Caching between pages via memcached

Web2 and caching example from a Well House Consultants training course
More on Web2 and caching [link]

This example is described in the following article(s):
• memcached - overview, installation, example of use in PHP - [link]

If you're searching for a page where you can try this code, select here

This example references the following resources:
http://www.wellho.net/pix/$imgname
http://www.wellho.net/course/ptfull.html
http://www.wellho.net/mouth/1733_memcached.html
http://www.danga.com/memcached/

Source code: cademo.php Module: H307


<?php

# Record number to look up
$calledfor = floor($_REQUEST[calledfor] + 0); // force numeric integer!
$calledfor or $calledfor = rand(3006,3012); // Fallback value!

# The database accessor is used if we do NOT have data in cache
function dbfetch ($recno) {
        $c = mysql_connect("127.0.0.1","wellho","xxxxxxxx");
        mysql_select_db("wellho",$c);
        $qr = mysql_query("select iid,filename,descriptor ".
                "from im_library where iid = $recno",$c);
        $row = mysql_fetch_assoc($qr);
        $value = "$row[filename] $row[descriptor]";
        return ($value);
}

$memcache = new Memcache;
if ($memcache->connect('127.0.0.1', 11211)) {
        $q = "connected (memcache daemon is running)";
        if ($gotten = $memcache->get("demo:$calledfor")) {
                ### Daemon running and provided data from cache
                $say = "key $calledfor retrieved from memcached";
        } else {
                ### Daemon running but it was NOT cached
                $say = "key $calledfor from database (was NOT cached)";
                # Never mind - fetch it and store for next time!
                $gotten = dbfetch($calledfor);
                $memcache->set("demo:$calledfor",$gotten);
        }
} else {
        ### No Daemon running - just fetch from database!
        $q = "failed (sorry - daemon is not running)";
        $say = "key $calledfor fetched from database";
        $gotten .= dbfetch($calledfor);
        # No point in trying to save it - cacher isn't running!
}

# Following code is common code whatever the source!
# and represents the application

$parts = explode(" ",$gotten) ;
$imgname = array_shift($parts);
$imgtag = "<img src=http://www.wellho.net/pix/$imgname>";
$text = htmlspecialchars(implode(" ",$parts));
?>
<html>
<head>
<style type="text/css">
<!--
h1 {
        font-family: Arial, Helvetica, sans-serif;
        font-size: 36px;
        font-weight: bold;
        color: #CC00CC;
}
.tabtext {
        font-family: Arial, Helvetica, sans-serif;
        font-size: 12px;
        color: #004400;
}
-->
</style>
<title>Memcache demonstration in PHP</title>
<head>
<body><center>
--- daemon connect status: <?= $q ?> ---<br>
--- <?= $say ?> ---<br>
--- value is: <?= $gotten ?> ---</center><hr>
<h1>Caching database queries in memory in PHP</h1>
<table class=tabtext><tr><td valign=top>
<?= $imgtag ?><br>
<b><?= $text ?></b>
</td><td valign=top>
If you have a busy server with repeated database queries,
you may wish to use the <b>memcached</b> daemon.  This
service allows you to store a query's results in memory
(and even to share the cache between computers) so that
you don't have to keep repeating SQL and disc accesses.
<br><br>
Memcached is used on many very busy sites - it's ideal
for blog articles (where the recent ones will be cached),
images, and so on.
<br><br>
This is a demonstration of memcached in use, via a PHP
web page.  It's provided by Well House Consultants who
cover such topics on their
<a href=http://www.wellho.net/course/ptfull.html>PHP
techniques workshop</a> or on private courses.
<br><br>
You are also very welcome to view the source code (link
below) and read a little more about it in our blog
<a href=http://www.wellho.net/mouth/1733_memcached.html>here</a>.
<br><br>
The home page of memcached is
<a href=http://www.danga.com/memcached/>here</a>.
</td></tr></table>

</body>
</html>

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Other Examples

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