The Tor Browser: dom/smil/nsSMILInstanceTime.h@97036ab72558 (annotated)

dom/smil/nsSMILInstanceTime.h@97036ab72558 (annotated)

dom/smil/nsSMILInstanceTime.h

Tue, 06 Jan 2015 21:39:09 +0100

author: Michael Schloh von Bennewitz <michael@schloh.com>
date: Tue, 06 Jan 2015 21:39:09 +0100
branch: TOR_BUG_9701
changeset 8: 97036ab72558
permissions: -rw-r--r--

Conditionally force memory storage according to privacy.thirdparty.isolate;
This solves Tor bug #9701, complying with disk avoidance documented in
https://www.torproject.org/projects/torbrowser/design/#disk-avoidance.

 /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
 /* 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/. */
 #ifndef NS_SMILINSTANCETIME_H_
 #define NS_SMILINSTANCETIME_H_
 #include "nsSMILTimeValue.h"
 #include "nsAutoPtr.h"
 class nsSMILInterval;
 class nsSMILTimeContainer;
 class nsSMILTimeValueSpec;
 //----------------------------------------------------------------------
 // nsSMILInstanceTime
 //
 // An instant in document simple time that may be used in creating a new
 // interval.
 //
 // For an overview of how this class is related to other SMIL time classes see
 // the documentation in nsSMILTimeValue.h
 //
 // These objects are owned by an nsSMILTimedElement but MAY also be referenced
 // by:
 //
 // a) nsSMILIntervals that belong to the same nsSMILTimedElement and which refer
 //    to the nsSMILInstanceTimes which form the interval endpoints; and/or
 // b) nsSMILIntervals that belong to other nsSMILTimedElements but which need to
 //    update dependent instance times when they change or are deleted.
 //    E.g. for begin='a.begin', 'a' needs to inform dependent
 //    nsSMILInstanceTimes if its begin time changes. This notification is
 //    performed by the nsSMILInterval.
 class nsSMILInstanceTime MOZ_FINAL
 {
 public:
   // Instance time source. Times generated by events, syncbase relationships,
   // and DOM calls behave differently in some circumstances such as when a timed
   // element is reset.
   enum nsSMILInstanceTimeSource {
     // No particularly significant source, e.g. offset time, 'indefinite'
     SOURCE_NONE,
     // Generated by a DOM call such as beginElement
     SOURCE_DOM,
     // Generated by a syncbase relationship
     SOURCE_SYNCBASE,
     // Generated by an event
     SOURCE_EVENT
   };
   nsSMILInstanceTime(const nsSMILTimeValue& aTime,
                      nsSMILInstanceTimeSource aSource = SOURCE_NONE,
                      nsSMILTimeValueSpec* aCreator = nullptr,
                      nsSMILInterval* aBaseInterval = nullptr);
   void Unlink();
   void HandleChangedInterval(const nsSMILTimeContainer* aSrcContainer,
                              bool aBeginObjectChanged,
                              bool aEndObjectChanged);
   void HandleDeletedInterval();
   void HandleFilteredInterval();
   const nsSMILTimeValue& Time() const { return mTime; }
   const nsSMILTimeValueSpec* GetCreator() const { return mCreator; }
   bool IsDynamic() const { return !!(mFlags & kDynamic); }
   bool IsFixedTime() const { return !(mFlags & kMayUpdate); }
   bool FromDOM() const { return !!(mFlags & kFromDOM); }
   bool ShouldPreserve() const;
   void   UnmarkShouldPreserve();
   void AddRefFixedEndpoint();
   void ReleaseFixedEndpoint();
   void DependentUpdate(const nsSMILTimeValue& aNewTime)
   {
     NS_ABORT_IF_FALSE(!IsFixedTime(),
         "Updating an instance time that is not expected to be updated");
     mTime = aNewTime;
   }
   bool IsDependent() const { return !!mBaseInterval; }
   bool IsDependentOn(const nsSMILInstanceTime& aOther) const;
   const nsSMILInterval* GetBaseInterval() const { return mBaseInterval; }
   const nsSMILInstanceTime* GetBaseTime() const;
   bool SameTimeAndBase(const nsSMILInstanceTime& aOther) const
   {
     return mTime == aOther.mTime && GetBaseTime() == aOther.GetBaseTime();
   }
   // Get and set a serial number which may be used by a containing class to
   // control the sort order of otherwise similar instance times.
   uint32_t Serial() const { return mSerial; }
   void SetSerial(uint32_t aIndex) { mSerial = aIndex; }
   NS_INLINE_DECL_REFCOUNTING(nsSMILInstanceTime)
 private:
   // Private destructor, to discourage deletion outside of Release():
   ~nsSMILInstanceTime();
   void SetBaseInterval(nsSMILInterval* aBaseInterval);
   nsSMILTimeValue mTime;
   // Internal flags used to represent the behaviour of different instance times
   enum {
     // Indicates that this instance time was generated by an event or a DOM
     // call. Such instance times require special handling when (i) the owning
     // element is reset, (ii) when they are to be added as a new end instance
     // times (as per SMIL's event sensitivity contraints), and (iii) when
     // a backwards seek is performed and the timing model is reconstructed.
     kDynamic = 1,
     // Indicates that this instance time is referred to by an
     // nsSMILTimeValueSpec and as such may be updated. Such instance time should
     // not be filtered out by the nsSMILTimedElement even if they appear to be
     // in the past as they may be updated to a future time.
     kMayUpdate = 2,
     // Indicates that this instance time was generated from the DOM as opposed
     // to an nsSMILTimeValueSpec. When a 'begin' or 'end' attribute is set or
     // reset we should clear all the instance times that have been generated by
     // that attribute (and hence an nsSMILTimeValueSpec), but not those from the
     // DOM.
     kFromDOM = 4,
     // Indicates that this instance time was used as the endpoint of an interval
     // that has been filtered or removed. However, since it is a dynamic time it
     // should be preserved and not filtered.
     kWasDynamicEndpoint = 8
   };
   uint8_t       mFlags;   // Combination of kDynamic, kMayUpdate, etc.
   mutable bool  mVisited; // Cycle tracking
   // Additional reference count to determine if this instance time is currently
   // used as a fixed endpoint in any intervals. Instance times that are used in
   // this way should not be removed when the owning nsSMILTimedElement removes
   // instance times in response to a restart or in an attempt to free up memory
   // by filtering out old instance times.
   //
   // Instance times are only shared in a few cases, namely:
   // a) early ends,
   // b) zero-duration intervals,
   // c) momentarily whilst establishing new intervals and updating the current
   //    interval, and
   // d) trimmed intervals
   // Hence the limited range of a uint16_t should be more than adequate.
   uint16_t      mFixedEndpointRefCnt;
   uint32_t      mSerial; // A serial number used by the containing class to
                          // specify the sort order for instance times with the
                          // same mTime.
   nsSMILTimeValueSpec* mCreator; // The nsSMILTimeValueSpec object that created
                                  // us. (currently only needed for syncbase
                                  // instance times.)
   nsSMILInterval* mBaseInterval; // Interval from which this time is derived
                                  // (only used for syncbase instance times)
 };
 #endif // NS_SMILINSTANCETIME_H_

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dom/smil/nsSMILInstanceTime.h@97036ab72558 (annotated)

dom/smil/nsSMILInstanceTime.h