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

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

xpcom/glue/nsCOMArray.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: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
 /* 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 nsCOMArray_h__
 #define nsCOMArray_h__
 #include "mozilla/Attributes.h"
 #include "mozilla/MemoryReporting.h"
 #include "nsCycleCollectionNoteChild.h"
 #include "nsTArray.h"
 #include "nsISupports.h"
 // See below for the definition of nsCOMArray<T>
 // a class that's nsISupports-specific, so that we can contain the
 // work of this class in the XPCOM dll
 class NS_COM_GLUE nsCOMArray_base
 {
     friend class nsArray;
 protected:
     nsCOMArray_base() {}
     nsCOMArray_base(int32_t aCount) : mArray(aCount) {}
     nsCOMArray_base(const nsCOMArray_base& other);
     ~nsCOMArray_base();
     int32_t IndexOf(nsISupports* aObject, uint32_t aStartIndex = 0) const;
     bool Contains(nsISupports* aObject) const {
         return IndexOf(aObject) != -1;
     }
     int32_t IndexOfObject(nsISupports* aObject) const;
     bool ContainsObject(nsISupports* aObject) const {
         return IndexOfObject(aObject) != -1;
     }
     typedef bool (* nsBaseArrayEnumFunc)
         (void* aElement, void *aData);
     // enumerate through the array with a callback.
     bool EnumerateForwards(nsBaseArrayEnumFunc aFunc, void* aData) const;
     bool EnumerateBackwards(nsBaseArrayEnumFunc aFunc, void* aData) const;
     typedef int (* nsBaseArrayComparatorFunc)
         (nsISupports* aElement1, nsISupports* aElement2, void* aData);
     struct nsCOMArrayComparatorContext {
         nsBaseArrayComparatorFunc mComparatorFunc;
         void* mData;
     };
     static int nsCOMArrayComparator(const void* aElement1, const void* aElement2, void* aData);
     void Sort(nsBaseArrayComparatorFunc aFunc, void* aData);
     bool InsertObjectAt(nsISupports* aObject, int32_t aIndex);
     void InsertElementAt(uint32_t aIndex, nsISupports* aElement);
     bool InsertObjectsAt(const nsCOMArray_base& aObjects, int32_t aIndex);
     void InsertElementsAt(uint32_t aIndex, const nsCOMArray_base& aElements);
     void InsertElementsAt(uint32_t aIndex, nsISupports* const* aElements, uint32_t aCount);
     bool ReplaceObjectAt(nsISupports* aObject, int32_t aIndex);
     void ReplaceElementAt(uint32_t aIndex, nsISupports* aElement) {
         nsISupports* oldElement = mArray[aIndex];
         NS_IF_ADDREF(mArray[aIndex] = aElement);
         NS_IF_RELEASE(oldElement);
     }
     bool AppendObject(nsISupports *aObject) {
         return InsertObjectAt(aObject, Count());
     }
     void AppendElement(nsISupports* aElement) {
         InsertElementAt(Length(), aElement);
     }
     bool AppendObjects(const nsCOMArray_base& aObjects) {
         return InsertObjectsAt(aObjects, Count());
     }
     void AppendElements(const nsCOMArray_base& aElements) {
         return InsertElementsAt(Length(), aElements);
     }
     void AppendElements(nsISupports* const* aElements, uint32_t aCount) {
         return InsertElementsAt(Length(), aElements, aCount);
     }
     bool RemoveObject(nsISupports *aObject);
     nsISupports** Elements() {
         return mArray.Elements();
     }
     void SwapElements(nsCOMArray_base& aOther) {
         mArray.SwapElements(aOther.mArray);
     }
     void Adopt(nsISupports** aElements, uint32_t aCount);
     uint32_t Forget(nsISupports*** aElements);
 public:
     // elements in the array (including null elements!)
     int32_t Count() const {
         return mArray.Length();
     }
     // nsTArray-compatible version
     uint32_t Length() const {
         return mArray.Length();
     }
     bool IsEmpty() const {
         return mArray.IsEmpty();
     }
     // If the array grows, the newly created entries will all be null;
     // if the array shrinks, the excess entries will all be released.
