Data::Dump brings in dd, sorry about that :)

. I don't know what you were trying to point out in those results; perhaps you can clarify.

Huh?

If you want to figure out what is going on, you start by gathering information -- the beginning

Then you either see your problem (wrong value, wrong condition, wrong assumption...) or look for more/different data or you throw away the whole thing and start over

I'm not sure where your confusion lies so I can't clarify

Maybe its as simple as

while( tenSecondsHasPassed() ){
   doStuff();
}

sub tenSecondsHasPassed {
    my $newtime = time;
    my $diff  = $newtime - $lasttime;
    ...
    ## if expired "end loop"
    ## if not ten seconds, sleep to make it ten seconds
    ## if expired "end loop"
    ## otherwise continue looping
}
[download]

Thank you again. I'm still not sure what was wrong with my original code, but using a subroutine has helped; thus:

use strict;
use warnings;

my $expiry = time + 3600;

my $time = time;

sub sleepy {
  my $oldtime = pop;
  my $newtime = time;
  my $diff = $newtime - $oldtime;
  sleep 10 - $diff if $diff < 10;
  return 1;
}

while ( (sleepy $time)
        and $time + 300 < $expiry
      ) {
  $time = time;
  warn $time;
}
[download]

Hooray :D

Taking it up a notch here is my thoughts

#!/usr/bin/perl --
use strict;
use warnings;


{
    my $sentinel = expireAfter( 1, 9 );
    print "begin ", scalar(gmtime),"\n";
    while( $sentinel->() ){
        print "loop ", scalar(gmtime),"\n";
    }
    print "end ", scalar(gmtime),"\n";
}
{
    my $sentinel = expireAfter( 1, 5 );
    print "begin ", scalar(gmtime),"\n";
    while( $sentinel->() ){
        print "loop ", scalar(gmtime),"\n";
    }
    print "end ", scalar(gmtime),"\n";
}

#~ use constant DEBUG => 1 || !!$ENV{PERL_MYAPP_DEBUG};
use constant DEBUG => 0 || !!$ENV{PERL_MYAPP_DEBUG};

=head2 C<<< checkEveryExpireAfter( $every, $after ) >>>

check $every seconds, if it hasn't been $every seconds yet, wait until
+ it has

stop checking $after seconds have elapsed


    checkExpire( $every, $after )
    intervalExpire( $every, $after )
    afterExpire( $every, $expire )
    everyUntil( $second, $expire )
    breatheUntil( $second, $expire )
    

=cut

sub expireAfter {
    my( $ten, $after ) = @_;
    my $lasttime = time;
    my $expire   = $lasttime + $after;
    DEBUG and warn "## eA ## ten($ten)after($after)lasttime($lasttime)
+expire($expire)";
    return sub {
        my $newtime = time;
        my $diff    = $newtime - $lasttime;
        if( $expire < $newtime ){
            DEBUG and warn "## eA ## expired ( $expire < $newtime )";
            return !!0;
        } elsif( $diff < $ten ){
            DEBUG and warn "## eA ## sleep ( $diff < $ten )";
            sleep abs( $diff - $ten );
        }
        $lasttime = time;
        if( $expire < $lasttime ){
            DEBUG and warn "## eA ## expired ( $expire > $lasttime )";
            return !!0;
        } else {
            DEBUG and warn "## eA ## loop ( $expire > $lasttime )";
            return !!1;
        }
    };
}

sub expireAfterGood {
    my( $ten, $after ) = @_;
    my $lasttime = time;
    my $expire   = $lasttime + $after;
    return sub {
        my $newtime = time;
        my $diff    = $newtime - $lasttime;
        if( $expire < $newtime ){
            warn "( $expire < $newtime )";
            return !!0;
        } elsif( $diff < $ten ){
            warn "expired ( $diff < $ten )";
            sleep abs( $diff - $ten );
        }
        $lasttime = time;
        if( $expire < $lasttime ){
            warn "expired ( $expire > $lasttime )";
            return !!0;
        } else {
            return !!1;
        }
    };
}

sub expireAfterBuggy {
    my( $ten, $after ) = @_;
    my $lasttime = time;
    my $expire   = $lasttime + $after;
    return sub {
        my $newtime = time;
        my $diff    = $newtime - $lasttime;
        if( $expire > $lasttime ){
            warn "( $expire > $lasttime )";
            return !!0;
        } elsif( $diff < $ten ){
            warn "expired ( $diff < $ten )";
            sleep abs( $diff - $ten );
        }
        $lasttime = time;
        if( $expire > $lasttime ){
            warn "expired ( $expire > $lasttime )";
            return !!0;
        } else {
            return !!1;
        }
    };
}
[download]

I started with expireAfterBuggy,

tweaked it until it did the right thing, and then called it expireAfterGood,

then improved the diagnostics, added documentation, tried to come up with a better name (this part needs work )

It is also possible to write it so that this does the right thing  while( nameHere( 'timername', 10, 3600 ) ){ ... } but it could "leak" memory if not used in a loop like that

Important thing, instead of  while( ( sleepy $time) and $time + 300 < $expiry )

have  while( oneThing($time, $expiry, 300) )

oneThing can have a sleepy and whatever else you need to make oneThing easier to understand ;) but since they both share $time and its simple scalar, stick it together under oneName