1 files changed, 367 insertions, 0 deletions
diff --git a/xpcom/ds/nsObserverService.cpp b/xpcom/ds/nsObserverService.cpp
new file mode 100644
index 0000000000..8f7a09d1aa
--- /dev/null
+++ b/xpcom/ds/nsObserverService.cpp
@@ -0,0 +1,367 @@
+/* -*- 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 "mozilla/Logging.h"
+#include "nsComponentManagerUtils.h"
+#include "nsContentUtils.h"
+#include "nsIConsoleService.h"
+#include "nsIObserverService.h"
+#include "nsIObserver.h"
+#include "nsIScriptError.h"
+#include "nsObserverService.h"
+#include "nsObserverList.h"
+#include "nsServiceManagerUtils.h"
+#include "nsThreadUtils.h"
+#include "nsEnumeratorUtils.h"
+#include "xpcpublic.h"
+#include "mozilla/AppShutdown.h"
+#include "mozilla/net/NeckoCommon.h"
+#include "mozilla/ProfilerLabels.h"
+#include "mozilla/ProfilerMarkers.h"
+#include "mozilla/ResultExtensions.h"
+#include "mozilla/Telemetry.h"
+#include "mozilla/TimeStamp.h"
+#include "nsString.h"
+
+static const uint32_t kMinTelemetryNotifyObserversLatencyMs = 1;
+
+// Log module for nsObserverService logging...
+//
+// To enable logging (see prlog.h for full details):
+//
+//    set MOZ_LOG=ObserverService:5
+//    set MOZ_LOG_FILE=service.log
+//
+// This enables LogLevel::Debug level information and places all output in
+// the file service.log.
+static mozilla::LazyLogModule sObserverServiceLog("ObserverService");
+#define LOG(x) MOZ_LOG(sObserverServiceLog, mozilla::LogLevel::Debug, x)
+
+using namespace mozilla;
+
+NS_IMETHODIMP
+nsObserverService::CollectReports(nsIHandleReportCallback* aHandleReport,
+                                  nsISupports* aData, bool aAnonymize) {
+  struct SuspectObserver {
+    SuspectObserver(const char* aTopic, size_t aReferentCount)
+        : mTopic(aTopic), mReferentCount(aReferentCount) {}
+    const char* mTopic;
+    size_t mReferentCount;
+  };
+
+  size_t totalNumStrong = 0;
+  size_t totalNumWeakAlive = 0;
+  size_t totalNumWeakDead = 0;
+  nsTArray<SuspectObserver> suspectObservers;
+
+  for (auto iter = mObserverTopicTable.Iter(); !iter.Done(); iter.Next()) {
+    nsObserverList* observerList = iter.Get();
+    if (!observerList) {
+      continue;
+    }
+
+    size_t topicNumStrong = 0;
+    size_t topicNumWeakAlive = 0;
+    size_t topicNumWeakDead = 0;
+
+    nsMaybeWeakPtrArray<nsIObserver>& observers = observerList->mObservers;
+    for (uint32_t i = 0; i < observers.Length(); i++) {
+      if (observers[i].IsWeak()) {
+        nsCOMPtr<nsIObserver> ref = observers[i].GetValue();
+        if (ref) {
+          topicNumWeakAlive++;
+        } else {
+          topicNumWeakDead++;
+        }
+      } else {
+        topicNumStrong++;
+      }
+    }
+
+    totalNumStrong += topicNumStrong;
+    totalNumWeakAlive += topicNumWeakAlive;
+    totalNumWeakDead += topicNumWeakDead;
+
+    // Keep track of topics that have a suspiciously large number
+    // of referents (symptom of leaks).
+    size_t topicTotal = topicNumStrong + topicNumWeakAlive + topicNumWeakDead;
+    if (topicTotal > kSuspectReferentCount) {
+      SuspectObserver suspect(observerList->GetKey(), topicTotal);
+      suspectObservers.AppendElement(suspect);
+    }
+  }
+
+  // These aren't privacy-sensitive and so don't need anonymizing.
