• Russell Lewis (21/21) Aug 22 2002 Somebody mentioned smart pointers and how they might be separate from
• Sean L. Palmer (9/30) Aug 23 2002 I definitely like this.
• Walter (1/1) Aug 24 2002 It's a good idea. -Walter

Russell Lewis <spamhole-2001-07-16 deming-os.org> writes:

Somebody mentioned smart pointers and how they might be separate from 
normal GC issues.  It got me thinking: it would be nice to be able to 
take a block of memory and hand it off to the GC, along with a routine 
that should be used to release it.

In particular, I was thinking about mmap() calls.  For those who don't 
already know, mmap() takes a file pointer and has the kernel set up a 
region in memory where the contents of that file are mapped to.  You can 
then read the contents just like an array, instead of using the fgets() 
function or something like that.  What if you could to this:

    char[] gc_mmap(FILE *fp)
    {
        void *ptr = mmap(...);
        gc.AddRegion(ptr, <length>, &munmap);
        return (char[<len>])ptr;
    }

Then, the user would call gc_mmap instead of the standard mmap defined 
by the OS.  He would get a char[] from it, which he could use to read 
the data.  At some point in the future, when the last reference to that 
location was lost, the GC would recognize that the data was now garbage. 
 However, instead of its normal cleanup routines, it would call the 
callback function you gave it (munmap, in this case) to release the memory.

"Sean L. Palmer" <seanpalmer earthlink.net> writes:

I definitely like this.

Heck for handles you could specify a 1-byte "memory" region at the handle's
value and a special cleanup function to release the handle.  But for handles
allocated sequentially from 1 this wouldn't work so well if there were
multiple kinds of handles.

Sean

"Russell Lewis" <spamhole-2001-07-16 deming-os.org> wrote in message
news:3D655542.9050807 deming-os.org...
 Somebody mentioned smart pointers and how they might be separate from
 normal GC issues.  It got me thinking: it would be nice to be able to
 take a block of memory and hand it off to the GC, along with a routine
 that should be used to release it.

 In particular, I was thinking about mmap() calls.  For those who don't
 already know, mmap() takes a file pointer and has the kernel set up a
 region in memory where the contents of that file are mapped to.  You can
 then read the contents just like an array, instead of using the fgets()
 function or something like that.  What if you could to this:

     char[] gc_mmap(FILE *fp)
     {
         void *ptr = mmap(...);
         gc.AddRegion(ptr, <length>, &munmap);
         return (char[<len>])ptr;
     }

 Then, the user would call gc_mmap instead of the standard mmap defined
 by the OS.  He would get a char[] from it, which he could use to read
 the data.  At some point in the future, when the last reference to that
 location was lost, the GC would recognize that the data was now garbage.
  However, instead of its normal cleanup routines, it would call the
 callback function you gave it (munmap, in this case) to release the

memory.

"Walter" <walter digitalmars.com> writes:

It's a good idea. -Walter