xpcom/ds/nsObserverService.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
   5  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   6
   7 #include "mozilla/Logging.h"
   8 #include "nsComponentManagerUtils.h"
   9 #include "nsContentUtils.h"
  10 #include "nsIConsoleService.h"
  11 #include "nsIObserverService.h"
  12 #include "nsIObserver.h"
  13 #include "nsIScriptError.h"
  14 #include "nsObserverService.h"
  15 #include "nsObserverList.h"
  16 #include "nsServiceManagerUtils.h"
  17 #include "nsThreadUtils.h"
  18 #include "nsEnumeratorUtils.h"
  19 #include "xpcpublic.h"
  20 #include "mozilla/AppShutdown.h"
  21 #include "mozilla/net/NeckoCommon.h"
  22 #include "mozilla/ProfilerLabels.h"
  23 #include "mozilla/ProfilerMarkers.h"
  24 #include "mozilla/ResultExtensions.h"
  25 #include "mozilla/Telemetry.h"
  26 #include "mozilla/TimeStamp.h"
  27 #include "mozilla/Try.h"
  28 #include "nsString.h"
  29
  30 // Log module for nsObserverService logging...
  31 //
  32 // To enable logging (see prlog.h for full details):
  33 //
  34 //    set MOZ_LOG=ObserverService:5
  35 //    set MOZ_LOG_FILE=service.log
  36 //
  37 // This enables LogLevel::Debug level information and places all output in
  38 // the file service.log.
  39 static mozilla::LazyLogModule sObserverServiceLog("ObserverService");
  40 #define LOG(x) MOZ_LOG(sObserverServiceLog, mozilla::LogLevel::Debug, x)
  41
  42 using namespace mozilla;
  43
  44 NS_IMETHODIMP
  45 nsObserverService::CollectReports(nsIHandleReportCallback* aHandleReport,
  46                                   nsISupports* aData, bool aAnonymize) {
  47   struct SuspectObserver {
  48     SuspectObserver(const char* aTopic, size_t aReferentCount)
  49         : mTopic(aTopic), mReferentCount(aReferentCount) {}
  50     const char* mTopic;
  51     size_t mReferentCount;
  52   };
  53
  54   size_t totalNumStrong = 0;
  55   size_t totalNumWeakAlive = 0;
  56   size_t totalNumWeakDead = 0;
  57   nsTArray<SuspectObserver> suspectObservers;
  58
  59   for (auto iter = mObserverTopicTable.Iter(); !iter.Done(); iter.Next()) {
  60     nsObserverList* observerList = iter.Get();
  61     if (!observerList) {
  62       continue;
  63     }
  64
  65     size_t topicNumStrong = 0;
  66     size_t topicNumWeakAlive = 0;
  67     size_t topicNumWeakDead = 0;
  68
  69     nsMaybeWeakPtrArray<nsIObserver>& observers = observerList->mObservers;
  70     for (uint32_t i = 0; i < observers.Length(); i++) {
  71       if (observers[i].IsWeak()) {
  72         nsCOMPtr<nsIObserver> ref = observers[i].GetValue();
  73         if (ref) {
  74           topicNumWeakAlive++;
  75         } else {
  76           topicNumWeakDead++;
  77         }
  78       } else {
  79         topicNumStrong++;
  80       }
  81     }
  82
  83     totalNumStrong += topicNumStrong;
  84     totalNumWeakAlive += topicNumWeakAlive;
  85     totalNumWeakDead += topicNumWeakDead;
  86
  87     // Keep track of topics that have a suspiciously large number
  88     // of referents (symptom of leaks).
  89     size_t topicTotal = topicNumStrong + topicNumWeakAlive + topicNumWeakDead;
  90     if (topicTotal > kSuspectReferentCount) {
  91       SuspectObserver suspect(observerList->GetKey(), topicTotal);
  92       suspectObservers.AppendElement(suspect);
  93     }
  94   }
  95
  96   // These aren't privacy-sensitive and so don't need anonymizing.
