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<?php |
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/** |
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* Class HTTPCacheControl |
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* |
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* @see https://docs.silverstripe.org/en/developer_guides/performance/http_cache_headers/ |
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*/ |
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class HTTPCacheControl extends SS_Object { |
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/** |
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* @var static |
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*/ |
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private static $inst; |
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/** |
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* Store for all the current directives and their values |
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* Starts with an implicit config for disabled caching |
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* |
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* @var array |
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*/ |
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private $state = array(); |
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/** |
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* Forcing level of previous setting; higher number wins |
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* Combination of consts belo |
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*w |
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* @var int |
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*/ |
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protected $forcingLevel = 0; |
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/** |
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* Forcing level forced, optionally combined with one of the below. |
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*/ |
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const LEVEL_FORCED = 10; |
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/** |
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* Forcing level caching disabled. Overrides public/private. |
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*/ |
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const LEVEL_DISABLED = 3; |
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/** |
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* Forcing level private-cached. Overrides public. |
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*/ |
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const LEVEL_PRIVATE = 2; |
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/** |
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* Forcing level public cached. Lowest priority. |
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*/ |
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const LEVEL_PUBLIC = 1; |
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/** |
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* Forcing level caching enabled. |
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*/ |
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const LEVEL_ENABLED = 0; |
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/** |
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* A list of allowed cache directives for HTTPResponses |
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* |
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* This doesn't include any experimental directives, |
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* use the config system to add to these if you want to enable them |
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* |
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* @config |
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* @var array |
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*/ |
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private static $allowed_directives = array( |
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'public', |
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'private', |
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'no-cache', |
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'max-age', |
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's-maxage', |
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'must-revalidate', |
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'proxy-revalidate', |
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'no-store', |
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'no-transform', |
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); |
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public function __construct() |
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{ |
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parent::__construct(); |
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// If we've not been provided an initial state, then grab HTTP.cache_contrpl from config |
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if (!$this->state) { |
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$this->setDirectivesFromArray(Config::inst()->get('HTTP', 'cache_control')); |
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} |
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} |
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/** |
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* Instruct the cache to apply a change with a given level, optionally |
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* modifying it with a force flag to increase priority of this action. |
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* |
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* If the apply level was successful, the change is made and the internal level |
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* threshold is incremented. |
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* |
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* @param int $level Priority of the given change |
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* @param bool $force If usercode has requested this action is forced to a higher priority. |
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* Note: Even if $force is set to true, other higher-priority forced changes can still |
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* cause a change to be rejected if it is below the required threshold. |
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* @return bool True if the given change is accepted, and that the internal |
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* level threshold is updated (if necessary) to the new minimum level. |
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*/ |
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protected function applyChangeLevel($level, $force) |
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{ |
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$forcingLevel = $level + ($force ? self::LEVEL_FORCED : 0); |
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if ($forcingLevel < $this->forcingLevel) { |
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return false; |
