On Fri, Sep 12, 2014 at 11:38 PM, Flying Jester <[email protected]>
wrote:

>
>
> Since V8 does not know how the memory backing an ArrayBuffer has been
>> allocated in this case, there is now good way for V8 to free it.
>>
>
> This doesn't make sense.
>
> A part of v8::ArrayBuffer::Allocator is a Free method. When you pass an
> allocator to v8::V8::SetArrayBufferAllocator, you are giving V8 all the
> tools to both allocate and deallocate memory for an ArrayBuffer.
>

You can create an ArrayBuffer over external memory
(v8::ArrayBuffer::New(v8::Isolate*, void*, size_t)). V8 has no idea how
this data has been allocated.

>
> I see absolutely no reason why you can't make the ArrayBuffer take
> ownership of the memory again when you are done with it. It took ownership
> when it was created. If it can't take ownership again, this sounds to me
> like a limitation of it's implementation, not an actual virtue of its
> design.
>

I can imagine the API where embedder says to V8: "hey ArrayBuffer I
absolutely know what I am doing take ownership of this void*". The problem
with that is that people usually don't, they keep the reference to the
void* somewhere and later when an ArrayBuffer is garbage-collected it is
use-after-free and misery. I do not have a good solution for that yet.

Dmitry

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