timer-deque-rs 0.6.0

/*-
 * timer-deque-rs - a Rust crate which provides timer and timer queues based on target OS
 *  functionality.
 * 
 * Copyright (C) 2025 Aleksandr Morozov alex@nixd.org
 *  4neko.org alex@4neko.org
 * 
 * The timer-rs crate can be redistributed and/or modified
 * under the terms of either of the following licenses:
 *
 *   1. the Mozilla Public License Version 2.0 (the “MPL”) OR
 *                     
 *   2. The MIT License (MIT)
 *                     
 *   3. EUROPEAN UNION PUBLIC LICENCE v. 1.2 EUPL © the European Union 2007, 2016
 */

use std::{borrow::Cow, cmp::Ordering, fmt, io::{self}, ops, os::fd::{AsFd, AsRawFd, BorrowedFd, RawFd}, sync::Arc, time::Duration};

use chrono::{DateTime, TimeZone};
use nix::libc::{self, ECANCELED, EWOULDBLOCK};
use bitflags::bitflags;


use crate::{common, timer_portable::portable_error::TimerPortResult};

#[cfg(target_os = "linux")]
pub use super::linux::timer_fd_linux::TimerFdInternal;

#[cfg(
    all(
        any(
            target_os = "freebsd",
            target_os = "dragonfly",
            target_os = "netbsd",
            target_os = "openbsd",
            target_os = "macos",
        ),
        feature = "bsd_use_timerfd"
    )
)]
pub use super::bsd::timer_fd_bsd::TimerFdInternal;

#[cfg(
    all(
        any(
            target_os = "freebsd",
            target_os = "dragonfly",
            target_os = "netbsd",
            target_os = "openbsd",
            target_os = "macos",
        ),
        not(feature = "bsd_use_timerfd")
    )
)]
pub use super::bsd::timer_kqueue_fd_bsd::TimerFdInternal;


/// A timer type
#[allow(non_camel_case_types)]
#[repr(i32)]
#[derive(Debug)]
pub enum TimerType
{
    /// A settable system-wide real-time clock.
    CLOCK_REALTIME = libc::CLOCK_REALTIME,

    /// A nonsettable monotonically increasing clock that measures  time
    /// from some unspecified point in the past that does not change af‐
    /// ter system startup.

    CLOCK_MONOTONIC = libc::CLOCK_MONOTONIC,

    
    /// Like CLOCK_MONOTONIC, this is a monotonically increasing  clock.
    /// However,  whereas the CLOCK_MONOTONIC clock does not measure the
    /// time while a system is suspended, the CLOCK_BOOTTIME clock  does
    /// include  the time during which the system is suspended.  This is
    /// useful  for  applications  that  need   to   be   suspend-aware.
    /// CLOCK_REALTIME is not suitable for such applications, since that
    /// clock is affected by discontinuous changes to the system clock.
    #[cfg(target_os = "linux")]
    CLOCK_BOOTTIME = libc::CLOCK_BOOTTIME,

    /// This clock is like CLOCK_REALTIME, but will wake the  system  if
    /// it  is suspended.  The caller must have the CAP_WAKE_ALARM capa‐
    /// bility in order to set a timer against this clock.
    #[cfg(target_os = "linux")]
    CLOCK_REALTIME_ALARM = libc::CLOCK_REALTIME_ALARM,

    /// This clock is like CLOCK_BOOTTIME, but will wake the  system  if
    /// it  is suspended.  The caller must have the CAP_WAKE_ALARM capa‐
    /// bility in order to set a timer against this clock.
    #[cfg(target_os = "linux")]
    CLOCK_BOOTTIME_ALARM = libc::CLOCK_BOOTTIME_ALARM,
}

/*
impl Into<libc::clockid_t> for TimerType 
{
    fn into(self) -> libc::clockid_t
    {
        match self
        {
            Self::CLOCK_REALTIME        => return ,
            Self::CLOCK_MONOTONIC       => return ,
            #[cfg(target_os = "linux")]
            Self::CLOCK_BOOTTIME        => return libc::CLOCK_BOOTTIME,
            #[cfg(target_os = "linux")]
            Self::CLOCK_REALTIME_ALARM  => return libc::CLOCK_REALTIME_ALARM,
            #[cfg(target_os = "linux")]
            Self::CLOCK_BOOTTIME_ALARM  => return libc::CLOCK_BOOTTIME_ALARM,
            #[cfg(any(
                target_os = "freebsd",
                target_os = "dragonfly",
                target_os = "netbsd",
                target_os = "openbsd",
                target_os = "macos",
            ))]
            _ => return libc::CLOCK_REALTIME,
        }
    }
}*/

impl From<TimerType> for libc::clockid_t 
{
    fn from(value: TimerType) -> Self 
    {
        return value as libc::clockid_t;
    }
}


bitflags! {     
    /// Flags controling the type of the timer type.  
    #[derive(Default, Debug, Clone, Copy, PartialEq, Eq)] 
    pub struct TimerFlags: i32  
    {     
        /// Set the O_NONBLOCK file status flag on the open file  de‐
        /// scription  (see  open(2)) referred to by the new file de‐
        /// scriptor.  Using this flag saves extra calls to  fcntl(2)
        /// to achieve the same result.
        const TFD_NONBLOCK = libc::TFD_NONBLOCK;

