global_instance.h

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/*
 *  Copyright (C) 2004-2026 Savoir-faire Linux Inc.
 *
 *  This program 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, 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 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 <https://www.gnu.org/licenses/>.
 */
 
#pragma once
 
#include <memory>
#include <mutex>
 
namespace jami {
 
template<class T, signed MaxRespawn = -1>
std::shared_ptr<T>
getGlobalInstance()
{
    static std::recursive_mutex mutex; // recursive as instance calls recursively
    static std::weak_ptr<T> wlink;
 
    std::unique_lock lock(mutex);
 
    if (wlink.expired()) {
        static signed counter {MaxRespawn};
        if (not counter)
            return nullptr;
        auto link = std::make_shared<T>();
        wlink = link;
        if (counter > 0)
            --counter;
        return link;
    }
 
    return wlink.lock();
}
 
} // namespace jami