback(JSContext* aCx,
                       js::CTypesActivityType aType)
{
  WorkerPrivate* worker = GetWorkerPrivateFromContext(aCx);
  worker->AssertIsOnWorkerThread();

  switch (aType) {
    case js::CTYPES_CALL_BEGIN:
      worker->BeginCTypesCall();
      break;

    case js::CTYPES_CALL_END:
      worker->EndCTypesCall();
      break;

    case js::CTYPES_CALLBACK_BEGIN:
      worker->BeginCTypesCallback();
      break;

    case js::CTYPES_CALLBACK_END:
      worker->EndCTypesCallback();
      break;

    default:
      MOZ_CRASH("Unknown type flag!");
  }
}

static nsIPrincipal*
GetPrincipalForAsmJSCacheOp()
{
  WorkerPrivate* workerPrivate = GetCurrentThreadWorkerPrivate();
  if (!workerPrivate) {
    return nullptr;
  }

  // asmjscache::OpenEntryForX guarnatee to only access the given nsIPrincipal
  // from the main thread.
  return workerPrivate->GetPrincipalDontAssertMainThread();
}

static bool
AsmJSCacheOpenEntryForRead(JS::Handle<JSObject*> aGlobal,
                           const char16_t* aBegin,
                           const char16_t* aLimit,
                           size_t* aSize,
                           const uint8_t** aMemory,
                           intptr_t *aHandle)
{
  nsIPrincipal* principal = GetPrincipalForAsmJSCacheOp();
  if (!principal) {
    return false;
  }

  return asmjscache::OpenEntryForRead(principal, aBegin, aLimit, aSize, aMemory,
                                      aHandle);
}

static JS::AsmJSCacheResult
AsmJSCacheOpenEntryForWrite(JS::Handle<JSObject*> aGlobal,
                            bool aInstalled,
                            const char16_t* aBegin,
                            const char16_t* aEnd,
                            size_t aSize,
                            uint8_t** aMemory,
                            intptr_t* aHandle)
{
  nsIPrincipal* principal = GetPrincipalForAsmJSCacheOp();
  if (!principal) {
    return JS::AsmJSCache_InternalError;
  }

  return asmjscache::OpenEntryForWrite(principal, aInstalled, aBegin, aEnd,
                                       aSize, aMemory, aHandle);
}

class AsyncTaskWorkerHolder final : public WorkerHolder
{
  bool Notify(Status aStatus) override
  {
    // The async task must complete in bounded time and there is not (currently)
    // a clean way to cancel it. Async tasks do not run arbitrary content.
    return true;
  }

public:
  WorkerPrivate* Worker() const
  {
    return mWorkerPrivate;
  }
};

template <class RunnableBase>
class AsyncTaskBase : public RunnableBase
{
  UniquePtr<AsyncTaskWorkerHolder> mHolder;

  // Disable the usual pre/post-dispatch thread assertions since we are
  // dispatching from some random JS engine internal thread:

  bool PreDispatch(WorkerPrivate* aWorkerPrivate) override
  {
    return true;
  }

  void PostDispatch(WorkerPrivate* aWorkerPrivate, bool aDispatchResult) override
  { }

protected:
  explicit AsyncTaskBase(UniquePtr<AsyncTaskWorkerHolder> aHolder)
    : RunnableBase(aHolder->Worker(),
                   WorkerRunnable::WorkerThreadUnchangedBusyCount)
    , mHolder(Move(aHolder))
  {
    MOZ_ASSERT(mHolder);
  }

  ~AsyncTaskBase()
  {
    MOZ_ASSERT(!mHolder);
  }

  void DestroyHolder()
  {
    MOZ_ASSERT(mHolder);
    mHolder.reset();
  }

public:
  UniquePtr<AsyncTaskWorkerHolder> StealHolder()
  {
    return Move(mHolder);
  }
};

class AsyncTaskRunnable final : public AsyncTaskBase<WorkerRunnable>
{
  JS::AsyncTask* mTask;

  ~AsyncTaskRunnable()
  {
    MOZ_ASSERT(!mTask);
  }

  void PostDispatch(WorkerPrivate* aWorkerPrivate, bool aDispatchResult) override
  {
    // For the benefit of the destructor assert.
    if (!aDispatchResult) {
      mTask = nullptr;
    }
  }

public:
  AsyncTaskRunnable(UniquePtr<AsyncTaskWorkerHolder> aHolder,
                    JS::AsyncTask* aTask)
    : AsyncTaskBase<WorkerRunnable>(Move(aHolder))
    , mTask(aTask)
  {
    MOZ_ASSERT(mTask);
  }

  bool WorkerRun(JSContext* aCx, WorkerPrivate* aWorkerPrivate) override
  {
    MOZ_ASSERT(aWorkerPrivate == mWorkerPrivate);
    MOZ_ASSERT(aCx == mWorkerPrivate->GetJSContext());
    MOZ_ASSERT(mTask);

    AutoJSAPI jsapi;
    jsapi.Init();

    mTask->finish(mWorkerPrivate->GetJSContext());
    mTask = nullptr;  // mTask may delete itself

    DestroyHolder();

    return true;
  }

  nsresult Cancel() override
  {
    MOZ_ASSERT(mTask);

    AutoJSAPI jsapi;
    jsapi.Init();

    mTask->cancel(mWorkerPrivate->GetJSContext());
    mTask = nullptr;  // mTask may delete itself

    DestroyHolder();

    return WorkerRunnable::Cancel();
  }
};

class AsyncTaskControlRunnable final
  : public AsyncTaskBase<WorkerControlRunnable>
{
public:
  explicit AsyncTaskControlRunnable(UniquePtr<AsyncTaskWorkerHolder> aHolder)
    : AsyncTaskBase<WorkerControlRunnable>(Move(aHolder))
  { }

  bool WorkerRun(JSContext* aCx, WorkerPrivate* aWorkerPrivate) override
  {
    // See comment in FinishAsyncTaskCallback.
    DestroyHolder();
    return true;
  }
};

static bool
StartAsyncTaskCallback(JSContext* aCx, JS::AsyncTask* aTask)
{
  WorkerPrivate* worker = GetWorkerPrivateFromContext(aCx);
  worker->AssertIsOnWorkerThread();

  auto holder = MakeUnique<AsyncTaskWorkerHolder>();
  if (!holder->HoldWorker(worker, Status::Closing)) {
    return false;
  }

  // Matched by a UniquePtr in FinishAsyncTaskCallback which, by
  // interface contract, must be called in the future.
  aTask->user = holder.release();
  return true;
}

static bool
FinishAsyncTaskCallback(JS::AsyncTask* aTask)
{
  // May execute either on the worker thread or a random JS-internal helper
  // thread.

  // Match the release() in StartAsyncTaskCallback.
  UniquePtr<AsyncTaskWorkerHolder> holder(
    static_cast<AsyncTaskWorkerHolder*>(aTask->user));

  RefPtr<AsyncTaskRunnable> r = new AsyncTaskRunnable(Move(holder), aTask);

  // WorkerRunnable::Dispatch() can fail during worker shutdown. In that case,
  // report failure back to the JS engine but make sure to release the
  // WorkerHolder on the worker thread using a control runnable. Control
  // runables aren't suitable for calling AsyncTask::finish() since they are run
  // via the interrupt callback which breaks JS run-to-completion.
  if (!r->Dispatch()) {
    RefPtr<AsyncTaskControlRunnable> cr =
      new AsyncTaskControlRunnable(r->StealHolder());

    MOZ_ALWAYS_TRUE(cr->Dispatch());
    return false;
  }

  return true;
}

class WorkerJSContext;

class WorkerThreadContextPrivate : private PerThreadAtomCache
{
  friend class WorkerJSContext;

  WorkerPrivate* mWorkerPrivate;

public:
  // This can't return null, but we can't lose the "Get" prefix in the name or
  // it will be ambiguous with the WorkerPrivate class name.
  WorkerPrivate*
  GetWorkerPrivate() const
  {
    MOZ_ASSERT(!NS_IsMainThread());
    MOZ_ASSERT(mWorkerPrivate);

    return mWorkerPrivate;
  }

private:
  explicit
  WorkerThreadContextPrivate(WorkerPrivate* aWorkerPrivate)
    : mWorkerPrivate(aWorkerPrivate)
  {
    MOZ_ASSERT(!NS_IsMainThread());

    // Zero out the base class members.
    memset(this, 0, sizeof(PerThreadAtomCache));

    MOZ_ASSERT(mWorkerPrivate);
  }

  ~WorkerThreadContextPrivate()
  {
    MOZ_ASSERT(!NS_IsMainThread());
  }

  WorkerThreadContextPrivate(const WorkerThreadContextPrivate&) = delete;

  WorkerThreadContextPrivate&
  operator=(const WorkerThreadContextPrivate&) = delete;
};

bool
InitJSContextForWorker(WorkerPrivate* aWorkerPrivate, JSContext* aWorkerCx)
{
  aWorkerPrivate->AssertIsOnWorkerThread();
  NS_ASSERTION(!aWorkerPrivate->GetJSContext(), "Already has a context!");

  JSSettings settings;
  aWorkerPrivate->CopyJSSettings(settings);

  {
    JS::UniqueChars defaultLocale = aWorkerPrivate->AdoptDefaultLocale();
    MOZ_ASSERT(defaultLocale,
               "failure of a WorkerPrivate to have a default locale should "
               "have made the worker fail to spawn");

    if (!JS_SetDefaultLocale(aWorkerCx, defaultLocale.get())) {
      NS_WARNING("failed to set workerCx's default locale");
      return false;
    }
  }

  JS::ContextOptionsRef(aWorkerCx) = settings.contextOptions;

  JSSettings::JSGCSettingsArray& gcSettings = settings.gcSettings;

  // This is the real place where we set the max memory for the runtime.
  for (uint32_t index = 0; index < ArrayLength(gcSettings); index++) {
    const JSSettings::JSGCSetting& setting = gcSettings[index];
    if (setting.IsSet()) {
      NS_ASSERTION(setting.value, "Can't handle 0 values!");
      JS_SetGCParameter(aWorkerCx, setting.key, setting.value);
    }
  }

