file writing / caching

[scrupul0us]

does this look about right for caching web page results into a file and then checking to see if it needs to be refreshed again by using mtime?

$cache_time = 300; //time in seconds
$myFile = "testFile.txt";
$modified = filemtime($myfile));
$now=strtotime("now");
$difference = $now - $modified;

if ($difference >= $cache_time)
{
$fh = fopen($myFile, 'w') or die("can't open file");
$stringData = file_get_contents("http://www.google.com");
fwrite($fh, $stringData);
fclose($fh);
}

[leatherback]

Hi Scruplous,

I like your approach. Very smooth. I am not sure whther the actual coding is valid, but the idea of caching your files. I like it.

I did a similar thing for google-earth plots of a spectrum database I built. Too many people hitting the database to create things on the fly.

This is what I did, hope it helps you:

  $cached_file_name = $cache_folder."spec".$specid."img.png";

  if($spectrum_caching)
    {

// is a cached file available?
if(file_exists($cached_file_name))
  {
  $file_modified = filemtime($cached_file_name);  // unix timestamp of lat modified time

  // check whether cache is not older then insert date
  $query = "select sp_insert_date from ".$spectra_table." where sp_id = $specid";
  $DBH = db_connect();
    $result = mysql_query($query) or handle_errors('PLOTSP','71', mysql_error(), $query);
    if($result)
      {
      while($row = mysql_fetch_array($result))
       {
       $insert_date = $row['sp_insert_date'];
       if($insert_date < $file_modified)
         {
         $show_cached = false;
         }
       }
     }
   else
     {
     $show_cached = true;
     }      
 db_disconnect($DBH);
 }
   }

[scrupul0us]

$cache_time = 300; //time in seconds
$myfile 	= "test.txt";
$modified 	= filemtime($myfile);
$now		= strtotime("now");
$difference = $now - $modified;

im gettin an error:

Warning: filemtime() [function.filemtime]: stat failed for test.txt

[leatherback]

I bet test.txt is not in the root of your server.
You need to add the filepath to it

[scrupul0us]

i got it to work... it was a permissions issue

man that code is slick... it REALLY helps load time on my page which makes AJAX all the happier

[leatherback]

Yeah, my server load dropped a bit too, after I switched caching on. (In my case, it retrieves up to 2000 values from the database, plots it x-y and shows a transparent area under the curves made of the points. Can you imagine how much server load caching saves) In action: http://database.hyperspectral.info/details/index.php

[scrupul0us]

ugh now i actually have issues with perms again...

if apache/php runs under nobody:nobody then im a bit confused

all my www files (below htdocs) belong to scrupul0us:root
but htdocs belongs to scrupul0us:users
im trying to put my txt files in:

htdocs/feeds/

that directory is set as such:

drwxrwxrwx   2 scrupul0us users 4096 2007-03-05 18:37 feeds

and the files within are set to:

-rwxrwxrwx   1 scrupul0us users   2777 2007-03-05 18:43 av.txt
-rwxrwxrwx   1 scrupul0us users  11321 2007-03-05 18:43 avg.txt
-rwxrwxrwx   1 scrupul0us users 568152 2007-03-05 18:43 hosts.txt
-rwxrwxrwx   1 scrupul0us users   9701 2007-03-05 18:43 pg.txt
-rwxrwxrwx   1 scrupul0us users  22696 2007-03-05 18:43 spy.txt
-rwxrwxrwx   1 scrupul0us users  13635 2007-03-05 18:40 tagg.txt
-rwxrwxrwx   1 scrupul0us users  28372 2007-03-05 18:40 woot.txt

yet php cant open the files for writing

[scrupul0us]

oh NM... AJAX was making my life miserable

heres my final code:

##################################
#CACHE THE FILE FROM THE SERVER
##################################
$url 		= "http://www.feedurl.com/";
$path		= "/path/to/feeds";
$cache_time = 300; //time in seconds
$myfile 	= "$path/file.txt";
$modified 	= @filemtime($myfile);
$now		= strtotime("now");
$difference = $now - $modified;

if ($difference >= $cache_time)
{
$fh = fopen($myfile, 'w') or die("File Error");
$stringData = file_get_contents($url,"r");
fwrite($fh, $stringData);
fclose($fh);
}