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 "nsString.h"
  28
  29 static const uint32_t kMinTelemetryNotifyObserversLatencyMs = 1;
  30
  31 // Log module for nsObserverService logging...
  32 //
  33 // To enable logging (see prlog.h for full details):
  34 //
  35 //    set MOZ_LOG=ObserverService:5
  36 //    set MOZ_LOG_FILE=service.log
  37 //
  38 // This enables LogLevel::Debug level information and places all output in
  39 // the file service.log.
  40 static mozilla::LazyLogModule sObserverServiceLog("ObserverService");
  41 #define LOG(x) MOZ_LOG(sObserverServiceLog, mozilla::LogLevel::Debug, x)
  42
  43 using namespace mozilla;
  44
  45 NS_IMETHODIMP
  46 nsObserverService::CollectReports(nsIHandleReportCallback* aHandleReport,
  47                                   nsISupports* aData, bool aAnonymize) {
  48   struct SuspectObserver {
  49     SuspectObserver(const char* aTopic, size_t aReferentCount)
  50         : mTopic(aTopic), mReferentCount(aReferentCount) {}
  51     const char* mTopic;
  52     size_t mReferentCount;
  53   };
  54
  55   size_t totalNumStrong = 0;
  56   size_t totalNumWeakAlive = 0;
  57   size_t totalNumWeakDead = 0;
  58   nsTArray<SuspectObserver> suspectObservers;
  59
  60   for (auto iter = mObserverTopicTable.Iter(); !iter.Done(); iter.Next()) {
  61     nsObserverList* observerList = iter.Get();
  62     if (!observerList) {
  63       continue;
  64     }
  65
  66     size_t topicNumStrong = 0;
  67     size_t topicNumWeakAlive = 0;
  68     size_t topicNumWeakDead = 0;
  69
  70     nsMaybeWeakPtrArray<nsIObserver>& observers = observerList->mObservers;
  71     for (uint32_t i = 0; i < observers.Length(); i++) {
  72       if (observers[i].IsWeak()) {
  73         nsCOMPtr<nsIObserver> ref = observers[i].GetValue();
  74         if (ref) {
  75           topicNumWeakAlive++;
  76         } else {
  77           topicNumWeakDead++;
  78         }
  79       } else {
  80         topicNumStrong++;
  81       }
  82     }
  83
  84     totalNumStrong += topicNumStrong;
  85     totalNumWeakAlive += topicNumWeakAlive;
  86     totalNumWeakDead += topicNumWeakDead;
  87
  88     // Keep track of topics that have a suspiciously large number
  89     // of referents (symptom of leaks).
  90     size_t topicTotal = topicNumStrong + topicNumWeakAlive + topicNumWeakDead;
  91     if (topicTotal > kSuspectReferentCount) {
  92       SuspectObserver suspect(observerList->GetKey(), topicTotal);
  93       suspectObservers.AppendElement(suspect);
  94     }
  95   }
  96
  97   // These aren't privacy-sensitive and so don't need anonymizing.
  98   for (uint32_t i = 0; i < suspectObservers.Length(); i++) {
  99     SuspectObserver& suspect = suspectObservers[i];
 100     nsPrintfCString suspectPath("observer-service-suspect/referent(topic=%s)",
 101                                 suspect.mTopic);
 102     aHandleReport->Callback(
 103         /* process */ ""_ns, suspectPath, KIND_OTHER, UNITS_COUNT,
 104         suspect.mReferentCount,
 105         nsLiteralCString("A topic with a suspiciously large number of "
 106                          "referents.  This may be symptomatic of a leak "
 107                          "if the number of referents is high with "
 108                          "respect to the number of windows."),
 109         aData);
 110   }
 111
 112   MOZ_COLLECT_REPORT(
 113       "observer-service/referent/strong", KIND_OTHER, UNITS_COUNT,
 114       totalNumStrong,
 115       "The number of strong references held by the observer service.");
 116
 117   MOZ_COLLECT_REPORT(
 118       "observer-service/referent/weak/alive", KIND_OTHER, UNITS_COUNT,
 119       totalNumWeakAlive,
 120       "The number of weak references held by the observer service that are "
 121       "still alive.");
 122
 123   MOZ_COLLECT_REPORT(
 124       "observer-service/referent/weak/dead", KIND_OTHER, UNITS_COUNT,
 125       totalNumWeakDead,
 126       "The number of weak references held by the observer service that are "
 127       "dead.");
 128
 129   return NS_OK;
 130 }
 131
 132 ////////////////////////////////////////////////////////////////////////////////
 133 // nsObserverService Implementation
 134
 135 NS_IMPL_ISUPPORTS(nsObserverService, nsIObserverService, nsObserverService,
 136                   nsIMemoryReporter)
 137
 138 nsObserverService::nsObserverService() : mShuttingDown(false) {}
 139
 140 nsObserverService::~nsObserverService(void) { Shutdown(); }
 141
 142 void nsObserverService::RegisterReporter() { RegisterWeakMemoryReporter(this); }
 143
 144 void nsObserverService::Shutdown() {
 145   if (mShuttingDown) {
 146     return;
 147   }
 148
 149   mShuttingDown = true;
 150   UnregisterWeakMemoryReporter(this);
 151   mObserverTopicTable.Clear();
 152 }
 153
 154 nsresult nsObserverService::Create(nsISupports* aOuter, const nsIID& aIID,
 155                                    void** aInstancePtr) {
 156   LOG(("nsObserverService::Create()"));
 157
 158   RefPtr<nsObserverService> os = new nsObserverService();
 159
 160   // The memory reporter can not be immediately registered here because
 161   // the nsMemoryReporterManager may attempt to get the nsObserverService
 162   // during initialization, causing a recursive GetService.