  JS_SetNativeStackQuota(aWorkerCx, WORKER_CONTEXT_NATIVE_STACK_LIMIT);

  // Security policy:
  static const JSSecurityCallbacks securityCallbacks = {
    ContentSecurityPolicyAllows
  };
  JS_SetSecurityCallbacks(aWorkerCx, &securityCallbacks);

  // Set up the asm.js cache callbacks
  static const JS::AsmJSCacheOps asmJSCacheOps = {
    AsmJSCacheOpenEntryForRead,
    asmjscache::CloseEntryForRead,
    AsmJSCacheOpenEntryForWrite,
    asmjscache::CloseEntryForWrite
  };
  JS::SetAsmJSCacheOps(aWorkerCx, &asmJSCacheOps);

  JS::SetAsyncTaskCallbacks(aWorkerCx, StartAsyncTaskCallback, FinishAsyncTaskCallback);

  if (!JS::InitSelfHostedCode(aWorkerCx)) {
    NS_WARNING("Could not init self-hosted code!");
    return false;
  }

  JS_AddInterruptCallback(aWorkerCx, InterruptCallback);

  js::SetCTypesActivityCallback(aWorkerCx, CTypesActivityCallback);

#ifdef JS_GC_ZEAL
  JS_SetGCZeal(aWorkerCx, settings.gcZeal, settings.gcZealFrequency);
#endif

  return true;
}

static bool
PreserveWrapper(JSContext *cx, JSObject *obj)
{
    MOZ_ASSERT(cx);
    MOZ_ASSERT(obj);
    MOZ_ASSERT(mozilla::dom::IsDOMObject(obj));

    return mozilla::dom::TryPreserveWrapper(obj);
}

JSObject*
Wrap(JSContext *cx, JS::HandleObject existing, JS::HandleObject obj)
{
  JSObject* targetGlobal = JS::CurrentGlobalOrNull(cx);
  if (!IsDebuggerGlobal(targetGlobal) && !IsDebuggerSandbox(targetGlobal)) {
    MOZ_CRASH("There should be no edges from the debuggee to the debugger.");
  }

  JSObject* originGlobal = js::GetGlobalForObjectCrossCompartment(obj);

  const js::Wrapper* wrapper = nullptr;
  if (IsDebuggerGlobal(originGlobal) || IsDebuggerSandbox(originGlobal)) {
    wrapper = &js::CrossCompartmentWrapper::singleton;
  } else {
    wrapper = &js::OpaqueCrossCompartmentWrapper::singleton;
  }

  if (existing) {
    js::Wrapper::Renew(cx, existing, obj, wrapper);
  }
  return js::Wrapper::New(cx, obj, wrapper);
}

static const JSWrapObjectCallbacks WrapObjectCallbacks = {
  Wrap,
  nullptr,
};

class MOZ_STACK_CLASS WorkerJSContext final : public mozilla::CycleCollectedJSContext
{
public:
  // The heap size passed here doesn't matter, we will change it later in the
  // call to JS_SetGCParameter inside InitJSContextForWorker.
  explicit WorkerJSContext(WorkerPrivate* aWorkerPrivate)
    : mWorkerPrivate(aWorkerPrivate)
  {
    MOZ_ASSERT(aWorkerPrivate);
  }

  ~WorkerJSContext()
  {
    JSContext* cx = MaybeContext();
    if (!cx) {
      return;   // Initialize() must have failed
    }

    delete static_cast<WorkerThreadContextPrivate*>(JS_GetContextPrivate(cx));
    JS_SetContextPrivate(cx, nullptr);

    // The worker global should be unrooted and the shutdown cycle collection
    // should break all remaining cycles. The superclass destructor will run
    // the GC one final time and finalize any JSObjects that were participating
    // in cycles that were broken during CC shutdown.
    nsCycleCollector_shutdown();

    // The CC is shut down, and the superclass destructor will GC, so make sure
    // we don't try to CC again.
    mWorkerPrivate = nullptr;
  }

  nsresult Initialize(JSContext* aParentContext)
  {
    nsresult rv =
      CycleCollectedJSContext::Initialize(aParentContext,
                                          WORKER_DEFAULT_RUNTIME_HEAPSIZE,
                                          WORKER_DEFAULT_NURSERY_SIZE);
     if (NS_WARN_IF(NS_FAILED(rv))) {
       return rv;
     }

    JSContext* cx = Context();

    JS_SetContextPrivate(cx, new WorkerThreadContextPrivate(mWorkerPrivate));

    js::SetPreserveWrapperCallback(cx, PreserveWrapper);
    JS_InitDestroyPrincipalsCallback(cx, DestroyWorkerPrincipals);
    JS_SetWrapObjectCallbacks(cx, &WrapObjectCallbacks);
    if (mWorkerPrivate->IsDedicatedWorker()) {
      JS_SetFutexCanWait(cx);
    }

    return NS_OK;
  }

  virtual void
  PrepareForForgetSkippable() override
  {
  }

  virtual void
  BeginCycleCollectionCallback() override
  {
  }

  virtual void
  EndCycleCollectionCallback(CycleCollectorResults &aResults) override
  {
  }

  void
  DispatchDeferredDeletion(bool aContinuation, bool aPurge) override
  {
    MOZ_ASSERT(!aContinuation);

    // Do it immediately, no need for asynchronous behavior here.
    nsCycleCollector_doDeferredDeletion();
  }

  virtual void CustomGCCallback(JSGCStatus aStatus) override
  {
    if (!mWorkerPrivate) {
      // We're shutting down, no need to do anything.
      return;
    }

    mWorkerPrivate->AssertIsOnWorkerThread();

    if (aStatus == JSGC_END) {
      nsCycleCollector_collect(nullptr);
    }
  }

  virtual void AfterProcessTask(uint32_t aRecursionDepth) override
  {
    // Only perform the Promise microtask checkpoint on the outermost event
    // loop.  Don't run it, for example, during sync XHR or importScripts.
    if (aRecursionDepth == 2) {
      CycleCollectedJSContext::AfterProcessTask(aRecursionDepth);
    } else if (aRecursionDepth > 2) {
      AutoDisableMicroTaskCheckpoint disableMicroTaskCheckpoint;
      CycleCollectedJSContext::AfterProcessTask(aRecursionDepth);
    }
  }

  virtual void DispatchToMicroTask(already_AddRefed<nsIRunnable> aRunnable) override
  {
    RefPtr<nsIRunnable> runnable(aRunnable);

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

    std::queue<nsCOMPtr<nsIRunnable>>* microTaskQueue = nullptr;

    JSContext* cx = GetCurrentThreadJSContext();
    NS_ASSERTION(cx, "This should never be null!");

    JS::Rooted<JSObject*> global(cx, JS::CurrentGlobalOrNull(cx));
    NS_ASSERTION(global, "This should never be null!");

    // On worker threads, if the current global is the worker global, we use the
    // main promise micro task queue. Otherwise, the current global must be
    // either the debugger global or a debugger sandbox, and we use the debugger
    // promise micro task queue instead.
    if (IsWorkerGlobal(global)) {
      microTaskQueue = &mPromiseMicroTaskQueue;
    } else {
      MOZ_ASSERT(IsDebuggerGlobal(global) || IsDebuggerSandbox(global));

      microTaskQueue = &mDebuggerPromiseMicroTaskQueue;
    }

    microTaskQueue->push(runnable.forget());
  }

private:
  WorkerPrivate* mWorkerPrivate;
};

class WorkerThreadPrimaryRunnable final : public Runnable
{
  WorkerPrivate* mWorkerPrivate;
  RefPtr<WorkerThread> mThread;
  JSContext* mParentContext;

  class FinishedRunnable final : public Runnable
  {
    RefPtr<WorkerThread> mThread;

  public:
    explicit FinishedRunnable(already_AddRefed<WorkerThread> aThread)
    : mThread(aThread)
    {
      MOZ_ASSERT(mThread);
    }

    NS_DECL_ISUPPORTS_INHERITED

  private:
    ~FinishedRunnable()
    { }

    NS_DECL_NSIRUNNABLE
  };

public:
  WorkerThreadPrimaryRunnable(WorkerPrivate* aWorkerPrivate,
                              WorkerThread* aThread,
                              JSContext* aParentContext)
  : mWorkerPrivate(aWorkerPrivate), mThread(aThread), mParentContext(aParentContext)
  {
    MOZ_ASSERT(aWorkerPrivate);
    MOZ_ASSERT(aThread);
  }

  NS_DECL_ISUPPORTS_INHERITED

private:
  ~WorkerThreadPrimaryRunnable()
  { }

  NS_DECL_NSIRUNNABLE
};

class WorkerTaskRunnable final : public WorkerRunnable
{
  RefPtr<WorkerTask> mTask;

public:
  WorkerTaskRunnable(WorkerPrivate* aWorkerPrivate, WorkerTask* aTask)
  : WorkerRunnable(aWorkerPrivate, WorkerThreadUnchangedBusyCount), mTask(aTask)
  {
    MOZ_ASSERT(aTask);
  }

private:
  virtual bool
  PreDispatch(WorkerPrivate* aWorkerPrivate) override
  {
    // May be called on any thread!
    return true;
  }

  virtual void
  PostDispatch(WorkerPrivate* aWorkerPrivate, bool aDispatchResult) override
  {
    // May be called on any thread!
  }

  virtual bool
  WorkerRun(JSContext* aCx, WorkerPrivate* aWorkerPrivate) override
  {
    return mTask->RunTask(aCx);
  }
};

void
PrefLanguagesChanged(const char* /* aPrefName */, void* /* aClosure */)
{
  AssertIsOnMainThread();

  nsTArray<nsString> languages;
  Navigator::GetAcceptLanguages(languages);