        /// Set  the  close-on-exec (FD_CLOEXEC) flag on the new file
        /// descriptor.  See the description of the O_CLOEXEC flag in
        /// open(2) for reasons why this may be useful.
        const TFD_CLOEXEC = libc::TFD_CLOEXEC;
    }
}


bitflags! {     
    /// A bit mask that can include the values.
    #[derive(Default, Debug, Eq, PartialEq, Clone, Copy)] 
    pub struct TimerSetTimeFlags: i32  
    {     
        /// > Interpret  new_value.it_value as an absolute value on the timer's
        /// > clock.  The timer will expire when the value of the timer's clock
        /// > reaches the value specified in new_value.it_value.
        const TFD_TIMER_ABSTIME = libc::TFD_TIMER_ABSTIME;

        /// > If this flag is specified along with  TFD_TIMER_ABSTIME  and  the
        /// > clock  for  this timer is CLOCK_REALTIME or CLOCK_REALTIME_ALARM,
        /// > then mark this timer as cancelable if the real-time clock  under‐
        /// > goes  a  discontinuous change (settimeofday(2), clock_settime(2),
        /// > or similar).  When  such  changes  occur,  a  current  or  future
        /// > read(2)  from  the file descriptor will fail with the error 
        /// > ECANCELED.
        const TFD_TIMER_CANCEL_ON_SET = libc::TFD_TIMER_CANCEL_ON_SET;
    }
}


/// A trait which defines a standart interface for the different time types i.e
/// 
/// - [RelativeTime] a relative time to the system's clock.
/// 
/// - [AbsoluteTime] an absolute time to the systmem's clock.
/// 
/// This is an internal trait and should not be exposed to the outside of the crate.
pub trait ModeTimeType: Eq + PartialEq + Ord + PartialOrd + fmt::Display + fmt::Debug + Clone + Copy
{
    
    /// Creates new instance from the two components: seconds and subnanoseconds of the seconds.
    /// 
    /// # Arguments
    /// 
    /// `time_spec` - [timespec] - a time to convert. It is assumed that the values
    ///     are correct.
    /// 
    /// # Returns
    /// 
    /// An instance is returend.
    fn new(time_spec: timespec) -> Self where Self: Sized;

    /// Returns the seconds without the nanoseconds fraction.
    fn get_sec(&self) -> i64;

    /// Returns the nanoseconds fraction from seconds, not a full time in nanoseconds.
    fn get_nsec(&self) -> i64;

    /// Verifies that the timer is not set to zero. For the [RelativeTime] it always returns true.
    fn is_value_valid(&self) -> bool;

    /// Returns the [TimerSetTimeFlags] which are autoinitialized for both types. This flags
    /// should be passed to timer.
    fn get_flags() -> TimerSetTimeFlags;
}

/// A `relative` time i.e time which is not binded to the system's clock.
#[derive(Debug, PartialEq, Eq, Clone, Copy)]
pub struct RelativeTime
{
    /// Seconds
    time_sec: i64,

    /// A fraction of ns from second
    time_nsec: i64,
}

/// Converts the [Duration] to [RelativeTime] taking the `subsec_nanos`
/// for the `time_nsec`.
impl From<Duration> for RelativeTime
{
    fn from(value: Duration) -> Self 
    {
        return Self
        {
            time_sec: 
                value.as_secs() as i64,
            time_nsec: 
                value.subsec_nanos() as i64,
        };
    }
}

impl From<RelativeTime> for Duration
{
    fn from(value: RelativeTime) -> Self 
    {
        return Duration::new(value.time_sec as u64, value.time_nsec as u32);
    }
}

impl Ord for RelativeTime
{
    fn cmp(&self, other: &Self) -> Ordering 
    {
        return 
            self
                .time_sec
                .cmp(&other.time_sec)
                .then(
                    self
                        .time_nsec
                        .cmp(&other.time_nsec)
                );
    }
}

impl PartialOrd for RelativeTime
{
    fn partial_cmp(&self, other: &Self) -> Option<Ordering> 
    {
        return Some(self.cmp(other));
    }
}

impl fmt::Display for RelativeTime
{
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result 
    {
        write!(f, "[relative] sec: {}, nsec: {}", self.time_sec, self.time_nsec)
    }
}

impl ModeTimeType for RelativeTime
{
    fn new(time_spec: timespec) -> RelativeTime
    {
        return   
            Self::new_time(time_spec.tv_sec, time_spec.tv_nsec);
    }
    
    fn get_sec(&self) -> i64 
    {
        return self.time_sec;
    }
    
    fn get_nsec(&self) -> i64 {

        return self.time_nsec;
    }

    fn is_value_valid(&self) -> bool 
    {
        return true;    
    }

    fn get_flags() -> TimerSetTimeFlags
    {
        return TimerSetTimeFlags::empty();
    }
}

impl RelativeTime
{
    /// max nanoseconds
    pub const MAX_NS: i64 = 1_000_000_000;

