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

#include <Kernel/Process.h>
#include <Kernel/Scheduler.h>
#include <Kernel/Sections.h>
#include <Kernel/Tasks/FinalizerTask.h>

namespace Kernel {

static constexpr StringView finalizer_task_name = "Finalizer Task"sv;

static void finalizer_task(void*)
{
    Thread::current()->set_priority(THREAD_PRIORITY_LOW);
    for (;;) {
        // The order of this if-else is important: We want to continue trying to finalize the threads in case
        // Thread::finalize_dying_threads set g_finalizer_has_work back to true due to OOM conditions
        if (g_finalizer_has_work.exchange(false, AK::MemoryOrder::memory_order_acq_rel) == true)
            Thread::finalize_dying_threads();
        else
            g_finalizer_wait_queue->wait_forever(finalizer_task_name);
    }
};

UNMAP_AFTER_INIT void FinalizerTask::spawn()
{
    RefPtr<Thread> finalizer_thread;
    auto finalizer_process = Process::create_kernel_process(finalizer_thread, KString::must_create(finalizer_task_name), finalizer_task, nullptr);
    VERIFY(finalizer_process);
    g_finalizer = finalizer_thread;
}

}