add scheduler based on Algorithm::Cron

Netdisco/lib/App/Netdisco/Daemon/Worker/Scheduler.pm

@@ -0,0 +1,79 @@
+package App::Netdisco::Daemon::Worker::Scheduler;
+
+use Dancer qw/:moose :syntax :script/;
+use Dancer::Plugin::DBIC 'schema';
+
+use Algorithm::Cron;
+use Try::Tiny;
+
+use Role::Tiny;
+use namespace::clean;
+
+my $jobactions = {
+  map {$_ => undef} qw/
+    discoverall
+    refresh
+    macwalk
+    arpwalk
+    nbtwalk
+    backup
+  /
+};
+
+sub worker_begin {
+  my $self = shift;
+  my $wid = $self->wid;
+  debug "entering Scheduler ($wid) worker_begin()";
+
+  foreach my $a (keys %$jobactions) {
+      next unless setting('job_schedule')
+        and exists setting('job_schedule')->{$a};
+      my $config = setting('job_schedule')->{$a};
+
+      # accept either single crontab format, or individual time fields
+      my $cron = Algorithm::Cron->new(@{
+        ref [] eq ref $config->{when}
+          ? $config->{when}
+          : [crontab => $config->{when}];
+      });
+
+      $jobactions->{$a} = $config;
+      $jobactions->{$a}->{when} = $cron;
+  }
+}
+
+sub worker_body {
+  my $self = shift;
+  my $wid = $self->wid;
+
+  while (1) {
+      # sleep until some point in the next minute
+      my $naptime = 60 - (time % 60) + int(rand(45));
+      debug "scheduler ($wid): sleeping for $naptime seconds";
+      sleep $naptime;
+
+      my $win_start = time - (time % 60);
+      my $win_end   = $win_start + 60;
+
+      # if any job is due, add it to the queue
+      foreach my $a (keys %$jobactions) {
+          next unless defined $jobactions->{$a};
+          my $sched = $jobactions->{$a};
+
+          if ($sched->{when}->next_time($win_start) < $win_end) {
+              # queue it!
+              try {
+                  debug "scheduler ($wid): queueing $a job";
+                  schema('netdisco')->resultset('Admin')->create({
+                    action => $a,
+                    device => ($sched->{device} || undef),
+                    subaction => ($sched->{extra} || undef),
+                    status => 'queued',
+                  });
+              };
+          }
+      }
+  }
+}
+
+1;