    /// Creates new instance for relative time accepting the user input.
    /// 
    /// Automatically corrects the `time_nsec` value if it is larger than
    /// 999_999_999ns.
    /// 
    /// # Arguments
    /// 
    /// `time_sec` - [i64] a seconds in relative notation.
    /// 
    /// `time_nsec` - [i64] nanoseconds of relative seconds value. Should not be 
    ///     larger than 999_999_999 which is defined by const [Self::MAX_NS]. In
    ///     case if it is larger, the `nsec` will be rounded and an extra secons
    ///     will be added.
    pub 
    fn new_time(time_sec: i64, time_nsec: i64) -> Self
    {
        let extra_sec = time_nsec / Self::MAX_NS;
        let nsec_new = time_nsec % Self::MAX_NS;

        return 
            Self
            { 
                time_nsec: nsec_new, 
                time_sec: time_sec + extra_sec,
            };
    }

    pub 
    fn is_zero(&self) -> bool
    {
        return self.time_nsec == 0 && self.time_sec == 0;
    } 
}

/// An `absolute` time which are binded to the system's clock
/// and never be zero except when timer is reset.
#[derive(Debug, PartialEq, Eq, Clone, Copy)]
pub struct AbsoluteTime
{
    /// A full seconds.
    time_sec: i64,

    /// A fraction (subset) of nanoseconds from the second.
    time_nsec: i64,
}

/// Convers the `chrono` [DateTime<TZ>] into the [AbsoluteTime] using 
/// the `TZ` [TimeZone]  taking the `ns` fraction of a second (subsec_nano) 
/// using `timestamp_subsec_nanos` function.
impl<TZ: TimeZone> From<DateTime<TZ>> for AbsoluteTime
{
    fn from(value: DateTime<TZ>) -> Self 
    {
        return Self
        {
            time_sec: 
                value.timestamp(), 
            time_nsec: 
                value.timestamp_subsec_nanos() as i64,
        };
    }
}

/// Converts the [Duration] to [RelativeTime] taking the `subsec_nanos`
/// for the `time_nsec`.
impl From<Duration> for AbsoluteTime
{
    fn from(value: Duration) -> Self 
    {
        return Self
        {
            time_sec: 
                value.as_secs() as i64,
            time_nsec: 
                value.subsec_nanos() as i64,
        };
    }
}

impl From<AbsoluteTime> for Duration
{
    fn from(value: AbsoluteTime) -> Self 
    {
        return Duration::new(value.time_sec as u64, value.time_nsec as u32);
    }
}

impl Ord for AbsoluteTime
{
    fn cmp(&self, other: &Self) -> Ordering 
    {
        return 
            self
                .time_sec
                .cmp(&other.time_sec)
                .then(
                    self
                        .time_nsec
                        .cmp(&other.time_nsec)
                );
    }
}

impl PartialOrd for AbsoluteTime
{
    fn partial_cmp(&self, other: &Self) -> Option<Ordering> 
    {
        return Some(self.cmp(other));
    }
}

impl ops::AddAssign<Duration> for AbsoluteTime
{
    fn add_assign(&mut self, rhs: Duration) 
    {
        self.time_nsec += rhs.subsec_nanos() as i64;
        let add_sec = self.time_nsec / Self::MAX_NS;

        if add_sec > 0
        {
            self.time_nsec %=  Self::MAX_NS;
        }
        
        self.time_sec += rhs.as_secs() as i64 + add_sec;
    }
}

impl ops::AddAssign<RelativeTime> for AbsoluteTime
{
    fn add_assign(&mut self, rhs: RelativeTime) 
    {
        self.time_nsec += rhs.time_nsec;
        let add_sec = self.time_nsec / Self::MAX_NS;

        if add_sec > 0
        {
            self.time_nsec %=  Self::MAX_NS;
        }
        
        self.time_sec += rhs.time_sec + add_sec;
    }
}

impl ops::Add<Duration> for AbsoluteTime
{
    type Output = AbsoluteTime;

    fn add(mut self, rhs: Duration) -> Self::Output 
    {
        self += rhs;

        return self;
    }
}

impl ops::Add<RelativeTime> for AbsoluteTime
{
    type Output = AbsoluteTime;

    fn add(mut self, rhs: RelativeTime) -> Self::Output 
    {
        self += rhs;

        return self;
    }
}

impl ops::SubAssign<Duration> for AbsoluteTime
{
    fn sub_assign(&mut self, rhs: Duration) 
    {
        let mut sec = rhs.as_secs() as i64;
        let mut nsec = self.time_nsec - rhs.subsec_nanos() as i64;

        if nsec < 0
        {
            sec += 1;

            nsec = Self::MAX_NS + nsec;
        }
        
        self.time_nsec = nsec;
        self.time_sec -= sec;

        return;
    }
}

impl ops::SubAssign<RelativeTime> for AbsoluteTime
{
    fn sub_assign(&mut self, mut rhs: RelativeTime) 
    {

        let mut nsec = self.time_nsec - rhs.time_nsec;

        if nsec < 0
        {
            rhs.time_sec += 1;

            nsec = Self::MAX_NS + nsec;
        }
        
        self.time_nsec = nsec;
        self.time_sec -= rhs.time_sec;

        return;
    }
}

impl ops::Sub<Duration> for AbsoluteTime
{
    type Output = AbsoluteTime;

    fn sub(mut self, rhs: Duration) -> Self::Output 
    {
        self -= rhs;

        return self;
    }
}

impl ops::Sub<RelativeTime> for AbsoluteTime
{
    type Output = AbsoluteTime;

