dom/promise/PromiseDebugging.cpp

   1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* vim: set ts=8 sts=2 et sw=2 tw=80: */
   3 /* This Source Code Form is subject to the terms of the Mozilla Public
   4  * License, v. 2.0. If a copy of the MPL was not distributed with this file,
   5  * You can obtain one at http://mozilla.org/MPL/2.0/. */
   6
   7 #include "js/Value.h"
   8 #include "nsThreadUtils.h"
   9
  10 #include "mozilla/CycleCollectedJSContext.h"
  11 #include "mozilla/RefPtr.h"
  12 #include "mozilla/SchedulerGroup.h"
  13 #include "mozilla/ThreadLocal.h"
  14 #include "mozilla/TimeStamp.h"
  15
  16 #include "mozilla/dom/BindingDeclarations.h"
  17 #include "mozilla/dom/ContentChild.h"
  18 #include "mozilla/dom/Promise.h"
  19 #include "mozilla/dom/PromiseBinding.h"
  20 #include "mozilla/dom/PromiseDebugging.h"
  21 #include "mozilla/dom/PromiseDebuggingBinding.h"
  22
  23 namespace mozilla {
  24 namespace dom {
  25
  26 class FlushRejections : public DiscardableRunnable {
  27  public:
  28   FlushRejections() : DiscardableRunnable("dom::FlushRejections") {}
  29
  30   static void Init() {
  31     if (!sDispatched.init()) {
  32       MOZ_CRASH("Could not initialize FlushRejections::sDispatched");
  33     }
  34     sDispatched.set(false);
  35   }
  36
  37   static void DispatchNeeded() {
  38     if (sDispatched.get()) {
  39       // An instance of `FlushRejections` has already been dispatched
  40       // and not run yet. No need to dispatch another one.
  41       return;
  42     }
  43     sDispatched.set(true);
  44
  45     // Dispatch the runnable to the current thread where
  46     // the Promise was rejected, e.g. workers or worklets.
  47     NS_DispatchToCurrentThread(new FlushRejections());
  48   }
  49
  50   static void FlushSync() {
  51     sDispatched.set(false);
  52
  53     // Call the callbacks if necessary.
  54     // Note that these callbacks may in turn cause Promise to turn
  55     // uncaught or consumed. Since `sDispatched` is `false`,
  56     // `FlushRejections` will be called once again, on an ulterior
  57     // tick.
  58     PromiseDebugging::FlushUncaughtRejectionsInternal();
  59   }
  60
  61   NS_IMETHOD Run() override {
  62     FlushSync();
  63     return NS_OK;
  64   }
  65
  66  private:
  67   // `true` if an instance of `FlushRejections` is currently dispatched
  68   // and has not been executed yet.
  69   static MOZ_THREAD_LOCAL(bool) sDispatched;
  70 };
  71
  72 /* static */ MOZ_THREAD_LOCAL(bool) FlushRejections::sDispatched;
  73
  74 /* static */
  75 void PromiseDebugging::GetState(GlobalObject& aGlobal,
  76                                 JS::Handle<JSObject*> aPromise,
  77                                 PromiseDebuggingStateHolder& aState,
  78                                 ErrorResult& aRv) {
  79   JSContext* cx = aGlobal.Context();
  80   // CheckedUnwrapStatic is fine, since we're looking for promises only.
  81   JS::Rooted<JSObject*> obj(cx, js::CheckedUnwrapStatic(aPromise));
  82   if (!obj || !JS::IsPromiseObject(obj)) {
  83     aRv.ThrowTypeError<MSG_IS_NOT_PROMISE>();
  84     return;
  85   }
  86   switch (JS::GetPromiseState(obj)) {
  87     case JS::PromiseState::Pending:
  88       aState.mState = PromiseDebuggingState::Pending;
  89       break;
  90     case JS::PromiseState::Fulfilled:
  91       aState.mState = PromiseDebuggingState::Fulfilled;
  92       aState.mValue = JS::GetPromiseResult(obj);
  93       break;
  94     case JS::PromiseState::Rejected:
  95       aState.mState = PromiseDebuggingState::Rejected;
  96       aState.mReason = JS::GetPromiseResult(obj);
  97       break;
  98   }
  99 }
 100
 101 /* static */
 102 void PromiseDebugging::GetPromiseID(GlobalObject& aGlobal,
 103                                     JS::Handle<JSObject*> aPromise,
 104                                     nsString& aID, ErrorResult& aRv) {
 105   JSContext* cx = aGlobal.Context();
 106   // CheckedUnwrapStatic is fine, since we're looking for promises only.
