read() performance - Linux.too?

[Derek Parnell]

On Mon, 24 Jul 2006 23:04:09 -0700, Unknown W. Brackets wrote:

> Derek,
> 
> Your question doesn't make complete sense to me, so I'm going to back up 
> a bit.  Please forgive me if I patronize you, or fail to answer your 
> question.

Not a problem.
 
> The garbage collector has "ranges" of memory it scans (as I'm completely 
> sure you already know.)  For example, you could add an arbitrary range. 
>   Consider:
> 
> void* p = malloc(100);
> std.gc.addRange(p, p + cast(ptrdiff_t) 100);
> 
> This will cause it to scan the space between (p) and (p + 100) or 
> pointers (roots.)  Removing a range does not mean, as far as I can see, 
> that the memory it points to will never be freed; just that it will not 
> be scanned.

So long as the root itself is stored somewhere that the GC can find it. I
guess this is done via the addRoot() call and I assume that 'new'
automatically calls this.

> I completely agree that Phobos' read() should have a removeRange() call 
> there, unless it is decided to add such a thing to the standard library.

I just tried something like that out. In file.d I changed 

    buf = new byte[size];

to ...

    void *p = malloc(size);
    if (p == null)
        throw new OutOfMemoryException;
    buf = cast(byte[])p[0..size];


I assume that the " = p[x..y]" construct adds the root to the GC.

-- 
Derek
(skype: derek.j.parnell)
Melbourne, Australia
"Down with mediocrity!"
25/07/2006 4:17:40 PM