Autarchy of the Private Cave

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    Archive for May 23rd, 2007

    Radical Alternative to caching: On-the-fly Content-Regeneration

    23rd May 2007

    Refreshing my scarce knowledge of Apache’s mod-rewrite, I read through the mod_rewrite guide, and found an extremely interesting section, titled

    On-the-fly Content-Regeneration

    Here’s the theoretical problem:

    1. we are building a high-traffic site with lots of once-per-(hour|day) updated items
    2. we have a CMS with just all the features we need, but it’s really CPU/DB-consuming and slow (does it sound familiar? :) )
    3. there’s a need to serve static files

    And here’s the ‘radical alternative’ solution:

    1. install the CMS of choice
    2. tweak the CMS’s output layer to both produce/write to disk (or update) static HTML files, and to dump those same pages directly to browser
    3. use the “On-the-fly Content-Regeneration” mod_rewrite rules set

    This is it, in short. The “On-the-fly Content-Regeneration” will read the static files if they exist, or will query the CMS, which will create/update the static files and output the necessary page. You can also setup a cron-job to remove all static files older than XX minutes, to force content refresh.

    Below is the copy of “On-the-fly Content-Regeneration” from the mod_rewrite guide.
    Read the rest of this entry »


    Posted in CMS, Links, Notepad, Programming, Web | No Comments »

    Directory-based random image rotation PHP script

    23rd May 2007

    Yesterday I needed to put together a rather simple PHP script: it would read the contents of a single pre-configured directory, and randomly select up to a pre-configured number of files. These files were images, and were just dumped as IMG tags into the webpage. I came up with a solution, shown below.

    The script is simple, but still it’s easier to use the ready solution than to write your own :).
    It is heavily commented, and should be easy to understand.
    Read the rest of this entry »


    Posted in PHP, Programming, Web | No Comments »

    Executing and checking background shell process from PHP

    23rd May 2007

    Found a nicely illustrated method for running a background shell command from PHP and continuously checking if the process is still running.

    Here’s sample code without explanations:

    1. function run_in_background($Command, $Priority = 0)
    2. {
    3.  if($Priority)
    4.   $PID = shell_exec("nohup nice -n $Priority $Command 2> /dev/null & echo $!");
    5.  else
    6.   $PID = shell_exec("nohup $Command 2> /dev/null & echo $!");
    7.  return($PID);
    8. }
    10. function is_process_running($PID)
    11. {
    12.  exec("ps $PID", $ProcessState);
    13.  return(count($ProcessState) >= 2);
    14. }

    To run something like hmmsearch from the HMMER package, you’d do this:

    1. echo("Running hmmsearch. . .")
    2. $ps = run_in_background("hmmsearch $hmmfile $fastafile > $outfile");
    3. while(is_process_running($ps))
    4. {
    5.  echo(" . ");
    6.  ob_flush();flush();
    7.  sleep(1);
    8. }

    Posted in Links, PHP, Programming | 8 Comments »