gnu-social/lib/queuehandler.php
Brion Vibber ec145b73fc Major refactoring of queue handlers to support running multiple sites in one daemon.
Key changes:
* Initialization code moved from common.php to StatusNet class;
  can now switch configurations during runtime.
* As a consequence, configuration files must now be idempotent...
  Be careful with constant, function or class definitions.
* Control structure for daemons/QueueManager/QueueHandler has been refactored;
  the run loop is now managed by IoMaster run via scripts/queuedaemon.php
  IoManager subclasses are woken to handle socket input or polling, and may
  cover multiple sites.
* Plugins can implement notice queue handlers more easily by registering a
  QueueHandler class; no more need to add a daemon.

The new QueueDaemon runs from scripts/queuedaemon.php:

* This replaces most of the old *handler.php scripts; they've been refactored
  to the bare handler classes.
* Spawns multiple child processes to spread load; defaults to CPU count on
  Linux and Mac OS X systems, or override with --threads=N
* When multithreaded, child processes are automatically respawned on failure.
* Threads gracefully shut down and restart when passing a soft memory limit
  (defaults to 90% of memory_limit), limiting damage from memory leaks.
* Support for UDP-based monitoring: http://www.gitorious.org/snqmon

Rough control flow diagram:
QueueDaemon -> IoMaster -> IoManager
                           QueueManager [listen or poll] -> QueueHandler
                           XmppManager [ping & keepalive]
                           XmppConfirmManager [poll updates]

Todo:

* Respawning features not currently available running single-threaded.
* When running single-site, configuration changes aren't picked up.
* New sites or config changes affecting queue subscriptions are not yet
  handled without a daemon restart.
* SNMP monitoring output to integrate with general tools (nagios, ganglia)
* Convert XMPP confirmation message sends to use stomp queue instead of polling
* Convert xmppdaemon.php to IoManager?
* Convert Twitter status, friends import polling daemons to IoManager
* Clean up some error reporting and failure modes
* May need to adjust queue priorities for best perf in backlog/flood cases

Detailed code history available in my daemon-work branch:
http://www.gitorious.org/~brion/statusnet/brion-fixes/commits/daemon-work
2010-01-12 20:45:09 -08:00

144 lines
3.9 KiB
PHP

<?php
/*
* StatusNet - the distributed open-source microblogging tool
* Copyright (C) 2008, 2009, StatusNet, Inc.
*
* 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/>.
*/
if (!defined('STATUSNET') && !defined('LACONICA')) { exit(1); }
/**
* Base class for queue handlers.
*
* As extensions of the Daemon class, each queue handler has the ability
* to launch itself in the background, at which point it'll pass control
* to the configured QueueManager class to poll for updates.
*
* Subclasses must override at least the following methods:
* - transport
* - handle_notice
*/
#class QueueHandler extends Daemon
class QueueHandler
{
# function __construct($id=null, $daemonize=true)
# {
# parent::__construct($daemonize);
#
# if ($id) {
# $this->set_id($id);
# }
# }
/**
* How many seconds a polling-based queue manager should wait between
* checks for new items to handle.
*
* Defaults to 60 seconds; override to speed up or slow down.
*
* @fixme not really compatible with global queue manager
* @return int timeout in seconds
*/
# function timeout()
# {
# return 60;
# }
# function class_name()
# {
# return ucfirst($this->transport()) . 'Handler';
# }
# function name()
# {
# return strtolower($this->class_name().'.'.$this->get_id());
# }
/**
* Return transport keyword which identifies items this queue handler
* services; must be defined for all subclasses.
*
* Must be 8 characters or less to fit in the queue_item database.
* ex "email", "jabber", "sms", "irc", ...
*
* @return string
*/
function transport()
{
return null;
}
/**
* Here's the meat of your queue handler -- you're handed a Notice
* object, which you may do as you will with.
*
* If this function indicates failure, a warning will be logged
* and the item is placed back in the queue to be re-run.
*
* @param Notice $notice
* @return boolean true on success, false on failure
*/
function handle_notice($notice)
{
return true;
}
/**
* Setup and start of run loop for this queue handler as a daemon.
* Most of the heavy lifting is passed on to the QueueManager's service()
* method, which passes control back to our handle_notice() method for
* each notice that comes in on the queue.
*
* Most of the time this won't need to be overridden in a subclass.
*
* @return boolean true on success, false on failure
*/
function run()
{
if (!$this->start()) {
$this->log(LOG_WARNING, 'failed to start');
return false;
}
$this->log(LOG_INFO, 'checking for queued notices');
$queue = $this->transport();
$timeout = $this->timeout();
$qm = QueueManager::get();
$qm->service($queue, $this);
$this->log(LOG_INFO, 'finished servicing the queue');
if (!$this->finish()) {
$this->log(LOG_WARNING, 'failed to clean up');
return false;
}
$this->log(LOG_INFO, 'terminating normally');
return true;
}
function log($level, $msg)
{
common_log($level, $this->class_name() . ' ('. $this->get_id() .'): '.$msg);
}
}