silverstripe-framework/src/Core/Cache.php

<?php

namespace SilverStripe\Core;

use Zend_Cache;
use Zend_Cache_Core;

/**
 * The `[api:Cache]` class provides a bunch of static functions wrapping the Zend_Cache system
 * in something a little more easy to use with the SilverStripe config system.
 *
 * @see https://docs.silverstripe.org/en/3.4/developer_guides/performance/caching/
 */
class Cache
{

    /**
     * @var array $backends
     */
    protected static $backends = array();

    /**
     * @var array $backend_picks
     */
    protected static $backend_picks = array();

    /**
     * @var array $cache_lifetime
     */
    protected static $cache_lifetime = array();

    /**
     * Initialize the 'default' named cache backend.
     */
    protected static function init()
    {
        if (!isset(self::$backends['default'])) {
            $cachedir = TEMP_FOLDER . DIRECTORY_SEPARATOR . 'cache';

            if (!is_dir($cachedir)) {
                mkdir($cachedir);
            }

            /** @skipUpgrade */
            self::$backends['default'] = array(
                'File',
                array(
                    'cache_dir' => $cachedir
                )
            );

            self::$cache_lifetime['default'] = array(
                'lifetime' => 600,
                'priority' => 1
            );
        }
    }

    /**
     * Add a new named cache backend.
     *
     * @see http://framework.zend.com/manual/en/zend.cache.html
     *
     * @param string $name The name of this backend as a freeform string
     * @param string $type The Zend_Cache backend ('File' or 'Sqlite' or ...)
     * @param array $options The Zend_Cache backend options
     */
    public static function add_backend($name, $type, $options = array())
    {
        self::init();
        self::$backends[$name] = array($type, $options);
    }

    /**
     * Pick a named cache backend for a particular named cache.
     *
     * The priority call with the highest number will be the actual backend
     * picked. A backend picked for a specific cache name will always be used
     * instead of 'any' if it exists, no matter the priority.
     *
     * @param string $name The name of the backend, as passed as the first argument to add_backend
     * @param string $for The name of the cache to pick this backend for (or 'any' for any backend)
     * @param integer $priority The priority of this pick
     */
    public static function pick_backend($name, $for, $priority = 1)
    {
        self::init();

        $current = -1;

        if (isset(self::$backend_picks[$for])) {
            $current = self::$backend_picks[$for]['priority'];
        }

        if ($priority >= $current) {
            self::$backend_picks[$for] = array(
                'name' => $name,
                'priority' => $priority
            );
        }
    }

    /**
     * Return the cache lifetime for a particular named cache.
     *
     * @param string $for
     *
     * @return string
     */
    public static function get_cache_lifetime($for)
    {
        if (isset(self::$cache_lifetime[$for])) {
            return self::$cache_lifetime[$for];
        }

        return null;
    }

    /**
     * Set the cache lifetime for a particular named cache
     *
     * @param string $for The name of the cache to set this lifetime for (or 'any' for all backends)
     * @param integer $lifetime The lifetime of an item of the cache, in seconds, or -1 to disable caching
     * @param integer $priority The priority. The highest priority setting is used. Unlike backends, 'any' is not
     *                          special in terms of priority.
     */
    public static function set_cache_lifetime($for, $lifetime = 600, $priority = 1)
    {
        self::init();

        $current = -1;

        if (isset(self::$cache_lifetime[$for])) {
            $current = self::$cache_lifetime[$for]['priority'];
        }

        if ($priority >= $current) {
            self::$cache_lifetime[$for] = array(
                'lifetime' => $lifetime,
                'priority' => $priority
            );
        }
    }

    /**
     * Build a cache object.
     *
     * @see http://framework.zend.com/manual/en/zend.cache.html
     *
     * @param string $for The name of the cache to build
     * @param string $frontend (optional) The type of Zend_Cache frontend
     * @param array $frontendOptions (optional) Any frontend options to use.
     * @return Zend_Cache_Core The cache object
     */
    public static function factory($for, $frontend = 'Output', $frontendOptions = null)
    {
        self::init();

        $backend_name = 'default';
        $backend_priority = -1;
        $cache_lifetime = self::$cache_lifetime['default']['lifetime'];
        $lifetime_priority = -1;

        foreach (array('any', $for) as $name) {
            if (isset(self::$backend_picks[$name])) {
                if (self::$backend_picks[$name]['priority'] > $backend_priority) {
                    $backend_name = self::$backend_picks[$name]['name'];
                    $backend_priority = self::$backend_picks[$name]['priority'];
                }
            }

            if (isset(self::$cache_lifetime[$name])) {
                if (self::$cache_lifetime[$name]['priority'] > $lifetime_priority) {
                    $cache_lifetime = self::$cache_lifetime[$name]['lifetime'];
                    $lifetime_priority = self::$cache_lifetime[$name]['priority'];
                }
            }
        }

        $backend = self::$backends[$backend_name];

        $basicOptions = array('cache_id_prefix' => $for);

        if ($cache_lifetime >= 0) {
            $basicOptions['lifetime'] = $cache_lifetime;
        } else {
            $basicOptions['caching'] = false;
        }

        $frontendOptions = $frontendOptions ? array_merge($basicOptions, $frontendOptions) : $basicOptions;

        require_once 'Zend/Cache.php';

        return Zend_Cache::factory(
            $frontend,
            $backend[0],
            $frontendOptions,
            $backend[1]
        );
    }
}