rcube_cache.php
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rcube_cache.php
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	<?php

	/**
	+-----------------------------------------------------------------------+
	\| This file is part of the Roundcube Webmail client \|
	\| \|
	\| Copyright (C) The Roundcube Dev Team \|
	\| Copyright (C) Kolab Systems AG \|
	\| \|
	\| Licensed under the GNU General Public License version 3 or \|
	\| any later version with exceptions for skins & plugins. \|
	\| See the README file for a full license statement. \|
	\| \|
	\| PURPOSE: \|
	\| Caching engine \|
	+-----------------------------------------------------------------------+
	\| Author: Thomas Bruederli <roundcube@gmail.com> \|
	\| Author: Aleksander Machniak <alec@alec.pl> \|
	+-----------------------------------------------------------------------+
	*/

	/**
	* Interface class for accessing Roundcube cache
	*
	* @package Framework
	* @subpackage Cache
	*/
	class rcube_cache
	{
	protected $type;
	protected $userid;
	protected $prefix;
	protected $ttl;
	protected $packed;
	protected $indexed;
	protected $index;
	protected $index_update;
	protected $cache = [];
	protected $updates = [];
	protected $exp_records = [];
	protected $refresh_time = 0.5; // how often to refresh/save the index and cache entries
	protected $debug = false;
	protected $max_packet = -1;

	const MAX_EXP_LEVEL = 2;
	const DATE_FORMAT = 'Y-m-d H:i:s.u';
	const DATE_FORMAT_REGEX = '[0-9]{4}-[0-9]{2}-[0-9]{2} [0-9]{2}:[0-9]{2}:[0-9]{2}\.[0-9]{1,6}';


	/**
	* Object factory
	*
	* @param string $type Engine type ('db', 'memcache', 'apc', 'redis')
	* @param int $userid User identifier
	* @param string $prefix Key name prefix
	* @param string $ttl Expiration time of memcache/apc items
	* @param bool $packed Enables/disabled data serialization.
	* It's possible to disable data serialization if you're sure
	* stored data will be always a safe string
	* @param bool $indexed Use indexed cache. Indexed cache is more appropriate for
	* storing big data with possibility to remove it by a key prefix.
	* Non-indexed cache does not remove data, but flags it for expiration,
	* also stores it in memory until close() method is called.
	*
	* @param rcube_cache Cache object
	*/
	public static function factory($type, $userid, $prefix = '', $ttl = 0, $packed = true, $indexed = false)
	{
	$driver = strtolower($type) ?: 'db';
	$class = "rcube_cache_$driver";

	if (!$driver \|\| !class_exists($class)) {
	rcube::raise_error([
	'code' => 600, 'type' => 'db',
	'line' => __LINE__, 'file' => __FILE__,
	'message' => "Configuration error. Unsupported cache driver: $driver"
	],
	true, true
	);
	}

	return new $class($userid, $prefix, $ttl, $packed, $indexed);
	}

	/**
	* Object constructor.
	*
	* @param int $userid User identifier
	* @param string $prefix Key name prefix
	* @param string $ttl Expiration time of memcache/apc items
	* @param bool $packed Enables/disabled data serialization.
	* It's possible to disable data serialization if you're sure
	* stored data will be always a safe string
	* @param bool $indexed Use indexed cache. Indexed cache is more appropriate for
	* storing big data with possibility to remove it by key prefix.
	* Non-indexed cache does not remove data, but flags it for expiration,
	* also stores it in memory until close() method is called.
	*/
	public function __construct($userid, $prefix = '', $ttl = 0, $packed = true, $indexed = false)
	{
	$this->userid = (int) $userid;
	$this->ttl = min(get_offset_sec($ttl), 2592000);
	$this->prefix = $prefix;
	$this->packed = $packed;
	$this->indexed = $indexed;
	}

	/**
	* Returns cached value.
	*
	* @param string $key Cache key name
	*
	* @return mixed Cached value
	*/
	public function get($key)
	{
	if (array_key_exists($key, $this->cache)) {
	return $this->cache[$key];
	}

	return $this->read_record($key);
	}

	/**
	* Sets (add/update) value in cache.
	*
	* @param string $key Cache key name
	* @param mixed $data Cache data
	*
	* @return bool True on success, False on failure
	*/
	public function set($key, $data)
	{
	return $this->write_record($key, $data);
	}

