serenity/AK/IDAllocator.h

/*
 * Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
 *
 * SPDX-License-Identifier: BSD-2-Clause
 */

#pragma once

#include <AK/Forward.h>
#include <AK/HashTable.h>

namespace AK {

class IDAllocator {

public:
    IDAllocator() = default;
    ~IDAllocator() = default;

    int allocate()
    {
        int r = rand();
        for (int i = 0; i < 100000; ++i) {
            int allocated_id = r + i;
            // Make sure we never vend ID 0, as some code may interpret that as "no ID"
            if (allocated_id == 0)
                ++allocated_id;
            if (!m_allocated_ids.contains(allocated_id)) {
                m_allocated_ids.set(allocated_id);
                return allocated_id;
            }
        }
        VERIFY_NOT_REACHED();
    }

    void deallocate(int id)
    {
        m_allocated_ids.remove(id);
    }

private:
    HashTable<int> m_allocated_ids;
};
}

using AK::IDAllocator;