     bool SetCount(int32_t aNewCount);
     // nsTArray-compatible version
     void TruncateLength(uint32_t aNewLength) {
         if (mArray.Length() > aNewLength)
             RemoveElementsAt(aNewLength, mArray.Length() - aNewLength);
     }
     // remove all elements in the array, and call NS_RELEASE on each one
     void Clear();
     nsISupports* ObjectAt(int32_t aIndex) const {
         return mArray[aIndex];
     }
     // nsTArray-compatible version
     nsISupports* ElementAt(uint32_t aIndex) const {
         return mArray[aIndex];
     }
     nsISupports* SafeObjectAt(int32_t aIndex) const {
         return mArray.SafeElementAt(aIndex, nullptr);
     }
     // nsTArray-compatible version
     nsISupports* SafeElementAt(uint32_t aIndex) const {
         return mArray.SafeElementAt(aIndex, nullptr);
     }
     nsISupports* operator[](int32_t aIndex) const {
         return mArray[aIndex];
     }
     // remove an element at a specific position, shrinking the array
     // as necessary
     bool RemoveObjectAt(int32_t aIndex);
     // nsTArray-compatible version
     void RemoveElementAt(uint32_t aIndex);
     // remove a range of elements at a specific position, shrinking the array
     // as necessary
     bool RemoveObjectsAt(int32_t aIndex, int32_t aCount);
     // nsTArray-compatible version
     void RemoveElementsAt(uint32_t aIndex, uint32_t aCount);
     void SwapElementsAt(uint32_t aIndex1, uint32_t aIndex2) {
         nsISupports *tmp = mArray[aIndex1];
         mArray[aIndex1] = mArray[aIndex2];
         mArray[aIndex2] = tmp;
     }
     // Ensures there is enough space to store a total of aCapacity objects.
     // This method never deletes any objects.
     void SetCapacity(uint32_t aCapacity) {
         mArray.SetCapacity(aCapacity);
     }
     uint32_t Capacity() {
         return mArray.Capacity();
     }
     typedef size_t (* nsBaseArraySizeOfElementIncludingThisFunc)
         (nsISupports* aElement, mozilla::MallocSizeOf aMallocSizeOf, void *aData);
     // Measures the size of the array's element storage, and if
     // |aSizeOfElement| is non-nullptr, measures the size of things pointed to
     // by elements.
     size_t SizeOfExcludingThis(
              nsBaseArraySizeOfElementIncludingThisFunc aSizeOfElementIncludingThis,
              mozilla::MallocSizeOf aMallocSizeOf, void* aData = nullptr) const;
 private:
     // the actual storage
     nsTArray<nsISupports*> mArray;
     // don't implement these, defaults will muck with refcounts!
     nsCOMArray_base& operator=(const nsCOMArray_base& other) MOZ_DELETE;
 };
 inline void
 ImplCycleCollectionUnlink(nsCOMArray_base& aField)
 {
     aField.Clear();
 }
 inline void
 ImplCycleCollectionTraverse(nsCycleCollectionTraversalCallback& aCallback,
                             nsCOMArray_base& aField,
                             const char* aName,
                             uint32_t aFlags = 0)
 {
     aFlags |= CycleCollectionEdgeNameArrayFlag;
     int32_t length = aField.Count();
     for (int32_t i = 0; i < length; ++i) {
         CycleCollectionNoteChild(aCallback, aField[i], aName, aFlags);
     }
 }
 // a non-XPCOM, refcounting array of XPCOM objects
 // used as a member variable or stack variable - this object is NOT
 // refcounted, but the objects that it holds are
 //
 // most of the read-only accessors like ObjectAt()/etc do NOT refcount
 // on the way out. This means that you can do one of two things:
 //
 // * does an addref, but holds onto a reference
 // nsCOMPtr<T> foo = array[i];
 //
 // * avoids the refcount, but foo might go stale if array[i] is ever
 // * modified/removed. Be careful not to NS_RELEASE(foo)!
