/**
* Override of the set_cache method, works in exactly the same way except
* the check for the max-age header in the response has been removed so that
* Codebase API responses will always be cached, this breaks HTTP Cache
* rules but is the cleanest way of enabling caching for all responses
* within Kohana.
*
* @param Response $response
* @return boolean
*/
public function set_cache(Response $response)
{
$headers = $response->headers()->getArrayCopy();
if ($cache_control = Arr::get($headers, 'cache-control')) {
// Parse the cache control
$cache_control = HTTP_Header::parse_cache_control($cache_control);
// If the no-cache or no-store directive is set, return
if (array_intersect($cache_control, array('no-cache', 'no-store'))) {
return FALSE;
}
// Check for private cache and get out of here if invalid
if (!$this->_allow_private_cache and in_array('private', $cache_control)) {
if (!isset($cache_control['s-maxage'])) {
return FALSE;
}
// If there is a s-maxage directive we can use that
$cache_control['max-age'] = $cache_control['s-maxage'];
}
}
/**
* if the max-age cache control header is set to 0 in the response, set
* it to 1 hour so the reponse will be cacheable
*/
$cache_control_header = $response->headers('Cache-Control');
$response->headers('Cache-Control', str_replace('max-age=0', 'max-age=3600', $cache_control_header));
if ($expires = Arr::get($headers, 'expires') and !isset($cache_control['max-age'])) {
// Can't cache things that have expired already
if (strtotime($expires) <= time()) {
return FALSE;
}
}
return TRUE;
}
/**
* Calculates the total Time To Live based on the specification
* RFC 2616 cache lifetime rules.
*
* @param Response $response Response to evaluate
* @return mixed TTL value or false if the response should not be cached
*/
public function cache_lifetime(Response $response)
{
// Get out of here if this cannot be cached
if (!$this->set_cache($response)) {
return FALSE;
}
// Calculate apparent age
if ($date = $response->headers('date')) {
$apparent_age = max(0, $this->_response_time - strtotime($date));
} else {
$apparent_age = max(0, $this->_response_time);
}
// Calculate corrected received age
if ($age = $response->headers('age')) {
$corrected_received_age = max($apparent_age, intval($age));
} else {
$corrected_received_age = $apparent_age;
}
// Corrected initial age
$corrected_initial_age = $corrected_received_age + $this->request_execution_time();
// Resident time
$resident_time = time() - $this->_response_time;
// Current age
$current_age = $corrected_initial_age + $resident_time;
// Prepare the cache freshness lifetime
$ttl = NULL;
// Cache control overrides
if ($cache_control = $response->headers('cache-control')) {
// Parse the cache control header
$cache_control = HTTP_Header::parse_cache_control($cache_control);
if (isset($cache_control['max-age'])) {
$ttl = $cache_control['max-age'];
}
if (isset($cache_control['s-maxage']) and isset($cache_control['private']) and $this->_allow_private_cache) {
$ttl = $cache_control['s-maxage'];
}
if (isset($cache_control['max-stale']) and !isset($cache_control['must-revalidate'])) {
$ttl = $current_age + $cache_control['max-stale'];
}
}
// If we have a TTL at this point, return
if ($ttl !== NULL) {
return $ttl;
}
if ($expires = $response->headers('expires')) {
return strtotime($expires) - $current_age;
}
return FALSE;
}
/**
* Tests that `parse_cache_control()` outputs the correct cache control
* parsed data from the input string
*
* @dataProvider provider_parse_cache_control
*
* @param string $input input
* @param array $expected expected
* @return void
*/
public function test_parse_cache_control($input, array $expected)
{
$parsed = HTTP_Header::parse_cache_control($input);
$this->assertInternalType('array', $parsed);
foreach ($expected as $key => $value) {
if (is_int($key)) {
$this->assertTrue(in_array($value, $parsed));
} else {
$this->assertTrue(array_key_exists($key, $parsed));
$this->assertSame($value, $parsed[$key]);
}
}
}
