roundcubemail-plugins-kolab/plugins/libkolab/lib/kolab_storage_cache.php

<?php

/**
 * Kolab storage cache class providing a local caching layer for Kolab groupware objects.
 *
 * @version @package_version@
 * @author Thomas Bruederli <bruederli@kolabsys.com>
 *
 * Copyright (C) 2012, Kolab Systems AG <contact@kolabsys.com>
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as
 * published by the Free Software Foundation, either version 3 of the
 * License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program. If not, see <http://www.gnu.org/licenses/>.
 */

class kolab_storage_cache
{
    private $db;
    private $imap;
    private $folder;
    private $uid2msg;
    private $objects;
    private $resource_uri;
    private $enabled = true;
    private $synched = false;
    private $ready = false;

    private $binary_cols = array('photo','pgppublickey','pkcs7publickey');


    /**
     * Default constructor
     */
    public function __construct(kolab_storage_folder $storage_folder = null)
    {
        $rcmail = rcube::get_instance();
        $this->db = $rcmail->get_dbh();
        $this->imap = $rcmail->get_storage();
        $this->enabled = $rcmail->config->get('kolab_cache', false);

        if ($storage_folder)
            $this->set_folder($storage_folder);
    }


    /**
     * Connect cache with a storage folder
     *
     * @param kolab_storage_folder The storage folder instance to connect with
     */
    public function set_folder(kolab_storage_folder $storage_folder)
    {
        $this->folder = $storage_folder;

        if (empty($this->folder->name)) {
            $this->ready = false;
            return;
        }

        // strip namespace prefix from folder name
        $ns = $this->folder->get_namespace();
        $nsdata = $this->imap->get_namespace($ns);
        if (is_array($nsdata[0]) && strpos($this->folder->name, $nsdata[0][0]) === 0) {
            $subpath = substr($this->folder->name, strlen($nsdata[0][0]));
            if ($ns == 'other') {
                list($user, $suffix) = explode($nsdata[0][1], $subpath);
                $subpath = $suffix;
            }
        }
        else {
            $subpath = $this->folder->name;
        }

        // compose fully qualified ressource uri for this instance
        $this->resource_uri = 'imap://' . urlencode($this->folder->get_owner()) . '@' . $this->imap->options['host'] . '/' . $subpath;
        $this->ready = $this->enabled;
    }


    /**
     * Synchronize local cache data with remote
     */
    public function synchronize()
    {
        // only sync once per request cycle
        if ($this->synched)
            return;

        // synchronize IMAP mailbox cache
        $this->imap->folder_sync($this->folder->name);

        // compare IMAP index with object cache index
        $imap_index = $this->imap->index($this->folder->name);
        $this->index = $imap_index->get();

        // determine objects to fetch or to invalidate
        if ($this->ready) {
            // read cache index
            $sql_result = $this->db->query(
                "SELECT msguid, uid FROM kolab_cache WHERE resource=?",
                $this->resource_uri
            );

            $old_index = array();
            while ($sql_arr = $this->db->fetch_assoc($sql_result)) {
                $old_index[] = $sql_arr['msguid'];
                $this->uid2msg[$sql_arr['uid']] = $sql_arr['msguid'];
            }

            // fetch new objects from imap
            $fetch_index = array_diff($this->index, $old_index);
            foreach ($this->_fetch($fetch_index, '*') as $object) {
                $msguid = $object['_msguid'];
                $this->set($msguid, $object);
            }

            // delete invalid entries from local DB
            $del_index = array_diff($old_index, $this->index);
            if (!empty($del_index)) {
                $quoted_ids = join(',', array_map(array($this->db, 'quote'), $del_index));
                $this->db->query(
                    "DELETE FROM kolab_cache WHERE resource=? AND msguid IN ($quoted_ids)",
                    $this->resource_uri
                );
            }
        }

        $this->synched = time();
    }


    /**
     * Read a single entry from cache or
     */
    public function get($msguid, $type = null, $folder = null)
    {
        // load object if not in memory
        if (!isset($this->objects[$msguid])) {
            if ($this->ready) {
                // TODO: handle $folder != $this->folder->name situations
                