 107   JS::Rooted<JSObject*> obj(cx, js::CheckedUnwrapStatic(aPromise));
 108   if (!obj || !JS::IsPromiseObject(obj)) {
 109     aRv.ThrowTypeError<MSG_IS_NOT_PROMISE>();
 110     return;
 111   }
 112   uint64_t promiseID = JS::GetPromiseID(obj);
 113   aID = sIDPrefix;
 114   aID.AppendInt(promiseID);
 115 }
 116
 117 /* static */
 118 void PromiseDebugging::GetAllocationStack(GlobalObject& aGlobal,
 119                                           JS::Handle<JSObject*> aPromise,
 120                                           JS::MutableHandle<JSObject*> aStack,
 121                                           ErrorResult& aRv) {
 122   JSContext* cx = aGlobal.Context();
 123   // CheckedUnwrapStatic is fine, since we're looking for promises only.
 124   JS::Rooted<JSObject*> obj(cx, js::CheckedUnwrapStatic(aPromise));
 125   if (!obj || !JS::IsPromiseObject(obj)) {
 126     aRv.ThrowTypeError<MSG_IS_NOT_PROMISE>();
 127     return;
 128   }
 129   aStack.set(JS::GetPromiseAllocationSite(obj));
 130 }
 131
 132 /* static */
 133 void PromiseDebugging::GetRejectionStack(GlobalObject& aGlobal,
 134                                          JS::Handle<JSObject*> aPromise,
 135                                          JS::MutableHandle<JSObject*> aStack,
 136                                          ErrorResult& aRv) {
 137   JSContext* cx = aGlobal.Context();
 138   // CheckedUnwrapStatic is fine, since we're looking for promises only.
 139   JS::Rooted<JSObject*> obj(cx, js::CheckedUnwrapStatic(aPromise));
 140   if (!obj || !JS::IsPromiseObject(obj)) {
 141     aRv.ThrowTypeError<MSG_IS_NOT_PROMISE>();
 142     return;
 143   }
 144   aStack.set(JS::GetPromiseResolutionSite(obj));
 145 }
 146
 147 /* static */
 148 void PromiseDebugging::GetFullfillmentStack(GlobalObject& aGlobal,
 149                                             JS::Handle<JSObject*> aPromise,
 150                                             JS::MutableHandle<JSObject*> aStack,
 151                                             ErrorResult& aRv) {
 152   JSContext* cx = aGlobal.Context();
 153   // CheckedUnwrapStatic is fine, since we're looking for promises only.
 154   JS::Rooted<JSObject*> obj(cx, js::CheckedUnwrapStatic(aPromise));
 155   if (!obj || !JS::IsPromiseObject(obj)) {
 156     aRv.ThrowTypeError<MSG_IS_NOT_PROMISE>();
 157     return;
 158   }
 159   aStack.set(JS::GetPromiseResolutionSite(obj));
 160 }
 161
 162 /*static */
 163 nsString PromiseDebugging::sIDPrefix;
 164
 165 /* static */
 166 void PromiseDebugging::Init() {
 167   FlushRejections::Init();
 168
 169   // Generate a prefix for identifiers: "PromiseDebugging.$processid."
 170   sIDPrefix = u"PromiseDebugging."_ns;
 171   if (XRE_IsContentProcess()) {
 172     sIDPrefix.AppendInt(ContentChild::GetSingleton()->GetID());
 173     sIDPrefix.Append('.');
 174   } else {
 175     sIDPrefix.AppendLiteral("0.");
 176   }
 177 }
 178
 179 /* static */
 180 void PromiseDebugging::Shutdown() { sIDPrefix.SetIsVoid(true); }
 181
 182 /* static */
 183 void PromiseDebugging::FlushUncaughtRejections() {
 184   MOZ_ASSERT(!NS_IsMainThread());
 185   FlushRejections::FlushSync();
 186 }
 187
 188 /* static */
 189 void PromiseDebugging::AddUncaughtRejectionObserver(
 190     GlobalObject&, UncaughtRejectionObserver& aObserver) {
 191   CycleCollectedJSContext* storage = CycleCollectedJSContext::Get();
 192   nsTArray<nsCOMPtr<nsISupports>>& observers =
 193       storage->mUncaughtRejectionObservers;
 194   observers.AppendElement(&aObserver);
 195 }
 196
 197 /* static */
 198 bool PromiseDebugging::RemoveUncaughtRejectionObserver(
 199     GlobalObject&, UncaughtRejectionObserver& aObserver) {
 200   CycleCollectedJSContext* storage = CycleCollectedJSContext::Get();
 201   nsTArray<nsCOMPtr<nsISupports>>& observers =
 202       storage->mUncaughtRejectionObservers;
 203   for (size_t i = 0; i < observers.Length(); ++i) {
 204     UncaughtRejectionObserver* observer =
 205         static_cast<UncaughtRejectionObserver*>(observers[i].get());
 206     if (*observer == aObserver) {
 207       observers.RemoveElementAt(i);
 208       return true;
 209     }
 210   }
 211   return false;
 212 }
 213
 214 /* static */
 215 void PromiseDebugging::AddUncaughtRejection(JS::HandleObject aPromise) {
 216   // This might OOM, but won't set a pending exception, so we'll just ignore it.
