Timetriggered Events (Cron)

cronwant

Hi all

I'm using PHP on Apache and want to create Logfiles (certain actions on my website should be logged).

I found a pear package that supports logging into files.

I would like to change the log file every day and this isn't directly supported.

Does anyone know a possibility to trigger an event in PHP (event handler?) every midnight for example, so that the log file can be changed?

Many thanks for every hint.

AstroTeg

If you're on *nix, hit google up for tutorials and instructions on using CRONTAB. You can use that to run a script of your choice. I might recommend first building and testing your script (make sure it works ok on its own). Then you can set it up with crontab and test your crontab setup.

If you're on Windows, you can use the task scheduler and follow the same procedure above.

qnorx

I think what he's looking for is somewhat different from a "normal" cron tool/job.

He has a singelton instance of a LogFile object (that is linked to an output file) in his web application running under apache. Each time he gets a request, he's getting the singleton instance of his LogFile object. Now, he would like to schedule a timer to call a method on his LogFile object that creates a new output file and then swaps it, i.e. all 24 hours at midnight.

I think the first question to be answered is, if there is something like a persistent runtime environment for PHP in Apache (actually there must be some kind of it, otherwise a singleton instance of an object would not be able to exist - i think the session object i.e. is kind of such object). So then he should get to know how such an object may be defined and instanciated (i dunno otherwise i would have explain).

Once he knows how to do this, he would have to create a class that could act as a timer (which would require some kind of mutlithreading - is that supported under PHP?). This class/object is sent to sleep until midnight and then upon waking up calls the required swap method of the LogFile object (of course the timer needs to get a reference to LogFile but that sould be easy since the LogFile is a singleton instance).

Any ideas, comments?

drew010

i would create a script to do whatever i need done with the logfiles and a simple cron line to run the script at midnight.

0 php -f /path/to/myscript.php

would run myscript.php at midnight every day.

qnorx

For what he likes to do the cron job wouldn't work. I will explain why:

As far as i found out until now, there are three alternatives how a webserver may work with PHP.
The first method is to use PHP as CGI Wrapper. Using this method, the webserver will create an instance of the php interpreter upon each request and close it afterwards. Like this, no persistence is given, no objects may be shared over more than one request.
The second method (and widly used these days) uses PHP as a Modul in a multi-process/multi-threaded webserver. Each request is passed from the parent process (kind of request handler) to one of it's childs. Each of this child processes is persistent, means within one of these child processes an object may life for a longer period than the request it was created in.
Third method is a plugin for a multi-threaded webserver. This will work very similar to the second alternativ

This means, that, as far as i understand now, there is no such thing as single persistent runtime environment on the webserver side that would allow to create objects and let them life there for later use. This would only work in the second method if there is only one parent and maybe one but no more child processes.

Do i get this right?

Back to the LogFile and cron job problem - running a cron job from outside one of the webserver's processes you will have no chance to get a reference to the current instance of the LogFile object to call its swap() method (you will only be able to create a new Instance of the LogFile object with the same parameter an than swap the LogFile, but the LogFile object in the webserver would not know about this). So this couldn't ever work.
But also his approach witha time object will not work because of the missing server-wide persistent runtime env.

But, what i am still wondering about is, if there in no server-wide persistent runtime env, how then do sessions work? Session objects seem to be persistently available no matter of what child process is handling the request......

AstroTeg

Maybe the ultimate goal isn't clear to me, but isn't this just a matter of swapping the log file out and saving it for a particular day/time period?

I was figuring the goal here was to create a collection of log files based on day. Cronjob can do this (with the idea a script writes to one log file and cron renames the file with the date).

Cronwant will be responsible for adding logging functionality within his code (for those events he wants logged).

drew010

and in php objects have no persistance, meaning once execution of a given script ends, all variables are destroyed, objects, arrays, and plain old primitive types. sessions are just a nice way of being able to use cookies to save user data, or alternatively, having sessions store the data in a file on the server, and associate the data with a given user when they are identified.