                $sql_result = $this->db->query(
                    "SELECT * FROM kolab_cache ".
                    "WHERE resource=? AND msguid=?",
                    $this->resource_uri,
                    $msguid
                );

                if ($sql_arr = $this->db->fetch_assoc($sql_result)) {
                    $this->objects[$msguid] = $this->_unserialize($sql_arr);
                }
            }

            // fetch from IMAP if not present in cache
            if (empty($this->objects[$msguid])) {
                $result = $this->_fetch(array($msguid), $type, $folder);
                $this->objects[$msguid] = $result[0];
            }
        }

        return $this->objects[$msguid];
    }


    /**
     *
     */
    public function set($msguid, $object, $folder = null)
    {
        // write to cache
        if ($this->ready) {
            // TODO: handle $folder != $this->folder->name situations

            // remove old entry
            $this->db->query("DELETE FROM kolab_cache WHERE resource=? AND msguid=?",
                $this->resource_uri, $msguid);

            // write new object data if not false (wich means deleted)
            if ($object) {
                $sql_data = $this->_serialize($object);
                $objtype = $object['_type'] ? $object['_type'] : $this->folder->type;

                $result = $this->db->query(
                    "INSERT INTO kolab_cache ".
                    " (resource, type, msguid, uid, data, xml, dtstart, dtend)".
                    " VALUES (?, ?, ?, ?, ?, ?, ?, ?)",
                    $this->resource_uri,
                    $objtype,
                    $msguid,
                    $object['uid'],
                    $sql_data['data'],
                    $sql_data['xml'],
                    $sql_data['dtstart'],
                    $sql_data['dtend']
                );

                if (!$this->db->affected_rows($result)) {
                    rcmail::raise_error(array(
                        'code' => 900, 'type' => 'php',
                        'message' => "Failed to write to kolab cache"
                    ), true);
                }
            }
        }

        // keep a copy in memory for fast access
        $this->objects[$msguid] = $object;

        if ($object)
            $this->uid2msg[$object['uid']] = $msguid;
    }


    /**
     * Remove all objects from local cache
     */
    public function purge($type = null)
    {
        $result = $this->db->query(
            "DELETE FROM kolab_cache WHERE resource=?".
            ($type ? ' AND type=?' : ''),
            $this->resource_uri,
            $type
        );
        return $this->db->affected_rows($result);
    }


    /**
     * Select Kolab objects filtered by the given query
     *
     * @param array Pseudo-SQL query as list of filter parameter triplets
     *   triplet: array('<colname>', '<comparator>', '<value>')
     * @return array List of Kolab data objects (each represented as hash array)
     */
    public function select($query = array())
    {
        $result = array();

        // read from local cache DB (assume it to be synchronized)
        if ($this->ready) {
            $sql_result = $this->db->query(
                "SELECT * FROM kolab_cache ".
                "WHERE resource=? " . $this->_sql_where($query),
                $this->resource_uri
            );

            while ($sql_arr = $this->db->fetch_assoc($sql_result)) {
                if ($object = $this->_unserialize($sql_arr))
                    $result[] = $object;
            }
        }
        else {
            // extract object type from query parameter
            $filter = $this->_query2assoc($query);
            $result = $this->_fetch($this->index, $filter['type']);

            // TODO: post-filter result according to query
        }

        return $result;
    }


    /**
     * Get number of objects mathing the given query
     *
     * @param string  $type Object type (e.g. contact, event, todo, journal, note, configuration)
     * @return integer The number of objects of the given type
     */
    public function count($query = array())
    {
        $count = 0;

        // cache is in sync, we can count records in local DB
        if ($this->synched) {
            $sql_result = $this->db->query(
                "SELECT COUNT(*) AS NUMROWS FROM kolab_cache ".
                "WHERE resource=? " . $this->_sql_where($query),
                $this->resource_uri
            );

