pronto/core/cache/shm.php

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<?php
class Cache_SHM extends Cache
{
        var $shmkey;
        var $shmid;
        var $memsize = CACHE_SHM_SIZE;

        function Cache_SHM()
        {
                $this->Cache();

                // use the primary entry script as our ftok filename
                $this->shmkey = ftok(DIR_FS_BASE.DS.'index.php', 'p');
                if($this->shmkey == -1) {
                        trigger_error("Unable to create SHM Key");
                        return;
                }

                $this->shmid = shm_attach($this->shmkey, $this->memsize, 0600);
        }

        function set($key, $var, $expire=0)
        {
                $key = SITE_NAME."|$key";
                // hash the string key into a unique integer
                $varkey = $this->_hash_key($key);

                $dict = $this->_get_dict();
                if(@shm_put_var($this->shmid, $varkey, $var)) {
                        $dict['keys'][$key] = array(
                                'varkey' => $varkey,
                                'expire' => $expire ? time()+$expire : 0
                        );
                } else {
                        // failed to put it in the cache, make sure it's gone entirely
                        $this->delete($key);
                        unset($dict['keys'][$key]);
                        // if in DEBUG mode, throw out a warning so the developer knows it might be
                        // a good idea to bump up the SHM size
                        if(DEBUG === true) {
                                echo "<p><b>Warning:</b> SHM Cache is out of space, consider enlarging it.</p>";
                        }
                }
                $this->_set_dict($dict);
        }

        function &get($key)
        {
                $key = SITE_NAME."|$key";
                $varkey = $this->_hash_key($key);
                $d = @shm_get_var($this->shmid, $varkey);
                return $d;
        }

        function delete($key)
        {
                $key = SITE_NAME."|$key";
                $varkey = $this->_hash_key($key);
                return @shm_remove_var($this->shmid, $varkey);
        }

        function flush()
        {
                // remove and reconnect to the SHM block
                shm_remove($this->shmid);
                $this->shmid = shm_attach($this->shmkey, $this->memsize, 0600);
        }

        function gc()
        {
                $dict = $this->_get_dict();
                foreach($dict['keys'] as $k=>$v) {
                        if($v['expire'] && $v['expire'] <= time()) {
                                shm_remove_var($this->shmid, $v['varkey']);
                                unset($dict['keys'][$k]);
                        }
                }
                $this->_set_dict($dict);
        }

        function stats()
        {
                // TODO: make this better and more uniform
                $dict = $this->_get_dict();
                return array(
                        'shmkey' => dechex($this->shmkey),
                        'shmid'  => $this->shmid,
                        'dict'   => $dict
                );
        }

        function _get_dict()
        {
                $dict = @shm_get_var($this->shmid, 0);
                if(!$dict) $dict = array('nextvar'=>1, 'keys' => array());
                return $dict;
        }

        function _set_dict($dict)
        {
                shm_put_var($this->shmid, 0, $dict);
        }

        function _hash_key($key)
        {
                $dict = $this->_get_dict();
                if(isset($dict['keys'][$key])) {
                        $varkey = $dict['keys'][$key]['varkey'];
                } else {
                        $varkey = $dict['nextvar']++;
                        $this->_set_dict($dict);
                }
                return $varkey;
        }
}

?>

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