 217   if (CycleCollectedJSContext::Get()->mUncaughtRejections.append(aPromise)) {
 218     FlushRejections::DispatchNeeded();
 219   }
 220 }
 221
 222 /* void */
 223 void PromiseDebugging::AddConsumedRejection(JS::HandleObject aPromise) {
 224   // If the promise is in our list of uncaught rejections, we haven't yet
 225   // reported it as unhandled. In that case, just remove it from the list
 226   // and don't add it to the list of consumed rejections.
 227   auto& uncaughtRejections =
 228       CycleCollectedJSContext::Get()->mUncaughtRejections;
 229   for (size_t i = 0; i < uncaughtRejections.length(); i++) {
 230     if (uncaughtRejections[i] == aPromise) {
 231       // To avoid large amounts of memmoves, we don't shrink the vector here.
 232       // Instead, we filter out nullptrs when iterating over the vector later.
 233       uncaughtRejections[i].set(nullptr);
 234       return;
 235     }
 236   }
 237   // This might OOM, but won't set a pending exception, so we'll just ignore it.
 238   if (CycleCollectedJSContext::Get()->mConsumedRejections.append(aPromise)) {
 239     FlushRejections::DispatchNeeded();
 240   }
 241 }
 242
 243 /* static */
 244 void PromiseDebugging::FlushUncaughtRejectionsInternal() {
 245   CycleCollectedJSContext* storage = CycleCollectedJSContext::Get();
 246
 247   auto& uncaught = storage->mUncaughtRejections;
 248   auto& consumed = storage->mConsumedRejections;
 249
 250   AutoJSAPI jsapi;
 251   jsapi.Init();
 252   JSContext* cx = jsapi.cx();
 253
 254   // Notify observers of uncaught Promise.
 255   auto& observers = storage->mUncaughtRejectionObservers;
 256
 257   for (size_t i = 0; i < uncaught.length(); i++) {
 258     JS::RootedObject promise(cx, uncaught[i]);
 259     // Filter out nullptrs which might've been added by
 260     // PromiseDebugging::AddConsumedRejection.
 261     if (!promise) {
 262       continue;
 263     }
 264
 265     bool suppressReporting = false;
 266     for (size_t j = 0; j < observers.Length(); ++j) {
 267       RefPtr<UncaughtRejectionObserver> obs =
 268           static_cast<UncaughtRejectionObserver*>(observers[j].get());
 269
 270       if (obs->OnLeftUncaught(promise, IgnoreErrors())) {
 271         suppressReporting = true;
 272       }
 273     }
 274
 275     if (!suppressReporting) {
 276       JSAutoRealm ar(cx, promise);
 277       Promise::ReportRejectedPromise(cx, promise);
 278     }
 279   }
 280   storage->mUncaughtRejections.clear();
 281
 282   // Notify observers of consumed Promise.
 283
 284   for (size_t i = 0; i < consumed.length(); i++) {
 285     JS::RootedObject promise(cx, consumed[i]);
 286
 287     for (size_t j = 0; j < observers.Length(); ++j) {
 288       RefPtr<UncaughtRejectionObserver> obs =
 289           static_cast<UncaughtRejectionObserver*>(observers[j].get());
 290
 291       obs->OnConsumed(promise, IgnoreErrors());
 292     }
 293   }
 294   storage->mConsumedRejections.clear();
 295 }
 296
 297 }  // namespace dom
 298 }  // namespace mozilla