Commit 9bc7f17b authored by Nicholas Nethercote's avatar Nicholas Nethercote
Browse files

Bug 1442433 - Make nsAtom::mString more const. r=froydnj 

The patch also uses GetStringBuffer() in a couple of appropriate places.

MozReview-Commit-ID: JufCUgmO8JL

--HG--
extra : rebase_source : ecd3f17b5560b19622c86759d605fa122d70e48a
parent f39f6d12

xpcom/ds/nsAtom.h

+4 −3
Original line number Diff line number Diff line
@@ -51,11 +51,12 @@ public: 
  void ToString(nsAString& aString) const;

  void ToUTF8String(nsACString& aString) const;



  // This is only valid for dynamic atoms.

  // This is not valid for static atoms. The caller must *not* mutate the

  // string buffer, otherwise all hell will break loose.

  nsStringBuffer* GetStringBuffer() const

  {

    // See the comment on |mString|'s declaration.

    MOZ_ASSERT(IsDynamicAtom());

    MOZ_ASSERT(IsDynamicAtom() || IsHTML5Atom());

    return nsStringBuffer::FromData(mString);

  }
@@ -98,7 +99,7 @@ protected: 
  // non-static atoms it points to the chars in an nsStringBuffer. This means

  // that nsStringBuffer::FromData(mString) calls are only valid for non-static

  // atoms.

  char16_t* mString;

  char16_t* const mString;

};



// A trivial subclass of nsAtom that can be used for known static atoms. The

xpcom/ds/nsAtomTable.cpp

+31 −23
Original line number Diff line number Diff line
@@ -92,38 +92,47 @@ private: 
  mozilla::ThreadSafeAutoRefCnt mRefCnt;

};



// This constructor is for dynamic atoms and HTML5 atoms.

nsAtom::nsAtom(AtomKind aKind, const nsAString& aString, uint32_t aHash)

  : mLength(aString.Length())

  , mKind(static_cast<uint32_t>(aKind))

  , mHash(aHash)

static char16_t*

FromStringBuffer(const nsAString& aString)

{

  MOZ_ASSERT(aKind == AtomKind::DynamicAtom || aKind == AtomKind::HTML5Atom);

  char16_t* str;

  size_t length = aString.Length();

  RefPtr<nsStringBuffer> buf = nsStringBuffer::FromString(aString);

  if (buf) {

    mString = static_cast<char16_t*>(buf->Data());

    str = static_cast<char16_t*>(buf->Data());

  } else {

    const size_t size = (mLength + 1) * sizeof(char16_t);

    const size_t size = (length + 1) * sizeof(char16_t);

    buf = nsStringBuffer::Alloc(size);

    if (MOZ_UNLIKELY(!buf)) {

      // We OOM because atom allocations should be small and it's hard to

      // handle them more gracefully in a constructor.

      NS_ABORT_OOM(size);

      NS_ABORT_OOM(size); // OOM because atom allocations should be small.

    }

    mString = static_cast<char16_t*>(buf->Data());

    CopyUnicodeTo(aString, 0, mString, mLength);

    mString[mLength] = char16_t(0);

    str = static_cast<char16_t*>(buf->Data());

    CopyUnicodeTo(aString, 0, str, length);

    str[length] = char16_t(0);

  }



  MOZ_ASSERT(buf && buf->StorageSize() >= (length + 1) * sizeof(char16_t),

             "enough storage");



  // Take ownership of the string buffer.

  mozilla::Unused << buf.forget();



  return str;

}



// This constructor is for dynamic atoms and HTML5 atoms.

nsAtom::nsAtom(AtomKind aKind, const nsAString& aString, uint32_t aHash)

  : mLength(aString.Length())

  , mKind(static_cast<uint32_t>(aKind))

  , mHash(aHash)

  , mString(FromStringBuffer(aString))

{

  MOZ_ASSERT(aKind == AtomKind::DynamicAtom || aKind == AtomKind::HTML5Atom);



  MOZ_ASSERT_IF(!IsHTML5Atom(), mHash == HashString(mString, mLength));



  MOZ_ASSERT(mString[mLength] == char16_t(0), "null terminated");

  MOZ_ASSERT(buf && buf->StorageSize() >= (mLength + 1) * sizeof(char16_t),

             "enough storage");

  MOZ_ASSERT(Equals(aString), "correct data");



  // Take ownership of buffer

  mozilla::Unused << buf.forget();

}



// This constructor is for static atoms.
@@ -143,7 +152,7 @@ nsAtom::~nsAtom() 
{

  if (!IsStaticAtom()) {

    MOZ_ASSERT(IsDynamicAtom() || IsHTML5Atom());

    nsStringBuffer::FromData(mString)->Release();

    GetStringBuffer()->Release();

  }

}
@@ -157,7 +166,7 @@ nsAtom::ToString(nsAString& aString) const 
    // which is what's important.

    aString.AssignLiteral(mString, mLength);

  } else {

    nsStringBuffer::FromData(mString)->ToString(mLength, aString);

    GetStringBuffer()->ToString(mLength, aString);

  }

}
@@ -182,8 +191,7 @@ nsAtom::AddSizeOfIncludingThis(MallocSizeOf aMallocSizeOf, AtomsSizes& aSizes) 
  } else {

    aSizes.mDynamicAtomObjects += thisSize;

    aSizes.mDynamicUnsharedBuffers +=

      nsStringBuffer::FromData(mString)->SizeOfIncludingThisIfUnshared(

        aMallocSizeOf);

      GetStringBuffer()->SizeOfIncludingThisIfUnshared(aMallocSizeOf);

  }

}