  RuntimeService* runtime = RuntimeService::GetService();
  if (runtime) {
    runtime->UpdateAllWorkerLanguages(languages);
  }
}

void
AppNameOverrideChanged(const char* /* aPrefName */, void* /* aClosure */)
{
  AssertIsOnMainThread();

  const nsAdoptingString& override =
    mozilla::Preferences::GetString("general.appname.override");

  RuntimeService* runtime = RuntimeService::GetService();
  if (runtime) {
    runtime->UpdateAppNameOverridePreference(override);
  }
}

void
AppVersionOverrideChanged(const char* /* aPrefName */, void* /* aClosure */)
{
  AssertIsOnMainThread();

  const nsAdoptingString& override =
    mozilla::Preferences::GetString("general.appversion.override");

  RuntimeService* runtime = RuntimeService::GetService();
  if (runtime) {
    runtime->UpdateAppVersionOverridePreference(override);
  }
}

void
PlatformOverrideChanged(const char* /* aPrefName */, void* /* aClosure */)
{
  AssertIsOnMainThread();

  const nsAdoptingString& override =
    mozilla::Preferences::GetString("general.platform.override");

  RuntimeService* runtime = RuntimeService::GetService();
  if (runtime) {
    runtime->UpdatePlatformOverridePreference(override);
  }
}

class BackgroundChildCallback final
  : public nsIIPCBackgroundChildCreateCallback
{
public:
  BackgroundChildCallback()
  {
    AssertIsOnMainThread();
  }

  NS_DECL_ISUPPORTS

private:
  ~BackgroundChildCallback()
  {
    AssertIsOnMainThread();
  }

  virtual void
  ActorCreated(PBackgroundChild* aActor) override
  {
    AssertIsOnMainThread();
    MOZ_ASSERT(aActor);
  }

  virtual void
  ActorFailed() override
  {
    AssertIsOnMainThread();
    MOZ_CRASH("Unable to connect PBackground actor for the main thread!");
  }
};

NS_IMPL_ISUPPORTS(BackgroundChildCallback, nsIIPCBackgroundChildCreateCallback)

} /* anonymous namespace */

BEGIN_WORKERS_NAMESPACE

void
CancelWorkersForWindow(nsPIDOMWindowInner* aWindow)
{
  AssertIsOnMainThread();
  RuntimeService* runtime = RuntimeService::GetService();
  if (runtime) {
    runtime->CancelWorkersForWindow(aWindow);
  }
}

void
FreezeWorkersForWindow(nsPIDOMWindowInner* aWindow)
{
  AssertIsOnMainThread();
  RuntimeService* runtime = RuntimeService::GetService();
  if (runtime) {
    runtime->FreezeWorkersForWindow(aWindow);
  }
}

void
ThawWorkersForWindow(nsPIDOMWindowInner* aWindow)
{
  AssertIsOnMainThread();
  RuntimeService* runtime = RuntimeService::GetService();
  if (runtime) {
    runtime->ThawWorkersForWindow(aWindow);
  }
}

void
SuspendWorkersForWindow(nsPIDOMWindowInner* aWindow)
{
  AssertIsOnMainThread();
  RuntimeService* runtime = RuntimeService::GetService();
  if (runtime) {
    runtime->SuspendWorkersForWindow(aWindow);
  }
}

void
ResumeWorkersForWindow(nsPIDOMWindowInner* aWindow)
{
  AssertIsOnMainThread();
  RuntimeService* runtime = RuntimeService::GetService();
  if (runtime) {
    runtime->ResumeWorkersForWindow(aWindow);
  }
}

WorkerCrossThreadDispatcher::WorkerCrossThreadDispatcher(
                                                  WorkerPrivate* aWorkerPrivate)
: mMutex("WorkerCrossThreadDispatcher::mMutex"),
  mWorkerPrivate(aWorkerPrivate)
{
  MOZ_ASSERT(aWorkerPrivate);
}

bool
WorkerCrossThreadDispatcher::PostTask(WorkerTask* aTask)
{
  MOZ_ASSERT(aTask);

  MutexAutoLock lock(mMutex);

  if (!mWorkerPrivate) {
    NS_WARNING("Posted a task to a WorkerCrossThreadDispatcher that is no "
               "longer accepting tasks!");
    return false;
  }

  RefPtr<WorkerTaskRunnable> runnable =
    new WorkerTaskRunnable(mWorkerPrivate, aTask);
  return runnable->Dispatch();
}

WorkerPrivate*
GetWorkerPrivateFromContext(JSContext* aCx)
{
  MOZ_ASSERT(!NS_IsMainThread());
  MOZ_ASSERT(aCx);

  void* cxPrivate = JS_GetContextPrivate(aCx);
  if (!cxPrivate) {
    return nullptr;
  }

  return
    static_cast<WorkerThreadContextPrivate*>(cxPrivate)->GetWorkerPrivate();
}

WorkerPrivate*
GetCurrentThreadWorkerPrivate()
{
  MOZ_ASSERT(!NS_IsMainThread());

  CycleCollectedJSContext* ccjscx = CycleCollectedJSContext::Get();
  if (!ccjscx) {
    return nullptr;
  }

  JSContext* cx = ccjscx->Context();
  MOZ_ASSERT(cx);

  // Note that we can return nullptr if the nsCycleCollector_shutdown() in
  // ~WorkerJSContext() triggers any calls to GetCurrentThreadWorkerPrivate().
  // At this stage CycleCollectedJSContext::Get() will still return a context,
  // but the context private has already been cleared.
  return GetWorkerPrivateFromContext(cx);
}

bool
IsCurrentThreadRunningChromeWorker()
{
  return GetCurrentThreadWorkerPrivate()->UsesSystemPrincipal();
}

JSContext*
GetCurrentThreadJSContext()
{
  WorkerPrivate* wp = GetCurrentThreadWorkerPrivate();
  if (!wp) {
    return nullptr;
  }
  return wp->GetJSContext();
}

JSObject*
GetCurrentThreadWorkerGlobal()
{
  WorkerPrivate* wp = GetCurrentThreadWorkerPrivate();
  if (!wp) {
    return nullptr;
  }
  WorkerGlobalScope* scope = wp->GlobalScope();
  if (!scope) {
    return nullptr;
  }
  return scope->GetGlobalJSObject();
}

END_WORKERS_NAMESPACE

struct RuntimeService::IdleThreadInfo
{
  RefPtr<WorkerThread> mThread;
  mozilla::TimeStamp mExpirationTime;
};

// This is only touched on the main thread. Initialized in Init() below.
JSSettings RuntimeService::sDefaultJSSettings;
bool RuntimeService::sDefaultPreferences[WORKERPREF_COUNT] = { false };

RuntimeService::RuntimeService()
: mMutex("RuntimeService::mMutex"), mObserved(false),
  mShuttingDown(false), mNavigatorPropertiesLoaded(false)
{
  AssertIsOnMainThread();
  NS_ASSERTION(!gRuntimeService, "More than one service!");
}

RuntimeService::~RuntimeService()
{
  AssertIsOnMainThread();

  // gRuntimeService can be null if Init() fails.
  NS_ASSERTION(!gRuntimeService || gRuntimeService == this,
               "More than one service!");

  gRuntimeService = nullptr;
}

// static
RuntimeService*
RuntimeService::GetOrCreateService()
{
  AssertIsOnMainThread();

  if (!gRuntimeService) {
    // The observer service now owns us until shutdown.
    gRuntimeService = new RuntimeService();
    if (NS_FAILED(gRuntimeService->Init())) {
      NS_WARNING("Failed to initialize!");
      gRuntimeService->Cleanup();
      gRuntimeService = nullptr;
      return nullptr;
    }
  }

  return gRuntimeService;
}

// static
RuntimeService*
RuntimeService::GetService()
{
  return gRuntimeService;
}

bool
RuntimeService::RegisterWorker(WorkerPrivate* aWorkerPrivate)
{
  aWorkerPrivate->AssertIsOnParentThread();

  WorkerPrivate* parent = aWorkerPrivate->GetParent();
  if (!parent) {
    AssertIsOnMainThread();

    if (mShuttingDown) {
      return false;
    }
  }

  const bool isServiceWorker = aWorkerPrivate->IsServiceWorker();
  const bool isSharedWorker = aWorkerPrivate->IsSharedWorker();
  const bool isDedicatedWorker = aWorkerPrivate->IsDedicatedWorker();
  if (isServiceWorker) {
    AssertIsOnMainThread();
    Telemetry::Accumulate(Telemetry::SERVICE_WORKER_SPAWN_ATTEMPTS, 1);
  }

  nsCString sharedWorkerScriptSpec;
  if (isSharedWorker) {
    AssertIsOnMainThread();

    nsCOMPtr<nsIURI> scriptURI = aWorkerPrivate->GetResolvedScriptURI();
    NS_ASSERTION(scriptURI, "Null script URI!");

    nsresult rv = scriptURI->GetSpec(sharedWorkerScriptSpec);
    if (NS_FAILED(rv)) {
      NS_WARNING("GetSpec failed?!");
      return false;
    }

    NS_ASSERTION(!sharedWorkerScriptSpec.IsEmpty(), "Empty spec!");
  }

  bool exemptFromPerDomainMax = false;
  if (isServiceWorker) {
    AssertIsOnMainThread();
    exemptFromPerDomainMax = Preferences::GetBool("dom.serviceWorkers.exemptFromPerDomainMax",
                                                  false);
  }

  const nsCString& domain = aWorkerPrivate->Domain();

  WorkerDomainInfo* domainInfo;
  bool queued = false;
  {
    MutexAutoLock lock(mMutex);

    if (!mDomainMap.Get(domain, &domainInfo)) {
      NS_ASSERTION(!parent, "Shouldn't have a parent here!");

      domainInfo = new WorkerDomainInfo();
      domainInfo->mDomain = domain;
      mDomainMap.Put(domain, domainInfo);
    }

    queued = gMaxWorkersPerDomain &&
             domainInfo->ActiveWorkerCount() >= gMaxWorkersPerDomain &&
             !domain.IsEmpty() &&
             !exemptFromPerDomainMax;

    if (queued) {
      domainInfo->mQueuedWorkers.AppendElement(aWorkerPrivate);