	/**
	* @deprecated Use self::get()
	*/
	public function read($key)
	{
	return $this->get($key);
	}

	/**
	* @deprecated Use self::set()
	*/
	public function write($key, $data)
	{
	return $this->set($key, $data);
	}

	/**
	* Clears the cache.
	*
	* @param string $key Cache key name or pattern
	* @param bool $prefix_mode Enable it to clear all keys starting
	* with prefix specified in $key
	*/
	public function remove($key = null, $prefix_mode = false)
	{
	// Remove record(s) from the backend
	$this->remove_record($key, $prefix_mode);
	}

	/**
	* Remove cache records older than ttl
	*/
	public function expunge()
	{
	// to be overwritten by engine class
	}

	/**
	* Remove expired records of all caches
	*/
	public static function gc()
	{
	// Only DB cache requires an action to remove expired entries
	rcube_cache_db::gc();
	}

	/**
	* Writes the cache back to the DB.
	*/
	public function close()
	{
	$this->write_index(true);
	$this->index = null;
	$this->cache = [];
	$this->updates = [];
	}

	/**
	* A helper to build cache key for specified parameters.
	*
	* @param string $prefix Key prefix (Max. length 64 characters)
	* @param array $params Additional parameters
	*
	* @return string Key name
	*/
	public static function key_name($prefix, $params = [])
	{
	$cache_key = $prefix;

	if (!empty($params)) {
	$func = function($v) {
	if (is_array($v)) {
	sort($v);
	}
	return is_string($v) ? $v : serialize($v);
	};

	$params = array_map($func, $params);
	$cache_key .= '.' . md5(implode(':', $params));
	}

	return $cache_key;
	}

	/**
	* Reads cache entry.
	*
	* @param string $key Cache key name
	*
	* @return mixed Cached value
	*/
	protected function read_record($key)
	{
	$this->load_index();

	// Consistency check (#1490390)
	if (is_array($this->index) && !in_array($key, $this->index)) {
	// we always check if the key exist in the index
	// to have data in consistent state. Keeping the index consistent
	// is needed for keys delete operation when we delete all keys or by prefix.
	return;
	}

	$ckey = $this->ckey($key);
	$data = $this->get_item($ckey);

	if ($this->indexed) {
	return $data !== false ? $this->unserialize($data) : null;
	}

	if ($data !== false) {
	$timestamp = 0;
	$utc = new DateTimeZone('UTC');

	// Extract timestamp from the data entry
	if (preg_match('/^(' . self::DATE_FORMAT_REGEX . '):/', $data, $matches)) {
	try {
	$timestamp = new DateTime($matches[1], $utc);
	$data = substr($data, strlen($matches[1]) + 1);
	}
	catch (Exception $e) {
	// invalid date = no timestamp
	}
	}

	// Check if the entry is still valid by comparing with EXP timestamps
	// For example for key 'mailboxes.123456789' we check entries:
	// 'EXP:*', 'EXP:mailboxes' and 'EXP:mailboxes.123456789'.
	if ($timestamp) {
	$path = explode('.', "*.$key");
	$path_len = min(self::MAX_EXP_LEVEL + 1, count($path));

	for ($x = 1; $x <= $path_len; $x++) {
	$prefix = implode('.', array_slice($path, 0, $x));
	if ($x > 1) {
	$prefix = substr($prefix, 2); // remove "*." prefix
	}

	if (($ts = $this->get_exp_timestamp($prefix)) && $ts > $timestamp) {
	$timestamp = 0;
	break;
	}
	}
	}