 163   NS_DispatchToCurrentThread(
 164       NewRunnableMethod("nsObserverService::RegisterReporter", os,
 165                         &nsObserverService::RegisterReporter));
 166
 167   return os->QueryInterface(aIID, aInstancePtr);
 168 }
 169
 170 nsresult nsObserverService::EnsureValidCall() const {
 171   if (!NS_IsMainThread()) {
 172     MOZ_CRASH("Using observer service off the main thread!");
 173     return NS_ERROR_UNEXPECTED;
 174   }
 175
 176   if (mShuttingDown) {
 177     NS_ERROR("Using observer service after XPCOM shutdown!");
 178     return NS_ERROR_ILLEGAL_DURING_SHUTDOWN;
 179   }
 180
 181   return NS_OK;
 182 }
 183
 184 nsresult nsObserverService::FilterHttpOnTopics(const char* aTopic) {
 185   // Specifically allow http-on-opening-request and http-on-stop-request in the
 186   // child process; see bug 1269765.
 187   if (mozilla::net::IsNeckoChild() && !strncmp(aTopic, "http-on-", 8) &&
 188       strcmp(aTopic, "http-on-failed-opening-request") &&
 189       strcmp(aTopic, "http-on-opening-request") &&
 190       strcmp(aTopic, "http-on-stop-request") &&
 191       strcmp(aTopic, "http-on-image-cache-response")) {
 192     nsCOMPtr<nsIConsoleService> console(
 193         do_GetService(NS_CONSOLESERVICE_CONTRACTID));
 194     nsCOMPtr<nsIScriptError> error(
 195         do_CreateInstance(NS_SCRIPTERROR_CONTRACTID));
 196     error->Init(u"http-on-* observers only work in the parent process"_ns,
 197                 u""_ns, u""_ns, 0, 0, nsIScriptError::warningFlag,
 198                 "chrome javascript", false /* from private window */,
 199                 true /* from chrome context */);
 200     console->LogMessage(error);
 201
 202     return NS_ERROR_NOT_IMPLEMENTED;
 203   }
 204
 205   return NS_OK;
 206 }
 207
 208 NS_IMETHODIMP
 209 nsObserverService::AddObserver(nsIObserver* aObserver, const char* aTopic,
 210                                bool aOwnsWeak) {
 211   LOG(("nsObserverService::AddObserver(%p: %s, %s)", (void*)aObserver, aTopic,
 212        aOwnsWeak ? "weak" : "strong"));
 213
 214   MOZ_TRY(EnsureValidCall());
 215   if (NS_WARN_IF(!aObserver) || NS_WARN_IF(!aTopic)) {
 216     return NS_ERROR_INVALID_ARG;
 217   }
 218
 219   MOZ_TRY(FilterHttpOnTopics(aTopic));
 220
 221   nsObserverList* observerList = mObserverTopicTable.PutEntry(aTopic);
 222   if (!observerList) {
 223     return NS_ERROR_OUT_OF_MEMORY;
 224   }
 225
 226   return observerList->AddObserver(aObserver, aOwnsWeak);
 227 }
 228
 229 NS_IMETHODIMP
 230 nsObserverService::RemoveObserver(nsIObserver* aObserver, const char* aTopic) {
 231   LOG(("nsObserverService::RemoveObserver(%p: %s)", (void*)aObserver, aTopic));
 232
 233   if (mShuttingDown) {
 234     // The service is shutting down. Let's ignore this call.
