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  Classes of Chris Volwerk   PHP Cron Scheduler Parser   readme.txt   Download  
File: readme.txt
Role: Documentation
Content type: text/plain
Description: Readme File
Class: PHP Cron Scheduler Parser
Compute the time of scheduled jobs in cron format
Author: By
Last change: Updated to reflect lates changes in class file
Date: 6 years ago
Size: 3,389 bytes
 

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Class for easy calculation of UNIX timestamps from cron scheduling definitions Created: May 27th 2013 Author: Volwerk, C Contact: vollie [at] vollie [dot] net License: LGPLv3 About ================================================================================ This class can calculate a (range of) unix timestamp(s) of either future or past occurences relative to a given time considering a single or a combination of multiple scheduling definitions. I made this class after finding most classes capable of parsing cron scheduling definitions either bloated or lacking in functionality. This was written to be completely independent of other classes, non-standard functionalities and frame- works, be bug-free, calculate reasonably fast and have little overhead. Features ================================================================================ - Full support of 'traditional' crontab format including ranges, increments and multiple list items, allowing for advanced statements, e.g.: 5-10 12 1-10/2,*/5 * 2,3 2013 - Support for combining multiple statements using an or like approach. e.g.: "0 10 * * *" combined with "0 0 5 * *" would run every day at 10 and once a month at 0:00 on the 5th. - Get both future and paste times by offset (e.g. 5 crons from now). - Get a range of times (e.g. from now untill one month from now). - Support for named entries (e.g. "monday" or "mon" instead of 1, or "june" or "jun" instead of 6). - Identifies error in definitions and trows 'regular' (supressable) errors for them identifying the list item and line in the error. - Overlaps, duplicates or out of range entries are corrected. - Calculate relative to an optionally provided (custom) time Usage ================================================================================ You can use either a static approach or create a new parser. E.g the below two options both fetch $which runtime(s) of $cron_string relative to $start_point. csd_parser::calc($cron_string, $which, $start_point); $parser = new csd_parser($cron_string, $start_point); $parser->get($which); For more (advanced) examples (and explanation of what they'll do) glance over the example.php file. It can be easily adjusted to run some tests as well. It is worth noting that the static approach always reparses and recalculates. So if you want multiple times, creating a new object will be (slightly) faster. Who can use this class? ================================================================================ Anyone who wants to use cron-like scheduling for anything other than 'pure' cron jobs, or who wants to avoid the relative hassle of creating (seperate) crons for every scheduled task. e.g.: Our own system simply runs one cron every minute which in turn picks and reschedules jobs that can easily be scheduled, configured and even written using forms in the administrative area. changes ================================================================================ Sep 1st 2014 - Fixed issue that may occur when calculating into the future stemming from compensation for leap years - Slightly increased performance Jul 31st 2017 - Fixed issue relating to weekday numbers which led to skipping an entire week instead of resuming on the earliest next weekday