<?php
/**
 * Memcached Object Cache
 * 
   在PHP中安装了 Memcached 扩展，然后复制此文件到 wp-content 目录下，WordPress 将使用 Memcached 作为对象缓存。
 *
 * @package WordPress
 */

if (isset($_GET['debug']) && $_GET['debug'] == 'sql') {
	return;
}

// 如果多个安装程序共用一个 wp-config.php 或 $table_prefix，
// 用户可以使用此功能来保证此对象缓存生成的密钥的唯一性。
if (!defined('WP_CACHE_KEY_SALT')) {
	if (isset($table_prefix) && !empty($table_prefix)) {
		define('WP_CACHE_KEY_SALT', $table_prefix);
	} else {
		define('WP_CACHE_KEY_SALT', md5(__FILE__));
	}
}

if (class_exists('Memcached')) {
	function wp_cache_add($key, $data, $group = '', $expire = 0)
	{
		global $wp_object_cache;
		return $wp_object_cache->add($key, $data, $group, (int) $expire);
	}

	function wp_cache_cas($cas_token, $key, $data, $group = '', $expire = 0)
	{
		global $wp_object_cache;
		return $wp_object_cache->cas($cas_token, $key, $data, $group, (int) $expire);
	}

	function wp_cache_close()
	{
		global $wp_object_cache;
		return $wp_object_cache->close();
	}

	function wp_cache_decr($key, $offset = 1, $group = '', $initial_value = 0, $expire = 0)
	{
		global $wp_object_cache;
		return $wp_object_cache->decr($key, $offset, $group, $initial_value, $expire);
	}

	function wp_cache_delete($key, $group = '')
	{
		global $wp_object_cache;
		return $wp_object_cache->delete($key, $group);
	}

	function wp_cache_flush()
	{
		global $wp_object_cache;
		return $wp_object_cache->flush();
	}

	function wp_cache_get($key, $group = '', $force = false, &$found = null)
	{
		global $wp_object_cache;
		return $wp_object_cache->get($key, $group, $force, $found);
	}

	function wp_cache_get_multiple($keys, $group = '', $force = false)
	{
		global $wp_object_cache;
		return $wp_object_cache->get_multiple($keys, $group, $force);
	}

	function wp_cache_set_multiple($data, $group = '', $expire = 0)
	{
		global $wp_object_cache;
		return $wp_object_cache->set_multiple($data, $group, $expire);
	}

	function wp_cache_delete_multiple($keys, $group = '')
	{
		global $wp_object_cache;
		return $wp_object_cache->delete_multiple($keys, $group);
	}

	function wp_cache_get_with_cas($key, $group = '', &$token = null)
	{
		global $wp_object_cache;
		return $wp_object_cache->get_with_cas($key, $group, $token);
	}

	function wp_cache_incr($key, $offset = 1, $group = '', $initial_value = 0, $expire = 0)
	{
		global $wp_object_cache;
		return $wp_object_cache->incr($key, $offset, $group, $initial_value, $expire);
	}

	if (!isset($_GET['debug']) || $_GET['debug'] != 'sql') {
		function wp_cache_init()
		{
			global $wp_object_cache;
			$wp_object_cache = new WP_Object_Cache();
		}
	}

	function wp_cache_replace($key, $data, $group = '', $expire = 0)
	{
		global $wp_object_cache;
		return $wp_object_cache->replace($key, $data, $group, (int) $expire);
	}

	function wp_cache_set($key, $data, $group = '', $expire = 0)
	{
		global $wp_object_cache;
		return $wp_object_cache->set($key, $data, $group, (int) $expire);
	}

	function wp_cache_switch_to_blog($blog_id)
	{
		global $wp_object_cache;
		return $wp_object_cache->switch_to_blog($blog_id);
	}

	function wp_cache_add_global_groups($groups)
	{
		global $wp_object_cache;
		$wp_object_cache->add_global_groups($groups);
	}

	function wp_cache_add_non_persistent_groups($groups)
	{
		global $wp_object_cache;
		$wp_object_cache->add_non_persistent_groups($groups);
	}

	function wp_cache_get_stats()
	{
		global $wp_object_cache;
		return $wp_object_cache->get_stats();
	}

	class WP_Object_Cache
	{
		private $cache = [];
		private $mc = null;

		private $blog_prefix;
		private $global_prefix;

		protected $global_groups = [];
		protected $non_persistent_groups = [];