      // Worker spawn gets queued due to hitting max workers per domain
      // limit so let's log a warning.
      WorkerPrivate::ReportErrorToConsole("HittingMaxWorkersPerDomain2");

      if (isServiceWorker) {
        Telemetry::Accumulate(Telemetry::SERVICE_WORKER_SPAWN_GETS_QUEUED, 1);
      } else if (isSharedWorker) {
        Telemetry::Accumulate(Telemetry::SHARED_WORKER_SPAWN_GETS_QUEUED, 1);
      } else if (isDedicatedWorker) {
        Telemetry::Accumulate(Telemetry::DEDICATED_WORKER_SPAWN_GETS_QUEUED, 1);
      }
    }
    else if (parent) {
      domainInfo->mChildWorkerCount++;
    }
    else if (isServiceWorker) {
      domainInfo->mActiveServiceWorkers.AppendElement(aWorkerPrivate);
    }
    else {
      domainInfo->mActiveWorkers.AppendElement(aWorkerPrivate);
    }

    if (isSharedWorker) {
      const nsCString& sharedWorkerName = aWorkerPrivate->WorkerName();
      nsAutoCString key;
      GenerateSharedWorkerKey(sharedWorkerScriptSpec, sharedWorkerName,
                              aWorkerPrivate->GetOriginAttributes(), key);
      MOZ_ASSERT(!domainInfo->mSharedWorkerInfos.Get(key));

      SharedWorkerInfo* sharedWorkerInfo =
        new SharedWorkerInfo(aWorkerPrivate, sharedWorkerScriptSpec,
                             sharedWorkerName);
      domainInfo->mSharedWorkerInfos.Put(key, sharedWorkerInfo);
    }
  }

  // From here on out we must call UnregisterWorker if something fails!
  if (parent) {
    if (!parent->AddChildWorker(aWorkerPrivate)) {
      UnregisterWorker(aWorkerPrivate);
      return false;
    }
  }
  else {
    if (!mNavigatorPropertiesLoaded) {
      Navigator::AppName(mNavigatorProperties.mAppName,
                         false /* aUsePrefOverriddenValue */);
      if (NS_FAILED(Navigator::GetAppVersion(mNavigatorProperties.mAppVersion,
                                             false /* aUsePrefOverriddenValue */)) ||
          NS_FAILED(Navigator::GetPlatform(mNavigatorProperties.mPlatform,
                                           false /* aUsePrefOverriddenValue */))) {
        UnregisterWorker(aWorkerPrivate);
        return false;
      }

      // The navigator overridden properties should have already been read.

      Navigator::GetAcceptLanguages(mNavigatorProperties.mLanguages);
      mNavigatorPropertiesLoaded = true;
    }

    nsPIDOMWindowInner* window = aWorkerPrivate->GetWindow();

    if (!isServiceWorker) {
      // Service workers are excluded since their lifetime is separate from
      // that of dom windows.
      nsTArray<WorkerPrivate*>* windowArray;
      if (!mWindowMap.Get(window, &windowArray)) {
        windowArray = new nsTArray<WorkerPrivate*>(1);
        mWindowMap.Put(window, windowArray);
      }

      if (!windowArray->Contains(aWorkerPrivate)) {
        windowArray->AppendElement(aWorkerPrivate);
      } else {
        MOZ_ASSERT(aWorkerPrivate->IsSharedWorker());
      }
    }
  }

  if (!queued && !ScheduleWorker(aWorkerPrivate)) {
    return false;
  }

  if (isServiceWorker) {
    AssertIsOnMainThread();
    Telemetry::Accumulate(Telemetry::SERVICE_WORKER_WAS_SPAWNED, 1);
  }
  return true;
}

void
RuntimeService::RemoveSharedWorker(WorkerDomainInfo* aDomainInfo,
                                   WorkerPrivate* aWorkerPrivate)
{
  for (auto iter = aDomainInfo->mSharedWorkerInfos.Iter();
       !iter.Done();
       iter.Next()) {
    SharedWorkerInfo* data = iter.UserData();
    if (data->mWorkerPrivate == aWorkerPrivate) {
#ifdef DEBUG
      nsAutoCString key;
      GenerateSharedWorkerKey(data->mScriptSpec, data->mName,
                              aWorkerPrivate->GetOriginAttributes(), key);
      MOZ_ASSERT(iter.Key() == key);
#endif
      iter.Remove();
      break;
    }
  }
}

void
RuntimeService::UnregisterWorker(WorkerPrivate* aWorkerPrivate)
{
  aWorkerPrivate->AssertIsOnParentThread();

  WorkerPrivate* parent = aWorkerPrivate->GetParent();
  if (!parent) {
    AssertIsOnMainThread();
  }

  const nsCString& domain = aWorkerPrivate->Domain();

  WorkerPrivate* queuedWorker = nullptr;
  {
    MutexAutoLock lock(mMutex);

    WorkerDomainInfo* domainInfo;
    if (!mDomainMap.Get(domain, &domainInfo)) {
      NS_ERROR("Don't have an entry for this domain!");
    }

    // Remove old worker from everywhere.
    uint32_t index = domainInfo->mQueuedWorkers.IndexOf(aWorkerPrivate);
    if (index != kNoIndex) {
      // Was queued, remove from the list.
      domainInfo->mQueuedWorkers.RemoveElementAt(index);
    }
    else if (parent) {
      MOZ_ASSERT(domainInfo->mChildWorkerCount, "Must be non-zero!");
      domainInfo->mChildWorkerCount--;
    }
    else if (aWorkerPrivate->IsServiceWorker()) {
      MOZ_ASSERT(domainInfo->mActiveServiceWorkers.Contains(aWorkerPrivate),
                 "Don't know about this worker!");
      domainInfo->mActiveServiceWorkers.RemoveElement(aWorkerPrivate);
    }
    else {
      MOZ_ASSERT(domainInfo->mActiveWorkers.Contains(aWorkerPrivate),
                 "Don't know about this worker!");
      domainInfo->mActiveWorkers.RemoveElement(aWorkerPrivate);
    }

    if (aWorkerPrivate->IsSharedWorker()) {
      RemoveSharedWorker(domainInfo, aWorkerPrivate);
    }

    // See if there's a queued worker we can schedule.
    if (domainInfo->ActiveWorkerCount() < gMaxWorkersPerDomain &&
        !domainInfo->mQueuedWorkers.IsEmpty()) {
      queuedWorker = domainInfo->mQueuedWorkers[0];
      domainInfo->mQueuedWorkers.RemoveElementAt(0);

      if (queuedWorker->GetParent()) {
        domainInfo->mChildWorkerCount++;
      }
      else if (queuedWorker->IsServiceWorker()) {
        domainInfo->mActiveServiceWorkers.AppendElement(queuedWorker);
      }
      else {
        domainInfo->mActiveWorkers.AppendElement(queuedWorker);
      }
    }

    if (domainInfo->HasNoWorkers()) {
      MOZ_ASSERT(domainInfo->mQueuedWorkers.IsEmpty());
      mDomainMap.Remove(domain);
    }
  }

  if (aWorkerPrivate->IsServiceWorker()) {
    AssertIsOnMainThread();
    Telemetry::AccumulateTimeDelta(Telemetry::SERVICE_WORKER_LIFE_TIME,
                                   aWorkerPrivate->CreationTimeStamp());
  }

  if (aWorkerPrivate->IsSharedWorker() ||
      aWorkerPrivate->IsServiceWorker()) {
    AssertIsOnMainThread();
    aWorkerPrivate->CloseAllSharedWorkers();
  }

  if (parent) {
    parent->RemoveChildWorker(aWorkerPrivate);
  }
  else if (aWorkerPrivate->IsSharedWorker()) {
    AssertIsOnMainThread();

    for (auto iter = mWindowMap.Iter(); !iter.Done(); iter.Next()) {
      nsAutoPtr<nsTArray<WorkerPrivate*>>& workers = iter.Data();
      MOZ_ASSERT(workers.get());

      if (workers->RemoveElement(aWorkerPrivate)) {
        MOZ_ASSERT(!workers->Contains(aWorkerPrivate),
                   "Added worker more than once!");

        if (workers->IsEmpty()) {
          iter.Remove();
        }
      }
    }
  }
  else if (aWorkerPrivate->IsDedicatedWorker()) {
    // May be null.
    nsPIDOMWindowInner* window = aWorkerPrivate->GetWindow();

    nsTArray<WorkerPrivate*>* windowArray;
    MOZ_ALWAYS_TRUE(mWindowMap.Get(window, &windowArray));

    MOZ_ALWAYS_TRUE(windowArray->RemoveElement(aWorkerPrivate));

    if (windowArray->IsEmpty()) {
      mWindowMap.Remove(window);
    }
  }

  if (queuedWorker && !ScheduleWorker(queuedWorker)) {
    UnregisterWorker(queuedWorker);
  }
}

bool
RuntimeService::ScheduleWorker(WorkerPrivate* aWorkerPrivate)
{
  if (!aWorkerPrivate->Start()) {
    // This is ok, means that we didn't need to make a thread for this worker.
    return true;
  }

  RefPtr<WorkerThread> thread;
  {
    MutexAutoLock lock(mMutex);
    if (!mIdleThreadArray.IsEmpty()) {
      uint32_t index = mIdleThreadArray.Length() - 1;
      mIdleThreadArray[index].mThread.swap(thread);
      mIdleThreadArray.RemoveElementAt(index);
    }
  }

  const WorkerThreadFriendKey friendKey;

  if (!thread) {
    thread = WorkerThread::Create(friendKey);
    if (!thread) {
      UnregisterWorker(aWorkerPrivate);
      return false;
    }
  }

  int32_t priority = aWorkerPrivate->IsChromeWorker() ?
                     nsISupportsPriority::PRIORITY_NORMAL :
                     nsISupportsPriority::PRIORITY_LOW;

  if (NS_FAILED(thread->SetPriority(priority))) {
    NS_WARNING("Could not set the thread's priority!");
  }

