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<?php
/*
+-----------------------------------------------------------------------+
| This file is part of the Roundcube Webmail client |
| Copyright (C) 2011-2013, The Roundcube Dev Team |
| Copyright (C) 2011-2013, 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: |
| Shared (cross-user) caching engine |
+-----------------------------------------------------------------------+
| Author: Thomas Bruederli <roundcube@gmail.com> |
| Author: Aleksander Machniak <alec@alec.pl> |
+-----------------------------------------------------------------------+
*/
/**
* Interface class for accessing Roundcube shared cache
*
* @package Framework
* @subpackage Cache
* @author Thomas Bruederli <roundcube@gmail.com>
* @author Aleksander Machniak <alec@alec.pl>
*/
class rcube_cache_shared
{
/**
* Instance of database handler
*
* @var rcube_db|Memcache|bool
*/
private $db;
private $type;
private $prefix;
private $ttl;
private $packed;
private $index;
private $table;
private $cache = array();
private $cache_changes = array();
private $cache_sums = array();
/**
* Object constructor.
*
* @param string $type Engine type ('db' or 'memcache' or 'apc')
* @param string $prefix Key name prefix
* @param string $ttl Expiration time of memcache/apc items
* @param bool $packed Enables/disabled data serialization.
* It's possible to disable data serialization if you're sure
* stored data will be always a safe string
*/
function __construct($type, $prefix='', $ttl=0, $packed=true)
{
$rcube = rcube::get_instance();
$type = strtolower($type);
if ($type == 'memcache') {
$this->type = 'memcache';
$this->db = $rcube->get_memcache();
}
else if ($type == 'apc') {
$this->type = 'apc';
$this->db = function_exists('apc_exists'); // APC 3.1.4 required
}
else {
$this->type = 'db';
$this->db = $rcube->get_dbh();
$this->table = $this->db->table_name('cache_shared');
}
// convert ttl string to seconds
$ttl = get_offset_sec($ttl);
if ($ttl > 2592000) $ttl = 2592000;
$this->ttl = $ttl;
$this->packed = $packed;
$this->prefix = $prefix;
}
/**
* Returns cached value.
*
* @param string $key Cache key name
*
* @return mixed Cached value
*/
function get($key)
{
if (!array_key_exists($key, $this->cache)) {
return $this->read_record($key);
}
return $this->cache[$key];
}
/**
* Sets (add/update) value in cache.
*
* @param string $key Cache key name
* @param mixed $data Cache data
*/
function set($key, $data)
{
$this->cache[$key] = $data;
$this->cache_changed = true;
$this->cache_changes[$key] = true;
}
/**
* Returns cached value without storing it in internal memory.
*
* @param string $key Cache key name
*
* @return mixed Cached value
*/
function read($key)
{
if (array_key_exists($key, $this->cache)) {
return $this->cache[$key];
}
return $this->read_record($key, true);
}
/**
* Sets (add/update) value in cache and immediately saves
* it in the backend, no internal memory will be used.
*
* @param string $key Cache key name
* @param mixed $data Cache data
*
* @param boolean True on success, False on failure
*/
function write($key, $data)
{
return $this->write_record($key, $this->serialize($data));
}
/**
* Clears the cache.
*
* @param string $key Cache key name or pattern
* @param boolean $prefix_mode Enable it to clear all keys starting
* with prefix specified in $key
*/
function remove($key=null, $prefix_mode=false)
{
// Remove all keys
if ($key === null) {
$this->cache = array();
$this->cache_changed = false;
$this->cache_changes = array();
$this->cache_sums = array();
}
// Remove keys by name prefix
else if ($prefix_mode) {
foreach (array_keys($this->cache) as $k) {
if (strpos($k, $key) === 0) {
$this->cache[$k] = null;
$this->cache_changes[$k] = false;
unset($this->cache_sums[$k]);
}
}
}
// Remove one key by name
else {
$this->cache[$key] = null;
$this->cache_changes[$key] = false;
unset($this->cache_sums[$key]);
}
// Remove record(s) from the backend
$this->remove_record($key, $prefix_mode);
}
/**
* Remove cache records older than ttl
*/
function expunge()
{
if ($this->type == 'db' && $this->db && $this->ttl) {
$this->db->query(
"DELETE FROM " . $this->table
. " WHERE cache_key LIKE ?"
