/* $Id: time-darwin.cpp 82968 2020-02-04 10:35:17Z vboxsync $ */
/** @file
 * IPRT - Time, Darwin.
 */

/*
 * Copyright (C) 2006-2020 Oracle Corporation
 *
 * This file is part of VirtualBox Open Source Edition (OSE), as
 * available from http://www.virtualbox.org. This file is free software;
 * you can redistribute it and/or modify it under the terms of the GNU
 * General Public License (GPL) as published by the Free Software
 * Foundation, in version 2 as it comes in the "COPYING" file of the
 * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
 * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
 *
 * The contents of this file may alternatively be used under the terms
 * of the Common Development and Distribution License Version 1.0
 * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
 * VirtualBox OSE distribution, in which case the provisions of the
 * CDDL are applicable instead of those of the GPL.
 *
 * You may elect to license modified versions of this file under the
 * terms and conditions of either the GPL or the CDDL or both.
 */


/*********************************************************************************************************************************
*   Header Files                                                                                                                 *
*********************************************************************************************************************************/
#define LOG_GROUP RTLOGGROUP_TIME
#define RTTIME_INCL_TIMEVAL
#include <mach/mach_time.h>
#include <mach/kern_return.h>
#include <sys/time.h>
#include <time.h>

#include <iprt/time.h>
#include <iprt/assert.h>
#include "internal/time.h"


/*********************************************************************************************************************************
*   Global Variables                                                                                                             *
*********************************************************************************************************************************/
static struct mach_timebase_info    g_Info = { 0, 0 };
static double                       g_rdFactor = 0.0;
static bool                         g_fFailedToGetTimeBaseInfo = false;


/**
 * Perform lazy init (pray we're not racing anyone in a bad way).
 */
static void rtTimeDarwinLazyInit(void)
{
    struct mach_timebase_info Info;
    if (mach_timebase_info(&Info) == KERN_SUCCESS)
    {
        g_rdFactor = (double)Info.numer / (double)Info.denom;
        g_Info = Info;
    }
    else
    {
        g_fFailedToGetTimeBaseInfo = true;
        Assert(g_Info.denom == 0 && g_Info.numer == 0 && g_rdFactor == 0.0);
    }
}


/**
 * Internal worker.
 * @returns Nanosecond timestamp.
 */
DECLINLINE(uint64_t) rtTimeGetSystemNanoTS(void)
{
    /* Lazy init. */
    if (RT_UNLIKELY(g_Info.denom == 0 && !g_fFailedToGetTimeBaseInfo))
        rtTimeDarwinLazyInit();

    /* special case: absolute time is in nanoseconds */
    if (g_Info.denom == 1 && g_Info.numer == 1)
        return mach_absolute_time();

    /* general case: multiply by factor to get nanoseconds. */
    if (g_rdFactor != 0.0)
        return mach_absolute_time() * g_rdFactor;

    /* worst case: fallback to gettimeofday(). */
    struct timeval tv;
    gettimeofday(&tv, NULL);
    return (uint64_t)tv.tv_sec  * RT_NS_1SEC_64
         + (uint64_t)(tv.tv_usec * RT_NS_1US);
}


RTDECL(uint64_t) RTTimeSystemNanoTS(void)
{
    return rtTimeGetSystemNanoTS();
}


RTDECL(uint64_t) RTTimeSystemMilliTS(void)
{
    return rtTimeGetSystemNanoTS() / RT_NS_1MS;
}


RTDECL(PRTTIMESPEC) RTTimeNow(PRTTIMESPEC pTime)
{
    /** @todo find nanosecond API for getting time of day. */
    struct timeval tv;
    gettimeofday(&tv, NULL);
    return RTTimeSpecSetTimeval(pTime, &tv);
}