parallel booting init in C - even larger speedup

[Petter Reinholdtsen]

[Olivier Sessink]
> I saw the posting from Petter Reinholdtsen, and some years ago I wrote a
> similar program in C: it runs all init scripts with the same sequence
> number in parallel.

Thank you.  I finally found time to look at it.  I managed to get it
running, but had to patch it slightly to get it working and avoid a
few compile warnings.

What is the license of this source?  GPL would be nice.

I did not measure the boot speed, so I do not know if this speeded up
the boot or not.  I hope to get to that soonish.

Here is the patch.

 - add clean target to makefile, and a few more warning flags.

 - convert to unsigned to signed int before comparing it to signed int.

 - enable some debug output, to figure out what is going on.

 - allow short circuiting the start scripts when moving from runlevel
   S too.

 - handle non-existing previous runlevel a bit better.

diff -urw parallel_init/Makefile parallel_init-pere/Makefile
--- parallel_init/Makefile      2004-05-20 23:36:33.000000000 +0200
+++ parallel_init-pere/Makefile 2005-11-14 00:48:12.197827916 +0100
@@ -1,9 +1,8 @@

-
-rc: rc.c
-       gcc -g -Wall -O2 rc.c -o rc
-
-
 all: rc

+rc: rc.c
+       gcc -g -Wall -W -pedantic -O2 rc.c -o rc

+clean:
+       $(RM) rc *~

--- parallel_init/rc.c  2004-05-23 23:52:47.000000000 +0200
+++ parallel_init-pere/rc.c     2005-11-14 00:49:05.891599618 +0100
@@ -75,12 +79,12 @@
        unsigned int count;

        count = count_strarr(arr);
-       if (max > 0 && max < count) {
+       if (max > 0 && max < (int)count) {
                count = max;
        }
        newarr = tmp2 = malloc((count+1)*sizeof(char *));
-       while (tmp1 - arr < count) {
-/*             printf("duplicated %s\n",*tmp1);*/
+       while (tmp1 - arr < (int)count) {
+               printf("duplicated %s\n",*tmp1);
                *tmp2 = strdup(*tmp1);
                tmp2++;
                tmp1++;
@@ -97,7 +101,7 @@
        pattern = strncat(pattern, runleveldir,14);
        pattern = strncat(pattern, startchar, 14);
        pattern = strncat(pattern, "*", 14);
-/*     printf("searching for %s\n", pattern);*/
+       printf("searching for %s\n", pattern);
        ret = glob(pattern, 0, NULL, &globbuf);
        free(pattern);
        if (0 == ret) {
@@ -218,31 +222,34 @@
        }

        Sscripts = return_scripts_sorted(runleveldir, "S");
-       if (prev_runlevel && strcmp(prev_runlevel,"S")!=0) {
+       if (prev_runlevel) {
                /* if this suffix is already started in the previous runlevel, and not
                stopped in this runlevel, we don't need to start it anymore */
                char **tmp;
                char *prevrunleveldir = build_runleveldir(prev_runlevel);
                prevSscripts = return_scripts_sorted(prevrunleveldir, "S");
+               if (prevSscripts) {
                tmp = prevSscripts;
                while (*tmp) {
                        char *suffix = get_suffix(*tmp);
-                       if (strarr_has_suffix(Sscripts, suffix) && !strarr_has_suffix(Kscripts, suffix)) {
+                               if (strarr_has_suffix(Sscripts, suffix) &&
+                                   !strarr_has_suffix(Kscripts, suffix)) {
                                Sscripts = remove_suffix_from_strarr(Sscripts, suffix);
                        }
                        tmp++;
                }
        }
+       }

        /* run batches of scripts with the same sequence number parallel */
        if (Sscripts) {
                unsigned short int start=0,len=1,i;
                char **batch;
                for (i=1;Sscripts[i]!=NULL;i++) {
-/*                     printf("comparing %s and %s\n",scripts[start], scripts[i]);*/
+                       printf("comparing %s and %s\n",Sscripts[start], Sscripts[i]);
                        if (strncmp(Sscripts[start], Sscripts[i], 14)==0) {
                                len++;
-/*                             printf("the same! len=%d\n",len);*/
+                               printf("the same! len=%d\n",len);
                        } else {
                                batch = duplicate_strarr(&Sscripts[start], len);
                                run_batch(batch, "start");