/*
    This file is part of the KDE Project
    SPDX-FileCopyrightText: 2008 Sebastian Trueg <trueg@kde.org>

    Parts of this file are based on code from Strigi
    SPDX-FileCopyrightText: 2006-2007 Jos van den Oever <jos@vandenoever.info>

    SPDX-License-Identifier: LGPL-2.0-or-later
*/

#include "priority.h"

#ifndef _GNU_SOURCE
#define _GNU_SOURCE
#endif

#include <QDebug>

#include <sys/time.h>
#include <sys/resource.h>

#include <unistd.h>
#ifndef _WIN32
#include <sys/syscall.h>
#include <cerrno>

#include <sched.h>
#endif

#ifdef SYS_ioprio_set
namespace {
#ifndef IOPRIO_CLASS_IDLE
    enum {
        IOPRIO_CLASS_NONE,
        IOPRIO_CLASS_RT,
        IOPRIO_CLASS_BE,
        IOPRIO_CLASS_IDLE,
    };
#endif

#ifndef IOPRIO_WHO_PROCESS
    enum {
        IOPRIO_WHO_PROCESS = 1,
        IOPRIO_WHO_PGRP,
        IOPRIO_WHO_USER,
    };
#endif

#ifndef IOPRIO_CLASS_SHIFT
    const int IOPRIO_CLASS_SHIFT = 13;
#endif
}
#endif

bool lowerIOPriority()
{
#ifdef SYS_ioprio_set
    if ( syscall( SYS_ioprio_set, IOPRIO_WHO_PROCESS, 0, IOPRIO_CLASS_IDLE<<IOPRIO_CLASS_SHIFT ) < 0 ) {
        qDebug( "cannot set io scheduling to idle (%s). Trying best effort.\n",  strerror( errno ));
        if ( syscall( SYS_ioprio_set, IOPRIO_WHO_PROCESS, 0, 7|IOPRIO_CLASS_BE<<IOPRIO_CLASS_SHIFT ) < 0 ) {
            qDebug( "cannot set io scheduling to best effort.\n");
            return false;
        }
    }
    return true;
#else
    return false;
#endif
}

bool lowerPriority()
{
#ifndef Q_OS_WIN
    return !setpriority( PRIO_PROCESS, 0, 19 );
#else
    return false;
#endif
}

bool lowerSchedulingPriority()
{
#ifdef SCHED_BATCH
    struct sched_param param;
    memset( &param, 0, sizeof(param) );
    param.sched_priority = 0;
    return !sched_setscheduler( 0, SCHED_BATCH, &param );
#else
    return false;
#endif
}

bool setIdleSchedulingPriority()
{
#ifdef SCHED_IDLE
    struct sched_param param;
    memset( &param, 0, sizeof(param) );
    param.sched_priority = 0;
    return !sched_setscheduler( 0, SCHED_IDLE, &param );
#else
    return false;
#endif
}