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Cache System Explanation (datastore)
Logikos
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Logikos Logikos is offline 03-16-2006, 10:00 PM
I'm going to try and explain the datastore system used in vBulltin. This tutorial is based around users who are already familar with PHP and MySQL.
What is Cache?
A memory area where frequently accessed data can be stored for rapid access. (View Definitions). Basicly, you can store information into the database, and grab all this information with just using 1 query. Some may question this and say: "Isn't all information in the database retrived by queires?". Yup, all information in the database is retrived using MySQL queries, though the method used is diffrent when using the datastore system in vBulletin.
I'll show you way using the datastore is a better solution for you and the users who will use your hacks.

Datastore Method
Lets say you want to use a drop down form with 3 options to choose from. Obviously you would need to create alittle script to add, delete, and edit the information; and when you make this script. Where does the info go? Well it would go into the database. Lets call the MySQL table "dropdownoptions" with 3 fields. ID, Name, and Value.

Attachment 44423
Now everytime you add, edit, or delete your information, it will be changed in the database. Here is an example of the database tree. We have 3 rows of information.
  • ID = (1) Name = (Dog) Value(Dog)
  • ID = (2) Name = (Cat) Value(Cat)
  • ID = (3) Name = (Cow) Value(Cow)
Attachment 44424

After you insert this information into the database, the next step would be to insert this info in the datastore. You can do that like this.

PHP Code:
$query = $vbulletin->db->query_read("
        SELECT *
        FROM " . TABLE_PREFIX . "dropdownmenu
        ORDER BY id DESC
");

while ($variable = $vbulletin->db->fetch_array($query))
{
        $variable_array[] = $variable;
}

build_datastore('dropmenu', serialize($variable_array)); 
Let me go ahead and tell you exacly what the above does. What we did was just grab all in the information in the database from the table dropdownmenu. The while() function will loop the information from the begging to the end. While it's getting all this information, It's storing it all into the variable named $variable_array.

Then you need to use the function called build_datastore(). This function requires the following. build_datastore(1, 2). #1 is the name of your datastore item, and number two is the serialize information to store. This function will create a new datastore item with the name and all your info.

The serialize info will look like this...
Code:
a:3:{i:0;a:3:{s:2:"id";s:1:"1";s:4:"name";s:3:"Dog";s:5:"value";s:3:"Dog";}i:1;a:3:{s:2:"id";s:1:"2";s:4:"name";s:3:"Cat";s:5:"value";s:3:"Cat";}i:2;a:3:{s:2:"id";s:1:"3";s:4:"name";s:3:"Cow";s:5:"value";s:3:"Cow";}}
So now we have all our infomation stored in another area of the database, in one row. Heres a picture so you can compair it to the other ones.

Attachment 44425

Don't let the serialize data freak you out. You don't really NEED to read that data. Though I kinda like doing it, so I'll break it down alittle for you. Here is a tree of the serialize data.

Code:
a:3:{
        i:0; a:3:{
                s:2:"id";s:1:"1";
                s:4:"name";s:3:"Dog";
                s:5:"value";s:3:"Dog";
        }

        i:1; a:3:{
                s:2:"id";s:1:"2";
                s:4:"name";s:3:"Cat";
                s:5:"value";s:3:"Cat";
        }

        i:2; a:3:{
                s:2:"id";s:1:"3";
                s:4:"name";s:3:"Cow";
                s:5:"value";s:3:"Cow";
        }
}
In PHP it would look like this.
PHP Code:
$data = array(
        '0' => array(
                'id' => '1',
                'name' => 'Dog',
                'value' => 'Dog'
        ),
        '1' => array(
                'id' => '2',
                'name' => 'Cat',
                'value' => 'Cat'
        ),
        '2' => array(
                'id' => '3',
                'name' => 'Cow',
                'value' => 'Cow'
        ),
); 
So now we have the info stored, lets get it back out in a readable formate. This is the easy part. This is the code I use.