            $sql_arr = $this->db->fetch_assoc($sql_result);
            $count = intval($sql_arr['NUMROWS']);
        }
        else {
            // search IMAP by object type
            $filter = $this->_query2assoc($query);
            $ctype  = kolab_storage_folder::KTYPE_PREFIX . $filter['type'];
            $index = $this->imap->search_once($this->folder->name, 'UNDELETED HEADER X-Kolab-Type ' . $ctype);
            $count = $index->count();
        }

        return $count;
    }


    /**
     * Helper method to compose a valid SQL query from pseudo filter triplets
     */
    private function _sql_where($query)
    {
        $sql_where = '';
        foreach ($query as $param) {
            $sql_where .= sprintf(' AND %s%s%s',
                $this->db->quote_identifier($param[0]),
                $param[1],
                $this->db->quote($param[2])
            );
        }
        return $sql_where;
    }

    /**
     * Helper method to convert the given pseudo-query triplets into
     * an associative filter array with 'equals' values only
     */
    private function _query2assoc($query)
    {
        // extract object type from query parameter
        $filter = array();
        foreach ($query as $param) {
            if ($param[1] == '=')
                $filter[$param[0]] = $param[2];
        }
        return $filter;
    }

    /**
     * Fetch messages from IMAP
     *
     * @param array List of message UIDs to fetch
     * @return array List of parsed Kolab objects
     */
    private function _fetch($index, $type = null, $folder = null)
    {
        $results = array();
        foreach ((array)$index as $msguid) {
            if ($object = $this->folder->read_object($msguid, $type, $folder)) {
                $results[] = $object;
                $this->uid2msg[$object['uid']] = $msguid;
            }
        }

        return $results;
    }


    /**
     * Helper method to convert the given Kolab object into a dataset to be written to cache
     */
    private function _serialize($object)
    {
        $bincols = array_flip($this->binary_cols);
        $sql_data = array('dtstart' => null, 'dtend' => null, 'xml' => '');

        // set type specific values
        if ($this->folder->type == 'event') {
            // database runs in server's timetone so using date() is safe
            $sql_data['dtstart'] = date('Y-m-d H:i:s', is_object($object['start']) ? $object['start']->format('U') : $object['start']);
            $sql_data['dtend']   = date('Y-m-d H:i:s', is_object($object['end'])   ? $object['end']->format('U')   : $object['end']);
        }

        if ($object['_formatobj'])
            $sql_data['xml'] = (string)$object['_formatobj']->write();

        // extract object data
        $data = array();
        foreach ($object as $key => $val) {
            if ($val === "" || $val === null) {
                // skip empty properties
                continue;
            }
            if (isset($bincols[$key])) {
                $data[$key] = base64_encode($val);
            }
            else if ($key[0] != '_') {
                $data[$key] = $val;
            }
            else if ($key == '_attachments') {
                foreach ($val as $k => $att) {
                    unset($att['content']);
                    if ($att['id'])
                        $data[$key][$k] = $att;
                }
            }
        }

        $sql_data['data'] = serialize($data);
        return $sql_data;
    }

    /**
     * Helper method to turn stored cache data into a valid storage object
     */
    private function _unserialize($sql_arr)
    {
        $object = unserialize($sql_arr['data']);

        // decode binary properties
        foreach ($this->binary_cols as $key) {
            if (!empty($object[$key]))
                $object[$key] = base64_decode($object[$key]);
        }

        // add meta data
        $object['_type'] = $sql_arr['type'];
        $object['_msguid'] = $sql_arr['msguid'];
        $object['_mailbox'] = $this->folder->name;
        $object['_formatobj'] = kolab_format::factory($sql_arr['type'], $sql_arr['xml']);

        return $object;
    }

    /**
     * Resolve an object UID into an IMAP message UID
     *
     * @param string  Kolab object UID
     * @param boolean Include deleted objects
     * @return int The resolved IMAP message UID
     */
    public function uid2msguid($uid, $deleted = false)
    {
        if (!isset($this->uid2msg[$uid])) {
            // use IMAP SEARCH to get the right message
            $index = $this->imap->search_once($this->folder->name, ($deleted ? '' : 'UNDELETED ') . 'HEADER SUBJECT ' . $uid);
            $results = $index->get();
            $this->uid2msg[$uid] = $results[0];
        }

        return $this->uid2msg[$uid];
    }

}