diff options
Diffstat (limited to 'src/mcron/base.scm')
| -rw-r--r-- | src/mcron/base.scm | 69 |
1 files changed, 29 insertions, 40 deletions
diff --git a/src/mcron/base.scm b/src/mcron/base.scm index a133f66..c100b4f 100644 --- a/src/mcron/base.scm +++ b/src/mcron/base.scm @@ -105,47 +105,36 @@ (set! user-job-list (cons entry user-job-list)) (set! system-job-list (cons entry system-job-list))))) - - -;; Procedure to locate the jobs in the global job-list with the lowest -;; (soonest) next-times. These are the jobs for which we must schedule the mcron -;; program (under any personality) to next wake up. The return value is a cons -;; cell consisting of the next time (maintained in the next-time variable) and a -;; list of the job entries that are to run at this time (maintained in the -;; next-jobs-list variable). -;; -;; The procedure works by first obtaining the time of the first job on the list, -;; and setting this job in the next-jobs-list. Then for each other entry on the -;; job-list, either the job runs earlier than any other that have been scanned, -;; in which case the next-time and next-jobs-list are re-initialized to -;; accomodate, or the job runs at the same time as the next job, in which case -;; the next-jobs-list is simply augmented with the new job, or else the job runs -;; later than others noted in which case we ignore it for now and continue to -;; recurse the list. - (define (find-next-jobs) - (let ((job-list (append system-job-list user-job-list))) - - (if (null? job-list) - - '(#f . '()) - - (let ((next-time 2000000000) - (next-jobs-list '())) - - (for-each - (lambda (job) - (let ((this-time (job:next-time job))) - (cond ((< this-time next-time) - (set! next-time this-time) - (set! next-jobs-list (list job))) - ((eqv? this-time next-time) - (set! next-jobs-list (cons job next-jobs-list)))))) - job-list) - - (cons next-time next-jobs-list))))) - - + "Procedure to locate the jobs in the global job-list with the +lowest (soonest) next-times. These are the jobs for which we must schedule +the mcron program (under any personality) to next wake up. The return value +is a cons cell consisting of the next time (maintained in the next-time +variable) and a list of the job entries that are to run at this +time (maintained in the next-jobs-list variable). + +The procedure works by first obtaining the time of the first job on the list, +and setting this job in the next-jobs-list. Then for each other entry on the +job-list, either the job runs earlier than any other that have been scanned, +in which case the next-time and next-jobs-list are re-initialized to +accomodate, or the job runs at the same time as the next job, in which case +the next-jobs-list is simply augmented with the new job, or else the job runs +later than others noted in which case we ignore it for now and continue to +recurse the list." + (let loop ((jobs (append system-job-list user-job-list)) + (next-time (inf)) + (next-jobs '())) + (match jobs + (() + (cons (and (finite? next-time) next-time) next-jobs)) + ((job . rest) + (let ((this-time (job:next-time job))) + (cond ((< this-time next-time) + (loop rest this-time (list job))) + ((= this-time next-time) + (loop rest next-time (cons job next-jobs))) + (else + (loop rest next-time next-jobs)))))))) ;; Create a string containing a textual list of the next count jobs to run. ;; |