. " AND expires < " . $this->db->now(),
$this->prefix . '.%');
}
}
/**
* Remove expired records of all caches
*/
static function gc()
{
$rcube = rcube::get_instance();
$db = $rcube->get_dbh();
$db->query("DELETE FROM " . $db->table_name('cache_shared') . " WHERE expires < " . $db->now());
}
/**
* Writes the cache back to the DB.
*/
function close()
{
if (!$this->cache_changed) {
return;
}
foreach ($this->cache as $key => $data) {
// The key has been used
if ($this->cache_changes[$key]) {
// Make sure we're not going to write unchanged data
// by comparing current md5 sum with the sum calculated on DB read
$data = $this->serialize($data);
if (!$this->cache_sums[$key] || $this->cache_sums[$key] != md5($data)) {
$this->write_record($key, $data);
}
}
}
$this->write_index();
}
/**
* Reads cache entry.
*
* @param string $key Cache key name
* @param boolean $nostore Enable to skip in-memory store
*
* @return mixed Cached value
*/
private function read_record($key, $nostore=false)
{
if (!$this->db) {
return null;
}
if ($this->type != 'db') {
if ($this->type == 'memcache') {
$data = $this->db->get($this->ckey($key));
}
else if ($this->type == 'apc') {
$data = apc_fetch($this->ckey($key));
}
if ($data) {
$md5sum = md5($data);
$data = $this->unserialize($data);
if ($nostore) {
return $data;
}
$this->cache_sums[$key] = $md5sum;
$this->cache[$key] = $data;
}
else {
$this->cache[$key] = null;
}
}
else {
$sql_result = $this->db->limitquery(
"SELECT data, cache_key".
" FROM " . $this->table .
" WHERE cache_key = ?".
// for better performance we allow more records for one key
// get the newer one
" ORDER BY created DESC",
0, 1, $this->prefix . '.' . $key);
if ($sql_arr = $this->db->fetch_assoc($sql_result)) {
$md5sum = $sql_arr['data'] ? md5($sql_arr['data']) : null;
if ($sql_arr['data']) {
$data = $this->unserialize($sql_arr['data']);
}
if ($nostore) {
return $data;
}
$this->cache[$key] = $data;
$this->cache_sums[$key] = $md5sum;
}
else {
$this->cache[$key] = null;
}
}
return $this->cache[$key];
}
/**
* Writes single cache record into DB.
*
* @param string $key Cache key name
* @param mxied $data Serialized cache data
*
* @param boolean True on success, False on failure
*/
private function write_record($key, $data)
{
if (!$this->db) {
return false;
}
if ($this->type == 'memcache' || $this->type == 'apc') {
return $this->add_record($this->ckey($key), $data);
}
$key_exists = array_key_exists($key, $this->cache_sums);
$key = $this->prefix . '.' . $key;
// Remove NULL rows (here we don't need to check if the record exist)
if ($data == 'N;') {
$this->db->query("DELETE FROM " . $this->table . " WHERE cache_key = ?", $key);
return true;
}
// update existing cache record
if ($key_exists) {
$result = $this->db->query(
"UPDATE " . $this->table .
" SET created = " . $this->db->now() .
", expires = " . ($this->ttl ? $this->db->now($this->ttl) : 'NULL') .
", data = ?".
" WHERE cache_key = ?",
$data, $key);
}
// add new cache record
else {
// for better performance we allow more records for one key
// so, no need to check if record exist (see rcube_cache::read_record())
$result = $this->db->query(
"INSERT INTO ".$this->table.
" (created, expires, cache_key, data)".
