On Wednesday 05 September 2001 21:22, Ouster wrote:
> I'm making a sort of cache system. I fell to this problem: I leave a
> cookie with the timestamp of the last access, and when the user
> reconnect, I compare the timestamp of the last change with the
> timestamp sent me with the cookie. Then I leave a new cookie.
>
> So:
> if($last_modified <= $last_access)
> {
> header("304 Not Modified);
> exit;
> }
> else
> {
> /* code genertating the new page */
> }
Tip: You don't even need a cookie for that. If you send a
"Last-Modified: " header along with all your pages (and perhaps even if
you don't), the browser will automatically add an "If-Modified-Since:"
header on each request. See the attached files for how to handle this
> Whether the If is TRUE, I get a blank page, else I see a new page
> (correct behaviour).
> Why I always get a blank page and not the cached page?
(see other responses)
--
Christian Reiniger
LGDC Webmaster (http://lgdc.sunsite.dk/)
/* you are not expected to understand this */
- from the UNIX V6 kernel source
<?php
/**
* Functions for HTTP info handling
*
* Authors : Christian Reiniger <[EMAIL PROTECTED]>
* License : GNU GPL V2 or later (http://www.fsf.org/copyleft/gpl.html)
*
* Last change by $Author$
* on $Date$
* to $Revision$
*/
/**
* Display the "404 - Not Found" page
*/
function pbHTTP_404 ()
{
global $pbGlobals;
header ("HTTP/1.0 404 Not Found");
include ($pbGlobals->Inc404);
exit ();
}
/**
* Send a "304 - Not Modified" response
*/
function pbHTTP_304 ()
{
header ('HTTP/1.0 304 Not Modified');
header ('Date: ' . gmdate ('D, d M Y H:i:s') . ' GMT');
exit ();
}
/**
* Get the value passed in an "If-Modified-Since" header or -1 if none set
* Returns a Unix timestamp;
*/
function pbHTTP_GetModifiedSince ()
{
foreach (getallheaders () as $Key => $Val) {
if ($Key == 'If-Modified-Since') {
return strtotime (trim ($Val));
}
}
return -1;
}
/**
* Send a "Last-Modified" header
*/
function pbHTTP_LastMod ($Unixtime = 0)
{
if ($Unixtime == 0)
$Unixtime = time ();
$TimeS = gmdate ('D, d M Y H:i:s', $Unixtime);
header ("Last-Modified: $TimeS GMT");
}
/**
* Send headers to disallow caching
*/
function pbHTTP_NoCache ()
{
header ('Expires: -1');
header ('Cache-Control: no-cache');
header ('Pragma: no-cache');
}
?>
<?php
/*
* Cached page handler
*
* Authors : Christian Reiniger <[EMAIL PROTECTED]>
* License : GNU GPL V2 or later (http://www.fsf.org/copyleft/gpl.html)
*
* Last change by $Author$
* on $Date$
* to $Revision$
*/
require_once ('base/defaults.php');
require_once ('phpbase/phpbase.php');
require_once ('phpbase/database.php');
require_once ('phpbase/session.php');
require_once ('phpbase/db/pagecache.php');
require_once ('phpbase/util/http.php');
assert (defined ('PAGETYPE'));
$TheSession = new KSession ();
$TheSession->OpenLight ();
/*
if ($pbSessionUser->IsRealUser () == false)
$TheSession->Relogin ();
*/
list ($Page, $CTime) = GetPage ($REQUEST_URI);
if ($Page === false)
pbHTTP_404 ();
HandleCacheHeaders ($CTime);
if (defined ('PAGE_HITCOUNTER') || defined ('PAGE_USERINFO'))
{
$Page = Postprocess ($Page);
}
// There should be a zlib.output_compression = on in a config file!
print $Page;
//Output ($Page);
$TheSession->Close ();
function GetPage ($TheURI)
{
$Usermode = GetUsermode ();
$TheURI = FixURI ($TheURI);
$Page = false;
if (!defined ('PAGE_NOSERVERCACHE'))
{
$Cache = new pbPageCache (PAGETYPE);
$Page = $Cache->Get ($TheURI, $Usermode);
$CTime = $Cache->GetCTime ();
}
if ($Page === false)
{
include ('ui/page_builder.php');
$Builder = new PageBuilder (PAGETYPE);
$Page = $Builder->Build ($TheURI, $Usermode);
$CTime = time ();
}
return array ($Page, $CTime);
}
function FixURI ($TheURI)
{
if (substr ($TheURI, -5) == '.html')
return $TheURI;
if (substr ($TheURI, -1) == '/')
return $TheURI . 'index.html';
else
return $TheURI . '/index.html';
}
function HandleCacheHeaders ($CTime)
{
if (defined ('PAGE_NOCACHE')) {
pbHTTP_NoCache ();
return;
}
$MS = pbHTTP_GetModifiedSince ();
if ($CTime == -1) {
pbHTTP_LastMod ();
return;
}
if (($MS != -1) && ($CTime < $MS)) { // changed in the meantime
pbHTTP_304 ();
}
else {
pbHTTP_LastMod ($CTime);
}
}
function GetUsermode ()
{
global $pbSessionUser;
if (isset ($pbSessionUser))
{
if ($pbSessionUser->CheckPerm (PAGETYPE, 'maintainer')) {
return 'maint';
}
elseif ($pbSessionUser->IsRealUser ()) {
return 'logged_in';
}
}
return 'std';
}
function Postprocess ($Page)
{
include ('ui/postprocess_page.php');
return PostprocessPage ($Page, GetUsermode ());
}
function Output ($Page)
{
global $HTTP_SERVER_VARS;
if (strstr($HTTP_SERVER_VARS['HTTP_ACCEPT_ENCODING'], 'gzip')) {
if (function_exists ('gzencode')) {
$Page = gzencode ($Page);
header("Content-Encoding: gzip");
}
}
header ("Content-Length: " . strlen ($Page));
print ($Page);
}
?>
--
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