	$data = $timestamp ? $this->unserialize($data) : null;
	}
	else {
	$data = null;
	}

	return $this->cache[$key] = $data;
	}

	/**
	* Writes single cache record into DB.
	*
	* @param string $key Cache key name
	* @param mixed $data Serialized cache data
	*
	* @return bool True on success, False on failure
	*/
	protected function write_record($key, $data)
	{
	if ($this->indexed) {
	$result = $this->store_record($key, $data);

	if ($result) {
	$this->load_index();
	$this->index[] = $key;

	if (!$this->index_update) {
	$this->index_update = time();
	}
	}
	}
	else {
	// In this mode we do not save the entry to the database immediately
	// It's because we have cases where the same entry is updated
	// multiple times in one request (e.g. 'messagecount' entry rcube_imap).
	$this->updates[$key] = new DateTime('now', new DateTimeZone('UTC'));
	$this->cache[$key] = $data;
	$result = true;
	}

	$this->write_index();

	return $result;
	}

	/**
	* Deletes the cache record(s).
	*
	* @param string $key Cache key name or pattern
	* @param boolean $prefix_mode Enable it to clear all keys starting
	* with prefix specified in $key
	*/
	protected function remove_record($key = null, $prefix_mode = false)
	{
	if ($this->indexed) {
	return $this->remove_record_indexed($key, $prefix_mode);
	}

	// "Remove" all keys
	if ($key === null) {
	$ts = new DateTime('now', new DateTimeZone('UTC'));
	$this->add_item($this->ekey('*'), $ts->format(self::DATE_FORMAT));
	$this->cache = [];
	}
	// "Remove" keys by name prefix
	else if ($prefix_mode) {
	$ts = new DateTime('now', new DateTimeZone('UTC'));
	$prefix = implode('.', array_slice(explode('.', trim($key, '. ')), 0, self::MAX_EXP_LEVEL));

	$this->add_item($this->ekey($prefix), $ts->format(self::DATE_FORMAT));

	foreach (array_keys($this->cache) as $k) {
	if (strpos($k, $key) === 0) {
	$this->cache[$k] = null;
	}
	}
	}
	// Remove one key by name
	else {
	$this->delete_item($this->ckey($key));
	$this->cache[$key] = null;
	}
	}

	/**
	* @see self::remove_record()
	*/
	protected function remove_record_indexed($key = null, $prefix_mode = false)
	{
	$this->load_index();

	// Remove all keys
	if ($key === null) {
	foreach ($this->index as $key) {
	$this->delete_item($this->ckey($key));
	if (!$this->index_update) {
	$this->index_update = time();
	}
	}

	$this->index = [];
	}
	// Remove keys by name prefix
	else if ($prefix_mode) {
	foreach ($this->index as $idx => $k) {
	if (strpos($k, $key) === 0) {
	$this->delete_item($this->ckey($k));
	unset($this->index[$idx]);
	if (!$this->index_update) {
	$this->index_update = time();
	}
	}
	}
	}
	// Remove one key by name
	else {
	$this->delete_item($this->ckey($key));
	if (($idx = array_search($key, $this->index)) !== false) {
	unset($this->index[$idx]);
	if (!$this->index_update) {
	$this->index_update = time();
	}
	}
	}

	$this->write_index();
	}

	/**
	* Writes the index entry as well as updated entries into memcache/apc/redis DB.
	*/
	protected function write_index($force = null)
	{
	// Write updated/new entries when needed
	if (!$this->indexed) {
	$need_update = $force === true;

	if (!$need_update && !empty($this->updates)) {
	$now = new DateTime('now', new DateTimeZone('UTC'));
	$need_update = floatval(min($this->updates)->format('U.u')) < floatval($now->format('U.u')) - $this->refresh_time;
	}

	if ($need_update) {
	foreach ($this->updates as $key => $ts) {
	if (isset($this->cache[$key])) {
	$this->store_record($key, $this->cache[$key], $ts);
	}
	}

	$this->updates = [];
	}
	}
	// Write index entry when needed
	else {
	$need_update = $this->index_update && $this->index !== null
	&& ($force === true \|\| $this->index_update > time() - $this->refresh_time);

	if ($need_update) {
	$index = serialize(array_values(array_unique($this->index)));

	$this->add_item($this->ikey(), $index);
	$this->index_update = null;
	$this->index = null;
	}
	}
	}

