From: Chris Jacobson <fear@ATHENET.NET>
>So I was thinking, what would be the SAFEST way to implement linked
>lists, and to iterate through the list without losing place, when there
>is the chance that the current, previous, next, or any other item in the
>list could be removed in mid-iteration....
>
<snip>
How about marking any 'deleted' entry with a flag variable, then using that
variable to skip processing that element of the list.
Then have a seperate routine to run every so often to compact the list. I
assume you only have one thread and just need to do stuff inside the loop
construct that might affect the linked list in a random location.
That'd keep your links happy and allow simple code (read: easy to debug). I
use this approach in a few places on Antares and find it works quite well.
Something like this fragment :-)
#define my_stuff_flag_deleted (1 <<0)
#define my_stuff_flag_blah1 (1 <<1)
...
#define my_stuff_flag_blahn (1 <<n)
struct my_stuff {
int flags;
int mynumber;
char *mystring;
};
struct my_stuff *stuff;
void look_through_stuff () {
struct my_stuff *stuff_next, *blah;
for (blah=stuff;blah;blah=stuff_next) {
stuff_next=blah->next;
if (IS_SET(blah->flags, my_stuff_flag_deleted))
continue;
/* handle element */
}
}
--Mallory
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