On 2021/11/01 10:36, Scott Cheloha wrote:
> How did you generate this input? Is it just ten million lines with a
> single 'z' character? `jot -bz 10000000`?
That one was lots of copies of ports/infrastructure/bsd.port.mk catted together.
> Updated patch.
>
> I screwed up. We don't need to free(3) prevline when we print a line.
> We can just swap the pointers (and now, sizes) as we did before and
> let getline(3) handle reallocation.
Aha! That's a lot better and restores performance to how it was before.
On a different machine so times aren't directly comparable with the
previous, but:
$ hyperfine 'uniq /tmp/z' 'obj/uniq /tmp/z'
Benchmark 1: uniq /tmp/z
Time (mean ± σ): 2.564 s ± 0.105 s [User: 2.380 s, System: 0.173 s]
Range (min … max): 2.423 s … 2.748 s 10 runs
Benchmark 2: obj/uniq /tmp/z
Time (mean ± σ): 2.575 s ± 0.141 s [User: 2.350 s, System: 0.214 s]
Range (min … max): 2.478 s … 2.940 s 10 runs
Summary
'uniq /tmp/z' ran
1.00 ± 0.07 times faster than 'obj/uniq /tmp/z'
Which I think is pretty much a noop in terms of time.
OK sthen@
> Index: uniq.c
> ===================================================================
> RCS file: /cvs/src/usr.bin/uniq/uniq.c,v
> retrieving revision 1.27
> diff -u -p -r1.27 uniq.c
> --- uniq.c 31 Jul 2018 02:55:57 -0000 1.27
> +++ uniq.c 1 Nov 2021 15:30:55 -0000
> @@ -45,8 +45,6 @@
> #include <wchar.h>
> #include <wctype.h>
>
> -#define MAXLINELEN (8 * 1024)
> -
> int cflag, dflag, iflag, uflag;
> int numchars, numfields, repeats;
>
> @@ -59,10 +57,10 @@ __dead void usage(void);
> int
> main(int argc, char *argv[])
> {
> - char *t1, *t2;
> + char *prevline, *t1, *t2, *thisline;
> FILE *ifp = NULL, *ofp = NULL;
> + size_t prevsize, thissize, tmpsize;
> int ch;
> - char *prevline, *thisline;
>
> setlocale(LC_CTYPE, "");
>
> @@ -133,15 +131,18 @@ main(int argc, char *argv[])
> if (pledge("stdio", NULL) == -1)
> err(1, "pledge");
>
> - prevline = malloc(MAXLINELEN);
> - thisline = malloc(MAXLINELEN);
> - if (prevline == NULL || thisline == NULL)
> - err(1, "malloc");
> -
> - if (fgets(prevline, MAXLINELEN, ifp) == NULL)
> + prevline = NULL;
> + prevsize = 0;
> + if (getline(&prevline, &prevsize, ifp) == -1) {
> + free(prevline);
> + if (ferror(ifp))
> + err(1, "getline");
> exit(0);
> -
> - while (fgets(thisline, MAXLINELEN, ifp)) {
> + }
> +
> + thisline = NULL;
> + thissize = 0;
> + while (getline(&thisline, &thissize, ifp) != -1) {
> /* If requested get the chosen fields + character offsets. */
> if (numfields || numchars) {
> t1 = skip(thisline);
> @@ -157,11 +158,20 @@ main(int argc, char *argv[])
> t1 = prevline;
> prevline = thisline;
> thisline = t1;
> + tmpsize = prevsize;
> + prevsize = thissize;
> + thissize = tmpsize;
> repeats = 0;
> } else
> ++repeats;
> }
> + free(thisline);
> + if (ferror(ifp))
> + err(1, "getline");
> +
> show(ofp, prevline);
> + free(prevline);
> +
> exit(0);
> }
>
>
