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<?php
/**
* StatusNet, the distributed open-source microblogging tool
*
* Abstract class for i/o managers
*
* PHP version 5
*
* LICENCE: 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/>.
*
* @category QueueManager
* @package StatusNet
* @author Evan Prodromou <evan@status.net>
* @author Sarven Capadisli <csarven@status.net>
* @author Brion Vibber <brion@status.net>
* @copyright 2009-2010 StatusNet, Inc.
* @license http://www.fsf.org/licensing/licenses/agpl-3.0.html GNU Affero General Public License version 3.0
* @link http://status.net/
*/
abstract class IoManager
{
const SINGLE_ONLY = 0;
const INSTANCE_PER_SITE = 1;
const INSTANCE_PER_PROCESS = 2;
/**
* Factory function to get an appropriate subclass.
*/
public abstract static function get();
/**
* Tell the i/o queue master if and how we can handle multi-site
* processes.
*
* Return one of:
* IoManager::SINGLE_ONLY
* IoManager::INSTANCE_PER_SITE
* IoManager::INSTANCE_PER_PROCESS
*/
public static function multiSite()
{
return IoManager::SINGLE_ONLY;
}
/**
* If in a multisite configuration, the i/o master will tell
* your manager about each site you'll have to handle so you
* can do any necessary per-site setup.
*
* The new site will be the currently live configuration during
* this call.
*/
public function addSite()
{
/* no-op */
}
/**
* This method is called when data is available on one of your
* i/o manager's sockets. The socket with data is passed in,
* in case you have multiple sockets.
*
* If your i/o manager is based on polling during idle processing,
* you don't need to implement this.
*
* @param resource $socket
* @return boolean true on success, false on failure
*/
public function handleInput($socket)
{
return true;
}
/**
* Return any open sockets that the run loop should listen
* for input on. If input comes in on a listed socket,
* the matching manager's handleInput method will be called.
*
* @return array of resources
*/
function getSockets()
{
return array();
}
/**
* Maximum planned time between poll() calls when input isn't waiting.
* Actual time may vary!
*
* When we get a polling hit, the timeout will be cut down to 0 while
* input is coming in, then will back off to this amount if no further
* input shows up.
*
* By default polling is disabled; you must override this to enable
* polling for this manager.
*
* @return int max poll interval in seconds, or 0 to disable polling
*/
function pollInterval()
{
return 0;
}
/**
* Request a maximum timeout for listeners before the next idle period.
* Actual wait may be shorter, so don't go crazy in your idle()!
* Wait could be longer if other handlers performed some slow activity.
*
* Return 0 to request that listeners return immediately if there's no
* i/o and speed up the idle as much as possible; but don't do that all
* the time as this will burn CPU.
*
* @return int seconds
*/
function timeout()
{
return 60;
}
/**
* Called by IoManager after each handled item or empty polling cycle.
* This is a good time to e.g. service your XMPP connection.
*
* Doesn't need to be overridden if there's no maintenance to do.
*/
function idle()
{
return true;
}
/**
* The meat of a polling manager... check for something to do
* and do it! Note that you should not take too long, as other
* i/o managers may need to do some work too!
*
* On a successful hit, the next poll() call will come as soon
* as possible followed by exponential backoff up to pollInterval()
* if no more data is available.
*
* @return boolean true if events were hit
*/
public function poll()
{
return false;
}
/**
* Initialization, run when the queue manager starts.
* If this function indicates failure, the handler run will be aborted.
*
* @param IoMaster $master process/event controller
* @return boolean true on success, false on failure
*/
public function start($master)
{
$this->master = $master;
return true;
}
/**
* Cleanup, run when the queue manager ends.
* If this function indicates failure, a warning will be logged.
*
* @return boolean true on success, false on failure
*/
public function finish()
{
return true;
}
/**
* Ping iomaster's queue status monitor with a stats update.
* Only valid during input loop!
*
* @param string $counter keyword for counter to increment
*/
public function stats($counter, $owners=array())
{
$this->master->stats($counter, $owners);
}
}
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