  JSContext* cx = CycleCollectedJSContext::Get()->Context();
  nsCOMPtr<nsIRunnable> runnable =
    new WorkerThreadPrimaryRunnable(aWorkerPrivate, thread,
                                    JS_GetParentContext(cx));
  if (NS_FAILED(thread->DispatchPrimaryRunnable(friendKey, runnable.forget()))) {
    UnregisterWorker(aWorkerPrivate);
    return false;
  }

  return true;
}

// static
void
RuntimeService::ShutdownIdleThreads(nsITimer* aTimer, void* /* aClosure */)
{
  AssertIsOnMainThread();

  RuntimeService* runtime = RuntimeService::GetService();
  NS_ASSERTION(runtime, "This should never be null!");

  NS_ASSERTION(aTimer == runtime->mIdleThreadTimer, "Wrong timer!");

  // Cheat a little and grab all threads that expire within one second of now.
  TimeStamp now = TimeStamp::NowLoRes() + TimeDuration::FromSeconds(1);

  TimeStamp nextExpiration;

  AutoTArray<RefPtr<WorkerThread>, 20> expiredThreads;
  {
    MutexAutoLock lock(runtime->mMutex);

    for (uint32_t index = 0; index < runtime->mIdleThreadArray.Length();
         index++) {
      IdleThreadInfo& info = runtime->mIdleThreadArray[index];
      if (info.mExpirationTime > now) {
        nextExpiration = info.mExpirationTime;
        break;
      }

      RefPtr<WorkerThread>* thread = expiredThreads.AppendElement();
      thread->swap(info.mThread);
    }

    if (!expiredThreads.IsEmpty()) {
      runtime->mIdleThreadArray.RemoveElementsAt(0, expiredThreads.Length());
    }
  }

  if (!nextExpiration.IsNull()) {
    TimeDuration delta = nextExpiration - TimeStamp::NowLoRes();
    uint32_t delay(delta > TimeDuration(0) ? delta.ToMilliseconds() : 0);

    // Reschedule the timer.
    MOZ_ALWAYS_SUCCEEDS(
      aTimer->InitWithFuncCallback(ShutdownIdleThreads,
                                   nullptr,
                                   delay,
                                   nsITimer::TYPE_ONE_SHOT));
  }

  for (uint32_t index = 0; index < expiredThreads.Length(); index++) {
    if (NS_FAILED(expiredThreads[index]->Shutdown())) {
      NS_WARNING("Failed to shutdown thread!");
    }
  }
}

nsresult
RuntimeService::Init()
{
  AssertIsOnMainThread();

  nsLayoutStatics::AddRef();

  // Make sure PBackground actors are connected as soon as possible for the main
  // thread in case workers clone remote blobs here.
  if (!BackgroundChild::GetForCurrentThread()) {
    RefPtr<BackgroundChildCallback> callback = new BackgroundChildCallback();
    if (!BackgroundChild::GetOrCreateForCurrentThread(callback)) {
      MOZ_CRASH("Unable to connect PBackground actor for the main thread!");
    }
  }

  // Initialize JSSettings.
  if (!sDefaultJSSettings.gcSettings[0].IsSet()) {
    sDefaultJSSettings.contextOptions = JS::ContextOptions();
    sDefaultJSSettings.chrome.maxScriptRuntime = -1;
    sDefaultJSSettings.chrome.compartmentOptions.behaviors().setVersion(JSVERSION_LATEST);
    sDefaultJSSettings.content.maxScriptRuntime = MAX_SCRIPT_RUN_TIME_SEC;
#ifdef JS_GC_ZEAL
    sDefaultJSSettings.gcZealFrequency = JS_DEFAULT_ZEAL_FREQ;
    sDefaultJSSettings.gcZeal = 0;
#endif
    SetDefaultJSGCSettings(JSGC_MAX_BYTES, WORKER_DEFAULT_RUNTIME_HEAPSIZE);
    SetDefaultJSGCSettings(JSGC_ALLOCATION_THRESHOLD,
                           WORKER_DEFAULT_ALLOCATION_THRESHOLD);
  }

  mIdleThreadTimer = do_CreateInstance(NS_TIMER_CONTRACTID);
  NS_ENSURE_STATE(mIdleThreadTimer);

  nsCOMPtr<nsIObserverService> obs = services::GetObserverService();
  NS_ENSURE_TRUE(obs, NS_ERROR_FAILURE);

  nsresult rv =
    obs->AddObserver(this, NS_XPCOM_SHUTDOWN_THREADS_OBSERVER_ID, false);
  NS_ENSURE_SUCCESS(rv, rv);

  rv = obs->AddObserver(this, NS_XPCOM_SHUTDOWN_OBSERVER_ID, false);
  NS_ENSURE_SUCCESS(rv, rv);

  mObserved = true;

  if (NS_FAILED(obs->AddObserver(this, GC_REQUEST_OBSERVER_TOPIC, false))) {
    NS_WARNING("Failed to register for GC request notifications!");
  }

  if (NS_FAILED(obs->AddObserver(this, CC_REQUEST_OBSERVER_TOPIC, false))) {
    NS_WARNING("Failed to register for CC request notifications!");
  }

  if (NS_FAILED(obs->AddObserver(this, MEMORY_PRESSURE_OBSERVER_TOPIC,
                                 false))) {
    NS_WARNING("Failed to register for memory pressure notifications!");
  }

  if (NS_FAILED(obs->AddObserver(this, NS_IOSERVICE_OFFLINE_STATUS_TOPIC, false))) {
    NS_WARNING("Failed to register for offline notification event!");
  }

  MOZ_ASSERT(!gRuntimeServiceDuringInit, "This should be false!");
  gRuntimeServiceDuringInit = true;

  if (NS_FAILED(Preferences::RegisterCallback(
                                 LoadJSGCMemoryOptions,
                                 PREF_JS_OPTIONS_PREFIX PREF_MEM_OPTIONS_PREFIX,
                                 nullptr)) ||
      NS_FAILED(Preferences::RegisterCallbackAndCall(
                            LoadJSGCMemoryOptions,
                            PREF_WORKERS_OPTIONS_PREFIX PREF_MEM_OPTIONS_PREFIX,
                            nullptr)) ||
#ifdef JS_GC_ZEAL
      NS_FAILED(Preferences::RegisterCallback(
                                             LoadGCZealOptions,
                                             PREF_JS_OPTIONS_PREFIX PREF_GCZEAL,
                                             nullptr)) ||
#endif

#define WORKER_SIMPLE_PREF(name, getter, NAME)                                \
      NS_FAILED(Preferences::RegisterCallbackAndCall(                         \
                  WorkerPrefChanged,                                          \
                  name,                                                       \
                  reinterpret_cast<void*>(WORKERPREF_##NAME))) ||
#define WORKER_PREF(name, callback)                                           \
      NS_FAILED(Preferences::RegisterCallbackAndCall(                         \
                  callback,                                                   \
                  name,                                                       \
                  nullptr)) ||
#include "WorkerPrefs.h"
#undef WORKER_SIMPLE_PREF
#undef WORKER_PREF

      NS_FAILED(Preferences::RegisterCallbackAndCall(
                                                   LoadContextOptions,
                                                   PREF_WORKERS_OPTIONS_PREFIX,
                                                   nullptr)) ||
      NS_FAILED(Preferences::RegisterCallback(LoadContextOptions,
                                              PREF_JS_OPTIONS_PREFIX,
                                              nullptr))) {
    NS_WARNING("Failed to register pref callbacks!");
  }

  MOZ_ASSERT(gRuntimeServiceDuringInit, "Should be true!");
  gRuntimeServiceDuringInit = false;

  // We assume atomic 32bit reads/writes. If this assumption doesn't hold on
  // some wacky platform then the worst that could happen is that the close
  // handler will run for a slightly different amount of time.
  if (NS_FAILED(Preferences::AddIntVarCache(
                                   &sDefaultJSSettings.content.maxScriptRuntime,
                                   PREF_MAX_SCRIPT_RUN_TIME_CONTENT,
                                   MAX_SCRIPT_RUN_TIME_SEC)) ||
      NS_FAILED(Preferences::AddIntVarCache(
                                    &sDefaultJSSettings.chrome.maxScriptRuntime,
                                    PREF_MAX_SCRIPT_RUN_TIME_CHROME, -1))) {
    NS_WARNING("Failed to register timeout cache!");
  }

  int32_t maxPerDomain = Preferences::GetInt(PREF_WORKERS_MAX_PER_DOMAIN,
                                             MAX_WORKERS_PER_DOMAIN);
  gMaxWorkersPerDomain = std::max(0, maxPerDomain);

  int32_t maxHardwareConcurrency =
    Preferences::GetInt(PREF_WORKERS_MAX_HARDWARE_CONCURRENCY,
                        MAX_HARDWARE_CONCURRENCY);
  gMaxHardwareConcurrency = std::max(0, maxHardwareConcurrency);

  rv = InitOSFileConstants();
  if (NS_FAILED(rv)) {
    return rv;
  }

  if (NS_WARN_IF(!IndexedDatabaseManager::GetOrCreate())) {
    return NS_ERROR_UNEXPECTED;
  }

  return NS_OK;
}

void
RuntimeService::Shutdown()
{
  AssertIsOnMainThread();

  MOZ_ASSERT(!mShuttingDown);
  // That's it, no more workers.
  mShuttingDown = true;

  nsCOMPtr<nsIObserverService> obs = services::GetObserverService();
  NS_WARNING_ASSERTION(obs, "Failed to get observer service?!");

  // Tell anyone that cares that they're about to lose worker support.
  if (obs && NS_FAILED(obs->NotifyObservers(nullptr, WORKERS_SHUTDOWN_TOPIC,
                                            nullptr))) {
    NS_WARNING("NotifyObservers failed!");
  }

