When you set a header via $this->output->set_header(), but also use caching via $this->output->cache(), those headers you sent will not be cached along with your content.
This can be very problematic: if you’re caching CSS, for example, you want the cache to return that CSS along with the Content-Type header “text/css” - otherwise most browsers will interpret your CSS as just plain text, and hence not use it for rendering.
With a few simple alterations to the Output class, headers will also be cached and returned. This involved small changes to the _write_cache() and _display_cache() functions, shown below.
_write_cache function, around line 300 (surrounding code also shown)
// Implode all the headers into a newline-delimited string
// String is prepended with a pseudo-header giving the expiration time
$headers = "X-CI-Timestamp: " . (time() + ($this->cache_expiration * 60)) . "\n";
$headers .= implode("\n", $this->headers);
flock($fp, LOCK_EX);
fwrite($fp, $headers . "\n\n" . $output); // This line changed
flock($fp, LOCK_UN);
fclose($fp);
@chmod($cache_path, DIR_WRITE_MODE);
_display_cache function, around line 360 (surrounding code also shown)
// Seperate headers and cache
list($headers, $cache) = explode("\n\n", $cache, 2);
// Get each header as an array item
$headers = explode("\n", $headers);
foreach ($headers as $header)
{
// Is this header the timestamp pseudo-header?
if (FALSE === strpos($header, "X-CI-Timestamp: "))
{
$this->set_header($header); // No, it's not: set the header
}
else
{
// Has the file expired? If so we'll delete it.
$timestamp = substr($header, strlen("X-CI-Timestamp: "));
if (time() >= trim($timestamp))
{
@unlink($filepath);
log_message('debug', "Cache file has expired. File deleted");
return FALSE;
}
}
}
// Display the cache
$this->_display($cache); // This line changed
These additions automatically write headers into the cache and incorporate the timestamping in the same mechanism.
This code is given for demonstration; it could be cleaned up, by, for instance, adding a variable holding the timestamp pseudo-variable identifier, so that it needn’t be repeated, and one for the delimiters too.
We can now remove:
Lines 103 and 104
/*
* Note: If a file is cached, headers will not be sent. We need to figure out
* how to permit header data to be saved with the cache data...
*/
Category:Contributions -> Modifications