+  for (uint32_t i = 0; i < suspectObservers.Length(); i++) {
+    SuspectObserver& suspect = suspectObservers[i];
+    nsPrintfCString suspectPath("observer-service-suspect/referent(topic=%s)",
+                                suspect.mTopic);
+    aHandleReport->Callback(
+        /* process */ ""_ns, suspectPath, KIND_OTHER, UNITS_COUNT,
+        suspect.mReferentCount,
+        nsLiteralCString("A topic with a suspiciously large number of "
+                         "referents.  This may be symptomatic of a leak "
+                         "if the number of referents is high with "
+                         "respect to the number of windows."),
+        aData);
+  }
+
+  MOZ_COLLECT_REPORT(
+      "observer-service/referent/strong", KIND_OTHER, UNITS_COUNT,
+      totalNumStrong,
+      "The number of strong references held by the observer service.");
+
+  MOZ_COLLECT_REPORT(
+      "observer-service/referent/weak/alive", KIND_OTHER, UNITS_COUNT,
+      totalNumWeakAlive,
+      "The number of weak references held by the observer service that are "
+      "still alive.");
+
+  MOZ_COLLECT_REPORT(
+      "observer-service/referent/weak/dead", KIND_OTHER, UNITS_COUNT,
+      totalNumWeakDead,
+      "The number of weak references held by the observer service that are "
+      "dead.");
+
+  return NS_OK;
+}
+
+////////////////////////////////////////////////////////////////////////////////
+// nsObserverService Implementation
+
+NS_IMPL_ISUPPORTS(nsObserverService, nsIObserverService, nsObserverService,
+                  nsIMemoryReporter)
+
+nsObserverService::nsObserverService() : mShuttingDown(false) {}
+
+nsObserverService::~nsObserverService(void) { Shutdown(); }
+
+void nsObserverService::RegisterReporter() { RegisterWeakMemoryReporter(this); }
+
+void nsObserverService::Shutdown() {
+  if (mShuttingDown) {
+    return;
+  }
+
+  mShuttingDown = true;
+  UnregisterWeakMemoryReporter(this);
+  mObserverTopicTable.Clear();
+}
+
+nsresult nsObserverService::Create(const nsIID& aIID, void** aInstancePtr) {
+  LOG(("nsObserverService::Create()"));
+
+  RefPtr<nsObserverService> os = new nsObserverService();
+
+  // The memory reporter can not be immediately registered here because
+  // the nsMemoryReporterManager may attempt to get the nsObserverService
+  // during initialization, causing a recursive GetService.
+  NS_DispatchToCurrentThread(
+      NewRunnableMethod("nsObserverService::RegisterReporter", os,
+                        &nsObserverService::RegisterReporter));
+
+  return os->QueryInterface(aIID, aInstancePtr);
+}
+
+nsresult nsObserverService::EnsureValidCall() const {
+  if (!NS_IsMainThread()) {
+    MOZ_CRASH("Using observer service off the main thread!");
+    return NS_ERROR_UNEXPECTED;
+  }
+
+  if (mShuttingDown) {
+    NS_ERROR("Using observer service after XPCOM shutdown!");
+    return NS_ERROR_ILLEGAL_DURING_SHUTDOWN;
+  }
+
+  return NS_OK;
+}
+
+nsresult nsObserverService::FilterHttpOnTopics(const char* aTopic) {
+  // Specifically allow http-on-opening-request and http-on-stop-request in the
+  // child process; see bug 1269765.
+  if (mozilla::net::IsNeckoChild() && !strncmp(aTopic, "http-on-", 8) &&
+      strcmp(aTopic, "http-on-failed-opening-request") &&
+      strcmp(aTopic, "http-on-opening-request") &&
+      strcmp(aTopic, "http-on-stop-request") &&
+      strcmp(aTopic, "http-on-image-cache-response")) {
+    nsCOMPtr<nsIConsoleService> console(
+        do_GetService(NS_CONSOLESERVICE_CONTRACTID));
+    nsCOMPtr<nsIScriptError> error(
+        do_CreateInstance(NS_SCRIPTERROR_CONTRACTID));
+    error->Init(u"http-on-* observers only work in the parent process"_ns,
+                u""_ns, u""_ns, 0, 0, nsIScriptError::warningFlag,
+                "chrome javascript"_ns, false /* from private window */,
+                true /* from chrome context */);
+    console->LogMessage(error);
+
+    return NS_ERROR_NOT_IMPLEMENTED;
+  }
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsObserverService::AddObserver(nsIObserver* aObserver, const char* aTopic,
+                               bool aOwnsWeak) {
+  LOG(("nsObserverService::AddObserver(%p: %s, %s)", (void*)aObserver, aTopic,
+       aOwnsWeak ? "weak" : "strong"));
+
+  MOZ_TRY(EnsureValidCall());
+  if (NS_WARN_IF(!aObserver) || NS_WARN_IF(!aTopic)) {
+    return NS_ERROR_INVALID_ARG;
+  }
+
+  MOZ_TRY(FilterHttpOnTopics(aTopic));
+
+  nsObserverList* observerList = mObserverTopicTable.PutEntry(aTopic);
+  if (!observerList) {
+    return NS_ERROR_OUT_OF_MEMORY;
+  }
+
+  return observerList->AddObserver(aObserver, aOwnsWeak);
+}
+
+NS_IMETHODIMP
+nsObserverService::RemoveObserver(nsIObserver* aObserver, const char* aTopic) {
+  LOG(("nsObserverService::RemoveObserver(%p: %s)", (void*)aObserver, aTopic));
+
+  if (mShuttingDown) {
+    // The service is shutting down. Let's ignore this call.
