The Tor Browser: xpcom/glue/nsBaseHashtable.h@97036ab72558 (annotated)

xpcom/glue/nsBaseHashtable.h@97036ab72558 (annotated)

xpcom/glue/nsBaseHashtable.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 nsBaseHashtable_h__
 #define nsBaseHashtable_h__
 #include "mozilla/MemoryReporting.h"
 #include "mozilla/Move.h"
 #include "nsTHashtable.h"
 #include "prlock.h"
 #include "nsDebug.h"
 template<class KeyClass,class DataType,class UserDataType>
 class nsBaseHashtable; // forward declaration
 /**
  * the private nsTHashtable::EntryType class used by nsBaseHashtable
  * @see nsTHashtable for the specification of this class
  * @see nsBaseHashtable for template parameters
  */
 template<class KeyClass,class DataType>
 class nsBaseHashtableET : public KeyClass
 {
 public:
   DataType mData;
   friend class nsTHashtable< nsBaseHashtableET<KeyClass,DataType> >;
 private:
   typedef typename KeyClass::KeyType KeyType;
   typedef typename KeyClass::KeyTypePointer KeyTypePointer;
   nsBaseHashtableET(KeyTypePointer aKey);
   nsBaseHashtableET(nsBaseHashtableET<KeyClass,DataType>&& toMove);
   ~nsBaseHashtableET();
 };
 /**
  * templated hashtable for simple data types
  * This class manages simple data types that do not need construction or
  * destruction.
  *
  * @param KeyClass a wrapper-class for the hashtable key, see nsHashKeys.h
  *   for a complete specification.
  * @param DataType the datatype stored in the hashtable,
  *   for example, uint32_t or nsCOMPtr.  If UserDataType is not the same,
  *   DataType must implicitly cast to UserDataType
  * @param UserDataType the user sees, for example uint32_t or nsISupports*
  */
 template<class KeyClass,class DataType,class UserDataType>
 class nsBaseHashtable :
   protected nsTHashtable< nsBaseHashtableET<KeyClass,DataType> >
 {
   typedef mozilla::fallible_t fallible_t;
 public:
   typedef typename KeyClass::KeyType KeyType;
   typedef nsBaseHashtableET<KeyClass,DataType> EntryType;
   using nsTHashtable<EntryType>::Contains;
   nsBaseHashtable()
   {
   }
   explicit nsBaseHashtable(uint32_t aInitSize)
     : nsTHashtable<EntryType>(aInitSize)
   {
   }
   /**
    * Return the number of entries in the table.
    * @return    number of entries
    */
   uint32_t Count() const
   { return nsTHashtable<EntryType>::Count(); }
   /**
    * retrieve the value for a key.
    * @param aKey the key to retreive
    * @param pData data associated with this key will be placed at this
    *   pointer.  If you only need to check if the key exists, pData
    *   may be null.
    * @return true if the key exists. If key does not exist, pData is not
    *   modified.
    */
   bool Get(KeyType aKey, UserDataType* pData) const
   {
     EntryType* ent = this->GetEntry(aKey);
     if (!ent)
       return false;
     if (pData)
       *pData = ent->mData;
     return true;
   }
   /**
    * For pointer types, get the value, returning nullptr if the entry is not
    * present in the table.
    *
    * @param aKey the key to retrieve
    * @return The found value, or nullptr if no entry was found with the given key.
    * @note If nullptr values are stored in the table, it is not possible to
    *       distinguish between a nullptr value and a missing entry.
    */
   UserDataType Get(KeyType aKey) const
   {
     EntryType* ent = this->GetEntry(aKey);
     if (!ent)
       return 0;
     return ent->mData;
   }
   /**
    * put a new value for the associated key
    * @param aKey the key to put
    * @param aData the new data
    * @return always true, unless memory allocation failed
    */
   void Put(KeyType aKey, const UserDataType& aData)
   {
     if (!Put(aKey, aData, fallible_t()))
       NS_ABORT_OOM(this->mTable.entrySize * this->mTable.entryCount);
   }
   bool Put(KeyType aKey, const UserDataType& aData, const fallible_t&) NS_WARN_UNUSED_RESULT
   {
     EntryType* ent = this->PutEntry(aKey);
     if (!ent)
       return false;
     ent->mData = aData;
     return true;
   }
   /**
    * remove the data for the associated key
    * @param aKey the key to remove from the hashtable
    */
   void Remove(KeyType aKey) { this->RemoveEntry(aKey); }
   /**
    * function type provided by the application for enumeration.
    * @param aKey the key being enumerated
    * @param aData data being enumerated
    * @parm userArg passed unchanged from Enumerate
    * @return either
    *   @link PLDHashOperator::PL_DHASH_NEXT PL_DHASH_NEXT @endlink or
    *   @link PLDHashOperator::PL_DHASH_STOP PL_DHASH_STOP @endlink
    */
   typedef PLDHashOperator
     (* EnumReadFunction)(KeyType      aKey,
