Add new cross-module event system

1 files changed, 146 insertions, 0 deletions

diff --git a/include/event.h b/include/event.h
new file mode 100644
index 000000000..c9bad7d04
--- /dev/null
+++ b/include/event.h
@@ -0,0 +1,146 @@
+/*
+ * InspIRCd -- Internet Relay Chat Daemon
+ *
+ *   Copyright (C) 2015 Attila Molnar <attilamolnar@hush.com>
+ *
+ * This file is part of InspIRCd.  InspIRCd is free software: you can
+ * redistribute it and/or modify it under the terms of the GNU General Public
+ * License as published by the Free Software Foundation, version 2.
+ *
+ * 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 General Public License for more
+ * details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+
+#pragma once
+
+namespace Events
+{
+	class ModuleEventListener;
+	class ModuleEventProvider;
+}
+
+/** Provider of one or more cross-module events.
+ * Modules who wish to provide events for other modules create instances of this class and use
+ * one of the macros below to fire the event, passing the instance of the event provider class
+ * to the macro.
+ * Event providers are identified using a unique identifier string.
+ */
+class Events::ModuleEventProvider : public ServiceProvider, private dynamic_reference_base::CaptureHook
+{
+ public:
+	typedef std::vector<ModuleEventListener*> SubscriberList;
+
+	/** Constructor
+	 * @param mod Module providing the event(s)
+	 * @param eventid Identifier of the event or event group provided, must be unique
+	 */
+	ModuleEventProvider(Module* mod, const std::string& eventid)
+		: ServiceProvider(mod, eventid, SERVICE_DATA)
+		, prov(mod, eventid)
+	{
+		prov.SetCaptureHook(this);
+	}
+
+	/** Get list of objects subscribed to this event
+	 * @return List of subscribed objects
+	 */
+	const SubscriberList& GetSubscribers() const { return prov->subscribers; }
+
+	friend class ModuleEventListener;
+
+ private:
+	void OnCapture() CXX11_OVERRIDE
+	{
+		// If someone else holds the list from now on, clear mine. See below for more info.
+		if (*prov != this)
+			subscribers.clear();
+	}
+
+	/** Reference to the active provider for this event. In case multiple event providers
+	 * exist for the same event, only one of them contains the list of subscribers.
+	 * To handle the case when we are not the ones with the list, we get it from the provider
+	 * where the dynref points to.
+	 */
+	dynamic_reference_nocheck<ModuleEventProvider> prov;
+
+	/** List of objects subscribed to the event(s) provided by us, or empty if multiple providers
+	 * exist with the same name and we are not the ones holding the list.
+	 */
+	SubscriberList subscribers;
+};
+
+/** Base class for abstract classes describing cross-module events.
+ * Subscribers should NOT inherit directly from this class.
+ */
+class Events::ModuleEventListener : private dynamic_reference_base::CaptureHook
+{
+	/** Reference to the provider, can be NULL if none of the provider modules are loaded
+	 */
+	dynamic_reference_nocheck<ModuleEventProvider> prov;
+
+	/** Called by the dynref when the event provider becomes available
+	 */
+	void OnCapture() CXX11_OVERRIDE
+	{
+		prov->subscribers.push_back(this);
+	}
+
+ public:
+	/** Constructor
+	 * @param mod Module subscribing
+	 * @param eventid Identifier of the event to subscribe to
+	 */
+	ModuleEventListener(Module* mod, const std::string& eventid)
+		: prov(mod, eventid)
+	{
+		prov.SetCaptureHook(this);
+		// If the dynamic_reference resolved at construction our capture handler wasn't called
+		if (prov)
+			ModuleEventListener::OnCapture();
+	}
+
+	~ModuleEventListener()
+	{
+		if (prov)
+			stdalgo::erase(prov->subscribers, this);
+	}
+};
+
+/**
+ * Run the given hook provided by a module
+ *
+ * FOREACH_MOD_CUSTOM(accountevprov, AccountEventListener, OnAccountChange, MOD_RESULT, (user, newaccount))
+ */
+#define FOREACH_MOD_CUSTOM(prov, listenerclass, func, params) do { \
+	const Events::ModuleEventProvider::SubscriberList& _handlers = (prov).GetSubscribers(); \
+	for (Events::ModuleEventProvider::SubscriberList::const_iterator _i = _handlers.begin(); _i != _handlers.end(); ++_i) \
+	{ \
+		listenerclass* _t = static_cast<listenerclass*>(*_i); \
+		_t->func params ; \
+	} \
+} while (0);
+
+/**
+ * Run the given hook provided by a module until some module returns MOD_RES_ALLOW or MOD_RES_DENY.
+ * If no module does that, result is set to MOD_RES_PASSTHRU.
+ *
+ * Example: ModResult MOD_RESULT;
+ * FIRST_MOD_RESULT_CUSTOM(httpevprov, HTTPRequestEventListener, OnHTTPRequest, MOD_RESULT, (request));
+ */
+#define FIRST_MOD_RESULT_CUSTOM(prov, listenerclass, func, result, params) do { \
+	result = MOD_RES_PASSTHRU; \
+	const Events::ModuleEventProvider::SubscriberList& _handlers = (prov).GetSubscribers(); \
+	for (Events::ModuleEventProvider::SubscriberList::const_iterator _i = _handlers.begin(); _i != _handlers.end(); ++_i) \
+	{ \
+		listenerclass* _t = static_cast<listenerclass*>(*_i); \
+		result = _t->func params ; \
+		if (result != MOD_RES_PASSTHRU) \
+			break; \
+	} \
+} while (0);