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Diffstat (limited to 'scm/mcron/mcron-core.scm')
| -rw-r--r-- | scm/mcron/mcron-core.scm | 271 |
1 files changed, 0 insertions, 271 deletions
diff --git a/scm/mcron/mcron-core.scm b/scm/mcron/mcron-core.scm deleted file mode 100644 index 518bcac..0000000 --- a/scm/mcron/mcron-core.scm +++ /dev/null @@ -1,271 +0,0 @@ -;; Copyright (C) 2003 Dale Mellor -;; -;; This file is part of GNU mcron. -;; -;; GNU mcron is free software: you can redistribute it and/or modify it under -;; the terms of the GNU General Public License as published by the Free -;; Software Foundation, either version 3 of the License, or (at your option) -;; any later version. -;; -;; GNU mcron is distributed in the hope that it will be useful, but WITHOUT -;; ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or -;; FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for -;; more details. -;; -;; You should have received a copy of the GNU General Public License along -;; with GNU mcron. If not, see <http://www.gnu.org/licenses/>. - - - -(define-module (mcron core) - #:use-module (mcron environment) - #:export (add-job - remove-user-jobs - get-schedule - run-job-loop - ;; These three are deprecated and not documented. - use-system-job-list - use-user-job-list - clear-system-jobs) - #:re-export (clear-environment-mods - append-environment-mods)) - - -(use-modules (srfi srfi-1) ;; For remove. - (srfi srfi-2)) ;; For and-let*. - - - -;; The list of all jobs known to the system. Each element of the list is -;; -;; (vector user next-time-function action environment displayable next-time) -;; -;; where action must be a procedure, and the environment is an alist of -;; modifications that need making to the UNIX environment before the action is -;; run. The next-time element is the only one that is modified during the -;; running of a cron process (i.e. all the others are set once and for all at -;; configuration time). -;; -;; The reason we maintain two lists is that jobs in /etc/crontab may be placed -;; in one, and all other jobs go in the other. This makes it possible to remove -;; all the jobs in the first list in one go, and separately we can remove all -;; jobs from the second list which belong to a particular user. This behaviour -;; is required for full vixie compatibility. - -(define system-job-list '()) -(define user-job-list '()) - -(define configuration-source 'user) - -(define (use-system-job-list) (set! configuration-source 'system)) -(define (use-user-job-list) (set! configuration-source 'user)) - - - -;; Convenience functions for getting and setting the elements of a job object. - -(define (job:user job) (vector-ref job 0)) -(define (job:next-time-function job) (vector-ref job 1)) -(define (job:action job) (vector-ref job 2)) -(define (job:environment job) (vector-ref job 3)) -(define (job:displayable job) (vector-ref job 4)) -(define (job:next-time job) (vector-ref job 5)) - - - -;; Remove jobs from the user-job-list belonging to this user. - -(define (remove-user-jobs user) - (if (or (string? user) - (integer? user)) - (set! user (getpw user))) - (set! user-job-list - (remove (lambda (job) (eqv? (passwd:uid user) - (passwd:uid (job:user job)))) - user-job-list))) - - - -;; Remove all the jobs on the system job list. - -(define (clear-system-jobs) (set! system-job-list '())) - - - -;; Add a new job with the given specifications to the head of the appropriate -;; jobs list. - -(define (add-job time-proc action displayable configuration-time - configuration-user) - (let ((entry (vector configuration-user - time-proc - action - (get-current-environment-mods-copy) - displayable - (time-proc configuration-time)))) - (if (eq? configuration-source 'user) - (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))))) - - - -;; Create a string containing a textual list of the next count jobs to run. -;; -;; Enter a loop of displaying the next set of jobs to run, artificially -;; forwarding the time to the next time point (instead of waiting for it to -;; occur as we would do in a normal run of mcron), and recurse around the loop -;; count times. -;; -;; Note that this has the effect of mutating the job timings. Thus the program -;; must exit after calling this function; the internal data state will be left -;; unusable. - -(define (get-schedule count) - (with-output-to-string - (lambda () - (do ((count count (- count 1))) - ((eqv? count 0)) - (and-let* ((next-jobs (find-next-jobs)) - (time (car next-jobs)) - (date-string (strftime "%c %z\n" (localtime time)))) - (for-each (lambda (job) - (display date-string) - (display (job:displayable job)) - (newline)(newline) - (vector-set! job - 5 - ((job:next-time-function job) - (job:next-time job)))) - (cdr next-jobs))))))) - - - -;; For proper housekeeping, it is necessary to keep a record of the number of -;; child processes we fork off to run the jobs. - -(define number-children 0) - - - -;; For every job on the list, fork a process to run it (noting the fact by -;; increasing the number-children counter), and in the new process set up the -;; run-time environment exactly as it should be before running the job proper. -;; -;; In the parent, update the job entry by computing the next time the job needs -;; to run. - -(define (run-jobs jobs-list) - (for-each (lambda (job) - (if (eqv? (primitive-fork) 0) - (begin - (setgid (passwd:gid (job:user job))) - (setuid (passwd:uid (job:user job))) - (chdir (passwd:dir (job:user job))) - (modify-environment (job:environment job) (job:user job)) - ((job:action job)) - (primitive-exit 0)) - (begin - (set! number-children (+ number-children 1)) - (vector-set! job - 5 - ((job:next-time-function job) - (current-time)))))) - jobs-list)) - - - -;; Give any zombie children a chance to die, and decrease the number known to -;; exist. - -(define (child-cleanup) - (do () ((or (<= number-children 0) - (eqv? (car (waitpid WAIT_ANY WNOHANG)) 0))) - (set! number-children (- number-children 1)))) - - - -;; Now the main loop. Loop over all job specifications, get a list of the next -;; ones to run (may be more than one). Set an alarm and go to sleep. When we -;; wake, run the jobs and reap any children (old jobs) that have -;; completed. Repeat ad infinitum. -;; -;; Note that, if we wake ahead of time, it can only mean that a signal has been -;; sent by a crontab job to tell us to re-read a crontab file. In this case we -;; break out of the loop here, and let the main procedure deal with the -;; situation (it will eventually re-call this function, thus maintaining the -;; loop). - -(define (run-job-loop . fd-list) - - (call-with-current-continuation - (lambda (break) - - (let ((fd-list (if (null? fd-list) '() (car fd-list)))) - - (let loop () - - (let* ((next-jobs (find-next-jobs)) - (next-time (car next-jobs)) - (next-jobs-list (cdr next-jobs)) - (sleep-time (if next-time (- next-time (current-time)) - 2000000000))) - - (and (> sleep-time 0) - (if (not (null? - (catch 'system-error - (lambda () - (car (select fd-list '() '() sleep-time))) - (lambda (key . args) ;; Exception add by Sergey - ;; Poznyakoff. - (if (member (car (last args)) - (list EINTR EAGAIN)) - (begin - (child-cleanup) '()) - (apply throw key args)))))) - (break))) - - (run-jobs next-jobs-list) - - (child-cleanup) - - (loop))))))) |