  97   for (uint32_t i = 0; i < suspectObservers.Length(); i++) {
  98     SuspectObserver& suspect = suspectObservers[i];
  99     nsPrintfCString suspectPath("observer-service-suspect/referent(topic=%s)",
 100                                 suspect.mTopic);
 101     aHandleReport->Callback(
 102         /* process */ ""_ns, suspectPath, KIND_OTHER, UNITS_COUNT,
 103         suspect.mReferentCount,
 104         nsLiteralCString("A topic with a suspiciously large number of "
 105                          "referents.  This may be symptomatic of a leak "
 106                          "if the number of referents is high with "
 107                          "respect to the number of windows."),
 108         aData);
 109   }
 110
 111   MOZ_COLLECT_REPORT(
 112       "observer-service/referent/strong", KIND_OTHER, UNITS_COUNT,
 113       totalNumStrong,
 114       "The number of strong references held by the observer service.");
 115
 116   MOZ_COLLECT_REPORT(
 117       "observer-service/referent/weak/alive", KIND_OTHER, UNITS_COUNT,
 118       totalNumWeakAlive,
 119       "The number of weak references held by the observer service that are "
 120       "still alive.");
 121
 122   MOZ_COLLECT_REPORT(
 123       "observer-service/referent/weak/dead", KIND_OTHER, UNITS_COUNT,
 124       totalNumWeakDead,
 125       "The number of weak references held by the observer service that are "
 126       "dead.");
 127
 128   return NS_OK;
 129 }
 130
 131 ////////////////////////////////////////////////////////////////////////////////
 132 // nsObserverService Implementation
 133
 134 NS_IMPL_ISUPPORTS(nsObserverService, nsIObserverService, nsObserverService,
 135                   nsIMemoryReporter)
 136
 137 nsObserverService::nsObserverService() : mShuttingDown(false) {}
 138
 139 nsObserverService::~nsObserverService(void) { Shutdown(); }
 140
 141 void nsObserverService::RegisterReporter() { RegisterWeakMemoryReporter(this); }
 142
 143 void nsObserverService::Shutdown() {
 144   if (mShuttingDown) {
 145     return;
 146   }
 147
 148   mShuttingDown = true;
 149   UnregisterWeakMemoryReporter(this);
 150   mObserverTopicTable.Clear();
 151 }
 152
 153 nsresult nsObserverService::Create(const nsIID& aIID, void** aInstancePtr) {
 154   LOG(("nsObserverService::Create()"));
 155
 156   RefPtr<nsObserverService> os = new nsObserverService();
 157
 158   // The memory reporter can not be immediately registered here because
 159   // the nsMemoryReporterManager may attempt to get the nsObserverService
 160   // during initialization, causing a recursive GetService.
 161   NS_DispatchToCurrentThread(
 162       NewRunnableMethod("nsObserverService::RegisterReporter", os,
 163                         &nsObserverService::RegisterReporter));
 164
 165   return os->QueryInterface(aIID, aInstancePtr);
 166 }
 167
 168 nsresult nsObserverService::EnsureValidCall() const {
 169   if (!NS_IsMainThread()) {
 170     MOZ_CRASH("Using observer service off the main thread!");
 171     return NS_ERROR_UNEXPECTED;
 172   }
 173
 174   if (mShuttingDown) {
 175     NS_ERROR("Using observer service after XPCOM shutdown!");
 176     return NS_ERROR_ILLEGAL_DURING_SHUTDOWN;
 177   }
 178
 179   return NS_OK;
 180 }
 181
 182 nsresult nsObserverService::FilterHttpOnTopics(const char* aTopic) {
 183   // Specifically allow some http-on-* observer notifications in the child
 184   // process.
