bug in every X minutes rules when remainder of 60 divided by X <> 0

I figureout what is the cause. The internal function _cronDecodeRule(),

the code is

<?php
// Used by elysia_cron_should_run
function _cronDecodeRule($rule, $min, $max) {
  if ($rule == '*')
    return range($min, $max);

  $result = array();
  foreach (explode(',', $rule) as $token) {
    if (preg_match('/^([0-9]+)-([0-9]+)$/', $token, $r)) {
      $result = array_merge($result, range($r[1], $r[2]));
    }
    elseif (preg_match('/^\*\/([0-9]+)$/', $token, $r)) {
      for ($i = $min; $i <= $max; $i++)
        if ($i % $r[1] == 0)
          $result[] = $i;
    }
    elseif (is_numeric($token)) {
      $result[] = $token;
    }
  }
  return $result;
}

// thats means if I put this rule

$rule = _cronDecodeRule('*/45', 0, 59); // to determine mins between every cron this will be the output

print_r($rule);
// array(0 => 0, 1 => 45);

/**
 * So with this pice of code how you can determine when execute a job every 45 min. 
 *
 *    elseif (preg_match('/^\*\/([0-9]+)$/', $token, $r)) {
 *      for ($i = $min; $i <= $max; $i++)
 *        if ($i % $r[1] == 0)
 *          $result[] = $i;
 *    }
 *
 * I guess this is a wrong way to determine the exactly next job.
 */

?>

The fast way I can think on how to fix this is to see if I'm decoding mins, so the code will be like this.

<?php
// Used by elysia_cron_should_run
function _cronDecodeRule($rule, $min, $max, $lastRun = 0) {
  if ($rule == '*')
    return range($min, $max);

  $result = array();
  foreach (explode(',', $rule) as $token) {
    if (preg_match('/^([0-9]+)-([0-9]+)$/', $token, $r)) {
      $result = array_merge($result, range($r[1], $r[2]));
    }
    // For determine minutes
    elseif ($lastRun > 0 && preg_match('/^\*\/([0-9]+)$/', $token, $r)) {
      $result[] = date('i', strtotime('+' . $r[1] . ' minutes', $lastRun));
    }
    // For determine month, days, hours, weeks, days of weeks,
    elseif ($lastRun ==  0 && preg_match('/^\*\/([0-9]+)$/', $token, $r)) {
      for ($i = $min; $i <= $max; $i++)
        if ($i % $r[1] == 0)
          $result[] = $i;
    }
    elseif (is_numeric($token)) {
      $result[] = $token;
    }
  }
  return $result;
}
?>

Hope to get some answers.

@NITEMAN: I don't like that quickly fix I did, thats why I said "The fast way I can think on how to fix ..." I believe that we don't need to create another function just for one small job (calculate de time in the crondecode) when you can put in a simple line like:

<?php
// in the same function elysia_cron_should_run().
preg_match('/^\*\/([0-9]+)$/', $token, $r);
$rules[1] = date('i', strtotime('+' . $r[1] . ' minutes', $lastRun));
?>

So this is not a patch to solve this bug, is just a bit of code to figure out how to solve this issue. I see it is not using the last_run timestamp to make a real aproach to the next job.

For sure, it needed (my point of view) to be remaking this part of the code, to handled in a good way this important step.

PS: Thanks for change the title of this bug, is more specific.

@NITEMAN: As we talk in IRC, I'll take a look how to handle it.

@gotheric: We (NITEMAN and I) are planing to make some spring code at setp 18 (may be 17 - 18 ) to rewrite this piece of code. If we can handle the DecodeRule in a good way (like unix for example) I'll ask you for share the mantenice to help you in the future for the rest of the task.

The last "stable" release was in 2009-Oct-01, I think is time to release a 1.3 or 1.5 stable version. ^_^

thanks for the feedback.

~~ [at]killua99

The 2.x-dev got the same problem. I got this rule */50 * * * * and it running at 12:50 then 13:00 ... why?

Well 2 things to change your idea.

- first at all you say this "Elysia Cron extends Drupal standard cron, allowing a fine grain control over each task and several ways to add custom cron jobs to your site." and "or use a powerful "linux crontab"-like syntax to set the accurate timings". So if I can't setup an accurate time, remove this line.

- If you support a real "linux crontab style" elysia definitive will be a "most have" module. Because you can control really your jobs.

ok so, my use case, I'm working in idealista.com/news (it/news and pt/news) is a web site of real state news, and for Spain and Italy we have a huge massive visits every single day. I need to control task really accurate. I did a tool for the editors to create a queue of events launcher and they know the audience and they know when every event need to be launch some times they need to be */35 * * * * or */10 * * * * its depends. Thats why I'm looking for this weird times.

So I'm gonna patch your code once more time, because you really don't see the needed to apply this feature.

I'll pass you the patch, and evaluate this.