		protected function action($action, $id, $group, $data, $expire = 0)
		{
			if ($this->is_non_persistent_group($group)) {
				$internal = $this->internal('get', $id, $group);

				if ($action == 'add') {
					if ($internal !== false) {
						return false;
					}
				} elseif ($action == 'replace') {
					if ($internal === false) {
						return false;
					}
				} elseif ($action == 'increment' || $action == 'decrement') {
					$data = $action == 'increment' ? $data : (0 - $data);
					$data = (int) $internal + $data;
					$data = $data < 0 ? 0 : $data;
				}

				return $this->internal('add', $id, $group, $data);
			} else {
				$key    = $this->build_key($id, $group);
				$expire = (!$expire && strlen($id) > 50) ? DAY_IN_SECONDS : $expire;

				if ($action == 'set') {
					$result = $this->mc->set($key, $data, $expire);
				} elseif ($action == 'add') {
					$result = $this->mc->add($key, $data, $expire);
				} elseif ($action == 'replace') {
					$result = $this->mc->replace($key, $data, $expire);
				} elseif ($action == 'increment') {
					$result = $data = $this->mc->increment($key, $data);
				} elseif ($action == 'decrement') {
					$result = $data = $this->mc->decrement($key, $data);
				}

				$code = $this->mc->getResultCode();

				if ($code === Memcached::RES_SUCCESS) {
					$this->internal('add', $id, $group, $data);
				} else {
					$this->internal('del', $id, $group);

					if ($code != Memcached::RES_NOTSTORED) {
						// trigger_error($code.' '.var_export($result, true).' '.var_export($key, true));
					}
				}

				return $result;
			}
		}

		protected function internal($action, $id, $group, $data = null)
		{
			$group = $this->parse_group($group);

			if ($action == 'get') {
				$data = $this->cache[$group][$id] ?? false;

				return is_object($data) ? clone $data : $data;
			} elseif ($action == 'add') {
				$this->cache[$group][$id] = is_object($data) ? clone $data : $data;

				return true;
			} elseif ($action == 'del') {
				unset($this->cache[$group][$id]);
			}
		}

		public function add($id, $data, $group = 'default', $expire = 0)
		{
			if (wp_suspend_cache_addition()) {
				return false;
			}

			return $this->action('add', $id, $group, $data, $expire);
		}

		public function replace($id, $data, $group = 'default', $expire = 0)
		{
			return $this->action('replace', $id, $group, $data, $expire);
		}

		public function set($id, $data, $group = 'default', $expire = 0)
		{
			return $this->action('set', $id, $group, $data, $expire);
		}

		public function incr($id, $offset = 1, $group = 'default', $initial_value = 0, $expire = 0)
		{
			$this->action('add', $id, $group, $initial_value, $expire);
			return $this->action('increment', $id, $group, $offset);
		}

		public function decr($id, $offset = 1, $group = 'default', $initial_value = 0, $expire = 0)
		{
			$this->action('add', $id, $group, $initial_value, $expire);
			return $this->action('decrement', $id, $group, $offset);
		}

		public function cas($cas_token, $id, $data, $group = 'default', $expire = 0)
		{
			$this->internal('del', $id, $group);

			return $this->mc->cas($cas_token, $this->build_key($id, $group), $data, $expire);
		}

		public function delete($id, $group = 'default')
		{
			$this->internal('del', $id, $group);

			return $this->is_non_persistent_group($group) ? true : $this->mc->delete($this->build_key($id, $group));
		}

		public function flush()
		{
			$this->cache = [];

			return $this->mc->flush();
		}

		public function get($id, $group = 'default', $force = false, &$found = null)
		{
			$value = $force ? false : $this->internal('get', $id, $group);
			$found = $value !== false;

			if (!$found && !$this->is_non_persistent_group($group)) {
				$value = $this->mc->get($this->build_key($id, $group));
				$code  = $this->mc->getResultCode();
				$found = $code !== Memcached::RES_NOTFOUND;

				if ($found) {
					if ($code !== Memcached::RES_SUCCESS) {
						trigger_error($code . ' ' . var_export([$id, $group, $value], true));
					}