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} |
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$this->forcingLevel = $forcingLevel; |
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return true; |
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} |
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/** |
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* Low level method for setting directives include any experimental or custom ones added via config |
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* |
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* @param string $directive |
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* @param string|bool $value |
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* |
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* @return $this |
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*/ |
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public function setDirective($directive, $value = null) |
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{ |
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// make sure the directive is in the list of allowed directives |
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$allowedDirectives = $this->config()->get('allowed_directives'); |
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$directive = strtolower($directive); |
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if (in_array($directive, $allowedDirectives)) { |
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$this->state[$directive] = $value; |
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} else { |
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throw new InvalidArgumentException('Directive ' . $directive . ' is not allowed'); |
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} |
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return $this; |
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} |
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/** |
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* Low level method to set directives from an associative array |
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* |
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* @param array $directives |
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* |
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* @return $this |
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*/ |
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public function setDirectivesFromArray($directives) |
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{ |
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foreach ($directives as $directive => $value) { |
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// null values mean remove |
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if (is_null($value)) { |
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$this->removeDirective($directive); |
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} else { |
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// for legacy reasons we accept the string literal "true" as a bool |
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// a bool value of true means there is no explicit value for the directive |
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if ($value && (is_bool($value) || strtolower($value) === 'true')) { |
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$value = null; |
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} |
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$this->setDirective($directive, $value); |
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} |
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} |
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return $this; |
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} |
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/** |
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* Low level method for removing directives |
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* |
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* @param string $directive |
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* |
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* @return $this |
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*/ |
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public function removeDirective($directive) |
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{ |
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unset($this->state[strtolower($directive)]); |
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return $this; |
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} |
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/** |
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* Low level method to check if a directive is currently set |
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* |
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* @param string $directive |
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* |
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* @return bool |
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*/ |
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public function hasDirective($directive) |
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{ |
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return array_key_exists(strtolower($directive), $this->state); |
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} |
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/** |
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* Low level method to get the value of a directive |
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* |
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* Note that `null` value is acceptable for a directive |
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* |
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* @param string $directive |
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* |
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* @return string|false|null |
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*/ |
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public function getDirective($directive) |
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{ |
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if ($this->hasDirective($directive)) { |
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return $this->state[strtolower($directive)]; |
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} |
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return false; |
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} |
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/** |
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* The cache should not store anything about the client request or server response. |
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* |
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* Set the no-store directive (also removes max-age and s-maxage for consistency purposes) |
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* |
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* @param bool $noStore |
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* |
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* @return $this |
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*/ |