" VALUES (".$this->db->now().", " . ($this->ttl ? $this->db->now($this->ttl) : 'NULL') . ", ?, ?)",
$key, $data);
}
return $this->db->affected_rows($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 $key
*/
private function remove_record($key=null, $prefix_mode=false)
{
if (!$this->db) {
return;
}
if ($this->type != 'db') {
$this->load_index();
// Remove all keys
if ($key === null) {
foreach ($this->index as $key) {
$this->delete_record($key, false);
}
$this->index = array();
}
// Remove keys by name prefix
else if ($prefix_mode) {
foreach ($this->index as $k) {
if (strpos($k, $key) === 0) {
$this->delete_record($k);
}
}
}
// Remove one key by name
else {
$this->delete_record($key);
}
return;
}
// Remove all keys (in specified cache)
if ($key === null) {
$where = " WHERE cache_key LIKE " . $this->db->quote($this->prefix.'.%');
}
// Remove keys by name prefix
else if ($prefix_mode) {
$where = " WHERE cache_key LIKE " . $this->db->quote($this->prefix.'.'.$key.'%');
}
// Remove one key by name
else {
$where = " WHERE cache_key = " . $this->db->quote($this->prefix.'.'.$key);
}
$this->db->query("DELETE FROM " . $this->table . $where);
}
/**
* Adds entry into memcache/apc DB.
*
* @param string $key Cache key name
* @param mxied $data Serialized cache data
* @param bollean $index Enables immediate index update
*
* @param boolean True on success, False on failure
*/
private function add_record($key, $data, $index=false)
{
if ($this->type == 'memcache') {
$result = $this->db->replace($key, $data, MEMCACHE_COMPRESSED, $this->ttl);
if (!$result) {
$result = $this->db->set($key, $data, MEMCACHE_COMPRESSED, $this->ttl);
}
}
else if ($this->type == 'apc') {
if (apc_exists($key)) {
apc_delete($key);
}
$result = apc_store($key, $data, $this->ttl);
}
// Update index
if ($index && $result) {
$this->load_index();
if (array_search($key, $this->index) === false) {
$this->index[] = $key;
$data = serialize($this->index);
$this->add_record($this->ikey(), $data);
}
}
return $result;
}
/**
* Deletes entry from memcache/apc DB.
*/
private function delete_record($key, $index=true)
{
if ($this->type == 'memcache') {
// #1488592: use 2nd argument
$this->db->delete($this->ckey($key), 0);
}
else {
apc_delete($this->ckey($key));
}
if ($index) {
if (($idx = array_search($key, $this->index)) !== false) {
unset($this->index[$idx]);
}
}
}
/**
* Writes the index entry into memcache/apc DB.
*/
private function write_index()
{
if (!$this->db) {
return;
}
if ($this->type == 'db') {
return;
}
$this->load_index();
// Make sure index contains new keys
foreach ($this->cache as $key => $value) {
if ($value !== null) {
if (array_search($key, $this->index) === false) {
$this->index[] = $key;
}
}
}
$data = serialize($this->index);
$this->add_record($this->ikey(), $data);
}
/**
* Gets the index entry from memcache/apc DB.
*/
private function load_index()
{
if (!$this->db) {
return;
}
if ($this->index !== null) {
return;
}
$index_key = $this->ikey();
if ($this->type == 'memcache') {
$data = $this->db->get($index_key);
}
else if ($this->type == 'apc') {
$data = apc_fetch($index_key);
}
$this->index = $data ? unserialize($data) : array();
}
/**
* Creates cache key name (for memcache and apc)
*
* @param string $key Cache key name
*
* @return string Cache key
*/
private function ckey($key)
{
return $this->prefix . ':' . $key;
}
/**
* Creates index cache key name (for memcache and apc)
*
* @return string Cache key
*/
private function ikey()
{
// This way each cache will have its own index
return $this->prefix . 'INDEX';
}
/**
* Serializes data for storing
*/
private function serialize($data)
{
if ($this->type == 'db') {
return $this->db->encode($data, $this->packed);
}
return $this->packed ? serialize($data) : $data;
}
/**
* Unserializes serialized data
*/
private function unserialize($data)
{
if ($this->type == 'db') {
return $this->db->decode($data, $this->packed);
}
return $this->packed ? @unserialize($data) : $data;
}
}
