Atmosphere/libraries/libstratosphere/source/diag/impl/diag_observer_manager.hpp

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/*
* Copyright (c) 2018-2020 Atmosphère-NX
*
* This program is free software; you can redistribute it and/or modify it
* under the terms and conditions of the GNU General Public License,
* version 2, as published by the Free Software Foundation.
*
* This program is distributed in the hope 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
#include <stratosphere.hpp>
namespace ams::diag::impl {
template<typename Holder, typename Context>
class ObserverManager {
NON_COPYABLE(ObserverManager);
NON_MOVEABLE(ObserverManager);
private:
Holder *m_observer_list_head;
Holder **m_observer_list_tail;
os::ReadWriteLock m_lock;
public:
constexpr ObserverManager() : m_observer_list_head(nullptr), m_observer_list_tail(std::addressof(m_observer_list_head)), m_lock() {
/* ... */
}
constexpr ~ObserverManager() {
if (std::is_constant_evaluated()) {
this->UnregisterAllObserverLocked();
} else {
this->UnregisterAllObserver();
}
}
void RegisterObserver(Holder *holder) {
/* Acquire a write hold on our lock. */
std::scoped_lock lk(m_lock);
this->RegisterObserverLocked(holder);
}
void UnregisterObserver(Holder *holder) {
/* Acquire a write hold on our lock. */
std::scoped_lock lk(m_lock);
/* Check that we can unregister. */
AMS_ASSERT(holder->is_registered);
/* Remove the holder. */
if (m_observer_list_head == holder) {
m_observer_list_head = holder->next;
if (m_observer_list_tail == std::addressof(holder->next)) {
m_observer_list_tail = std::addressof(m_observer_list_head);
}
} else {
for (auto *cur = m_observer_list_head; cur != nullptr; cur = cur->next) {
if (cur->next == holder) {
cur->next = holder->next;
if (m_observer_list_tail == std::addressof(holder->next)) {
m_observer_list_tail = std::addressof(cur->next);
}
break;
}
}
}
/* Set unregistered. */
holder->next = nullptr;
}
void UnregisterAllObserver() {
/* Acquire a write hold on our lock. */
std::scoped_lock lk(m_lock);
this->UnregisterAllObserverLocked();
}
void InvokeAllObserver(const Context &context) {
/* Use the holder's observer. */
InvokeAllObserver(context, [] (const Holder &holder, const Context &context) {
holder.observer(context);
});
}
template<typename Observer>
void InvokeAllObserver(const Context &context, Observer observer) {
/* Acquire a read hold on our lock. */
std::shared_lock lk(m_lock);
/* Invoke all observers. */
for (const auto *holder = m_observer_list_head; holder != nullptr; holder = holder->next) {
observer(*holder, context);
}
}
protected:
constexpr void RegisterObserverLocked(Holder *holder) {
/* Check that we can register. */
AMS_ASSERT(!holder->is_registered);
/* Insert the holder. */
*m_observer_list_tail = holder;
m_observer_list_tail = std::addressof(holder->next);
/* Set registered. */
holder->next = nullptr;
holder->is_registered = true;
}
constexpr void UnregisterAllObserverLocked() {
/* Unregister all observers. */
for (auto *holder = m_observer_list_head; holder != nullptr; holder = holder->next) {
holder->is_registered = false;
}
/* Reset head/fail. */
m_observer_list_head = nullptr;
m_observer_list_tail = std::addressof(m_observer_list_head);
}
};
template<typename Holder, typename Context>
class ObserverManagerWithDefaultHolder : public ObserverManager<Holder, Context> {
private:
Holder m_default_holder;
public:
template<typename Initializer, typename... Args>
constexpr ObserverManagerWithDefaultHolder(Initializer initializer, Args &&... args) : ObserverManager<Holder, Context>(), m_default_holder{} {
/* Initialize the default observer. */
initializer(std::addressof(m_default_holder), std::forward<Args>(args)...);
/* Register the default observer. */
if (std::is_constant_evaluated()) {
this->RegisterObserverLocked(std::addressof(m_default_holder));
} else {
this->RegisterObserver(std::addressof(m_default_holder));
}
}
Holder &GetDefaultObserverHolder() {
return m_default_holder;
}
const Holder &GetDefaulObservertHolder() const {
return m_default_holder;
}
};
}