How to save RAM in D programs (on zero initialized buffers)

[Michel Fortin]

On 2012-02-08 07:30:29 +0000, Jacob Carlborg <doob at me.com> said:

> On 2012-02-07 21:37, Michel Fortin wrote:
>> On 2012-02-07 20:24:40 +0000, "Marco Leise" <Marco.Leise at gmx.de> said:
>> 
>>> Am 07.02.2012, 21:11 Uhr, schrieb Nick Sabalausky <a at a.a>:
>>> 
>>>> Is void initialization not good enough?
>>>> 
>>>> IIRC it's something like:
>>>> 
>>>> ubyte[] buf = void;
>>> 
>>> That gives me a) no buffer, who's pointer is b) not initialized to null.
>>> I want instead a defined pointer, to a valid array, that is
>>> initialized to zero.
>>> 
>>> Anyway, I think the flaw in my proposal is the use of a GC. Since we
>>> don't get the memory directly from the operating system, but from a
>>> memory pool in the GC, it is generally 'recycled' and already used
>>> memory. It has to be zeroed out manually, unless there was a way to
>>> tell the OS to rebind some virtual memory addresses in our program to
>>> this magic 'zero page'.
>> 
>> What would be nice is a GC that would just track system-allocated memory
>> blocks. What would be really great is if you could allocate a block with
>> malloc/calloc (or something else) and later pass ownership to the GC, so
>> that the GC calls free (or something else) when all references
>> disappear. But I'm not sure how you can do that efficiently.
>> 
> 
> What about GC.addRoot ?

This is perfect if you want the GC to scan a memory range for pointers. 
But the GC can't track pointers pointing to the given memory range and 
notify you when that range is no longer referenced.


-- 
Michel Fortin
michel.fortin at michelf.com
http://michelf.com/