gnu-social/lib/event.php

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<?php
/**
* StatusNet, the distributed open-source microblogging tool
*
* utilities for defining and running event handlers
*
* 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 Event
* @package StatusNet
* @author Evan Prodromou <evan@status.net>
* @copyright 2008 StatusNet, Inc.
* @license http://www.fsf.org/licensing/licenses/agpl-3.0.html GNU Affero General Public License version 3.0
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* @link http://status.net/
*/
if (!defined('STATUSNET') && !defined('LACONICA')) {
exit(1);
}
/**
* Class for events
*
* This "class" two static functions for managing events in the StatusNet code.
*
* @category Event
* @package StatusNet
* @author Evan Prodromou <evan@status.net>
* @license http://www.fsf.org/licensing/licenses/agpl-3.0.html GNU Affero General Public License version 3.0
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* @link http://status.net/
*
* @todo Define a system for using Event instances
*/
class Event {
/* Global array of hooks, mapping eventname => array of callables */
protected static $_handlers = array();
/**
* Add an event handler
*
* To run some code at a particular point in StatusNet processing.
* Named events include receiving an XMPP message, adding a new notice,
* or showing part of an HTML page.
*
* The arguments to the handler vary by the event. Handlers can return
* two possible values: false means that the event has been replaced by
* the handler completely, and no default processing should be done.
* Non-false means successful handling, and that the default processing
* should succeed. (Note that this only makes sense for some events.)
*
* Handlers can also abort processing by throwing an exception; these will
* be caught by the closest code and displayed as errors.
*
* @param string $name Name of the event
* @param callable $handler Code to run
*
* @return void
*/
public static function addHandler($name, $handler) {
if (array_key_exists($name, Event::$_handlers)) {
Event::$_handlers[$name][] = $handler;
} else {
Event::$_handlers[$name] = array($handler);
}
}
/**
* Handle an event
*
* Events are any point in the code that we want to expose for admins
* or third-party developers to use.
*
* We pass in an array of arguments (including references, for stuff
* that can be changed), and each assigned handler gets run with those
* arguments. Exceptions can be thrown to indicate an error.
*
* @param string $name Name of the event that's happening
* @param array $args Arguments for handlers
*
* @return boolean flag saying whether to continue processing, based
* on results of handlers.
*/
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public static function handle($name, $args=array()) {
$result = null;
if (array_key_exists($name, Event::$_handlers)) {
foreach (Event::$_handlers[$name] as $handler) {
$result = call_user_func_array($handler, $args);
if ($result === false) {
break;
}
}
}
return ($result !== false);
}
/**
* Check to see if an event handler exists
*
* Look to see if there's any handler for a given event, or narrow
* by providing the name of a specific plugin class.
*
* @param string $name Name of the event to look for
* @param string $plugin Optional name of the plugin class to look for
*
* @return boolean flag saying whether such a handler exists
*
*/
public static function hasHandler($name, $plugin=null) {
if (array_key_exists($name, Event::$_handlers)) {
if (isset($plugin)) {
foreach (Event::$_handlers[$name] as $handler) {
if (get_class($handler[0]) == $plugin) {
return true;
}
}
} else {
return true;
}
}
return false;
}
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
2010-01-13 03:57:15 +00:00
/**
* Disables any and all handlers that have been set up so far;
* use only if you know it's safe to reinitialize all plugins.
*/
public static function clearHandlers() {
Event::$_handlers = array();
}
}