How index page caching works

[igolikov]

Hello,

I have run across a problem: home page generates very high system load.
I found out that index page calls (not all) executes about 170 sql queries every time.

Contao use following file name for reading page from cache (code from index.php)

if ($this->Environment->request == '' || $this->Environment->request == 'index.php')
{
	$strCacheKey = $this->Environment->base .'empty.'. $this->Environment->httpAcceptLanguage[0];
}
else
{
	$strCacheKey = $this->Environment->base . $this->Environment->request;
}
$strCacheFile = TL_ROOT . '/system/tmp/' . md5($strCacheKey);

index.php

When Contao writes cache to disk , it uses following file name (code from FrontendTemplate.php )

if ($this->Environment->request == '' || $this->Environment->request == 'index.php')
{
	$strUniqueKey = $this->Environment->base . 'empty.' . $objPage->language;
}
else
{
	$strUniqueKey = $this->Environment->base . $strUrl;
}
$objFile = new File('system/tmp/' . md5($strUniqueKey));

Difference only in postfix: $this->Environment->httpAcceptLanguage[0] and $objPage->language

// here contao define key for reading from cache
$strCacheKey = $this->Environment->base .'empty.'. $this->Environment->httpAcceptLanguage[0];

// here contao define key for writing to cache
$strUniqueKey = $this->Environment->base . 'empty.' . $objPage->language;

I tried to request index page from 1st browser.
/system/tmp folder was empty , so cache file was created

md5( 'www.domain.com/empty.en')

that I requested index page second time , and it was read from cache

md5('www.domain.com/empty.en')

that I opened another browser, and requested index page.
Contao tried to read cache from

md5('www.domain.com/empty.ru');

this file didn't exist, so contao write cache to

md5('www.domain.com/empty.en')

Contao tries to read cache from md5('www.domain.com/empty.ru') , it doesn't exists, Contao generates page and writes cache to md5('www.domain.com/empty.en')

In my case cache doesn't work because httpAcceptLanguage and objPage->language are different.

Is it normal behavior , and can it be fixed without scripts changing?

I fixed that, but not sure that is right way:

if ($this->Environment->request == '' || $this->Environment->request == 'index.php')
{
	$strCacheKey = $this->Environment->base .'empty.en';
}
else
...

[qrczak]

Interesting... maybe you should create ticket at http://dev.contao.org

[tsarma]

I thought this has been dealt with since version 2.9.1, It was a very long discussion in German forum (http://www.contao-community.de/showthre ... #post79882). Though you may not understand german, but look into the code snippet in this threat, you may get the idea.
But anyway create ticket and let clear the things up.