mfbt/RangedArray.h
author Petru Lingurar <petru.lingurar@softvision.ro>
Fri, 21 Dec 2018 08:56:47 +0000
changeset 501492 65621d0fe1262af0643cec37c23b2d9ec42588ad
parent 303600 c3e202bf0f25772c0eb34078db586449e51ccd00
child 508163 6f3709b3878117466168c40affa7bca0b60cf75b
permissions -rw-r--r--
Bug 1513938 - Enforce a Bundle size limit and drop `privateSession` if exceeds it. r=JanH, a=jcristau The `privateSession` key would normally allow persisting the Private Browsing session across OOMs in Activity's Bundle. We need to do that to avoid storing private, sensible data on disk like we do with the normal browsing session. In some cases `privateSession` would contain a lot of data which, along with other possible concurrent transactions could overflow Binder's buffer which has a limited fixed size, currently 1Mb. To avoid this, we will drop `privateSession` from the Bundle if the resulting size is greater than a _speculative_ size of 300KBs which would mean that in the case of an OOM all Private Browsing state would be lost. Bug 1515592 is filed to investigate for a better solution. Differential Revision: https://phabricator.services.mozilla.com/D15067

/* -*- 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/. */

/*
 * A compile-time constant-length array, with bounds-checking assertions -- but
 * unlike mozilla::Array, with indexes biased by a constant.
 *
 * Thus where mozilla::Array<int, 3> is a three-element array indexed by [0, 3),
 * mozilla::RangedArray<int, 8, 3> is a three-element array indexed by [8, 11).
 */

#ifndef mozilla_RangedArray_h
#define mozilla_RangedArray_h

#include "mozilla/Array.h"

namespace mozilla {

template<typename T, size_t MinIndex, size_t Length>
class RangedArray
{
private:
  typedef Array<T, Length> ArrayType;
  ArrayType mArr;

public:
  T& operator[](size_t aIndex)
  {
    MOZ_ASSERT(aIndex == MinIndex || aIndex > MinIndex);
    return mArr[aIndex - MinIndex];
  }

  const T& operator[](size_t aIndex) const
  {
    MOZ_ASSERT(aIndex == MinIndex || aIndex > MinIndex);
    return mArr[aIndex - MinIndex];
  }

  typedef typename ArrayType::iterator               iterator;
  typedef typename ArrayType::const_iterator         const_iterator;
  typedef typename ArrayType::reverse_iterator       reverse_iterator;
  typedef typename ArrayType::const_reverse_iterator const_reverse_iterator;

  // Methods for range-based for loops.
  iterator begin() { return mArr.begin(); }
  const_iterator begin() const { return mArr.begin(); }
  const_iterator cbegin() const { return mArr.cbegin(); }
  iterator end() { return mArr.end(); }
  const_iterator end() const { return mArr.end(); }
  const_iterator cend() const { return mArr.cend(); }

  // Methods for reverse iterating.
  reverse_iterator rbegin() { return mArr.rbegin(); }
  const_reverse_iterator rbegin() const { return mArr.rbegin(); }
  const_reverse_iterator crbegin() const { return mArr.crbegin(); }
  reverse_iterator rend() { return mArr.rend(); }
  const_reverse_iterator rend() const { return mArr.rend(); }
  const_reverse_iterator crend() const { return mArr.crend(); }
};

} // namespace mozilla

#endif // mozilla_RangedArray_h