/usr/share/awl/inc/AwlCache.php is in libawl-php 0.55-1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
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/**
* A simple Memcached wrapper supporting namespacing of stored values.
*
* @author Andrew McMillan
* @license LGPL v2 or later
*/
class AwlCache {
private static $m;
private static $servers;
private static $working;
/**
* Initialise the cache connection. We use getpid() to give us a persistent connection.
*/
function __construct() {
global $c;
if ( isset(self::$working) ) return;
self::$working = false;
if ( isset($c->memcache_servers) && class_exists('Memcached') ) {
dbg_error_log('Cache', 'Using Memcached interface connection');
self::$servers = $c->memcache_servers;
self::$m = new Memcached();
foreach( self::$servers AS $v ) {
dbg_error_log('Cache', 'Adding server '.$v);
$server = explode(',',$v);
if ( isset($server[2]) )
self::$m->addServer($server[0],$server[1],$server[2]);
else
self::$m->addServer($server[0],$server[1]);
}
self::$working = true;
// Hack to allow the regression tests to flush the cache at start
if ( isset($_SERVER['HTTP_X_DAVICAL_FLUSH_CACHE'])) $this->flush();
}
else {
dbg_error_log('Cache', 'Using NoCache dummy interface');
}
}
/**
* So we can find out if we are actually using the cache.
*/
function isActive() {
return self::$working;
}
/**
* Construct a string from the namespace & key
* @param unknown_type $namespace
* @param unknown_type $key
*/
private function nskey( $namespace, $key ) {
return str_replace(' ', '%20', $namespace . (isset($key) ? '~~' . $key: '')); // for now.
}
/**
* get a value from the specified namespace / key
* @param $namespace
* @param $key
*/
function get( $namespace, $key ) {
if ( !self::$working ) return false;
$ourkey = self::nskey($namespace,$key);
$value = self::$m->get($ourkey);
// var_dump($value);
// if ( $value !== false ) dbg_error_log('Cache', 'Got value for cache key "'.$ourkey.'" - '.strlen(serialize($value)).' bytes');
return $value;
}
/**
* Set a value for the specified namespace/key, perhaps with an expiry (default 10 days)
* @param $namespace
* @param $key
* @param $value
* @param $expiry
*/
function set( $namespace, $key, $value, $expiry=864000 ) {
if ( !self::$working ) return false;
$ourkey = self::nskey($namespace,$key);
$nskey = self::nskey($namespace,null);
$keylist = self::$m->get( $nskey, null, $cas_token );
if ( isset($keylist) && is_array($keylist) ) {
if ( !isset($keylist[$ourkey]) ) {
$keylist[$ourkey] = 1;
$success = self::$m->cas( $cas_token, $nskey, $keylist );
$i=0;
while( !$success && $i++ < 10 && self::$m->getResultCode() == Memcached::RES_DATA_EXISTS ) {
$keylist = self::$m->get( $nskey, null, $cas_token );
if ( $keylist === false ) return false;
if ( isset($keylist[$ourkey]) ) break;
$keylist[$ourkey] = 1;
$success = self::$m->cas( $cas_token, $nskey, $keylist );
}
if ( !$success ) return false;
}
}
else {
$keylist = array( $ourkey => 1 );
self::$m->set( $nskey, $keylist );
}
// var_dump($value);
// dbg_error_log('Cache', 'Setting value for cache key "'.$ourkey.'" - '.strlen(serialize($value)).' bytes');
return self::$m->set( $ourkey, $value, $expiry );
}
/**
* Delete a value from a namespace/key, or for everything in a namespace if a 'null' key is supplied.
* @param $namespace
* @param $key
*/
function delete( $namespace, $key ) {
if ( !self::$working ) return false;
$nskey = self::nskey($namespace,$key);
dbg_error_log('Cache', 'Deleting from cache key "'.$nskey.'"');
if ( isset($key) ) {
self::$m->delete( $nskey );
}
else {
$keylist = self::$m->get( $nskey, null, $cas_token );
if ( isset($keylist) ) {
self::$m->delete( $nskey );
if ( is_array($keylist) ) {
foreach( $keylist AS $k => $v ) self::$m->delete( $k );
}
}
}
}
/**
* Flush the entire cache
*/
function flush( ) {
if ( !self::$working ) return false;
dbg_error_log('Cache', 'Flushing cache');
self::$m->flush();
}
/**
* Acquire a lock on something
*/
function acquireLock( $something, $wait_for = 5 ) {
if ( !self::$working ) return $something;
$wait_until = time() + $wait_for;
while( self::$m->add('_lock_'+$something,1,5) === false && time() < $wait_until ) {
usleep(10000);
}
return $something;
}
/**
* Release a lock
*/
function releaseLock( $something ) {
if ( !self::$working ) return;
self::$m->delete('_lock_'+$something);
}
}
function getCacheInstance() {
static $ourCacheInstance;
if ( !isset($ourCacheInstance) ) $ourCacheInstance = new AWLCache('Memcached');
return $ourCacheInstance;
}
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