    fn sub(mut self, rhs: RelativeTime) -> Self::Output 
    {
        self -= rhs;

        return self;
    }
}

impl ops::SubAssign for AbsoluteTime
{
    fn sub_assign(&mut self, mut rhs: Self) 
    {

        let mut nsec = self.time_nsec - rhs.time_nsec;

        if nsec < 0
        {
            rhs.time_sec += 1;

            nsec = Self::MAX_NS + nsec;
        }
        
        self.time_nsec = nsec;
        self.time_sec -= rhs.time_sec;

        return;
    }
}

impl ops::Sub for AbsoluteTime
{
    type Output = AbsoluteTime;

    fn sub(mut self, rhs: Self) -> Self::Output 
    {
        self -= rhs;

        return self;
    }
}


impl fmt::Display for AbsoluteTime
{
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result 
    {
        write!(f, "[absolute] {}.{:09}sec", self.time_sec, self.time_nsec)
    }
}


impl ModeTimeType for AbsoluteTime
{
    fn new(time_spec: timespec) -> Self where Self: Sized 
    {
        return 
            unsafe { Self::new_time_unchecked(time_spec.tv_sec, time_spec.tv_nsec) };
    }

    fn get_sec(&self) -> i64 
    {
        return self.time_sec;
    }
    
    fn get_nsec(&self) -> i64 
    {

        return self.time_nsec;
    }

    fn is_value_valid(&self) -> bool 
    {
        return self.time_nsec != 0 || self.time_sec != 0;
    }

    fn get_flags() -> TimerSetTimeFlags
    {
        return TimerSetTimeFlags::TFD_TIMER_ABSTIME | TimerSetTimeFlags::TFD_TIMER_CANCEL_ON_SET;
    }
}

impl AbsoluteTime
{
    /// max nanoseconds
    pub const MAX_NS: i64 = 1_000_000_000;//999_999_999;
}

impl AbsoluteTime
{
    /// Creates an instance with the current local time.
    pub 
    fn now() -> Self
    {
        let value = common::get_current_timestamp();

        return Self
        {
            time_sec: value.timestamp(), 
            time_nsec: value.timestamp_subsec_nanos() as i64,
        }
    }

    pub 
    fn new_time(time_sec: i64, time_nsec: i64) -> Option<Self>
    {
        let tm = 
            unsafe { Self::new_time_unchecked(time_sec, time_nsec) };

        if tm.is_value_valid() == false
        {
            return None;
        }

        return Some(tm);
    }

    /// Creates new instance for absolute time accepting the user input.
    /// 
    /// Automatically corrects the `time_nsec` value if it is larger than
    /// 999_999_999ns.
    /// 
    /// # Arguments
    /// 
    /// `time_sec` - [i64] a seconds in absolute notation.
    /// 
    /// `time_nsec` - [i64] nanoseconds of absolute seconds value. Should not be 
    ///     larger than 999_999_999 which is defined by const [Self::MAX_NS]. In
    ///     case if it is larger, the `nsec` will be rounded and an extra secons
    ///     will be added.
    /// 
    /// # Returns 
    /// 
    /// An instance is returned. May panic on overflow.
    pub unsafe 
    fn new_time_unchecked(time_sec: i64, time_nsec: i64) -> Self
    {
        let extra_sec = time_nsec / Self::MAX_NS;
        let nsec_new = time_nsec % Self::MAX_NS;

        return 
            Self
            { 
                time_nsec: nsec_new, 
                time_sec: time_sec + extra_sec,
            };
    }

    /// Compares only full seconds without nanoseconds fraction (subnano).
    pub 
    fn seconds_cmp(&self, other: &Self) -> Ordering
    {
        return self.time_sec.cmp(&other.time_sec);
    }

    pub 
    fn add_sec(mut self, seconds: i64) -> Self
    {
        self.time_sec += seconds;

        return self;
    }

    pub 
    fn reset_nsec(mut self) -> Self
    {
        self.time_nsec = 0;

        return self;
    }
}



/// A timer expiry modes. Not every OS supports 
/// every mode. Read comments for the OS specific
/// timer. For the `nanoseconds` param the max value
/// is 999_999_999 for most OSes.
#[derive(Clone, Copy, Debug, PartialEq, Eq)]
pub enum TimerExpMode<TIMERTYPE: ModeTimeType>
{
    /// Disarmed
    None, 

    /// A timer which is triggered once.
    OneShot
    {
        timeout: TIMERTYPE
    },
    
    /// Interval with the initial delay.
    IntervalDelayed
    {
        /// First event delay.
        delay_tm: TIMERTYPE,

        /// Interval.
        interv_tm: TIMERTYPE
    },

    /// Interval, with the first timeout event 
    /// equal to interval values.
    Interval
    {
        /// Interval seconds.
        interv_tm: TIMERTYPE
    },
}


impl ops::AddAssign<RelativeTime> for TimerExpMode<AbsoluteTime>
{
    fn add_assign(&mut self, rhs: RelativeTime) 
    {
        match self
        {
            TimerExpMode::None => 
                return,
            TimerExpMode::OneShot { timeout } => 
            {
                *timeout += rhs;
                