  {
    MutexAutoLock lock(mMutex);

    AutoTArray<WorkerPrivate*, 100> workers;
    AddAllTopLevelWorkersToArray(workers);

    if (!workers.IsEmpty()) {
      // Cancel all top-level workers.
      {
        MutexAutoUnlock unlock(mMutex);

        for (uint32_t index = 0; index < workers.Length(); index++) {
          if (!workers[index]->Kill()) {
            NS_WARNING("Failed to cancel worker!");
          }
        }
      }
    }
  }
}

// This spins the event loop until all workers are finished and their threads
// have been joined.
void
RuntimeService::Cleanup()
{
  AssertIsOnMainThread();

  nsCOMPtr<nsIObserverService> obs = services::GetObserverService();
  NS_WARNING_ASSERTION(obs, "Failed to get observer service?!");

  if (mIdleThreadTimer) {
    if (NS_FAILED(mIdleThreadTimer->Cancel())) {
      NS_WARNING("Failed to cancel idle timer!");
    }
    mIdleThreadTimer = nullptr;
  }

  {
    MutexAutoLock lock(mMutex);

    AutoTArray<WorkerPrivate*, 100> workers;
    AddAllTopLevelWorkersToArray(workers);

    if (!workers.IsEmpty()) {
      nsIThread* currentThread = NS_GetCurrentThread();
      NS_ASSERTION(currentThread, "This should never be null!");

      // Shut down any idle threads.
      if (!mIdleThreadArray.IsEmpty()) {
        AutoTArray<RefPtr<WorkerThread>, 20> idleThreads;

        uint32_t idleThreadCount = mIdleThreadArray.Length();
        idleThreads.SetLength(idleThreadCount);

        for (uint32_t index = 0; index < idleThreadCount; index++) {
          NS_ASSERTION(mIdleThreadArray[index].mThread, "Null thread!");
          idleThreads[index].swap(mIdleThreadArray[index].mThread);
        }

        mIdleThreadArray.Clear();

        MutexAutoUnlock unlock(mMutex);

        for (uint32_t index = 0; index < idleThreadCount; index++) {
          if (NS_FAILED(idleThreads[index]->Shutdown())) {
            NS_WARNING("Failed to shutdown thread!");
          }
        }
      }

      // And make sure all their final messages have run and all their threads
      // have joined.
      while (mDomainMap.Count()) {
        MutexAutoUnlock unlock(mMutex);

        if (!NS_ProcessNextEvent(currentThread)) {
          NS_WARNING("Something bad happened!");
          break;
        }
      }
    }
  }

  NS_ASSERTION(!mWindowMap.Count(), "All windows should have been released!");

  if (mObserved) {
    if (NS_FAILED(Preferences::UnregisterCallback(LoadContextOptions,
                                                  PREF_JS_OPTIONS_PREFIX,
                                                  nullptr)) ||
        NS_FAILED(Preferences::UnregisterCallback(LoadContextOptions,
                                                  PREF_WORKERS_OPTIONS_PREFIX,
                                                  nullptr)) ||

#define WORKER_SIMPLE_PREF(name, getter, NAME)                                \
      NS_FAILED(Preferences::UnregisterCallback(                              \
                  WorkerPrefChanged,                                          \
                  name,                                                       \
                  reinterpret_cast<void*>(WORKERPREF_##NAME))) ||
#define WORKER_PREF(name, callback)                                           \
      NS_FAILED(Preferences::UnregisterCallback(                              \
                  callback,                                                   \
                  name,                                                       \
                  nullptr)) ||
#include "WorkerPrefs.h"
#undef WORKER_SIMPLE_PREF
#undef WORKER_PREF

#ifdef JS_GC_ZEAL
        NS_FAILED(Preferences::UnregisterCallback(
                                             LoadGCZealOptions,
                                             PREF_JS_OPTIONS_PREFIX PREF_GCZEAL,
                                             nullptr)) ||
#endif
        NS_FAILED(Preferences::UnregisterCallback(
                                 LoadJSGCMemoryOptions,
                                 PREF_JS_OPTIONS_PREFIX PREF_MEM_OPTIONS_PREFIX,
                                 nullptr)) ||
        NS_FAILED(Preferences::UnregisterCallback(
                            LoadJSGCMemoryOptions,
                            PREF_WORKERS_OPTIONS_PREFIX PREF_MEM_OPTIONS_PREFIX,
                            nullptr))) {
      NS_WARNING("Failed to unregister pref callbacks!");
    }

    if (obs) {
      if (NS_FAILED(obs->RemoveObserver(this, GC_REQUEST_OBSERVER_TOPIC))) {
        NS_WARNING("Failed to unregister for GC request notifications!");
      }

      if (NS_FAILED(obs->RemoveObserver(this, CC_REQUEST_OBSERVER_TOPIC))) {
        NS_WARNING("Failed to unregister for CC request notifications!");
      }

      if (NS_FAILED(obs->RemoveObserver(this,
                                        MEMORY_PRESSURE_OBSERVER_TOPIC))) {
        NS_WARNING("Failed to unregister for memory pressure notifications!");
      }

      if (NS_FAILED(obs->RemoveObserver(this,
                                        NS_IOSERVICE_OFFLINE_STATUS_TOPIC))) {
        NS_WARNING("Failed to unregister for offline notification event!");
      }
      obs->RemoveObserver(this, NS_XPCOM_SHUTDOWN_THREADS_OBSERVER_ID);
      obs->RemoveObserver(this, NS_XPCOM_SHUTDOWN_OBSERVER_ID);
      mObserved = false;
    }
  }

  CleanupOSFileConstants();
  nsLayoutStatics::Release();
}

void
RuntimeService::AddAllTopLevelWorkersToArray(nsTArray<WorkerPrivate*>& aWorkers)
{
  for (auto iter = mDomainMap.Iter(); !iter.Done(); iter.Next()) {

    WorkerDomainInfo* aData = iter.UserData();

#ifdef DEBUG
    for (uint32_t index = 0; index < aData->mActiveWorkers.Length(); index++) {
      MOZ_ASSERT(!aData->mActiveWorkers[index]->GetParent(),
                 "Shouldn't have a parent in this list!");
    }
    for (uint32_t index = 0; index < aData->mActiveServiceWorkers.Length(); index++) {
      MOZ_ASSERT(!aData->mActiveServiceWorkers[index]->GetParent(),
                 "Shouldn't have a parent in this list!");
    }
#endif

    aWorkers.AppendElements(aData->mActiveWorkers);
    aWorkers.AppendElements(aData->mActiveServiceWorkers);

    // These might not be top-level workers...
    for (uint32_t index = 0; index < aData->mQueuedWorkers.Length(); index++) {
      WorkerPrivate* worker = aData->mQueuedWorkers[index];
      if (!worker->GetParent()) {
        aWorkers.AppendElement(worker);
      }
    }
  }
}

void
RuntimeService::GetWorkersForWindow(nsPIDOMWindowInner* aWindow,
                                    nsTArray<WorkerPrivate*>& aWorkers)
{
  AssertIsOnMainThread();

  nsTArray<WorkerPrivate*>* workers;
  if (mWindowMap.Get(aWindow, &workers)) {
    NS_ASSERTION(!workers->IsEmpty(), "Should have been removed!");
    aWorkers.AppendElements(*workers);
  }
  else {
    NS_ASSERTION(aWorkers.IsEmpty(), "Should be empty!");
  }
}

void
RuntimeService::CancelWorkersForWindow(nsPIDOMWindowInner* aWindow)
{
  AssertIsOnMainThread();

  nsTArray<WorkerPrivate*> workers;
  GetWorkersForWindow(aWindow, workers);

  if (!workers.IsEmpty()) {
    for (uint32_t index = 0; index < workers.Length(); index++) {
      WorkerPrivate*& worker = workers[index];

      if (worker->IsSharedWorker()) {
        worker->CloseSharedWorkersForWindow(aWindow);
      } else {
        worker->Cancel();
      }
    }
  }
}

void
RuntimeService::FreezeWorkersForWindow(nsPIDOMWindowInner* aWindow)
{
  AssertIsOnMainThread();
  MOZ_ASSERT(aWindow);

  nsTArray<WorkerPrivate*> workers;
  GetWorkersForWindow(aWindow, workers);

  for (uint32_t index = 0; index < workers.Length(); index++) {
    workers[index]->Freeze(aWindow);
  }
}

void
RuntimeService::ThawWorkersForWindow(nsPIDOMWindowInner* aWindow)
{
  AssertIsOnMainThread();
  MOZ_ASSERT(aWindow);

  nsTArray<WorkerPrivate*> workers;
  GetWorkersForWindow(aWindow, workers);

  for (uint32_t index = 0; index < workers.Length(); index++) {
    workers[index]->Thaw(aWindow);
  }
}

void
RuntimeService::SuspendWorkersForWindow(nsPIDOMWindowInner* aWindow)
{
  AssertIsOnMainThread();
  MOZ_ASSERT(aWindow);

  nsTArray<WorkerPrivate*> workers;
  GetWorkersForWindow(aWindow, workers);

  for (uint32_t index = 0; index < workers.Length(); index++) {
    workers[index]->ParentWindowPaused();
  }
}

void
RuntimeService::ResumeWorkersForWindow(nsPIDOMWindowInner* aWindow)
{
  AssertIsOnMainThread();
  MOZ_ASSERT(aWindow);

  nsTArray<WorkerPrivate*> workers;
  GetWorkersForWindow(aWindow, workers);

  for (uint32_t index = 0; index < workers.Length(); index++) {
    workers[index]->ParentWindowResumed();
  }
}

nsresult
RuntimeService::CreateSharedWorker(const GlobalObject& aGlobal,
                                   const nsAString& aScriptURL,
                                   const nsACString& aName,
                                   SharedWorker** aSharedWorker)
{
  AssertIsOnMainThread();

  nsCOMPtr<nsPIDOMWindowInner> window = do_QueryInterface(aGlobal.GetAsSupports());
  MOZ_ASSERT(window);