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public function setNoStore($noStore = true) |
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{ |
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if ($noStore) { |
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$this->setDirective('no-store'); |
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$this->removeDirective('max-age'); |
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$this->removeDirective('s-maxage'); |
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} else { |
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$this->removeDirective('no-store'); |
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} |
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return $this; |
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} |
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/** |
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* Forces caches to submit the request to the origin server for validation before releasing a cached copy. |
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* |
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* @param bool $noCache |
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* |
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* @return $this |
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*/ |
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public function setNoCache($noCache = true) |
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{ |
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if ($noCache) { |
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$this->setDirective('no-cache'); |
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} else { |
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$this->removeDirective('no-cache'); |
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} |
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return $this; |
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} |
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/** |
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* Specifies the maximum amount of time (seconds) a resource will be considered fresh. |
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* This directive is relative to the time of the request. |
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* |
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* @param int $age |
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* |
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* @return $this |
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*/ |
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public function setMaxAge($age) |
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{ |
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$this->setDirective('max-age', $age); |
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return $this; |
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} |
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/** |
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* Overrides max-age or the Expires header, but it only applies to shared caches (e.g., proxies) |
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* and is ignored by a private cache. |
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* |
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* @param int $age |
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* |
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* @return $this |
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*/ |
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public function setSharedMaxAge($age) |
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{ |
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$this->setDirective('s-maxage', $age); |
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return $this; |
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} |
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/** |
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* The cache must verify the status of the stale resources before using it and expired ones should not be used. |
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* |
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* @param bool $mustRevalidate |
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* |
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* @return $this |
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*/ |
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public function setMustRevalidate($mustRevalidate = true) |
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{ |
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if ($mustRevalidate) { |
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$this->setDirective('must-revalidate'); |
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} else { |
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$this->removeDirective('must-revalidate'); |
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} |
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return $this; |
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} |
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/** |
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* Simple way to set cache control header to a cacheable state. |
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* Use this method over `publicCache()` if you are unsure about caching details. |
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* |
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* Removes `no-store` and `no-cache` directives; other directives will remain in place. |
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* Use alongside `setMaxAge()` to indicate caching. |
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* |
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* Does not set `public` directive. Usually, `setMaxAge()` is sufficient. Use `publicCache()` if this is explicitly required. |
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* See https://developers.google.com/web/fundamentals/performance/optimizing-content-efficiency/http-caching#public_vs_private |
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* |
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* @see https://docs.silverstripe.org/en/developer_guides/performance/http_cache_headers/ |
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* @param bool $force Force the cache to public even if its unforced private or public |
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* @return $this |
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*/ |
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public function enableCache($force = false) |
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{ |
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// Only execute this if its forcing level is high enough |
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if (!$this->applyChangeLevel(self::LEVEL_ENABLED, $force)) { |
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SS_Log::log("Call to enableCache($force) didn't execute as it's lower priority than a previous call", SS_Log::DEBUG); |
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return $this; |
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} |