            },
            TimerExpMode::IntervalDelayed { interv_tm, .. } => 
            {
                *interv_tm += rhs;
            },
            TimerExpMode::Interval { interv_tm } => 
            {
               *interv_tm += rhs;
            },
        }
    }
}


impl ops::Add<RelativeTime> for TimerExpMode<AbsoluteTime>
{
    type Output = TimerExpMode<AbsoluteTime>;

    fn add(mut self, rhs: RelativeTime) -> Self::Output 
    {
        self += rhs;

        return self;
    }
}


impl<TIMERTYPE: ModeTimeType> Ord for TimerExpMode<TIMERTYPE>
{
    fn cmp(&self, other: &Self) -> Ordering 
    {
        match (self, other)
        {
            (TimerExpMode::None, TimerExpMode::None) => 
                return Ordering::Equal,
            (TimerExpMode::OneShot{ timeout }, TimerExpMode::OneShot { timeout: timeout2 }) => 
            { 
                return timeout.cmp(timeout2);
            },
            (
                TimerExpMode::IntervalDelayed{ delay_tm, interv_tm }, 
                TimerExpMode::IntervalDelayed{ delay_tm: delay_tm2, interv_tm: interv_tm2 }
            ) =>
            {
                return 
                    delay_tm.cmp(delay_tm2)
                        .then(interv_tm.cmp(interv_tm2));
            },
            (TimerExpMode::Interval { interv_tm }, TimerExpMode::Interval { interv_tm: interv_tm2 }) => 
            {
                return interv_tm.cmp(interv_tm2);
            },
            _ => 
                panic!("cannot compare different types {} and {}", self, other)
        }
    }
}

impl<TIMERTYPE: ModeTimeType> PartialOrd for TimerExpMode<TIMERTYPE>
{
    fn partial_cmp(&self, other: &Self) -> Option<Ordering> 
    {
        return Some(self.cmp(other));
    }
}



/// Implementations of the [TimerExpMode] for [AbsoluteTime].
impl TimerExpMode<AbsoluteTime>
{
    /// Checks value for the `set_time` function. To disarm timer 
    /// use `unset_time`.
    #[inline]
    fn is_valid_inner(&self) -> bool
    {
        match self
        {
            Self::None => 
                return false,
            Self::OneShot{ timeout} => 
                return timeout.is_value_valid(),
            Self::IntervalDelayed{ delay_tm, interv_tm } => 
                return delay_tm.is_value_valid() && interv_tm.is_value_valid(),
            Self::Interval{ interv_tm } => 
                return interv_tm.is_value_valid()
        }
    }

    /// Construct the [TimerExpMode::OneShot] timer. For the `absolute` timer
    /// only this type is available. The [AbsoluteTime] should be provided which
    /// should be ahead of the OS'es timer.
    pub 
    fn new_oneshot(abs_time: AbsoluteTime) -> Self
    {
        return Self::OneShot { timeout: abs_time };
    }
}



/// Implementations of the [TimerExpMode] for [RelativeTime].
impl TimerExpMode<RelativeTime>
{
    /// Construct the [TimerExpMode::OneShot] timer. A [RelativeTime] should 
    /// be provided as argument. This type of timer is triggered only once.
    pub 
    fn new_oneshot(rel_time: RelativeTime) -> Self
    {
        return Self::OneShot { timeout: rel_time };
    }

    /// Constrcut the [TimerExpMode::Interval] timer. A [RelativeTime] should 
    /// be provided as agument which specifies the trigger interval.
    pub 
    fn new_interval(rel_time: RelativeTime) -> Self
    {
        return Self::Interval { interv_tm: rel_time };
    }

    /// Construct the [TimerExpMode::IntervalDelayed] timer. A two [RelativeTime] 
    /// arguments should be provided which would set the initial delay and further
    /// interval. The initial delay happens only once. Then the interval will be used.
    /// If `delay_time` and `intev_time` are same, acts as `new_interval`.
    pub 
    fn new_interval_with_init_delay(delay_time: RelativeTime, intev_time: RelativeTime) -> Self
    {
        return Self::IntervalDelayed { delay_tm: delay_time, interv_tm: intev_time };
    }
}

impl<TIMERTYPE: ModeTimeType> TimerExpMode<TIMERTYPE>
{
    /// Disarms the timer.
    #[inline]
    pub 
    fn reset() -> Self
    {
        return Self::None;
    }
}

impl<TIMERTYPE: ModeTimeType> fmt::Display for TimerExpMode<TIMERTYPE>
{
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result 
    {
        match self
        {
            Self::None => 
                write!(f, "disarmed"),
            Self::OneShot{ timeout } => 
                write!(f, "oneshot {}", timeout),
            Self::IntervalDelayed
                { delay_tm, interv_tm } => 
                write!(f, "interval {} with delay {}", interv_tm, delay_tm),
            Self::Interval{ interv_tm } => 
                write!(f, "interval {}", interv_tm),
        }
    }
}



/*
#[cfg(target_os = "macos")]
#[repr(C)]
pub struct timespec 
{
    pub tv_sec: libc::time_t,
    pub tv_nsec: libc::c_long,
}
#[cfg(target_os = "macos")]
#[repr(C)]
pub struct itimerspec 
{
    pub it_interval: timespec,
    pub it_value: timespec,
}
    */