 235     return NS_OK;
 236   }
 237
 238   MOZ_TRY(EnsureValidCall());
 239   if (NS_WARN_IF(!aObserver) || NS_WARN_IF(!aTopic)) {
 240     return NS_ERROR_INVALID_ARG;
 241   }
 242
 243   nsObserverList* observerList = mObserverTopicTable.GetEntry(aTopic);
 244   if (!observerList) {
 245     return NS_ERROR_FAILURE;
 246   }
 247
 248   return observerList->RemoveObserver(aObserver);
 249 }
 250
 251 NS_IMETHODIMP
 252 nsObserverService::EnumerateObservers(const char* aTopic,
 253                                       nsISimpleEnumerator** anEnumerator) {
 254   LOG(("nsObserverService::EnumerateObservers(%s)", aTopic));
 255
 256   MOZ_TRY(EnsureValidCall());
 257   if (NS_WARN_IF(!anEnumerator) || NS_WARN_IF(!aTopic)) {
 258     return NS_ERROR_INVALID_ARG;
 259   }
 260
 261   nsObserverList* observerList = mObserverTopicTable.GetEntry(aTopic);
 262   if (!observerList) {
 263     return NS_NewEmptyEnumerator(anEnumerator);
 264   }
 265
 266   observerList->GetObserverList(anEnumerator);
 267   return NS_OK;
 268 }
 269
 270 // Enumerate observers of aTopic and call Observe on each.
 271 NS_IMETHODIMP nsObserverService::NotifyObservers(nsISupports* aSubject,
 272                                                  const char* aTopic,
 273                                                  const char16_t* aSomeData) {
 274   LOG(("nsObserverService::NotifyObservers(%s)", aTopic));
 275
 276   MOZ_TRY(EnsureValidCall());
 277   if (NS_WARN_IF(!aTopic)) {
 278     return NS_ERROR_INVALID_ARG;
 279   }
 280
 281   MOZ_ASSERT(AppShutdown::IsNoOrLegalShutdownTopic(aTopic));
 282
 283   mozilla::TimeStamp start = TimeStamp::Now();
 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   uint32_t latencyMs = round((TimeStamp::Now() - start).ToMilliseconds());
 296   if (latencyMs >= kMinTelemetryNotifyObserversLatencyMs) {
 297     Telemetry::Accumulate(Telemetry::NOTIFY_OBSERVERS_LATENCY_MS,
 298                           nsDependentCString(aTopic), latencyMs);
 299   }
 300
 301   return NS_OK;
 302 }
 303
 304 NS_IMETHODIMP
 305 nsObserverService::UnmarkGrayStrongObservers() {
 306   MOZ_TRY(EnsureValidCall());
 307
 308   nsCOMArray<nsIObserver> strongObservers;
 309   for (auto iter = mObserverTopicTable.Iter(); !iter.Done(); iter.Next()) {
 310     nsObserverList* aObserverList = iter.Get();
 311     if (aObserverList) {
 312       aObserverList->AppendStrongObservers(strongObservers);
 313     }
 314   }
 315
 316   for (uint32_t i = 0; i < strongObservers.Length(); ++i) {
 317     xpc_TryUnmarkWrappedGrayObject(strongObservers[i]);
 318   }
 319
 320   return NS_OK;
 321 }
 322
 323 namespace {
 324
 325 class NotifyWhenScriptSafeRunnable : public mozilla::Runnable {
 326  public:
 327   NotifyWhenScriptSafeRunnable(nsIObserverService* aObs, nsISupports* aSubject,
 328                                const char* aTopic, const char16_t* aData)
 329       : mozilla::Runnable("NotifyWhenScriptSafeRunnable"),
 330         mObs(aObs),
 331         mSubject(aSubject),
 332         mTopic(aTopic) {
 333     if (aData) {
 334       mData.Assign(aData);
 335     } else {
 336       mData.SetIsVoid(true);
 337     }
 338   }
 339
 340   NS_IMETHOD Run() {
 341     const char16_t* data = mData.IsVoid() ? nullptr : mData.get();
 342     return mObs->NotifyObservers(mSubject, mTopic.get(), data);
 343   }
 344
 345  private:
 346   nsCOMPtr<nsIObserverService> mObs;
 347   nsCOMPtr<nsISupports> mSubject;
 348   nsCString mTopic;
 349   nsString mData;
 350 };
 351
 352 }  // namespace
 353
 354 nsresult nsIObserverService::NotifyWhenScriptSafe(nsISupports* aSubject,
 355                                                   const char* aTopic,
 356                                                   const char16_t* aData) {
 357   if (nsContentUtils::IsSafeToRunScript()) {
 358     return NotifyObservers(aSubject, aTopic, aData);
 359   }
 360
 361   nsContentUtils::AddScriptRunner(MakeAndAddRef<NotifyWhenScriptSafeRunnable>(
 362       this, aSubject, aTopic, aData));
 363   return NS_OK;
 364 }