sean@ukma.UUCP (Sean Casey) (06/23/85)
The batch system recently posted by Ken Lalonde had a unique() function
that was implemented in their kernel. He posted a way to implement it
using time(). This technique is certainly valid, but produces numbers
that I feel a bit too long. Submit files start looking like
"cfq488331903". These can be hard to remember, especially for someone
who often has a lot of jobs in the queue. I have written a short
routine to store sequence numbers in a file, wrapping them around when
they get to 4096. This keeps them reasonably small. Patch follows:
*** batch.c.orig Tue Jun 18 12:29:18 1985
--- batch.c Tue Jun 18 21:33:25 1985
***************
*** 90,96
* a unique sequential number. The files are sorted by this name
* for priority of execution.
*/
! spoolnumber = unique();
sprintf(tfname, tffmt, SPOOLDIR, queue, grade, spoolnumber);
deleteerr = tfname;
umask(0077);
--- 98,104 -----
* a unique sequential number. The files are sorted by this name
* for priority of execution.
*/
! spoolnumber = unique(queue);
sprintf(tfname, tffmt, SPOOLDIR, queue, grade, spoolnumber);
deleteerr = tfname;
umask(0077);
***************
*** 259,262
Usage()
{
error("Usage: batch [-Pn] queue [file ...]\n");
}
--- 269,310 -----
Usage()
{
error("Usage: batch [-Pn] queue [file ...]\n");
+ }
+
+
+ /* unique - return unique identifier for queue
+ *
+ * This takes a queue name and returns a new sequence number based
+ * on the contents of the file "seq" in that spool directory. The
+ * sequence numbers wrap at 4096. [ukma!sean 18-Jun-85]
+ */
+
+ unique(queue)
+ char *queue;
+
+ {
+ FILE *seqfp;
+ char seqfn[100];
+ long sequence;
+
+ sprintf(seqfn, "%s/%.14s/seq", SPOOLDIR, queue);
+
+ if((seqfp = fopen(seqfn, "r+")) == NULL) {
+
+ if((seqfp = fopen(seqfn, "w")) == NULL)
+ error("can't create seq file\n");
+ else {
+ sequence = 0;
+ fprintf(seqfp,"%ld",sequence);
+ fclose(seqfp);
+ }
+ }
+ else {
+ fscanf(seqfp,"%ld", &sequence);
+ sequence = (sequence + 1) % 4096;
+ rewind(seqfp);
+ fprintf(seqfp,"%ld",sequence);
+ fclose(seqfp);
+ }
+ return(sequence);
}