xpcom/base/AvailableMemoryWatcher.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 "AvailableMemoryWatcher.h"
   8
   9 #include "mozilla/ClearOnShutdown.h"
  10 #include "mozilla/dom/Promise.h"
  11 #include "mozilla/ErrorResult.h"
  12 #include "mozilla/RefPtr.h"
  13 #include "mozilla/Services.h"
  14 #include "mozilla/StaticPtr.h"
  15 #include "mozilla/Telemetry.h"
  16 #include "nsExceptionHandler.h"
  17 #include "nsMemoryPressure.h"
  18 #include "nsXULAppAPI.h"
  19
  20 namespace mozilla {
  21
  22 // Use this class as the initial value of
  23 // nsAvailableMemoryWatcherBase::mCallback until RegisterCallback() is called
  24 // so that nsAvailableMemoryWatcherBase does not have to check if its callback
  25 // object is valid or not.
  26 class NullTabUnloader final : public nsITabUnloader {
  27   ~NullTabUnloader() = default;
  28
  29  public:
  30   NullTabUnloader() = default;
  31
  32   NS_DECL_ISUPPORTS
  33   NS_DECL_NSITABUNLOADER
  34 };
  35
  36 NS_IMPL_ISUPPORTS(NullTabUnloader, nsITabUnloader)
  37
  38 NS_IMETHODIMP NullTabUnloader::UnloadTabAsync() {
  39   return NS_ERROR_NOT_IMPLEMENTED;
  40 }
  41
  42 StaticRefPtr<nsAvailableMemoryWatcherBase>
  43     nsAvailableMemoryWatcherBase::sSingleton;
  44
  45 /*static*/
  46 already_AddRefed<nsAvailableMemoryWatcherBase>
  47 nsAvailableMemoryWatcherBase::GetSingleton() {
  48   if (!sSingleton) {
  49     sSingleton = CreateAvailableMemoryWatcher();
  50     ClearOnShutdown(&sSingleton);
  51   }
  52
  53   return do_AddRef(sSingleton);
  54 }
  55
  56 NS_IMPL_ISUPPORTS(nsAvailableMemoryWatcherBase, nsIAvailableMemoryWatcherBase);
  57
  58 nsAvailableMemoryWatcherBase::nsAvailableMemoryWatcherBase()
  59     : mNumOfTabUnloading(0),
  60       mNumOfMemoryPressure(0),
  61       mTabUnloader(new NullTabUnloader),
  62       mInteracting(false) {
  63   MOZ_ASSERT(XRE_IsParentProcess(),
  64              "Watching memory only in the main process.");
  65 }
  66
  67 const char* const nsAvailableMemoryWatcherBase::kObserverTopics[] = {
  68     // Use this shutdown phase to make sure the instance is destroyed in GTest
  69     "xpcom-shutdown",
  70     "user-interaction-active",
  71     "user-interaction-inactive",
  72 };
  73
  74 nsresult nsAvailableMemoryWatcherBase::Init() {
  75   MOZ_ASSERT(NS_IsMainThread(),
  76              "nsAvailableMemoryWatcherBase needs to be initialized "
  77              "in the main thread.");
  78
  79   if (mObserverSvc) {
  80     return NS_ERROR_ALREADY_INITIALIZED;
  81   }
  82
  83   mObserverSvc = services::GetObserverService();
  84   MOZ_ASSERT(mObserverSvc);
  85
  86   for (auto topic : kObserverTopics) {
  87     nsresult rv = mObserverSvc->AddObserver(this, topic,
  88                                             /* ownsWeak */ false);
  89     NS_ENSURE_SUCCESS(rv, rv);
  90   }
  91   return NS_OK;
  92 }
  93
  94 void nsAvailableMemoryWatcherBase::Shutdown() {
  95   for (auto topic : kObserverTopics) {
  96     mObserverSvc->RemoveObserver(this, topic);
  97   }
  98 }
  99
 100 NS_IMETHODIMP
 101 nsAvailableMemoryWatcherBase::Observe(nsISupports* aSubject, const char* aTopic,
 102                                       const char16_t* aData) {
 103   MOZ_ASSERT(NS_IsMainThread());
 104
 105   if (strcmp(aTopic, "xpcom-shutdown") == 0) {
 106     Shutdown();
 107   } else if (strcmp(aTopic, "user-interaction-inactive") == 0) {
 108     mInteracting = false;
 109 #ifdef MOZ_CRASHREPORTER
 110     CrashReporter::SetInactiveStateStart();
 111 #endif
 112   } else if (strcmp(aTopic, "user-interaction-active") == 0) {
 113     mInteracting = true;
 114 #ifdef MOZ_CRASHREPORTER
 115     CrashReporter::ClearInactiveStateStart();
 116 #endif
 117   }
 118   return NS_OK;
 119 }
 120
 121 nsresult nsAvailableMemoryWatcherBase::RegisterTabUnloader(
 122     nsITabUnloader* aTabUnloader) {
 123   mTabUnloader = aTabUnloader;
 124   return NS_OK;
 125 }
 126
 127 nsresult nsAvailableMemoryWatcherBase::OnUnloadAttemptCompleted(
 128     nsresult aResult) {
 129   switch (aResult) {
 130     // A tab was unloaded successfully.
 131     case NS_OK:
 132       ++mNumOfTabUnloading;
 133       break;
 134
 135     // There was no unloadable tab.
 136     case NS_ERROR_NOT_AVAILABLE:
 137       ++mNumOfMemoryPressure;
 138       NS_NotifyOfEventualMemoryPressure(MemoryPressureState::LowMemory);
 139       break;
 140
 141     // There was a pending task to unload a tab.
 142     case NS_ERROR_ABORT:
 143       break;
 144
 145     default:
 146       MOZ_ASSERT_UNREACHABLE("Unexpected aResult");
 147       break;
 148   }
 149   return NS_OK;
 150 }
 151
 152 void nsAvailableMemoryWatcherBase::UpdateLowMemoryTimeStamp() {
 153   if (mLowMemoryStart.IsNull()) {
 154     mLowMemoryStart = TimeStamp::NowLoRes();
 155   }
 156 }
 157
 158 void nsAvailableMemoryWatcherBase::RecordTelemetryEventOnHighMemory() {
 159   Telemetry::SetEventRecordingEnabled("memory_watcher"_ns, true);
 160   Telemetry::RecordEvent(
 161       Telemetry::EventID::Memory_watcher_OnHighMemory_Stats,
 162       Some(nsPrintfCString(
 163           "%u,%u,%f", mNumOfTabUnloading, mNumOfMemoryPressure,
 164           (TimeStamp::NowLoRes() - mLowMemoryStart).ToSeconds())),
 165       Nothing());
 166   mNumOfTabUnloading = mNumOfMemoryPressure = 0;
 167   mLowMemoryStart = TimeStamp();
 168 }
 169
 170 // Define the fallback method for a platform for which a platform-specific
 171 // CreateAvailableMemoryWatcher() is not defined.
 172 #if defined(ANDROID) || \
 173     !defined(XP_WIN) && !defined(XP_MACOSX) && !defined(XP_LINUX)
 174 already_AddRefed<nsAvailableMemoryWatcherBase> CreateAvailableMemoryWatcher() {
 175   RefPtr instance(new nsAvailableMemoryWatcherBase);
 176   return do_AddRef(instance);
 177 }
 178 #endif
 179
 180 }  // namespace mozilla