/*
* InspIRCd -- Internet Relay Chat Daemon
*
* Copyright (C) 2018-2023 Sadie Powell <sadie@witchery.services>
* Copyright (C) 2015, 2018 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 Service::SimpleProvider
, private dynamic_reference_base::CaptureHook
{
private:
/** Determines whether a module is dying or has died.
* @param weakmod The module to check.
* @param modreq Whether a module is required.
*/
inline static bool IsModuleDead(const WeakModulePtr& weakmod, bool modreq)
{
if (!insp::empty_ptr(weakmod))
{
// We have a module. Is it dead?
auto mod = weakmod.lock();
if (mod)
return mod->dying; // Module might be dying?
return true; //Module is dead.
}
return modreq; // We never had a module.
}
public:
struct Comp final
{
bool operator()(ModuleEventListener* lhs, ModuleEventListener* rhs) const;
};
struct ElementComp final
{
bool operator()(ModuleEventListener* lhs, ModuleEventListener* rhs) const;
};
using SubscriberList = insp::flat_multiset<ModuleEventListener*, Comp, ElementComp>;
/** Constructor
* @param mod Module providing the event(s)
* @param eventid Identifier of the event or event group provided, must be unique
*/
ModuleEventProvider(const WeakModulePtr& mod, const std::string& eventid)
: Service::SimpleProvider(mod, "Events::ModuleEventProvider", eventid)
, prov(mod, this->service_type, this->service_name)
{
prov.SetCaptureHook(this);
}
/** Retrieves the module which created this listener. */
const auto& GetModule() const { return prov.creator; }
/** Get list of objects subscribed to this event
* @return List of subscribed objects
*/
const SubscriberList& GetSubscribers() const { return prov->subscribers; }
/** Subscribes a listener to this event.
* @param subscriber The listener to subscribe.
*/
void Subscribe(ModuleEventListener* subscriber)
{
subscribers.insert(subscriber);
OnSubscribe(subscriber);
}
/** Unsubscribes a listener from this event.
* @param subscriber The listener to unsubscribe.
*/
void Unsubscribe(ModuleEventListener* subscriber)
{
subscribers.erase(subscriber);
OnUnsubscribe(subscriber);
}
/** Run the given hook provided by a module. */
template<typename Class, typename... FunArgs, typename... FwdArgs>
inline void Call(void (Class::*function)(FunArgs...), FwdArgs&&... args) const;
/**
* Run the given hook provided by a module until some module returns MOD_RES_ALLOW or
* MOD_RES_DENY. If no module does that the result is set to MOD_RES_PASSTHRU.
*/
template<typename Class, typename... FunArgs, typename... FwdArgs>
inline ModResult FirstResult(ModResult (Class::*function)(FunArgs...), FwdArgs&&... args) const;
private:
void OnCapture() override
{
// If someone else holds the list from now on, clear mine. See below for more info.
if (*prov != this)
subscribers.clear();
}
/** Called when a listener subscribes to this event.
* @param subscriber The listener which subscribed.
*/
virtual void OnSubscribe(ModuleEventListener* subscriber) { }
/** Called when a listener unsubscribes from this event.
* @param subscriber The listener which unsubscribed.
*/
virtual void OnUnsubscribe(ModuleEventListener* subscriber) { }
/** 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
{
private:
/** Reference to the provider, can be NULL if none of the provider modules are loaded
*/
dynamic_reference_nocheck<ModuleEventProvider> prov;
const unsigned int eventpriority;
/** Called by the dynref when the event provider becomes available
*/
void OnCapture() override
{
prov->Subscribe(this);
}
protected:
/** Constructor
* @param mod Module subscribing
* @param eventid Identifier of the event to subscribe to
* @param eventprio The priority to give this event listener
*/
ModuleEventListener(const WeakModulePtr& mod, const std::string& eventid, unsigned int eventprio)
: prov(mod, "Events::ModuleEventProvider", eventid)
, eventpriority(eventprio)
{
prov.SetCaptureHook(this);
// If the dynamic_reference resolved at construction our capture handler wasn't called
if (prov)
ModuleEventListener::OnCapture();
}
public:
static constexpr unsigned int DefaultPriority = 100;
~ModuleEventListener()
{
if (prov)
prov->Unsubscribe(this);
}
/** Retrieves the module which created this listener. */
const auto& GetModule() const { return prov.creator; }
/** Retrieves the priority of this event. */
unsigned int GetPriority() const { return eventpriority; }
};
inline bool Events::ModuleEventProvider::Comp::operator()(Events::ModuleEventListener* lhs, Events::ModuleEventListener* rhs) const
{
return (lhs->GetPriority() < rhs->GetPriority());
}
inline bool Events::ModuleEventProvider::ElementComp::operator()(Events::ModuleEventListener* lhs, Events::ModuleEventListener* rhs) const
{
if (lhs->GetPriority() < rhs->GetPriority())
return true;
if (lhs->GetPriority() > rhs->GetPriority())
return false;
return std::less<>()(lhs, rhs);
}
template<typename Class, typename... FunArgs, typename... FwdArgs>
inline void Events::ModuleEventProvider::Call(void (Class::*function)(FunArgs...), FwdArgs&&... args) const
{
if (IsModuleDead(GetModule(), false))
return;
for (auto* subscriber : GetSubscribers())
{
if (IsModuleDead(subscriber->GetModule(), true))
continue;
Class* klass = static_cast<Class*>(subscriber);
(klass->*function)(std::forward<FwdArgs>(args)...);
}
}
template<typename Class, typename... FunArgs, typename... FwdArgs>
inline ModResult Events::ModuleEventProvider::FirstResult(ModResult (Class::*function)(FunArgs...), FwdArgs&&... args) const
{
if (IsModuleDead(GetModule(), false))
return MOD_RES_PASSTHRU;
ModResult result;
for (auto* subscriber : GetSubscribers())
{
if (IsModuleDead(subscriber->GetModule(), true))
continue;
Class* klass = static_cast<Class*>(subscriber);
result = (klass->*function)(std::forward<FwdArgs>(args)...);
if (result != MOD_RES_PASSTHRU)
break;
}
return result;
}