/// A timer FD read operation result.
#[derive(Debug, Clone, PartialEq, Eq)]
pub enum TimerReadRes<T: Sized + fmt::Debug + fmt::Display + Clone + Eq + PartialEq>
{
    /// Read successfull.
    Ok(T),

    /// TFD_TIMER_ABSTIME 
    /// > Marks this timer as cancelable if the real-time clock  under‐
    /// > goes  a  discontinuous change (settimeofday(2), clock_settime(2),
    /// > or similar).  When  such  changes  occur,  a  current  or  future
    /// > read(2)  from  the file descriptor will fail with the error 
    /// > ECANCELED.
    Cancelled,

    /// EAGAIN
    /// If FD is nonblocking then this will be returned.
    WouldBlock,
}

impl TimerReadRes<u64>
{
    pub 
    fn ok() -> Self
    {
        return Self::Ok(1);
    }
}

impl<T: Sized + fmt::Debug + fmt::Display + Clone + Eq + PartialEq> From<io::Error> for TimerReadRes<T>
{
    fn from(value: io::Error) -> Self 
    {
        if let Some(errn) = value.raw_os_error()
        {
            if errn == ECANCELED
            {
                return Self::Cancelled;
            }
            else if errn == EWOULDBLOCK
            {
                return Self::WouldBlock;
            }
        }

        return Self::Cancelled;
    }
}

impl<T: Sized + fmt::Debug + fmt::Display + Clone + Eq + PartialEq> fmt::Display for TimerReadRes<T>
{
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result 
    {
        match self
        {
            Self::Ok(ovfl) => 
                write!(f, "OK(overflows:{})", ovfl),
            Self::Cancelled => 
                write!(f, "CANCELLED"),
            Self::WouldBlock => 
                write!(f, "WOULDBLOCK"),
        }
    }
}

impl<T: Sized + fmt::Debug + fmt::Display + Clone + Eq + PartialEq> TimerReadRes<T>
{
    pub 
    fn unwrap(self) -> T
    {
        let Self::Ok(t) = self
        else { panic!("can not unwrap {:?}", self)};

        return t;
    }
}

pub trait FdTimerRead: AsFd + AsRawFd + fmt::Display + AsRef<str> + PartialEq<str> + PartialEq<RawFd>
{
    /// Attempts to read the timer. The realization is different on different OS. The main purpose 
    /// is to check if timer is ready (ended).
    /// 
    /// # Returns
    /// 
    /// * If FD is configured as non-blocking then returns 
    ///     [TimerReadRes::WouldBlock] otherwise would block.
    /// 
    /// * If daytime modification happened the 
    ///     [TimerReadRes::Cancelled] will be returned, however
    ///     it depends if the [TimerSetTimeFlags::TFD_TIMER_CANCEL_ON_SET]
    ///     is set with [TimerSetTimeFlags::TFD_TIMER_ABSTIME]. Does not
    ///     work on KQueue implementation.
    /// 
    /// * If read was successfull the amount of the overflows before
    ///     read will be returned i.e [TimerReadRes::Ok]. 
    ///     Normally is is `1`. If `0` is returned then probably the
    ///     time or day was modified.
    /// 
    /// * The [Result::Err] is returned if other error occured.
    fn read(&self) -> TimerPortResult<TimerReadRes<u64>>;
}

pub trait FdTimerMarker: FdTimerRead + Eq + PartialEq + PartialEq<RawFd>
{
    fn clone_timer(&self) -> TimerFd;

    fn get_strong_count(&self) -> usize;
}


/// A common trait which is implemented by all timer realizationss for different OSes.
pub trait FdTimerCom: FdTimerRead
{
    /// Creates new isntance of the timer.
    /// 
    /// # Arguments
    /// 
    /// * `label` - a [Cow] string which defines a title of the timer for identification.
    /// 
    /// * `timer_type` - a [TimerType] a clock source
    /// 
    /// * `timer_flags` - a [TimerFlags] configuration of the timer's FD.
    /// 
    /// # Returns
    /// 
    /// A [Result] is retuned with instance on success.
    fn new(label: Cow<'static, str>, timer_type: TimerType, timer_flags: TimerFlags) -> TimerPortResult<Self>
    where Self: Sized;

    /// Sets the timer. The timer starts immidiatly and working depending on the `timer_exp` mode.
    /// 
    /// In case of timer does not support [TimerExpMode::IntervalDelayed] nativly (on OS level), the
    /// crate will store the `interval` part and set interval on first `read()` i.e after the `delay`
    /// and remove the stored `interval` (or may not) from the inner field.
    fn set_time<TIMERTYPE: ModeTimeType>(&self, timer_exp: TimerExpMode<TIMERTYPE>) -> TimerPortResult<()>;

    /// Unsets the timer. The timer stops immidiatly.
    fn unset_time(&self) -> TimerPortResult<()>;

    /// Sets the timer to non-blocking (on case if `flag` is `true`). 
    /// If the timer was inited with
    /// [TimerFlags::TFD_NONBLOCK], then this will not do anything. 
    fn set_nonblocking(&self, flag: bool) -> TimerPortResult<()>;

    /// Reads the FD's flags and check if Fd is in non-blocking mode. 
    /// May return error.
    /// 
    /// # Returns
    /// 
    /// * `true` - FD is non-blocking
    /// 
    /// * `false` - FD is blocking
    fn is_nonblocking(&self) -> TimerPortResult<bool>;
}

