dom/power/WakeLockSentinel.h

   1 /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* vim:set ts=2 sw=2 sts=2 et cindent: */
   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 #ifndef DOM_WAKELOCKSENTINEL_H_
   8 #define DOM_WAKELOCKSENTINEL_H_
   9
  10 #include "js/TypeDecls.h"
  11 #include "mozilla/Attributes.h"
  12 #include "mozilla/DOMEventTargetHelper.h"
  13 #include "mozilla/TimeStamp.h"
  14 #include "mozilla/dom/WakeLockBinding.h"
  15
  16 namespace mozilla::dom {
  17
  18 class Promise;
  19
  20 }  // namespace mozilla::dom
  21
  22 namespace mozilla::dom {
  23
  24 class WakeLockSentinel final : public DOMEventTargetHelper {
  25  public:
  26   WakeLockSentinel(nsIGlobalObject* aOwnerWindow, WakeLockType aType)
  27       : DOMEventTargetHelper(aOwnerWindow),
  28         mType(aType),
  29         mCreationTime(TimeStamp::Now()) {}
  30
  31  protected:
  32   ~WakeLockSentinel() {
  33     MOZ_DIAGNOSTIC_ASSERT(mReleased);
  34     MOZ_DIAGNOSTIC_ASSERT(!mHoldsActualLock);
  35   }
  36
  37  public:
  38   JSObject* WrapObject(JSContext* aCx,
  39                        JS::Handle<JSObject*> aGivenProto) override;
  40
  41   bool Released() const;
  42
  43   WakeLockType Type() const { return mType; }
  44
  45   MOZ_CAN_RUN_SCRIPT
  46   already_AddRefed<Promise> ReleaseLock(ErrorResult& aRv);
  47
  48   MOZ_CAN_RUN_SCRIPT
  49   void NotifyLockReleased();
  50
  51   IMPL_EVENT_HANDLER(release);
  52
  53   // Acquire underlying system wake lock by modifying the HAL wake lock counter
  54   void AcquireActualLock();
  55
  56  private:
  57   WakeLockType mType;
  58
  59   bool mReleased = false;
  60
  61   /**
  62    * To avoid user fingerprinting, WakeLockJS::Request will provide a
  63    * WakeLockSentinel even if the lock type is not applicable or cannot be
  64    * obtained.
  65    * But when releasing this sentinel, we have to know whether
  66    * AcquireActualLock was called.
  67    *
  68    * https://w3c.github.io/screen-wake-lock/#dfn-applicable-wake-lock
  69    * https://w3c.github.io/screen-wake-lock/#the-request-method
  70    */
  71   bool mHoldsActualLock = false;
  72
  73   // Time when this object was created
  74   TimeStamp mCreationTime;
  75 };
  76
  77 }  // namespace mozilla::dom
  78
  79 #endif  // DOM_WAKELOCKSENTINEL_H_