	/**
	* Gets the index entry from memcache/apc/redis DB.
	*/
	protected function load_index()
	{
	if (!$this->indexed) {
	return;
	}

	if ($this->index !== null) {
	return;
	}

	$data = $this->get_item($this->ikey());
	$this->index = $data ? unserialize($data) : [];
	}

	/**
	* Write data entry into cache
	*/
	protected function store_record($key, $data, $ts = null)
	{
	$value = $this->serialize($data);

	if (!$this->indexed) {
	if (!$ts) {
	$ts = new DateTime('now', new DateTimeZone('UTC'));
	}

	$value = $ts->format(self::DATE_FORMAT) . ':' . $value;
	}

	$size = strlen($value);

	// don't attempt to write too big data sets
	if ($size > $this->max_packet_size()) {
	trigger_error("rcube_cache: max_packet_size ($this->max_packet) exceeded for key $key. Tried to write $size bytes", E_USER_WARNING);
	return false;
	}

	return $this->add_item($this->ckey($key), $value);
	}

	/**
	* Fetches cache entry.
	*
	* @param string $key Cache internal key name
	*
	* @return mixed Cached value
	*/
	protected function get_item($key)
	{
	// to be overwritten by engine class
	}

	/**
	* Adds entry into memcache/apc/redis DB.
	*
	* @param string $key Cache internal key name
	* @param mixed $data Serialized cache data
	*
	* @param bool True on success, False on failure
	*/
	protected function add_item($key, $data)
	{
	// to be overwritten by engine class
	}

	/**
	* Deletes entry from memcache/apc/redis DB.
	*
	* @param string $key Cache internal key name
	*
	* @param bool True on success, False on failure
	*/
	protected function delete_item($key)
	{
	// to be overwritten by engine class
	}

	/**
	* Get EXP:<key> record value from cache
	*/
	protected function get_exp_timestamp($key)
	{
	if (!array_key_exists($key, $this->exp_records)) {
	$data = $this->get_item($this->ekey($key));

	$this->exp_records[$key] = $data ? new DateTime($data, new DateTimeZone('UTC')) : null;
	}

	return $this->exp_records[$key];
	}

	/**
	* Creates per-user index cache key name (for memcache, apc, redis)
	*
	* @return string Cache key
	*/
	protected function ikey()
	{
	$key = $this->prefix . 'INDEX';

	if ($this->userid) {
	$key = $this->userid . ':' . $key;
	}

	return $key;
	}

	/**
	* Creates per-user cache key name (for memcache, apc, redis)
	*
	* @param string $key Cache key name
	*
	* @return string Cache key
	*/
	protected function ckey($key)
	{
	$key = $this->prefix . ':' . $key;

	if ($this->userid) {
	$key = $this->userid . ':' . $key;
	}

	return $key;
	}

	/**
	* Creates per-user cache key name for expiration time entry
	*
	* @param string $key Cache key name
	*
	* @return string Cache key
	*/
	protected function ekey($key, $prefix = null)
	{
	$key = $this->prefix . 'EXP:' . $key;

	if ($this->userid) {
	$key = $this->userid . ':' . $key;
	}

	return $key;
	}

	/**
	* Serializes data for storing
	*/
	protected function serialize($data)
	{
	return $this->packed ? serialize($data) : $data;
	}

	/**
	* Unserializes serialized data
	*/
	protected function unserialize($data)
	{
	return $this->packed ? @unserialize($data) : $data;
	}

	/**
	* Determine the maximum size for cache data to be written
	*/
	protected function max_packet_size()
	{
	if ($this->max_packet < 0) {
	$config = rcube::get_instance()->config;
	$max_packet = $config->get($this->type . '_max_allowed_packet');
	$this->max_packet = parse_bytes($max_packet) ?: 2097152; // default/max is 2 MB
	}

	return $this->max_packet;
	}

	/**
	* Write memcache/apc/redis debug info to the log
	*/
	protected function debug($type, $key, $data = null, $result = null)
	{
	$line = strtoupper($type) . ' ' . $key;

	if ($data !== null) {
	$line .= ' ' . ($this->packed ? $data : serialize($data));
	}

	rcube::debug($this->type, $line, $result);
	}
	}

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