+    return NS_OK;
+  }
+
+  MOZ_TRY(EnsureValidCall());
+  if (NS_WARN_IF(!aObserver) || NS_WARN_IF(!aTopic)) {
+    return NS_ERROR_INVALID_ARG;
+  }
+
+  nsObserverList* observerList = mObserverTopicTable.GetEntry(aTopic);
+  if (!observerList) {
+    return NS_ERROR_FAILURE;
+  }
+
+  return observerList->RemoveObserver(aObserver);
+}
+
+NS_IMETHODIMP
+nsObserverService::EnumerateObservers(const char* aTopic,
+                                      nsISimpleEnumerator** anEnumerator) {
+  LOG(("nsObserverService::EnumerateObservers(%s)", aTopic));
+
+  MOZ_TRY(EnsureValidCall());
+  if (NS_WARN_IF(!anEnumerator) || NS_WARN_IF(!aTopic)) {
+    return NS_ERROR_INVALID_ARG;
+  }
+
+  nsObserverList* observerList = mObserverTopicTable.GetEntry(aTopic);
+  if (!observerList) {
+    return NS_NewEmptyEnumerator(anEnumerator);
+  }
+
+  observerList->GetObserverList(anEnumerator);
+  return NS_OK;
+}
+
+// Enumerate observers of aTopic and call Observe on each.
+NS_IMETHODIMP nsObserverService::NotifyObservers(nsISupports* aSubject,
+                                                 const char* aTopic,
+                                                 const char16_t* aSomeData) {
+  LOG(("nsObserverService::NotifyObservers(%s)", aTopic));
+
+  MOZ_TRY(EnsureValidCall());
+  if (NS_WARN_IF(!aTopic)) {
+    return NS_ERROR_INVALID_ARG;
+  }
+
+  MOZ_ASSERT(AppShutdown::IsNoOrLegalShutdownTopic(aTopic));
+
+  mozilla::TimeStamp start = TimeStamp::Now();
+
+  AUTO_PROFILER_MARKER_TEXT("NotifyObservers", OTHER, MarkerStack::Capture(),
+                            nsDependentCString(aTopic));
+  AUTO_PROFILER_LABEL_DYNAMIC_CSTR_NONSENSITIVE(
+      "nsObserverService::NotifyObservers", OTHER, aTopic);
+
+  nsObserverList* observerList = mObserverTopicTable.GetEntry(aTopic);
+  if (observerList) {
+    observerList->NotifyObservers(aSubject, aTopic, aSomeData);
+  }
+
+  uint32_t latencyMs = round((TimeStamp::Now() - start).ToMilliseconds());
+  if (latencyMs >= kMinTelemetryNotifyObserversLatencyMs) {
+    Telemetry::Accumulate(Telemetry::NOTIFY_OBSERVERS_LATENCY_MS,
+                          nsDependentCString(aTopic), latencyMs);
+  }
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsObserverService::UnmarkGrayStrongObservers() {
+  MOZ_TRY(EnsureValidCall());
+
+  nsCOMArray<nsIObserver> strongObservers;
+  for (auto iter = mObserverTopicTable.Iter(); !iter.Done(); iter.Next()) {
+    nsObserverList* aObserverList = iter.Get();
+    if (aObserverList) {
+      aObserverList->AppendStrongObservers(strongObservers);
+    }
+  }
+
+  for (uint32_t i = 0; i < strongObservers.Length(); ++i) {
+    xpc_TryUnmarkWrappedGrayObject(strongObservers[i]);
+  }
+
+  return NS_OK;
+}
+
+bool nsObserverService::HasObservers(const char* aTopic) {
+  return mObserverTopicTable.Contains(aTopic);
+}
+
+namespace {
+
+class NotifyWhenScriptSafeRunnable : public mozilla::Runnable {
+ public:
+  NotifyWhenScriptSafeRunnable(nsIObserverService* aObs, nsISupports* aSubject,
+                               const char* aTopic, const char16_t* aData)
+      : mozilla::Runnable("NotifyWhenScriptSafeRunnable"),
+        mObs(aObs),
+        mSubject(aSubject),
+        mTopic(aTopic) {
+    if (aData) {
+      mData.Assign(aData);
+    } else {
+      mData.SetIsVoid(true);
+    }
+  }
+
+  NS_IMETHOD Run() override {
+    const char16_t* data = mData.IsVoid() ? nullptr : mData.get();
+    return mObs->NotifyObservers(mSubject, mTopic.get(), data);
+  }
+
+ private:
+  nsCOMPtr<nsIObserverService> mObs;
+  nsCOMPtr<nsISupports> mSubject;
+  nsCString mTopic;
+  nsString mData;
+};
+
+}  // namespace
+
+nsresult nsIObserverService::NotifyWhenScriptSafe(nsISupports* aSubject,
+                                                  const char* aTopic,
+                                                  const char16_t* aData) {
+  if (nsContentUtils::IsSafeToRunScript()) {
+    return NotifyObservers(aSubject, aTopic, aData);
+  }
+
+  nsContentUtils::AddScriptRunner(MakeAndAddRef<NotifyWhenScriptSafeRunnable>(
+      this, aSubject, aTopic, aData));
+  return NS_OK;
+}