  JSContext* cx = aGlobal.Context();

  WorkerLoadInfo loadInfo;
  nsresult rv = WorkerPrivate::GetLoadInfo(cx, window, nullptr, aScriptURL,
                                           false,
                                           WorkerPrivate::OverrideLoadGroup,
                                           WorkerTypeShared, &loadInfo);
  NS_ENSURE_SUCCESS(rv, rv);

  return CreateSharedWorkerFromLoadInfo(cx, &loadInfo, aScriptURL, aName,
                                        aSharedWorker);
}

nsresult
RuntimeService::CreateSharedWorkerFromLoadInfo(JSContext* aCx,
                                               WorkerLoadInfo* aLoadInfo,
                                               const nsAString& aScriptURL,
                                               const nsACString& aName,
                                               SharedWorker** aSharedWorker)
{
  AssertIsOnMainThread();
  MOZ_ASSERT(aLoadInfo);
  MOZ_ASSERT(aLoadInfo->mResolvedScriptURI);

  RefPtr<WorkerPrivate> workerPrivate;
  {
    MutexAutoLock lock(mMutex);

    WorkerDomainInfo* domainInfo;
    SharedWorkerInfo* sharedWorkerInfo;

    nsCString scriptSpec;
    nsresult rv = aLoadInfo->mResolvedScriptURI->GetSpec(scriptSpec);
    NS_ENSURE_SUCCESS(rv, rv);

    MOZ_ASSERT(aLoadInfo->mPrincipal);
    nsAutoCString key;
    GenerateSharedWorkerKey(scriptSpec, aName,
        aLoadInfo->mPrincipal->OriginAttributesRef(), key);

    if (mDomainMap.Get(aLoadInfo->mDomain, &domainInfo) &&
        domainInfo->mSharedWorkerInfos.Get(key, &sharedWorkerInfo)) {
      workerPrivate = sharedWorkerInfo->mWorkerPrivate;
    }
  }

  // Keep a reference to the window before spawning the worker. If the worker is
  // a Shared/Service worker and the worker script loads and executes before
  // the SharedWorker object itself is created before then WorkerScriptLoaded()
  // will reset the loadInfo's window.
  nsCOMPtr<nsPIDOMWindowInner> window = aLoadInfo->mWindow;

  // shouldAttachToWorkerPrivate tracks whether our SharedWorker should actually
  // get attached to the WorkerPrivate we're using.  It will become false if the
  // WorkerPrivate already exists and its secure context state doesn't match
  // what we want for the new SharedWorker.
  bool shouldAttachToWorkerPrivate = true;
  bool created = false;
  ErrorResult rv;
  if (!workerPrivate) {
    workerPrivate =
      WorkerPrivate::Constructor(aCx, aScriptURL, false,
                                 WorkerTypeShared, aName, aLoadInfo, rv);
    NS_ENSURE_TRUE(workerPrivate, rv.StealNSResult());

    created = true;
  } else {
    // Check whether the secure context state matches.  The current compartment
    // of aCx is the compartment of the SharedWorker constructor that was
    // invoked, which is the compartment of the document that will be hooked up
    // to the worker, so that's what we want to check.
    shouldAttachToWorkerPrivate =
      workerPrivate->IsSecureContext() ==
        JS_GetIsSecureContext(js::GetContextCompartment(aCx));

    // If we're attaching to an existing SharedWorker private, then we
    // must update the overriden load group to account for our document's
    // load group.
    if (shouldAttachToWorkerPrivate) {
      workerPrivate->UpdateOverridenLoadGroup(aLoadInfo->mLoadGroup);
    }
  }

  // We don't actually care about this MessageChannel, but we use it to 'steal'
  // its 2 connected ports.
  nsCOMPtr<nsIGlobalObject> global = do_QueryInterface(window);
  RefPtr<MessageChannel> channel = MessageChannel::Constructor(global, rv);
  if (NS_WARN_IF(rv.Failed())) {
    return rv.StealNSResult();
  }

  RefPtr<SharedWorker> sharedWorker = new SharedWorker(window, workerPrivate,
                                                       channel->Port1());

  if (!shouldAttachToWorkerPrivate) {
    // We're done here.  Just queue up our error event and return our
    // dead-on-arrival SharedWorker.
    RefPtr<AsyncEventDispatcher> errorEvent =
      new AsyncEventDispatcher(sharedWorker, NS_LITERAL_STRING("error"), false);
    errorEvent->PostDOMEvent();
    sharedWorker.forget(aSharedWorker);
    return NS_OK;
  }

  if (!workerPrivate->RegisterSharedWorker(sharedWorker, channel->Port2())) {
    NS_WARNING("Worker is unreachable, this shouldn't happen!");
    sharedWorker->Close();
    return NS_ERROR_FAILURE;
  }

  // This is normally handled in RegisterWorker, but that wasn't called if the
  // worker already existed.
  if (!created) {
    nsTArray<WorkerPrivate*>* windowArray;
    if (!mWindowMap.Get(window, &windowArray)) {
      windowArray = new nsTArray<WorkerPrivate*>(1);
      mWindowMap.Put(window, windowArray);
    }

    if (!windowArray->Contains(workerPrivate)) {
      windowArray->AppendElement(workerPrivate);
    }
  }

  sharedWorker.forget(aSharedWorker);
  return NS_OK;
}

void
RuntimeService::ForgetSharedWorker(WorkerPrivate* aWorkerPrivate)
{
  AssertIsOnMainThread();
  MOZ_ASSERT(aWorkerPrivate);
  MOZ_ASSERT(aWorkerPrivate->IsSharedWorker());

  MutexAutoLock lock(mMutex);

  WorkerDomainInfo* domainInfo;
  if (mDomainMap.Get(aWorkerPrivate->Domain(), &domainInfo)) {
    RemoveSharedWorker(domainInfo, aWorkerPrivate);
  }
}

void
RuntimeService::NoteIdleThread(WorkerThread* aThread)
{
  AssertIsOnMainThread();
  MOZ_ASSERT(aThread);

  bool shutdownThread = mShuttingDown;
  bool scheduleTimer = false;

  if (!shutdownThread) {
    static TimeDuration timeout =
      TimeDuration::FromSeconds(IDLE_THREAD_TIMEOUT_SEC);

    TimeStamp expirationTime = TimeStamp::NowLoRes() + timeout;

    MutexAutoLock lock(mMutex);

    uint32_t previousIdleCount = mIdleThreadArray.Length();

    if (previousIdleCount < MAX_IDLE_THREADS) {
      IdleThreadInfo* info = mIdleThreadArray.AppendElement();
      info->mThread = aThread;
      info->mExpirationTime = expirationTime;

      scheduleTimer = previousIdleCount == 0;
    } else {
      shutdownThread = true;
    }
  }

  MOZ_ASSERT_IF(shutdownThread, !scheduleTimer);
  MOZ_ASSERT_IF(scheduleTimer, !shutdownThread);

  // Too many idle threads, just shut this one down.
  if (shutdownThread) {
    MOZ_ALWAYS_SUCCEEDS(aThread->Shutdown());
  } else if (scheduleTimer) {
    MOZ_ALWAYS_SUCCEEDS(
      mIdleThreadTimer->InitWithFuncCallback(ShutdownIdleThreads,
                                             nullptr,
                                             IDLE_THREAD_TIMEOUT_SEC * 1000,
                                             nsITimer::TYPE_ONE_SHOT));
  }
}

void
RuntimeService::UpdateAllWorkerContextOptions()
{
  BROADCAST_ALL_WORKERS(UpdateContextOptions, sDefaultJSSettings.contextOptions);
}

void
RuntimeService::UpdateAppNameOverridePreference(const nsAString& aValue)
{
  AssertIsOnMainThread();
  mNavigatorProperties.mAppNameOverridden = aValue;
}

void
RuntimeService::UpdateAppVersionOverridePreference(const nsAString& aValue)
{
  AssertIsOnMainThread();
  mNavigatorProperties.mAppVersionOverridden = aValue;
}

void
RuntimeService::UpdatePlatformOverridePreference(const nsAString& aValue)
{
  AssertIsOnMainThread();
  mNavigatorProperties.mPlatformOverridden = aValue;
}

void
RuntimeService::UpdateAllWorkerPreference(WorkerPreference aPref, bool aValue)
{
  BROADCAST_ALL_WORKERS(UpdatePreference, aPref, aValue);
}

void
RuntimeService::UpdateAllWorkerLanguages(const nsTArray<nsString>& aLanguages)
{
  MOZ_ASSERT(NS_IsMainThread());

  mNavigatorProperties.mLanguages = aLanguages;
  BROADCAST_ALL_WORKERS(UpdateLanguages, aLanguages);
}

void
RuntimeService::UpdateAllWorkerMemoryParameter(JSGCParamKey aKey,
                                               uint32_t aValue)
{
  BROADCAST_ALL_WORKERS(UpdateJSWorkerMemoryParameter, aKey, aValue);
}

#ifdef JS_GC_ZEAL
void
RuntimeService::UpdateAllWorkerGCZeal()
{
  BROADCAST_ALL_WORKERS(UpdateGCZeal, sDefaultJSSettings.gcZeal,
                        sDefaultJSSettings.gcZealFrequency);
}
#endif

void
RuntimeService::GarbageCollectAllWorkers(bool aShrinking)
{
  BROADCAST_ALL_WORKERS(GarbageCollect, aShrinking);
}

void
RuntimeService::CycleCollectAllWorkers()
{
  BROADCAST_ALL_WORKERS(CycleCollect, /* dummy = */ false);
}

void
RuntimeService::SendOfflineStatusChangeEventToAllWorkers(bool aIsOffline)
{
  BROADCAST_ALL_WORKERS(OfflineStatusChangeEvent, aIsOffline);
}

void
RuntimeService::MemoryPressureAllWorkers()
{
  BROADCAST_ALL_WORKERS(MemoryPressure, /* dummy = */ false);
}

uint32_t
RuntimeService::ClampedHardwareConcurrency() const
{
  // This needs to be atomic, because multiple workers, and even mainthread,
  // could race to initialize it at once.
  static Atomic<uint32_t> clampedHardwareConcurrency;