 // T* foo = array[i];
 //
 // This array will accept null as an argument for any object, and will
 // store null in the array, just like nsVoidArray. But that also means
 // that methods like ObjectAt() may return null when referring to an
 // existing, but null entry in the array.
 template <class T>
 class nsCOMArray : public nsCOMArray_base
 {
  public:
     nsCOMArray() {}
     explicit
     nsCOMArray(int32_t aCount) : nsCOMArray_base(aCount) {}
     explicit
     nsCOMArray(const nsCOMArray<T>& aOther) : nsCOMArray_base(aOther) { }
     nsCOMArray(nsCOMArray<T>&& aOther) { SwapElements(aOther); }
     ~nsCOMArray() {}
     // We have a move assignment operator, but no copy assignment operator.
     nsCOMArray<T>& operator=(nsCOMArray<T>&& aOther) {
         SwapElements(aOther);
         return *this;
     }
     // these do NOT refcount on the way out, for speed
     T* ObjectAt(int32_t aIndex) const {
         return static_cast<T*>(nsCOMArray_base::ObjectAt(aIndex));
     }
     // nsTArray-compatible version
     T* ElementAt(uint32_t aIndex) const {
         return static_cast<T*>(nsCOMArray_base::ElementAt(aIndex));
     }
     // these do NOT refcount on the way out, for speed
     T* SafeObjectAt(int32_t aIndex) const {
         return static_cast<T*>(nsCOMArray_base::SafeObjectAt(aIndex));
     }
     // nsTArray-compatible version
     T* SafeElementAt(uint32_t aIndex) const {
         return static_cast<T*>(nsCOMArray_base::SafeElementAt(aIndex));
     }
     // indexing operator for syntactic sugar
     T* operator[](int32_t aIndex) const {
         return ObjectAt(aIndex);
     }
     // index of the element in question.. does NOT refcount
     // note: this does not check COM object identity. Use
     // IndexOfObject() for that purpose
     int32_t IndexOf(T* aObject, uint32_t aStartIndex = 0) const {
         return nsCOMArray_base::IndexOf(aObject, aStartIndex);
     }
     bool Contains(nsISupports* aObject) const {
         return nsCOMArray_base::Contains(aObject);
     }
     // index of the element in question.. be careful!
     // this is much slower than IndexOf() because it uses
     // QueryInterface to determine actual COM identity of the object
     // if you need to do this frequently then consider enforcing
     // COM object identity before adding/comparing elements
     int32_t IndexOfObject(T* aObject) const {
         return nsCOMArray_base::IndexOfObject(aObject);
     }
     bool ContainsObject(nsISupports* aObject) const {
         return nsCOMArray_base::ContainsObject(aObject);
     }
     // inserts aObject at aIndex, shifting the objects at aIndex and
     // later to make space
     bool InsertObjectAt(T* aObject, int32_t aIndex) {
         return nsCOMArray_base::InsertObjectAt(aObject, aIndex);
     }
     // nsTArray-compatible version
     void InsertElementAt(uint32_t aIndex, T* aElement) {
         nsCOMArray_base::InsertElementAt(aIndex, aElement);
     }
     // inserts the objects from aObject at aIndex, shifting the
     // objects at aIndex and later to make space
     bool InsertObjectsAt(const nsCOMArray<T>& aObjects, int32_t aIndex) {
         return nsCOMArray_base::InsertObjectsAt(aObjects, aIndex);
     }
     // nsTArray-compatible version
     void InsertElementsAt(uint32_t aIndex, const nsCOMArray<T>& aElements) {
         nsCOMArray_base::InsertElementsAt(aIndex, aElements);
     }
     void InsertElementsAt(uint32_t aIndex, T* const* aElements, uint32_t aCount) {
         nsCOMArray_base::InsertElementsAt(aIndex, reinterpret_cast<nsISupports* const*>(aElements), aCount);
     }
     // replaces an existing element. Warning: if the array grows,
     // the newly created entries will all be null
     bool ReplaceObjectAt(T* aObject, int32_t aIndex) {
         return nsCOMArray_base::ReplaceObjectAt(aObject, aIndex);
     }
     // nsTArray-compatible version
     void ReplaceElementAt(uint32_t aIndex, T* aElement) {
         nsCOMArray_base::ReplaceElementAt(aIndex, aElement);
     }
     // Enumerator callback function. Return false to stop
     // Here's a more readable form:
     // bool enumerate(T* aElement, void* aData)
     typedef bool (* nsCOMArrayEnumFunc)
         (T* aElement, void *aData);
     // enumerate through the array with a callback.
