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       strcmp(aTopic, "http-on-image-cache-response") &&
 189       strcmp(aTopic, "http-on-opening-request") &&
 190       strcmp(aTopic, "http-on-stop-request")) {
 191     nsCOMPtr<nsIConsoleService> console(
 192         do_GetService(NS_CONSOLESERVICE_CONTRACTID));
 193     nsCOMPtr<nsIScriptError> error(
 194         do_CreateInstance(NS_SCRIPTERROR_CONTRACTID));
 195     error->Init(u"http-on-* observers only work in the parent process"_ns,
 196                 u""_ns, u""_ns, 0, 0, nsIScriptError::warningFlag,
 197                 "chrome javascript"_ns, false /* from private window */,
 198                 true /* from chrome context */);
 199     console->LogMessage(error);
 200
 201     return NS_ERROR_NOT_IMPLEMENTED;
 202   }
 203
 204   return NS_OK;
 205 }
 206
 207 NS_IMETHODIMP
 208 nsObserverService::AddObserver(nsIObserver* aObserver, const char* aTopic,
 209                                bool aOwnsWeak) {
 210   LOG(("nsObserverService::AddObserver(%p: %s, %s)", (void*)aObserver, aTopic,
 211        aOwnsWeak ? "weak" : "strong"));
 212
 213   MOZ_TRY(EnsureValidCall());
 214   if (NS_WARN_IF(!aObserver) || NS_WARN_IF(!aTopic)) {
 215     return NS_ERROR_INVALID_ARG;
 216   }
 217
 218   MOZ_TRY(FilterHttpOnTopics(aTopic));
 219
 220   nsObserverList* observerList = mObserverTopicTable.PutEntry(aTopic);
 221   if (!observerList) {
 222     return NS_ERROR_OUT_OF_MEMORY;
 223   }
 224
 225   return observerList->AddObserver(aObserver, aOwnsWeak);
 226 }
 227
 228 NS_IMETHODIMP
 229 nsObserverService::RemoveObserver(nsIObserver* aObserver, const char* aTopic) {
 230   LOG(("nsObserverService::RemoveObserver(%p: %s)", (void*)aObserver, aTopic));
 231
 232   if (mShuttingDown) {
 233     // The service is shutting down. Let's ignore this call.
 234     return NS_OK;
 235   }
 236
 237   MOZ_TRY(EnsureValidCall());
 238   if (NS_WARN_IF(!aObserver) || NS_WARN_IF(!aTopic)) {
 239     return NS_ERROR_INVALID_ARG;
 240   }
 241
 242   nsObserverList* observerList = mObserverTopicTable.GetEntry(aTopic);
 243   if (!observerList) {
 244     return NS_ERROR_FAILURE;
 245   }
 246
 247   return observerList->RemoveObserver(aObserver);
 248 }
 249
 250 NS_IMETHODIMP
 251 nsObserverService::EnumerateObservers(const char* aTopic,
 252                                       nsISimpleEnumerator** anEnumerator) {
 253   LOG(("nsObserverService::EnumerateObservers(%s)", aTopic));
 254
 255   MOZ_TRY(EnsureValidCall());
 256   if (NS_WARN_IF(!anEnumerator) || NS_WARN_IF(!aTopic)) {
 257     return NS_ERROR_INVALID_ARG;
 258   }
 259
 260   nsObserverList* observerList = mObserverTopicTable.GetEntry(aTopic);
 261   if (!observerList) {
 262     return NS_NewEmptyEnumerator(anEnumerator);
 263   }
 264
 265   observerList->GetObserverList(anEnumerator);
 266   return NS_OK;
 267 }
 268
 269 // Enumerate observers of aTopic and call Observe on each.
 270 NS_IMETHODIMP nsObserverService::NotifyObservers(nsISupports* aSubject,
 271                                                  const char* aTopic,
 272                                                  const char16_t* aSomeData) {
 273   LOG(("nsObserverService::NotifyObservers(%s)", aTopic));
 274
 275   MOZ_TRY(EnsureValidCall());
 276   if (NS_WARN_IF(!aTopic)) {
 277     return NS_ERROR_INVALID_ARG;
 278   }
 279
 280   MOZ_ASSERT(AppShutdown::IsNoOrLegalShutdownTopic(aTopic));
 281
 282   AUTO_PROFILER_MARKER_TEXT("NotifyObservers", OTHER, MarkerStack::Capture(),
 283                             nsDependentCString(aTopic));
 284   AUTO_PROFILER_LABEL_DYNAMIC_CSTR_NONSENSITIVE(
 285       "nsObserverService::NotifyObservers", OTHER, aTopic);
 286
 287   nsObserverList* observerList = mObserverTopicTable.GetEntry(aTopic);
 288   if (observerList) {
 289     observerList->NotifyObservers(aSubject, aTopic, aSomeData);
 290   }
 291
 292   return NS_OK;
 293 }
 294
 295 NS_IMETHODIMP
 296 nsObserverService::UnmarkGrayStrongObservers() {
 297   MOZ_TRY(EnsureValidCall());
 298
 299   nsCOMArray<nsIObserver> strongObservers;
 300   for (auto iter = mObserverTopicTable.Iter(); !iter.Done(); iter.Next()) {
 301     nsObserverList* aObserverList = iter.Get();
 302     if (aObserverList) {
 303       aObserverList->AppendStrongObservers(strongObservers);
 304     }
 305   }
 306
 307   for (uint32_t i = 0; i < strongObservers.Length(); ++i) {
 308     xpc_TryUnmarkWrappedGrayObject(strongObservers[i]);
 309   }
 310
 311   return NS_OK;
 312 }
 313
 314 bool nsObserverService::HasObservers(const char* aTopic) {
 315   return mObserverTopicTable.Contains(aTopic);
 316 }
 317
 318 namespace {
 319
 320 class NotifyWhenScriptSafeRunnable : public mozilla::Runnable {
 321  public:
 322   NotifyWhenScriptSafeRunnable(nsIObserverService* aObs, nsISupports* aSubject,
 323                                const char* aTopic, const char16_t* aData)
 324       : mozilla::Runnable("NotifyWhenScriptSafeRunnable"),
 325         mObs(aObs),
 326         mSubject(aSubject),
 327         mTopic(aTopic) {
 328     if (aData) {
 329       mData.Assign(aData);
 330     } else {
 331       mData.SetIsVoid(true);
 332     }
 333   }
 334
 335   NS_IMETHOD Run() override {
 336     const char16_t* data = mData.IsVoid() ? nullptr : mData.get();
 337     return mObs->NotifyObservers(mSubject, mTopic.get(), data);
 338   }
 339
 340  private:
 341   nsCOMPtr<nsIObserverService> mObs;
 342   nsCOMPtr<nsISupports> mSubject;
 343   nsCString mTopic;
 344   nsString mData;
 345 };
 346
 347 }  // namespace
 348
 349 nsresult nsIObserverService::NotifyWhenScriptSafe(nsISupports* aSubject,
 350                                                   const char* aTopic,
 351                                                   const char16_t* aData) {
 352   if (nsContentUtils::IsSafeToRunScript()) {
 353     return NotifyObservers(aSubject, aTopic, aData);
 354   }
 355
 356   nsContentUtils::AddScriptRunner(MakeAndAddRef<NotifyWhenScriptSafeRunnable>(
 357       this, aSubject, aTopic, aData));
 358   return NS_OK;
 359 }