#[derive(Debug)]
pub struct TimerFd(Arc<TimerFdInternal>);

impl fmt::Display for TimerFd
{
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result 
    {
        write!(f, "{}", self.0)
    }
}

impl AsFd for TimerFd
{
    fn as_fd(&self) -> BorrowedFd<'_> 
    {
        return self.0.as_fd();
    }
}

impl AsRawFd for TimerFd
{
    fn as_raw_fd(&self) -> RawFd 
    {
        return self.0.as_raw_fd();
    }
}
impl AsRef<str> for TimerFd
{
    fn as_ref(&self) -> &str 
    {
        return self.0.as_ref().as_ref();
    }
}

impl Eq for TimerFd {}

impl PartialEq for TimerFd
{
    fn eq(&self, other: &Self) -> bool 
    {
        return self.0 == other.0
    }
}

impl PartialEq<RawFd> for TimerFd
{
    fn eq(&self, other: &RawFd) -> bool 
    {
        return self.0.as_raw_fd() == *other;
    }
}

impl PartialEq<str> for TimerFd
{
    fn eq(&self, other: &str) -> bool 
    {
        return self.0.as_ref() == other;
    }
}

impl FdTimerMarker for TimerFd
{
    fn clone_timer(&self) -> TimerFd 
    {
        return Self(self.0.clone());
    }

    fn get_strong_count(&self) -> usize 
    {
        return Arc::strong_count(&self.0);
    }
}

impl TimerFd
{
    pub 
    fn new(label: Cow<'static, str>, timer_type: TimerType, timer_flags: TimerFlags) -> TimerPortResult<Self>
    {
        return Ok(
            Self( Arc::new(TimerFdInternal::new(label, timer_type, timer_flags)?) )
        );
    }

    pub 
    fn get_timer(&self) -> &TimerFdInternal
    {
        return &self.0;
    }
}

impl FdTimerRead for TimerFd
{
    fn read(&self) -> TimerPortResult<TimerReadRes<u64>> 
    {
        return self.0.read();
    }
}

pub use nix::libc::{itimerspec, timespec};

/// Converts from [itimerspec] into [TimerExpMode] of the `TIMERTYPE`.
impl<TIMERTYPE: ModeTimeType> From<itimerspec> for TimerExpMode<TIMERTYPE>
{
    fn from(value: itimerspec) -> Self 
    {
        if value.it_interval.tv_sec == 0 && value.it_interval.tv_nsec == 0 &&
            value.it_value.tv_sec == 0 && value.it_value.tv_nsec == 0
        {
            // unset
            return Self::None;
        }
        else if value.it_interval.tv_sec == 0 && value.it_interval.tv_nsec == 0
        {
            // one shot
            return 
                Self::OneShot
                { 
                    timeout: TIMERTYPE::new(value.it_value) 
                };
        }
        else if value.it_interval.tv_sec == value.it_value.tv_sec &&
            value.it_interval.tv_nsec == value.it_value.tv_nsec
        {
            // interval
            return 
                Self::Interval
                { 
                    interv_tm: TIMERTYPE::new(value.it_interval) 
                };
        }
        else
        {
            // delayed interval
            return 
                Self::IntervalDelayed 
                { 
                    delay_tm: TIMERTYPE::new(value.it_value),
                    interv_tm: TIMERTYPE::new(value.it_interval) 
                };
        }
    }
}


impl<TIMERTYPE: ModeTimeType> From<TimerExpMode<TIMERTYPE>> for itimerspec
{
    fn from(value: TimerExpMode<TIMERTYPE>) -> Self 
    {
        return (&value).into();
    }
}

/// Converts from the reference to [TimerExpMode] of the `TIMERTYPE` into the 
/// [itimerspec].
impl<TIMERTYPE: ModeTimeType> From<&TimerExpMode<TIMERTYPE>> for itimerspec
{
    fn from(value: &TimerExpMode<TIMERTYPE>) -> Self 
    {
        match value
        {
            TimerExpMode::None => 
                return 
                    itimerspec 
                    {
                        it_interval: timespec 
                        {
                            tv_sec: 0,
                            tv_nsec: 0,
                        },
                        it_value: timespec
                        {
                            tv_sec: 0,
                            tv_nsec: 0,
                        },
                    },
            TimerExpMode::OneShot{ timeout} =>
                return 
                    itimerspec 
                    {
                        it_interval: timespec 
                        {
                            tv_sec: 0,
                            tv_nsec: 0,
                        },
                        it_value: timespec
                        {
                            tv_sec: timeout.get_sec(),
                            tv_nsec: timeout.get_nsec(),
                        },
                    },
            TimerExpMode::IntervalDelayed{ delay_tm, interv_tm } => 
                return 
                    itimerspec 
                    {
                        it_interval: timespec 
                        {
                            tv_sec: interv_tm.get_sec(),
                            tv_nsec: interv_tm.get_nsec(),
                        },
                        it_value: timespec
                        {
                            tv_sec: delay_tm.get_sec(),
                            tv_nsec: delay_tm.get_nsec(),
                        },
                    },
            TimerExpMode::Interval{ interv_tm } => 
                return 
                    itimerspec 
                    {
                        it_interval: timespec 
                        {
                            tv_sec: interv_tm.get_sec(),
                            tv_nsec: interv_tm.get_nsec(),
                        },
                        it_value: timespec
                        {
                            tv_sec: interv_tm.get_sec(),
                            tv_nsec: interv_tm.get_nsec(),
                        },
                    }
        }
    }
}