     bool EnumerateForwards(nsCOMArrayEnumFunc aFunc, void* aData) {
         return nsCOMArray_base::EnumerateForwards(nsBaseArrayEnumFunc(aFunc),
                                                   aData);
     }
     bool EnumerateBackwards(nsCOMArrayEnumFunc aFunc, void* aData) {
         return nsCOMArray_base::EnumerateBackwards(nsBaseArrayEnumFunc(aFunc),
                                                   aData);
     }
     typedef int (* nsCOMArrayComparatorFunc)
         (T* aElement1, T* aElement2, void* aData);
     void Sort(nsCOMArrayComparatorFunc aFunc, void* aData) {
         nsCOMArray_base::Sort(nsBaseArrayComparatorFunc(aFunc), aData);
     }
     // append an object, growing the array as necessary
     bool AppendObject(T *aObject) {
         return nsCOMArray_base::AppendObject(aObject);
     }
     // nsTArray-compatible version
     void AppendElement(T* aElement) {
         nsCOMArray_base::AppendElement(aElement);
     }
     // append objects, growing the array as necessary
     bool AppendObjects(const nsCOMArray<T>& aObjects) {
         return nsCOMArray_base::AppendObjects(aObjects);
     }
     // nsTArray-compatible version
     void AppendElements(const nsCOMArray<T>& aElements) {
         return nsCOMArray_base::AppendElements(aElements);
     }
     void AppendElements(T* const* aElements, uint32_t aCount) {
         InsertElementsAt(Length(), aElements, aCount);
     }
     // remove the first instance of the given object and shrink the
     // array as necessary
     // Warning: if you pass null here, it will remove the first null element
     bool RemoveObject(T *aObject) {
         return nsCOMArray_base::RemoveObject(aObject);
     }
     // nsTArray-compatible version
     bool RemoveElement(T* aElement) {
         return nsCOMArray_base::RemoveObject(aElement);
     }
     T** Elements() {
         return reinterpret_cast<T**>(nsCOMArray_base::Elements());
     }
     void SwapElements(nsCOMArray<T>& aOther) {
         nsCOMArray_base::SwapElements(aOther);
     }
     // Each element in an nsCOMArray<T> is actually a T*, so this function is
     // "IncludingThis" rather than "ExcludingThis" because it needs to measure
     // the memory taken by the T itself as well as anything it points to.
     typedef size_t (* nsCOMArraySizeOfElementIncludingThisFunc)
         (T* aElement, mozilla::MallocSizeOf aMallocSizeOf, void *aData);
     size_t SizeOfExcludingThis(
              nsCOMArraySizeOfElementIncludingThisFunc aSizeOfElementIncludingThis,
              mozilla::MallocSizeOf aMallocSizeOf, void *aData = nullptr) const {
         return nsCOMArray_base::SizeOfExcludingThis(
                  nsBaseArraySizeOfElementIncludingThisFunc(aSizeOfElementIncludingThis),
                  aMallocSizeOf, aData);
     }
     /**
      * Adopt parameters that resulted from an XPIDL outparam. The aElements
      * parameter will be freed as a result of the call.
      *
      * Example usage:
      * nsCOMArray<nsISomeInterface> array;
      * nsISomeInterface** elements;
      * uint32_t length;
      * ptr->GetSomeArray(&elements, &length);
      * array.Adopt(elements, length);
      */
     void Adopt(T** aElements, uint32_t aSize) {
         nsCOMArray_base::Adopt(reinterpret_cast<nsISupports**>(aElements),
             aSize);
     }
     /**
      * Export the contents of this array to an XPIDL outparam. The array will be
      * Clear()'d after this operation.
      *
      * Example usage:
      * nsCOMArray<nsISomeInterface> array;
      * *length = array.Forget(retval);
      */
     uint32_t Forget(T*** elements) {
         return nsCOMArray_base::Forget(
             reinterpret_cast<nsISupports***>(elements));
     }
 private:
     // don't implement these!
     nsCOMArray<T>& operator=(const nsCOMArray<T>& other) MOZ_DELETE;
 };
 template <typename T>
 inline void
 ImplCycleCollectionUnlink(nsCOMArray<T>& aField)
 {
     aField.Clear();
 }
 template <typename E>
 inline void
 ImplCycleCollectionTraverse(nsCycleCollectionTraversalCallback& aCallback,
                             nsCOMArray<E>& aField,
                             const char* aName,
                             uint32_t aFlags = 0)
 {
     aFlags |= CycleCollectionEdgeNameArrayFlag;
     int32_t length = aField.Count();
     for (int32_t i = 0; i < length; ++i) {
         CycleCollectionNoteChild(aCallback, aField[i], aName, aFlags);
     }
 }
 #endif

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

xpcom/glue/nsCOMArray.h