The Tor Browser: xpcom/glue/nsRefPtrHashtable.h@97036ab72558

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.

     1 /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */

     2 /* This Source Code Form is subject to the terms of the Mozilla Public

     3  * License, v. 2.0. If a copy of the MPL was not distributed with this

     4  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

     6 #ifndef nsRefPtrHashtable_h__

     7 #define nsRefPtrHashtable_h__

     9 #include "nsBaseHashtable.h"

    10 #include "nsHashKeys.h"

    11 #include "nsAutoPtr.h"

    13 /**

    14  * templated hashtable class maps keys to reference pointers.

    15  * See nsBaseHashtable for complete declaration.

    16  * @param KeyClass a wrapper-class for the hashtable key, see nsHashKeys.h

    17  *   for a complete specification.

    18  * @param RefPtr the reference-type being wrapped

    19  * @see nsDataHashtable, nsClassHashtable

    20  */

    21 template<class KeyClass, class RefPtr>

    22 class nsRefPtrHashtable :

    23   public nsBaseHashtable< KeyClass, nsRefPtr<RefPtr> , RefPtr* >

    24 {

    25 public:

    26   typedef typename KeyClass::KeyType KeyType;

    27   typedef RefPtr* UserDataType;

    28   typedef nsBaseHashtable< KeyClass, nsRefPtr<RefPtr> , RefPtr* > base_type;

    30   nsRefPtrHashtable()

    31   {

    32   }

    33   explicit nsRefPtrHashtable(uint32_t aInitSize)

    34     : nsBaseHashtable<KeyClass,nsRefPtr<RefPtr>,RefPtr*>(aInitSize)

    35   {

    36   }

    38   /**

    39    * @copydoc nsBaseHashtable::Get

    40    * @param pData This is an XPCOM getter, so pData is already_addrefed.

    41    *   If the key doesn't exist, pData will be set to nullptr.

    42    */

    43   bool Get(KeyType aKey, UserDataType* pData) const;

    45   /**

    46    * Gets a weak reference to the hashtable entry.

    47    * @param aFound If not nullptr, will be set to true if the entry is found,

    48    *               to false otherwise.

    49    * @return The entry, or nullptr if not found. Do not release this pointer!

    50    */

    51   RefPtr* GetWeak(KeyType aKey, bool* aFound = nullptr) const;

    53   // Overload Remove, rather than overriding it.

    54   using base_type::Remove;

    56   /**

    57    * Remove the data for the associated key, swapping the current value into

    58    * pData, thereby avoiding calls to AddRef and Release.

    59    * @param aKey the key to remove from the hashtable

    60    * @param pData This is an XPCOM getter, so pData is already_addrefed.

    61    *   If the key doesn't exist, pData will be set to nullptr. Must be non-null.

    62    */

    63   bool Remove(KeyType aKey, UserDataType* pData);

    64 };

    66 template <typename K, typename T>

    67 inline void

    68 ImplCycleCollectionUnlink(nsRefPtrHashtable<K, T>& aField)

    69 {

    70   aField.Clear();

    71 }

    73 template <typename K, typename T>

    74 inline void

    75 ImplCycleCollectionTraverse(nsCycleCollectionTraversalCallback& aCallback,

    76                             nsRefPtrHashtable<K, T>& aField,

    77                             const char* aName,

    78                             uint32_t aFlags = 0)

    79 {

    80   nsBaseHashtableCCTraversalData userData(aCallback, aName, aFlags);

    82   aField.EnumerateRead(ImplCycleCollectionTraverse_EnumFunc<typename K::KeyType,T*>,

    83                        &userData);

    84 }

    86 //

    87 // nsRefPtrHashtable definitions

    88 //

    90 template<class KeyClass, class RefPtr>

    91 bool

    92 nsRefPtrHashtable<KeyClass,RefPtr>::Get

    93   (KeyType aKey, UserDataType* pRefPtr) const

    94 {

    95   typename base_type::EntryType* ent = this->GetEntry(aKey);

    97   if (ent) {

    98     if (pRefPtr) {

    99       *pRefPtr = ent->mData;

   101       NS_IF_ADDREF(*pRefPtr);

   102     }

   104     return true;

   105   }

   107   // if the key doesn't exist, set *pRefPtr to null

   108   // so that it is a valid XPCOM getter

   109   if (pRefPtr) {

   110     *pRefPtr = nullptr;

   111   }

   113   return false;

   114 }

   116 template<class KeyClass, class RefPtr>

   117 RefPtr*

   118 nsRefPtrHashtable<KeyClass,RefPtr>::GetWeak

   119   (KeyType aKey, bool* aFound) const

   120 {

   121   typename base_type::EntryType* ent = this->GetEntry(aKey);

   123   if (ent) {

   124     if (aFound) {

   125       *aFound = true;

   126     }

   128     return ent->mData;

   129   }

   131   // Key does not exist, return nullptr and set aFound to false

   132   if (aFound) {

   133     *aFound = false;

   134   }

   136   return nullptr;

   137 }

   139 template<class KeyClass, class RefPtr>

   140 bool

   141 nsRefPtrHashtable<KeyClass,RefPtr>::Remove(KeyType aKey,

   142                                            UserDataType* pRefPtr)

   143 {

   144   MOZ_ASSERT(pRefPtr);

   145   typename base_type::EntryType* ent = this->GetEntry(aKey);

   147   if (ent) {

   148     ent->mData.forget(pRefPtr);

   149     this->Remove(aKey);

   150     return true;

   151   }

   153   // If the key doesn't exist, set *pRefPtr to null

   154   // so that it is a valid XPCOM getter.

   155   *pRefPtr = nullptr;

   156   return false;

   157 }

   159 #endif // nsRefPtrHashtable_h__

The Tor Browser / file revision

xpcom/glue/nsRefPtrHashtable.h@97036ab72558

xpcom/glue/nsRefPtrHashtable.h