PHP Code:
$vbulletin->dropmenu = unserialize($vbulletin->dropmenu);
foreach ($vbulletin->dropmenu AS $dropmenu)
{
        echo "(ID: "  . $dropmenu['id'] . ") (Title: " . $dropmenu['title'] . ") (Value: " . $dropmenu['title'] . ")<br />";
} 
This will print the following:
(ID: 1) (Title: Dog) (Value: Dog)
(ID: 2) (Title: Cat) (Value: Cat)
(ID: 3) (Title: Cow) (Value: Cow)

What your doing is simple. The variable $vbulletin->dropmenu holds the information though it's still serialize. The reason why $vbulletin->dropmenu is the variable is because you need to tell vBulletin which datastore row to get. In this case it is dropmenu because remember we stored it in there like this: build_datastore('dropmenu', serialize($variable_array));

Now in order for vBulletin to know about that specific row, you need to add it to the $specialtemplates array. Example:

PHP Code:
$specialtemplates = array(
        'dropmenu'
); 
So now that you understand where the variable is coming from, we need to unserialize the data, cause it looks all ugly and weird.

So $vbulletin->dropmenu = unserialize($vbulletin->dropmenu); baiscly gets the serialize info and unserialize's it using the function called unserialize() Once that is finished you want to loop the info using a foreach() function. foreach ($vbulletin->dropmenu AS $dropmenu). Doing that is storing the array info into $dropmenu and you can get each one by using the following vaiables. $dropmenu['id'], $dropmenu['title'], and $dropmenu['value'].

The reason why this is better is because vBulletin allready runs one global query to get all the datatore information. So instead of running a query everytime you want to get the drop down information, you just get it from the datastore and save that query. Some may think this is kinda extreme when you can just run a query, though as your site grows; you want to save as many queires as possiable.

If your interested in saving queries and bandwidth. I would suggest taking a look at Trigunflames profile. He has released many hacks to help in these areas.

Copyright ?2004-2006 vBHackers.com All Rights Reserved.
This tutorial may not be redistributed in whole or significant part.
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  #2  
Old 03-17-2006, 11:53 AM
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Princeton Princeton is offline
 
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Excellent article!

The only thing I have to say, "Damn, these thumbnail size!"
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Old 03-25-2006, 04:16 PM
-=Sniper=- -=Sniper=- is offline
 
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great, now I can understand how it can be used
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Old 03-25-2006, 08:50 PM
akanevsky akanevsky is offline
 
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Great article. Thank you, LiveWire.
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Old 04-16-2006, 12:40 PM
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very, very, great tutorial 'ken'
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Old 09-13-2006, 12:45 PM
Wild-Wing Wild-Wing is offline
 
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huh now i get what the a:3 means its the size of the array. damn i feel dumb now.
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Old 01-07-2007, 10:38 AM
netwind netwind is offline
 
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Nice. Is it useful write my own items to file-based datastore cache?
If yes, how I can do this ?
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Old 01-12-2007, 12:00 AM
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right..

I'm being thick here, clearly :

I want to show $numbermembers and $totalposts at the top of each page of my forum, from within the header template.

As these two values are not available unless you've already parsed the forumhome stats, I've successfully cached these values just after they are calculated at the end of index.php.

I have added it to special templates on the index.php page.

The problem I'm having is getting the data back out again, and into a useable format so I can insert it into the template.

I'm missing a step somewhere..

If I stick $vbulletin->cachedstats into the header template I see the full serialised data in there, but I can't work out from the examples exactly how (and probably more importantly WHERE) to unserialise the data and turn it into eval variables that I can use in the header template.

If anyone could give me a bit of code and tell me where to put it, I would be eternally greatful!

Thanks in advance.

Simon
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Old 01-12-2007, 07:59 AM
netwind netwind is offline
 
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You need $vbulletin->cachedstats = unserialize($vbulletin->cachedstats);
for all data (except loaded from file based datastore in my case).
store full parsed html code for maximum speed.
If not, use like this in templates :
Total users : {$vbulletin->cachedstats[totalusers]}
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Old 01-12-2007, 08:30 AM
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Thank you netwind.

Could you please tell me where I can put the unserialise code?

I've tried lots of places, but wherever I'm placing it seems to be either before the cache memory is populated, or after the header has been built.

cheers
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