                          UserDataType aData,
                          void*        userArg);
   /**
    * enumerate entries in the hashtable, without allowing changes
    * @param enumFunc enumeration callback
    * @param userArg passed unchanged to the EnumReadFunction
    */
   uint32_t EnumerateRead(EnumReadFunction enumFunc, void* userArg) const
   {
     NS_ASSERTION(this->mTable.entrySize,
                  "nsBaseHashtable was not initialized properly.");
     s_EnumReadArgs enumData = { enumFunc, userArg };
     return PL_DHashTableEnumerate(const_cast<PLDHashTable*>(&this->mTable),
                                   s_EnumReadStub,
                                   &enumData);
   }
   /**
    * function type provided by the application for enumeration.
    * @param aKey the key being enumerated
    * @param aData Reference to data being enumerated, may be altered. e.g. for
    *        nsInterfaceHashtable this is an nsCOMPtr reference...
    * @parm userArg passed unchanged from Enumerate
    * @return bitflag combination of
    *   @link PLDHashOperator::PL_DHASH_REMOVE @endlink,
    *   @link PLDHashOperator::PL_DHASH_NEXT PL_DHASH_NEXT @endlink, or
    *   @link PLDHashOperator::PL_DHASH_STOP PL_DHASH_STOP @endlink
    */
   typedef PLDHashOperator
     (* EnumFunction)(KeyType       aKey,
                      DataType&     aData,
                      void*         userArg);
   /**
    * enumerate entries in the hashtable, allowing changes. This
    * functions write-locks the hashtable.
    * @param enumFunc enumeration callback
    * @param userArg passed unchanged to the EnumFunction
    */
   uint32_t Enumerate(EnumFunction enumFunc, void* userArg)
   {
     NS_ASSERTION(this->mTable.entrySize,
                  "nsBaseHashtable was not initialized properly.");
     s_EnumArgs enumData = { enumFunc, userArg };
     return PL_DHashTableEnumerate(&this->mTable,
                                   s_EnumStub,
                                   &enumData);
   }
   /**
    * reset the hashtable, removing all entries
    */
   void Clear() { nsTHashtable<EntryType>::Clear(); }
   /**
    * client must provide a SizeOfEntryExcludingThisFun function for
    *   SizeOfExcludingThis.
    * @param     aKey the key being enumerated
    * @param     aData Reference to data being enumerated.
    * @param     mallocSizeOf the function used to measure heap-allocated blocks
    * @param     userArg passed unchanged from SizeOf{In,Ex}cludingThis
    * @return    summed size of the things pointed to by the entries
    */
   typedef size_t
     (* SizeOfEntryExcludingThisFun)(KeyType           aKey,
                                     const DataType    &aData,
                                     mozilla::MallocSizeOf mallocSizeOf,
                                     void*             userArg);
   /**
    * Measure the size of the table's entry storage and the table itself.
    * If |sizeOfEntryExcludingThis| is non-nullptr, measure the size of things
    * pointed to by entries.
    *
    * @param    sizeOfEntryExcludingThis
    *           the <code>SizeOfEntryExcludingThisFun</code> function to call
    * @param    mallocSizeOf the function used to meeasure heap-allocated blocks
    * @param    userArg a point to pass to the
    *           <code>SizeOfEntryExcludingThisFun</code> function
    * @return   the summed size of the entries, the table, and the table's storage
    */
   size_t SizeOfIncludingThis(SizeOfEntryExcludingThisFun sizeOfEntryExcludingThis,
                              mozilla::MallocSizeOf mallocSizeOf, void *userArg = nullptr)
   {
     return mallocSizeOf(this) + this->SizeOfExcludingThis(sizeOfEntryExcludingThis,
                                                           mallocSizeOf, userArg);
   }
   /**
    * Measure the size of the table's entry storage, and if
    * |sizeOfEntryExcludingThis| is non-nullptr, measure the size of things pointed
    * to by entries.
    *
    * @param     sizeOfEntryExcludingThis the
    *            <code>SizeOfEntryExcludingThisFun</code> function to call
    * @param     mallocSizeOf the function used to measure heap-allocated blocks
    * @param     userArg a pointer to pass to the
    *            <code>SizeOfEntryExcludingThisFun</code> function
    * @return    the summed size of all the entries
    */
   size_t SizeOfExcludingThis(SizeOfEntryExcludingThisFun sizeOfEntryExcludingThis,
                              mozilla::MallocSizeOf mallocSizeOf, void *userArg = nullptr) const
   {
     if (sizeOfEntryExcludingThis) {
