Whisper/Graphite retentions string parsing (precision:period,precision:period,...)

whisper-graphite-retentions.pl

func parse_time($str) {
    # Mapping from whisper.py
    my %unit_multiplier = (
        s => 1,
        m => 60,
        h => 3600,
        d => 86400,
        w => 86400 * 7,
        y => 86400 * 365
    );

    my $unit = $str =~ s/[0-9]+//r;
    my $number = $str =~ s/[a-z]+//r;

    return int($number) if not $unit;
    return int($number * $unit_multiplier{$unit});
}

# parse_time('10s') -> 10
# parse_time('1h') -> 3600
# ...

func first(@array) { shift @array }

func get_precision($retentions, $ago) {
    my %period2precision = (
        reverse map { parse_time($_) } split(/:|,/, $retentions));

    return $period2precision{
        first sort { $a <=> $b } grep { $_ > $ago } keys %period2precision};
}

# get_precision('1s:60m,10s:7d', $less_than_hour) -> 1
# get_precision('1s:60m,10s:7d', $between_hour_and_week) -> 10
# ...