/**
* Finally activates a plugin. Called once the plugin's requirements are met (see
* PluginImpl.checkRequirementsForActivation()).
*
* <p>Activation comprises: - install the plugin in the database (includes migrations,
* post-install event, type introduction) - initialize the plugin - register the plugin's
* listeners - add the plugin to the pool of activated plugins
*
* <p>If this plugin is already activated, nothing is performed and false is returned. Otherwise
* true is returned.
*
* <p>Note: this method is synchronized. While a plugin is activated no other plugin must be
* activated. Otherwise the "type introduction" mechanism might miss some types. Consider this
* unsynchronized scenario: plugin B starts running its migrations just in the moment between
* plugin A's type introduction and listener registration. Plugin A might miss some of the types
* created by plugin B.
*/
synchronized boolean activatePlugin(PluginImpl plugin) {
try {
// Note: we must not activate a plugin twice.
// This would happen e.g. if a dependency plugin is redeployed.
if (isPluginActivated(plugin.getUri())) {
logger.info("Activation of " + plugin + " ABORTED -- already activated");
return false;
}
//
logger.info("----- Activating " + plugin + " -----");
plugin.installPluginInDB();
plugin.initializePlugin();
plugin.registerListeners();
// Note: registering the listeners is deferred until the plugin is installed in the database
// and the
// POST_INSTALL_PLUGIN event is delivered (see PluginImpl.installPluginInDB()).
// Consider the Access Control plugin: it can't set a topic's creator before the "admin" user
// is created.
addToActivatedPlugins(plugin);
logger.info("----- Activation of " + plugin + " complete -----");
return true;
} catch (Exception e) {
throw new RuntimeException("Activation of " + plugin + " failed", e);
}
}
void deactivatePlugin(PluginImpl plugin) {
plugin.unregisterListeners();
removeFromActivatedPlugins(plugin.getUri());
}
private void addToActivatedPlugins(PluginImpl plugin) {
activatedPlugins.put(plugin.getUri(), plugin);
}