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$this->removeDirective('no-store'); |
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$this->removeDirective('no-cache'); |
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return $this; |
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} |
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/** |
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* Simple way to set cache control header to a non-cacheable state. |
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* Use this method over `privateCache()` if you are unsure about caching details. |
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* Takes precendence over unforced `enableCache()`, `privateCache()` or `publicCache()` calls. |
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* |
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* Removes all state and replaces it with `no-cache, no-store, must-revalidate`. Although `no-store` is sufficient |
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* the others are added under recommendation from Mozilla (https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Cache-Control#Examples) |
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* |
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* Does not set `private` directive, use `privateCache()` if this is explicitly required. |
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* See https://developers.google.com/web/fundamentals/performance/optimizing-content-efficiency/http-caching#public_vs_private |
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* |
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* @see https://docs.silverstripe.org/en/developer_guides/performance/http_cache_headers/ |
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* @param bool $force Force the cache to diabled even if it's forced private or public |
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* @return $this |
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*/ |
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public function disableCache($force = false) |
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{ |
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// Only execute this if its forcing level is high enough |
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if (!$this->applyChangeLevel(self::LEVEL_DISABLED, $force )) { |
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SS_Log::log("Call to disableCache($force) didn't execute as it's lower priority than a previous call", SS_Log::DEBUG); |
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return $this; |
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} |
|
332
|
|
|
|
|
333
|
|
|
$this->state = array( |
|
334
|
|
|
'no-cache' => null, |
|
335
|
|
|
'no-store' => null, |
|
336
|
|
|
'must-revalidate' => null, |
|
337
|
|
|
); |
|
338
|
|
|
return $this; |
|
339
|
|
|
} |
|
340
|
|
|
|
|
341
|
|
|
/** |
|
342
|
|
|
* Advanced way to set cache control header to a non-cacheable state. |
|
343
|
|
|
* Indicates that the response is intended for a single user and must not be stored by a shared cache. |
|
344
|
|
|
* A private cache (e.g. Web Browser) may store the response. Also removes `public` as this is a contradictory directive. |
|
345
|
|
|
* |
|
346
|
|
|
* @see https://docs.silverstripe.org/en/developer_guides/performance/http_cache_headers/ |
|
347
|
|
|
* @param bool $force Force the cache to private even if it's forced public |
|
348
|
|
|
* @return $this |
|
349
|
|
|
*/ |
|
350
|
|
|
public function privateCache($force = false) |
|
351
|
|
|
{ |
|
352
|
|
|
// Only execute this if its forcing level is high enough |
|
353
|
|
|
if (!$this->applyChangeLevel(self::LEVEL_PRIVATE, $force)) { |
|
354
|
|
|
SS_Log::log("Call to privateCache($force) didn't execute as it's lower priority than a previous call", SS_Log::DEBUG); |
|
355
|
|
|
return $this; |
|
356
|
|
|
} |
|
357
|
|
|
|
|
358
|
|
|
// Update the directives |
|
359
|
|
|
$this->setDirective('private'); |
|
360
|
|
|
$this->removeDirective('public'); |
|
361
|
|
|
$this->removeDirective('no-cache'); |
|
362
|
|
|
$this->removeDirective('no-store'); |
|
363
|
|
|
return $this; |
|
364
|
|
|
} |
|
365
|
|
|
|
|
366
|
|
|
/** |
|
367
|
|
|
* Advanced way to set cache control header to a cacheable state. |
|
368
|
|
|
* Indicates that the response may be cached by any cache. (eg: CDNs, Proxies, Web browsers) |
|
369
|
|
|
* Also removes `private` as this is a contradictory directive |
|
370
|
|
|
* |
|
371
|
|
|
* @see https://docs.silverstripe.org/en/developer_guides/performance/http_cache_headers/ |
|
372
|
|
|
* @param bool $force Force the cache to public even if it's private, unless it's been forced private |
|
373
|
|
|
* @return $this |
|
374
|
|
|
*/ |
|
375
|
|
|
public function publicCache($force = false) |
|
376
|
|
|
{ |
|
377
|
|
|
// Only execute this if its forcing level is high enough |
|
378
|
|
|
if (!$this->applyChangeLevel(self::LEVEL_PUBLIC, $force)) { |
|
379
|
|
|
SS_Log::log("Call to publicCache($force) didn't execute as it's lower priority than a previous call", SS_Log::DEBUG); |
|
380
|
|
|
return $this; |
|
381
|
|
|
} |
|
382
|
|
|
|
|
383
|
|
|
$this->setDirective('public'); |
|
384
|
|
|
$this->removeDirective('private'); |
|
385
|
|
|
$this->removeDirective('no-cache'); |
|
386
|
|
|
$this->removeDirective('no-store'); |
|
387
|
|
|
return $this; |
|
388
|
|
|
} |
|
389
|
|
|
|
|
390
|
|
|
/** |
|
391
|
|
|
* Generate and add the `Cache-Control` header to a response object |
|
392
|
|
|
* |
|
393
|
|
|
* @param SS_HTTPResponse $response |
|
394
|
|
|
* |
|
395
|
|
|
* @return $this |
|
396
|
|
|
*/ |
|
397
|
|
|
public function applyToResponse($response) |
|
398
|
|
|
{ |
|
399
|
|
|
$headers = $this->generateHeaders(); |
|
400
|
|
|
foreach ($headers as $name => $value) { |
|
401
|
|
|
$response->addHeader($name, $value); |
|
402
|
|
|
} |
|
403
|
|
|
return $this; |
|
404
|
|
|
} |
|
405
|
|
|
|
|
406
|
|
|
/** |
|
407
|
|
|
* Generate the cache header |
|
408
|
|
|
* |
|
409
|
|
|
* @return string |
|
410
|
|
|
*/ |
|
411
|
|
|
protected function generateCacheHeader() |
|
412
|
|
|
{ |
|
413
|
|
|
$cacheControl = array(); |
|
414
|
|
|
foreach ($this->state as $directive => $value) { |
|
415
|
|
|
if (is_null($value)) { |
|
416
|
|
|
$cacheControl[] = $directive; |
|
417
|
|
|
} else { |
|
418
|
|
|
$cacheControl[] = $directive . '=' . $value; |
|
419
|
|
|
} |
|
420
|
|
|
} |
|
421
|
|
|
return implode(', ', $cacheControl); |
|
422
|
|
|
} |
|
423
|
|
|
|
|
424
|
|
|
/** |
|
425
|
|
|
* Generate all headers to output |
|
426
|
|
|
* |
|
427
|
|
|
* @return array |
|
428
|
|
|
*/ |
|
429
|
|
|
public function generateHeaders() |
|
430
|
|
|
{ |
|
431
|
|
|
return array( |
|
432
|
|
|
'Cache-Control' => $this->generateCacheHeader(), |
|
433
|
|
|
); |
|
434
|
|
|
} |
|
435
|
|
|
|
|
436
|
|
|
/** |
|
437
|
|
|
* Reset registered http cache control and force a fresh instance to be built |
|
438
|
|
|
*/ |
|
439
|
|
|
public static function reset() { |
|
440
|
|
|
Injector::inst()->unregisterNamedObject(__CLASS__); |
|
441
|
|
|
} |
|
442
|
|
|
} |
|
443
|
|
|
|
This check marks implicit conversions of arrays to boolean values in a comparison. While in PHP an empty array is considered to be equal (but not identical) to false, this is not always apparent.
Consider making the comparison explicit by using
empty(..)or! empty(...)instead.