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Implementing crontab code sharing in PHP_PHP tutorial

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Release： 2016-07-13 10:00:21

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Implementing crontab code sharing in PHP

This article mainly introduces the implementation of crontab code sharing in PHP. This article gives the implementation code and usage methods. Friends who need it can refer to it.

1. Prepare a standard crontab file ./crontab

The code is as follows:

# m h dom mon dow command
* * * * * date > /tmp/cron.date.run

2. crontab -e Add this cron.php script to the system cron

The code is as follows:

* * * * * /usr/bin/php cron.php

3. cron.php source code

The code is as follows:

// Read cron items from ./crontab or other persistent storage (mysql, redis)
$crontab = file('./crontab');
$now = $_SERVER['REQUEST_TIME'];

foreach ( $crontab as $cron ) {
$slices = preg_split("/[s] /", $cron, 6);
if( count($slices) !== 6 ) continue;

$cmd = array_pop($slices);
$cron_time = implode(' ', $slices);
$next_time = Crontab::parse($cron_time, $now);
if ( $next_time !== $now ) continue;

$pid = pcntl_fork();
if ($pid == -1) {
die('could not fork');
} else if ($pid) {
// we are the parent
pcntl_wait($status, WNOHANG); //Protect against Zombie children
} else {
// we are the child
`$cmd`;
exit;
}
}

/* https://github.com/jkonieczny/PHP-Crontab */
class Crontab {
/**
* Finds next execution time(stamp) parsin crontab syntax,
* after given starting timestamp (or current time if ommited)
*
* @param string $_cron_string:
*
* 0 1 2 3 4
* * * * * *
* - - - - -
* | | | | |
* | | | | ----- day of week (0 - 6) (Sunday=0)
* | | | ------- month (1 - 12)
* | | --------- day of month (1 - 31)
* | ----------- hour (0 - 23)
* ------------- min (0 - 59)
* @param int $_after_timestamp timestamp [default=current timestamp]
* @return int unix timestamp - next execution time will be greater
* than given timestamp (defaults to the current timestamp)
* @throws InvalidArgumentException
*/
public static function parse($_cron_string,$_after_timestamp=null)
{
if(!preg_match('/^((*(/[0-9] )?)|[0-9-,/] )s ((*(/[0-9] )?)|[0-9 -,/] )s ((*(/[0-9] )?)|[0-9-,/] )s ((*(/[0-9] )?)|[0-9-, /] )s ((*(/[0-9] )?)|[0-9-,/] )$/i',trim($_cron_string))){
throw new InvalidArgumentException("Invalid cron string: ".$_cron_string);
}
if($_after_timestamp && !is_numeric($_after_timestamp)){
throw new InvalidArgumentException("$_after_timestamp must be a valid unix timestamp ($_after_timestamp given)");
}
$cron = preg_split("/[s] /i",trim($_cron_string));
$start = empty($_after_timestamp)?time():$_after_timestamp;

$date = array( 'minutes' =>self::_parseCronNumbers($cron[0],0,59),
'hours' =>self::_parseCronNumbers($cron[1],0,23),
'dom' =>self::_parseCronNumbers($cron[2],1,31),
'month' =>self::_parseCronNumbers($cron[3],1,12),
'dow' =>self::_parseCronNumbers($cron[4],0,6),
);
// limited to time() 366 - no need to check more than 1year ahead
for($i=0;$i<=60*60*24*366;$i =60){
if( in_array(intval(date('j',$start $i)),$date['dom']) &&
in_array(intval(date('n',$start $i)),$date['month']) &&
in_array(intval(date('w',$start $i)),$date['dow']) &&
in_array(intval(date('G',$start $i)),$date['hours']) &&
in_array(intval(date('i',$start $i)),$date['minutes'])

){
return $start $i;
}
}
return null;
}

/**
* get a single cron style notation and parse it into numeric value
*
* @param string $s cron string element
* @param int $min minimum possible value
* @param int $max maximum possible value
* @return int parsed number
*/
protected static function _parseCronNumbers($s,$min,$max)
{
$result = array();

$v = explode(',',$s);
foreach($v as $vv){
$vvv = explode('/',$vv);
$step = empty($vvv[1])?1:$vvv[1];
$vvvv = explode('-',$vvv[0]);
$_min = count($vvvv)==2?$vvvv[0]:($vvv[0]=='*'?$min:$vvv[0]);
$_max = count($vvvv)==2?$vvvv[1]:($vvv[0]=='*'?$max:$vvv[0]);

for($i=$_min;$i<=$_max;$i =$step){
$result[$i]=intval($i);
}
}
ksort($result);
return $result;
}
}