 185   if (mozilla::net::IsNeckoChild() && !strncmp(aTopic, "http-on-", 8) &&
 186       strcmp(aTopic, "http-on-before-stop-request") &&
 187       strcmp(aTopic, "http-on-failed-opening-request") &&
 188       // TODO: Merge cache response notifications (bug 1919218)
 189       strcmp(aTopic, "http-on-image-cache-response") &&
 190       strcmp(aTopic, "http-on-stylesheet-cache-response") &&
 191       strcmp(aTopic, "http-on-resource-cache-response") &&
 192       strcmp(aTopic, "http-on-opening-request") &&
 193       strcmp(aTopic, "http-on-stop-request")) {
 194     nsCOMPtr<nsIConsoleService> console(
 195         do_GetService(NS_CONSOLESERVICE_CONTRACTID));
 196     nsCOMPtr<nsIScriptError> error(
 197         do_CreateInstance(NS_SCRIPTERROR_CONTRACTID));
 198     error->Init(u"http-on-* observers only work in the parent process"_ns,
 199                 ""_ns, 0, 0, nsIScriptError::warningFlag,
 200                 "chrome javascript"_ns, false /* from private window */,
 201                 true /* from chrome context */);
 202     console->LogMessage(error);
 203
 204     return NS_ERROR_NOT_IMPLEMENTED;
 205   }
 206
 207   return NS_OK;
 208 }
 209
 210 NS_IMETHODIMP
 211 nsObserverService::AddObserver(nsIObserver* aObserver, const char* aTopic,
 212                                bool aOwnsWeak) {
 213   LOG(("nsObserverService::AddObserver(%p: %s, %s)", (void*)aObserver, aTopic,
 214        aOwnsWeak ? "weak" : "strong"));
 215
 216   MOZ_TRY(EnsureValidCall());
 217   if (NS_WARN_IF(!aObserver) || NS_WARN_IF(!aTopic)) {
 218     return NS_ERROR_INVALID_ARG;
 219   }
 220
 221   MOZ_TRY(FilterHttpOnTopics(aTopic));
 222
 223   nsObserverList* observerList = mObserverTopicTable.PutEntry(aTopic);
 224   if (!observerList) {
 225     return NS_ERROR_OUT_OF_MEMORY;
 226   }
 227
 228   return observerList->AddObserver(aObserver, aOwnsWeak);
 229 }
 230
 231 NS_IMETHODIMP
 232 nsObserverService::RemoveObserver(nsIObserver* aObserver, const char* aTopic) {
 233   LOG(("nsObserverService::RemoveObserver(%p: %s)", (void*)aObserver, aTopic));
 234
 235   if (mShuttingDown) {
 236     // The service is shutting down. Let's ignore this call.
 237     return NS_OK;
 238   }
 239
 240   MOZ_TRY(EnsureValidCall());
 241   if (NS_WARN_IF(!aObserver) || NS_WARN_IF(!aTopic)) {
 242     return NS_ERROR_INVALID_ARG;
 243   }
 244
 245   nsObserverList* observerList = mObserverTopicTable.GetEntry(aTopic);
 246   if (!observerList) {
 247     return NS_ERROR_FAILURE;
 248   }
 249
 250   return observerList->RemoveObserver(aObserver);
 251 }
 252
 253 NS_IMETHODIMP
 254 nsObserverService::EnumerateObservers(const char* aTopic,
 255                                       nsISimpleEnumerator** anEnumerator) {
 256   LOG(("nsObserverService::EnumerateObservers(%s)", aTopic));
 257
 258   MOZ_TRY(EnsureValidCall());
 259   if (NS_WARN_IF(!anEnumerator) || NS_WARN_IF(!aTopic)) {
 260     return NS_ERROR_INVALID_ARG;
 261   }
 262
 263   nsObserverList* observerList = mObserverTopicTable.GetEntry(aTopic);
 264   if (!observerList) {
 265     return NS_NewEmptyEnumerator(anEnumerator);
 266   }
 267
 268   observerList->GetObserverList(anEnumerator);
 269   return NS_OK;
 270 }
 271
 272 // Enumerate observers of aTopic and call Observe on each.