       s_SizeOfArgs args = { sizeOfEntryExcludingThis, userArg };
       return PL_DHashTableSizeOfExcludingThis(&this->mTable, s_SizeOfStub,
                                               mallocSizeOf, &args);
     }
     return PL_DHashTableSizeOfExcludingThis(&this->mTable, nullptr,
                                             mallocSizeOf);
   }
 #ifdef DEBUG
   using nsTHashtable<EntryType>::MarkImmutable;
 #endif
 protected:
   /**
    * used internally during EnumerateRead.  Allocated on the stack.
    * @param func the enumerator passed to EnumerateRead
    * @param userArg the userArg passed to EnumerateRead
    */
   struct s_EnumReadArgs
   {
     EnumReadFunction func;
     void* userArg;
   };
   static PLDHashOperator s_EnumReadStub(PLDHashTable    *table,
                                         PLDHashEntryHdr *hdr,
                                         uint32_t         number,
                                         void            *arg);
   struct s_EnumArgs
   {
     EnumFunction func;
     void* userArg;
   };
   static PLDHashOperator s_EnumStub(PLDHashTable      *table,
                                     PLDHashEntryHdr   *hdr,
                                     uint32_t           number,
                                     void              *arg);
   struct s_SizeOfArgs
   {
     SizeOfEntryExcludingThisFun func;
     void* userArg;
   };
   static size_t s_SizeOfStub(PLDHashEntryHdr *entry,
                              mozilla::MallocSizeOf mallocSizeOf,
                              void *arg);
 };
 class nsCycleCollectionTraversalCallback;
 struct MOZ_STACK_CLASS nsBaseHashtableCCTraversalData
 {
   nsBaseHashtableCCTraversalData(nsCycleCollectionTraversalCallback& aCallback,
                                  const char* aName,
                                  uint32_t aFlags)
   : mCallback(aCallback),
     mName(aName),
     mFlags(aFlags)
   {
   }
   nsCycleCollectionTraversalCallback& mCallback;
   const char* mName;
   uint32_t mFlags;
 };
 template <typename K, typename T>
 PLDHashOperator
 ImplCycleCollectionTraverse_EnumFunc(K aKey,
                                      T aData,
                                      void* aUserData)
 {
   nsBaseHashtableCCTraversalData* userData =
     static_cast<nsBaseHashtableCCTraversalData*>(aUserData);
   CycleCollectionNoteChild(userData->mCallback,
                            aData,
                            userData->mName,
                            userData->mFlags);
   return PL_DHASH_NEXT;
 }
 //
 // nsBaseHashtableET definitions
 //
 template<class KeyClass,class DataType>
 nsBaseHashtableET<KeyClass,DataType>::nsBaseHashtableET(KeyTypePointer aKey) :
   KeyClass(aKey)
 { }
 template<class KeyClass,class DataType>
 nsBaseHashtableET<KeyClass,DataType>::nsBaseHashtableET
   (nsBaseHashtableET<KeyClass,DataType>&& toMove) :
   KeyClass(mozilla::Move(toMove)),
   mData(mozilla::Move(toMove.mData))
 { }
 template<class KeyClass,class DataType>
 nsBaseHashtableET<KeyClass,DataType>::~nsBaseHashtableET()
 { }
 //
 // nsBaseHashtable definitions
 //
 template<class KeyClass,class DataType,class UserDataType>
 PLDHashOperator
 nsBaseHashtable<KeyClass,DataType,UserDataType>::s_EnumReadStub
   (PLDHashTable *table, PLDHashEntryHdr *hdr, uint32_t number, void* arg)
 {
   EntryType* ent = static_cast<EntryType*>(hdr);
   s_EnumReadArgs* eargs = (s_EnumReadArgs*) arg;
   PLDHashOperator res = (eargs->func)(ent->GetKey(), ent->mData, eargs->userArg);
   NS_ASSERTION( !(res & PL_DHASH_REMOVE ),
                 "PL_DHASH_REMOVE return during const enumeration; ignoring.");
   if (res & PL_DHASH_STOP)
     return PL_DHASH_STOP;
   return PL_DHASH_NEXT;
 }
 template<class KeyClass,class DataType,class UserDataType>
 PLDHashOperator
 nsBaseHashtable<KeyClass,DataType,UserDataType>::s_EnumStub
   (PLDHashTable *table, PLDHashEntryHdr *hdr, uint32_t number, void* arg)
 {
   EntryType* ent = static_cast<EntryType*>(hdr);
   s_EnumArgs* eargs = (s_EnumArgs*) arg;
   return (eargs->func)(ent->GetKey(), ent->mData, eargs->userArg);
 }
 template<class KeyClass,class DataType,class UserDataType>
 size_t
 nsBaseHashtable<KeyClass,DataType,UserDataType>::s_SizeOfStub
   (PLDHashEntryHdr *hdr, mozilla::MallocSizeOf mallocSizeOf, void *arg)
 {
   EntryType* ent = static_cast<EntryType*>(hdr);
   s_SizeOfArgs* eargs = static_cast<s_SizeOfArgs*>(arg);
   return (eargs->func)(ent->GetKey(), ent->mData, mallocSizeOf, eargs->userArg);
 }
 #endif // nsBaseHashtable_h__

The Tor Browser / annotate

xpcom/glue/nsBaseHashtable.h@97036ab72558 (annotated)

xpcom/glue/nsBaseHashtable.h