  // No need to loop here: if compareExchange fails, that just means that some
  // other worker has initialized numberOfProcessors, so we're good to go.
  if (!clampedHardwareConcurrency) {
    int32_t numberOfProcessors = PR_GetNumberOfProcessors();
    if (numberOfProcessors <= 0) {
      numberOfProcessors = 1; // Must be one there somewhere
    }
    uint32_t clampedValue = std::min(uint32_t(numberOfProcessors),
                                     gMaxHardwareConcurrency);
    clampedHardwareConcurrency.compareExchange(0, clampedValue);
  }

  return clampedHardwareConcurrency;
}

// nsISupports
NS_IMPL_ISUPPORTS(RuntimeService, nsIObserver)

// nsIObserver
NS_IMETHODIMP
RuntimeService::Observe(nsISupports* aSubject, const char* aTopic,
                        const char16_t* aData)
{
  AssertIsOnMainThread();

  if (!strcmp(aTopic, NS_XPCOM_SHUTDOWN_OBSERVER_ID)) {
    Shutdown();
    return NS_OK;
  }
  if (!strcmp(aTopic, NS_XPCOM_SHUTDOWN_THREADS_OBSERVER_ID)) {
    Cleanup();
    return NS_OK;
  }
  if (!strcmp(aTopic, GC_REQUEST_OBSERVER_TOPIC)) {
    GarbageCollectAllWorkers(/* shrinking = */ false);
    return NS_OK;
  }
  if (!strcmp(aTopic, CC_REQUEST_OBSERVER_TOPIC)) {
    CycleCollectAllWorkers();
    return NS_OK;
  }
  if (!strcmp(aTopic, MEMORY_PRESSURE_OBSERVER_TOPIC)) {
    GarbageCollectAllWorkers(/* shrinking = */ true);
    CycleCollectAllWorkers();
    MemoryPressureAllWorkers();
    return NS_OK;
  }
  if (!strcmp(aTopic, NS_IOSERVICE_OFFLINE_STATUS_TOPIC)) {
    SendOfflineStatusChangeEventToAllWorkers(NS_IsOffline());
    return NS_OK;
  }

  NS_NOTREACHED("Unknown observer topic!");
  return NS_OK;
}

/* static */ void
RuntimeService::WorkerPrefChanged(const char* aPrefName, void* aClosure)
{
  AssertIsOnMainThread();

  const WorkerPreference key =
    static_cast<WorkerPreference>(reinterpret_cast<uintptr_t>(aClosure));

  switch (key) {
#define WORKER_SIMPLE_PREF(name, getter, NAME) case WORKERPREF_##NAME:
#define WORKER_PREF(name, callback)
#include "WorkerPrefs.h"
#undef WORKER_SIMPLE_PREF
#undef WORKER_PREF
      sDefaultPreferences[key] = Preferences::GetBool(aPrefName, false);
      break;

    default:
      MOZ_ASSERT_UNREACHABLE("Invalid pref key");
      break;
  }

  RuntimeService* rts = RuntimeService::GetService();
  if (rts) {
    rts->UpdateAllWorkerPreference(key, sDefaultPreferences[key]);
  }
}

void
RuntimeService::JSVersionChanged(const char* /* aPrefName */, void* /* aClosure */)
{
  AssertIsOnMainThread();

  bool useLatest = Preferences::GetBool("dom.workers.latestJSVersion", false);
  JS::CompartmentOptions& options = sDefaultJSSettings.content.compartmentOptions;
  options.behaviors().setVersion(useLatest ? JSVERSION_LATEST : JSVERSION_DEFAULT);
}

bool
LogViolationDetailsRunnable::MainThreadRun()
{
  AssertIsOnMainThread();

  nsIContentSecurityPolicy* csp = mWorkerPrivate->GetCSP();
  if (csp) {
    NS_NAMED_LITERAL_STRING(scriptSample,
        "Call to eval() or related function blocked by CSP.");
    if (mWorkerPrivate->GetReportCSPViolations()) {
      csp->LogViolationDetails(nsIContentSecurityPolicy::VIOLATION_TYPE_EVAL,
                               mFileName, scriptSample, mLineNum,
                               EmptyString(), EmptyString());
    }
  }

  return true;
}

NS_IMPL_ISUPPORTS_INHERITED0(WorkerThreadPrimaryRunnable, Runnable)

NS_IMETHODIMP
WorkerThreadPrimaryRunnable::Run()
{
  using mozilla::ipc::BackgroundChild;

  char stackBaseGuess;

  PR_SetCurrentThreadName("DOM Worker");

  nsAutoCString threadName;
  threadName.AssignLiteral("DOM Worker '");
  threadName.Append(NS_LossyConvertUTF16toASCII(mWorkerPrivate->ScriptURL()));
  threadName.Append('\'');

  profiler_register_thread(threadName.get(), &stackBaseGuess);

  // Note: SynchronouslyCreateForCurrentThread() must be called prior to
  //       mWorkerPrivate->SetThread() in order to avoid accidentally consuming
  //       worker messages here.
  if (NS_WARN_IF(!BackgroundChild::SynchronouslyCreateForCurrentThread())) {
    // XXX need to fire an error at parent.
    // Failed in creating BackgroundChild: probably in shutdown. Continue to run
    // without BackgroundChild created.
  }

  class MOZ_STACK_CLASS SetThreadHelper final
  {
    // Raw pointer: this class is on the stack.
    WorkerPrivate* mWorkerPrivate;

  public:
    SetThreadHelper(WorkerPrivate* aWorkerPrivate, WorkerThread* aThread)
      : mWorkerPrivate(aWorkerPrivate)
    {
      MOZ_ASSERT(aWorkerPrivate);
      MOZ_ASSERT(aThread);

      mWorkerPrivate->SetThread(aThread);
    }

    ~SetThreadHelper()
    {
      if (mWorkerPrivate) {
        mWorkerPrivate->SetThread(nullptr);
      }
    }

    void Nullify()
    {
      MOZ_ASSERT(mWorkerPrivate);
      mWorkerPrivate->SetThread(nullptr);
      mWorkerPrivate = nullptr;
    }
  };

  SetThreadHelper threadHelper(mWorkerPrivate, mThread);

  mWorkerPrivate->AssertIsOnWorkerThread();

  {
    nsCycleCollector_startup();

    WorkerJSContext context(mWorkerPrivate);
    nsresult rv = context.Initialize(mParentContext);
    if (NS_WARN_IF(NS_FAILED(rv))) {
      return rv;
    }

    JSContext* cx = context.Context();

    if (!InitJSContextForWorker(mWorkerPrivate, cx)) {
      // XXX need to fire an error at parent.
      NS_ERROR("Failed to create context!");
      return NS_ERROR_FAILURE;
    }

    {
#ifdef MOZ_ENABLE_PROFILER_SPS
      PseudoStack* stack = profiler_get_pseudo_stack();
      if (stack) {
        stack->sampleContext(cx);
      }
#endif

      {
        JSAutoRequest ar(cx);

        mWorkerPrivate->DoRunLoop(cx);
        // The AutoJSAPI in DoRunLoop should have reported any exceptions left
        // on cx.  Note that we still need the JSAutoRequest above because
        // AutoJSAPI on workers does NOT enter a request!
        MOZ_ASSERT(!JS_IsExceptionPending(cx));
      }

      BackgroundChild::CloseForCurrentThread();

#ifdef MOZ_ENABLE_PROFILER_SPS
      if (stack) {
        stack->sampleContext(nullptr);
      }
#endif
    }

    // There may still be runnables on the debugger event queue that hold a
    // strong reference to the debugger global scope. These runnables are not
    // visible to the cycle collector, so we need to make sure to clear the
    // debugger event queue before we try to destroy the context. If we don't,
    // the garbage collector will crash.
    mWorkerPrivate->ClearDebuggerEventQueue();

    // Perform a full GC. This will collect the main worker global and CC,
    // which should break all cycles that touch JS.
    JS_GC(cx);

    // Before shutting down the cycle collector we need to do one more pass
    // through the event loop to clean up any C++ objects that need deferred
    // cleanup.
    mWorkerPrivate->ClearMainEventQueue(WorkerPrivate::WorkerRan);

    // Now WorkerJSContext goes out of scope and its destructor will shut
    // down the cycle collector. This breaks any remaining cycles and collects
    // any remaining C++ objects.
  }

  threadHelper.Nullify();

  mWorkerPrivate->ScheduleDeletion(WorkerPrivate::WorkerRan);

  // It is no longer safe to touch mWorkerPrivate.
  mWorkerPrivate = nullptr;

  // Now recycle this thread.
  nsCOMPtr<nsIThread> mainThread = do_GetMainThread();
  MOZ_ASSERT(mainThread);

  RefPtr<FinishedRunnable> finishedRunnable =
    new FinishedRunnable(mThread.forget());
  MOZ_ALWAYS_SUCCEEDS(mainThread->Dispatch(finishedRunnable,
                                           NS_DISPATCH_NORMAL));

  profiler_unregister_thread();
  return NS_OK;
}

NS_IMPL_ISUPPORTS_INHERITED0(WorkerThreadPrimaryRunnable::FinishedRunnable,
                             Runnable)

NS_IMETHODIMP
WorkerThreadPrimaryRunnable::FinishedRunnable::Run()
{
  AssertIsOnMainThread();

  RefPtr<WorkerThread> thread;
  mThread.swap(thread);

  RuntimeService* rts = RuntimeService::GetService();
  if (rts) {
    rts->NoteIdleThread(thread);
  }
  else if (thread->ShutdownRequired()) {
    MOZ_ALWAYS_SUCCEEDS(thread->Shutdown());
  }

  return NS_OK;
}