 273 NS_IMETHODIMP nsObserverService::NotifyObservers(nsISupports* aSubject,
 274                                                  const char* aTopic,
 275                                                  const char16_t* aSomeData) {
 276   LOG(("nsObserverService::NotifyObservers(%s)", aTopic));
 277
 278   MOZ_TRY(EnsureValidCall());
 279   if (NS_WARN_IF(!aTopic)) {
 280     return NS_ERROR_INVALID_ARG;
 281   }
 282
 283   MOZ_ASSERT(AppShutdown::IsNoOrLegalShutdownTopic(aTopic));
 284
 285   AUTO_PROFILER_MARKER_TEXT("NotifyObservers", OTHER, MarkerStack::Capture(),
 286                             nsDependentCString(aTopic));
 287   AUTO_PROFILER_LABEL_DYNAMIC_CSTR_NONSENSITIVE(
 288       "nsObserverService::NotifyObservers", OTHER, aTopic);
 289
 290   nsObserverList* observerList = mObserverTopicTable.GetEntry(aTopic);
 291   if (observerList) {
 292     observerList->NotifyObservers(aSubject, aTopic, aSomeData);
 293   }
 294
 295   return NS_OK;
 296 }
 297
 298 NS_IMETHODIMP
 299 nsObserverService::UnmarkGrayStrongObservers() {
 300   MOZ_TRY(EnsureValidCall());
 301
 302   nsCOMArray<nsIObserver> strongObservers;
 303   for (auto iter = mObserverTopicTable.Iter(); !iter.Done(); iter.Next()) {
 304     nsObserverList* aObserverList = iter.Get();
 305     if (aObserverList) {
 306       aObserverList->AppendStrongObservers(strongObservers);
 307     }
 308   }
 309
 310   for (uint32_t i = 0; i < strongObservers.Length(); ++i) {
 311     xpc_TryUnmarkWrappedGrayObject(strongObservers[i]);
 312   }
 313
 314   return NS_OK;
 315 }
 316
 317 bool nsObserverService::HasObservers(const char* aTopic) {
 318   return mObserverTopicTable.Contains(aTopic);
 319 }
 320
 321 namespace {
 322
 323 class NotifyWhenScriptSafeRunnable : public mozilla::Runnable {
 324  public:
 325   NotifyWhenScriptSafeRunnable(nsIObserverService* aObs, nsISupports* aSubject,
 326                                const char* aTopic, const char16_t* aData)
 327       : mozilla::Runnable("NotifyWhenScriptSafeRunnable"),
 328         mObs(aObs),
 329         mSubject(aSubject),
 330         mTopic(aTopic) {
 331     if (aData) {
 332       mData.Assign(aData);
 333     } else {
 334       mData.SetIsVoid(true);
 335     }
 336   }
 337
 338   NS_IMETHOD Run() override {
 339     const char16_t* data = mData.IsVoid() ? nullptr : mData.get();
 340     return mObs->NotifyObservers(mSubject, mTopic.get(), data);
 341   }
 342
 343  private:
 344   nsCOMPtr<nsIObserverService> mObs;
 345   nsCOMPtr<nsISupports> mSubject;
 346   nsCString mTopic;
 347   nsString mData;
 348 };
 349
 350 }  // namespace
 351
 352 nsresult nsIObserverService::NotifyWhenScriptSafe(nsISupports* aSubject,
 353                                                   const char* aTopic,
 354                                                   const char16_t* aData) {
 355   if (nsContentUtils::IsSafeToRunScript()) {
 356     return NotifyObservers(aSubject, aTopic, aData);
 357   }
 358
 359   nsContentUtils::AddScriptRunner(MakeAndAddRef<NotifyWhenScriptSafeRunnable>(
 360       this, aSubject, aTopic, aData));
 361   return NS_OK;
 362 }