Just one caveat when using sleep and usleep... you generally will want to use code like this:
my $time_to_sleep = ... #
while ($time_to_sleep > 0) {
$time_to_sleep = Time::HiRes::usleep($time_to_sleep);
}
The use of signals in your program can cause sleep and usleep to return before the amount of time specified. Here's an example:
use Time::HiRes;
$SIG{ALRM} = sub { warn "alarm went off" };
alarm(5);
my $t = Time::HiRes::usleep(10_000_000); # 10 seconds
print "done, t = $t\n";
The 'done' message is printed approx. 5 seconds into program execution.
Yet another implementation possibility is to use the OS's interval timers like this:
use Time::HiRes qw(setitimer ITIMER_VIRTUAL);
my $state;
$SIG{ALRM} = sub {
if ($state == 0) {
warn "starting application"; # start application here
$state = 1;
my $wait_time = 10; # compute time to wait here
setitimer(ITIMER_REAL, $wait_time, 0);
} else {
warn "stopping application"; # stop application here
$state = 2;
setitimer(ITIMER_REAL, 0, 0); # disable interval timer
}
};
# wait for 5 seconds before starting app
$state = 0;
setitimer(ITIMER_REAL, 5, 0);
while ($state != 2) { # do other stuff... }
This is more of a multi-threaded approach which allows you to perform other tasks during the wait periods.
|