					$this->internal('add', $id, $group, $value);
				}
			}

			return $value;
		}

		public function get_with_cas($id, $group = 'default', &$cas_token = null)
		{
			$key = $this->build_key($id, $group);

			if (defined('Memcached::GET_EXTENDED')) {
				$result = $this->mc->get($key, null, Memcached::GET_EXTENDED);

				if ($this->mc->getResultCode() === Memcached::RES_NOTFOUND) {
					return false;
				} else {
					$cas_token = $result['cas'];
					return $result['value'];
				}
			} else {
				$value = $this->mc->get($key, null, $cas_token);

				if ($this->mc->getResultCode() === Memcached::RES_NOTFOUND) {
					return false;
				} else {
					return $value;
				}
			}
		}

		public function get_multiple($ids, $group = 'default', $force = false)
		{
			$caches = [];
			$keys   = [];

			$non_persistent = $this->is_non_persistent_group($group);

			if ($non_persistent || !$force) {
				foreach ($ids as $id) {
					$caches[$id] = $this->internal('get', $id, $group);
					$keys[$id]   = $this->build_key($id, $group);

					if (!$non_persistent && $caches[$id] === false) {
						$force = true;
					}
				}

				if ($non_persistent || !$force) {
					return $caches;
				}
			}

			$results = $this->mc->getMulti(array_values($keys)) ?: [];

			foreach ($keys as $id => $key) {
				$caches[$id] = $results[$key] ?? false;

				$this->internal('add', $id, $group, $caches[$id]);
			}

			return $caches;
		}

		public function set_multiple($data, $group = 'default', $expire = 0)
		{
			$items = [];

			foreach ($data as $id => $value) {
				$this->internal('add', $id, $group, $value);

				$key = $this->build_key($id, $group);

				$items[$key] = $value;
			}

			if ($this->is_non_persistent_group($group)) {
				$result = true;
			} else {
				$result = $this->mc->setMulti($items, $expire);
				$code   = $this->mc->getResultCode();

				if ($code !== Memcached::RES_SUCCESS) {
					if ($code != Memcached::RES_NOTSTORED) {
						// trigger_error($code.' '.var_export($result,true));
					}

					foreach ($data as $id => $value) {
						$this->internal('del', $id, $group);
					}

					return $result;
				}
			}

			return $result;
		}

		public function delete_multiple($ids, $group = 'default')
		{
			foreach ($ids as $id) {
				$this->internal('del', $id, $group);

				$keys[] = $this->build_key($id, $group);
			}

			return (empty($keys) || $this->is_non_persistent_group($group)) ? true : $this->mc->deleteMulti($keys);
		}

		public function add_global_groups($groups)
		{
			$this->global_groups = array_merge($this->global_groups, array_fill_keys((array) $groups, true));
		}

		public function add_non_persistent_groups($groups)
		{
			$this->non_persistent_groups = array_merge($this->non_persistent_groups, array_fill_keys((array) $groups, true));
		}

		public function switch_to_blog($blog_id)
		{
			if (is_multisite()) {
				$this->blog_prefix = ((int) $blog_id) . ':';
			}
		}

		private function is_non_persistent_group($group)
		{
			return $group ? isset($this->non_persistent_groups[$group]) : false;
		}

		private function parse_group($group)
		{
			$group  = $group ?: 'default';
			$prefix = isset($this->global_groups[$group]) ? $this->global_prefix : $this->blog_prefix;

			return WP_CACHE_KEY_SALT . $prefix . $group;
		}

		public function build_key($id, $group = 'default')
		{
			return preg_replace('/\s+/', '', $this->parse_group($group) . ':' . $id);
		}

		public function get_stats()
		{
			return $this->mc->getStats();
		}

		public function get_mc()
		{
			return $this->mc;
		}

		public function failure_callback($host, $port)
		{
		}

		public function close()
		{
			$this->mc->quit();
		}

		public function __construct()
		{
			$this->mc = new Memcached();
			// $this->mc->setOption(Memcached::OPT_LIBKETAMA_COMPATIBLE, true);	// 用于启用与 libketama 一致性哈希算法兼容的服务器分布策略

			if (!$this->mc->getServerList()) {
				global $memcached_servers;

				if (isset($memcached_servers)) {
					foreach ($memcached_servers as $memcached) {
						$this->mc->addServer(...$memcached);
					}
				} else {
					$this->mc->addServer('127.0.0.1', 11211);
				}
			}

			if (is_multisite()) {
				$this->blog_prefix   = get_current_blog_id() . ':';
				$this->global_prefix = '';
			} else {
				$this->blog_prefix   = $GLOBALS['table_prefix'] . ':';
				$this->global_prefix = defined('CUSTOM_USER_TABLE') ? '' : $this->blog_prefix;
			}
		}
	}
}