SQLITE缓存

<?php

/**
 * Sqlite缓存类
 * @author WeakSun <52132522@qq.com>
 */

class Sqlite {

	static protected $handler;
	protected $options = array(
		'table' => 'iCaches'
	);

	/**
	 * 架构函数
	 * @access public
	 */
	public function __construct($options = array()) {
		$this->options['prefix'] = isset($options['prefix']) ? $options['prefix'] : C('DATA_CACHE_PREFIX', null, '');
		$this->options['expire'] = isset($options['expire']) ? $options['expire'] : C('DATA_CACHE_TIME', null, 36000);
		$this->options['nowTime'] = isset($GLOBALS['_beginTime']) ? $GLOBALS['_beginTime'] : microtime(true);
		$dbFile = TEMP_PATH . 'Caches.tmp';
		$isCreate = is_file($dbFile);
		if (empty(static::$handler)) {
			static::$handler = new PDO("sqlite:{$dbFile}", null, null, array(PDO::ATTR_PERSISTENT => true));
			empty($isCreate) && $this->exec("PRAGMA encoding = 'UTF8';PRAGMA temp_store = 2;PRAGMA auto_vacuum = 0;PRAGMA count_changes = 1;PRAGMA cache_size = 9000;");
			$this->chkTable() || $this->createTable();
		}
	}

	public function __destruct() {
		return $this->exec("DELETE FROM `{$this->options['table']}` WHERE `expire` < strftime('%s','now');VACUUM;");
	}

	public function __call($method, $arguments) {
		if (method_exists(self::$handler, $method)) {
			return call_user_func_array(array(self::$handler, $method), $arguments);
		} else {
			E(__CLASS__ . ':' . $method . L('_METHOD_NOT_EXIST_'));
			return;
		}
	}

	/**
	 * 读取缓存
	 * @access public
	 * @param string $name 缓存变量名
	 * @return mixed
	 */
	public function get($name) {
		$id = $this->getName($name);
		$sth = static::$handler->query("SELECT `value` FROM `{$this->options['table']}` WHERE `id`='{$id}' AND `expire` > strftime('%s','now') LIMIT 1", PDO::FETCH_NUM);
		if (!empty($sth)) {
			N('cache_read', 1);
			list($data) = $sth->fetch();
			return unserialize($data);
		} else {
			return false;
		}
	}

	/**
	 * 写入缓存
	 * @access public
	 * @param string $name 缓存变量名
	 * @param mixed $value  存储数据
	 * @param int $expire  有效时间 0为永久
	 * @return boolean
	 */
	public function set($name, $value, $expire = 0) {
		N('cache_write', 1);
		$data = serialize($value);
		if ($expire < 0 || $expire === false) {
			return true;
		} elseif (is_null($value) || $value === false) {
			return $this->rm($name);
		} elseif ($expire < 1) {
			$expire = 315360000;
		}
		$id = $this->getName($name);
		return $this->exec("REPLACE INTO `{$this->options['table']}` VALUES('{$id}','{$data}',{$expire}+strftime('%s','now'))");
	}

	/**
	 * 删除缓存
	 * @access public
	 * @param string $name 缓存变量名
	 * @return boolean
	 */
	public function rm($name) {
		$id = $this->getName($name);
		return $this->exec("DELETE FROM `{$this->options['table']}` WHERE `id` = '{$id}'");
	}

	/**
	 * 清除缓存
	 * @access public
	 * @param string $name 缓存变量名
	 * @return boolean
	 */
	public function clear() {
		return $this->exec("DELETE FROM `{$this->options['table']}`;");
	}

	/**
	 * 检查当前表是否存在
	 * @return bool 返回检查结果，存在返回True，失败返回False
	 */
	protected function chkTable() {
		return in_array($this->options['table'], $this->getTables());
	}

	/**
	 * 获取当前数据库的数据表列表
	 * @return array 返回获取到的数据表列表数组
	 */
	protected function getTables() {
		$tables = $data = array();
		$sth = $this->query("SELECT `name` FROM `sqlite_master` WHERE `type` = 'table' UNION ALL SELECT `name` FROM `sqlite_temp_master`");
		if (!empty($sth)) {
			while ($row = $sth->fetch(PDO::FETCH_NUM, PDO::FETCH_ORI_NEXT)) {
				$tables[] = $row[0];
			}
			unset($sth, $row);
		}
		return $tables;
	}

	/**
	 * 创建当前数据表
	 * @return integer 成功返回1，失败返回0
	 */
	protected function createTable() {
		return $this->exec("CREATE TABLE IF NOT EXISTS `{$this->options['table']}` (`id` VARCHAR PRIMARY KEY ON CONFLICT FAIL NOT NULL COLLATE 'NOCASE',`value` TEXT NOT NULL,`expire` INTEGER NOT NULL);");
	}

	/**
	 * 获取缓存名称
	 * @param string $name
	 * @return string
	 */
	protected function getName($name) {
		if (!is_string($name) && !is_numeric($name)) {
			$name = md5(serialize($name));
		}
		return $this->options['prefix'] . $name;
	}

}