#[cfg(test)]
mod tests
{

    use crate::{common, timer_portable::timer::{AbsoluteTime, ModeTimeType, RelativeTime, TimerExpMode}};

    #[test]
    fn test_0() 
    {
        let ts = common::get_current_timestamp();

        let texp1 = TimerExpMode::<AbsoluteTime>::new_oneshot(AbsoluteTime::from(ts));

        assert_eq!(
            TimerExpMode::OneShot { timeout: AbsoluteTime::from(ts) },
            texp1
        );
        
    }

    #[test]
    fn test_1() 
    {
        let ts = common::get_current_timestamp();

        let texp1 = 
            TimerExpMode::<AbsoluteTime>::new_oneshot(AbsoluteTime::from(ts));

        let texp2 = 
            texp1 + RelativeTime::new_time(1, 0);

        assert_eq!(texp1 < texp2, true);
        assert_eq!(texp2 > texp1, true);
        assert_eq!(texp2 != texp1, true);
        assert_eq!(texp2 < texp1, false);
    }

    #[test]
    fn test_2() 
    {

        let texp1 = 
            TimerExpMode::<AbsoluteTime>::new_oneshot(
                unsafe {AbsoluteTime::new_time_unchecked(100, AbsoluteTime::MAX_NS)}
            );
       
        let texp2 = 
            texp1 + RelativeTime::new_time(0, 1);


        assert_eq!(texp1 < texp2, true);
        assert_eq!(texp2 > texp1, true);
        assert_eq!(texp2 != texp1, true);
        assert_eq!(texp2 < texp1, false);
    }

    #[should_panic]
    #[test]
    fn test_2_fail() 
    {
        let ts = common::get_current_timestamp();

        let texp1 = 
            TimerExpMode::<AbsoluteTime>::new_oneshot(AbsoluteTime::from(ts));

        let texp2 = 
            TimerExpMode::<AbsoluteTime>::Interval { interv_tm:  AbsoluteTime::from(ts)};

        assert_eq!(texp1 == texp2, true);
    }

    #[test]
    fn test_abstime_cmp()
    {
        let abs_time = AbsoluteTime::now();
        let abs_time_future = abs_time + RelativeTime::new_time(10, 1);
        let abs_time_past = abs_time - RelativeTime::new_time(10, 1);

        assert_eq!(abs_time < abs_time_future, true);
        assert_eq!(abs_time_future > abs_time, true);
        assert_eq!(abs_time > abs_time_past, true);
        assert_eq!(abs_time_past < abs_time, true);
        assert_eq!(abs_time_future > abs_time_past, true);
        assert_eq!(abs_time_past < abs_time_future, true);
    }

    #[test]
    fn test_abstime_new()
    {
        let abs = AbsoluteTime::new_time(1, 999_999_999).unwrap();
        assert_eq!(abs.time_nsec, 999_999_999);
        assert_eq!(abs.time_sec, 1);

        let abs = AbsoluteTime::new_time(1, 1_000_000_000).unwrap();
        assert_eq!(abs.time_nsec, 0);
        assert_eq!(abs.time_sec, 2);

        let abs = AbsoluteTime::new_time(1, 1_000_000_001).unwrap();
        assert_eq!(abs.time_nsec, 1);
        assert_eq!(abs.time_sec, 2);

        let abs = AbsoluteTime::new_time(1, 2_000_000_001).unwrap();
        assert_eq!(abs.time_nsec, 1);
        assert_eq!(abs.time_sec, 3);
    }

    #[test]
    fn test_abstime_add()
    {
        let mut abs = AbsoluteTime::new_time(1, 999_999_999).unwrap();

        abs += RelativeTime::new_time(0, 1);

        assert_eq!(abs.time_nsec, 0);
        assert_eq!(abs.time_sec, 2);

        abs += RelativeTime::new_time(1, 1);

        assert_eq!(abs.time_nsec, 1);
        assert_eq!(abs.time_sec, 3);

        abs += RelativeTime::new_time(0, 999_999_999);

        assert_eq!(abs.time_nsec, 0);
        assert_eq!(abs.time_sec, 4);

        abs -= RelativeTime::new_time(0, 999_999_999);

        assert_eq!(abs.time_nsec, 1);
        assert_eq!(abs.time_sec, 3);

        abs -= RelativeTime::new_time(0, 1);

        assert_eq!(abs.time_nsec, 0);
        assert_eq!(abs.time_sec, 3);

        abs -= RelativeTime::new_time(0, 500_000_000);

        assert_eq!(abs.time_nsec, 500_000_000);
        assert_eq!(abs.time_sec, 2);

        abs -= RelativeTime::new_time(0, 400_000_000);

        assert_eq!(abs.time_nsec, 100_000_000);
        assert_eq!(abs.time_sec, 2);

        abs -= RelativeTime::new_time(1, 200_000_000);

        assert_eq!(abs.time_nsec, 900_000_000);
        assert_eq!(abs.time_sec, 0);
    }
}