System time and timestamps

Beginner

Concept

Overview

System time is a publicly exposed and verified part of the IC state tree. System time is expressed in nanoseconds since 1970-01-01 and indicates the time at which the state is current. It is exposed at /time, and all partial state trees include a timestamp.

System time observed by the canister is monotonically increasing, even across canister upgrades. Since the ICP network is decentralized, the system times of different canisters are unrelated, and there is no notion of a timezone, sometimes resulting in calls appearing to travel back in time.

System time, expressed in nanoseconds, may require conversion into different formats, like DateTime. This guide will detail some of the commonly used conversions.

Getting system time

Your canister can programmatically get system time to be used within your application.

Motoko

import { now } = "mo:base/Time";
import Debug "mo:base/Debug";

actor {
    let time = now();
    Debug.print(debug_show(time));
};

Rust

let current_time = IC_API::time();

TypeScriptBeta

import { Canister, ic, nat64, query } from 'azle/experimental';

export default Canister({
    time: query([], nat64, () => {
        return ic.time();
    })
});

PythonBeta

from kybra import ic, nat64, query

@query
def time() -> nat64:
    return ic.time()

Conversion packages

For Motoko canisters:

• time Mops package: Supports functions for converting system time into microseconds, milliseconds, string date format, and more.

• dateTime Mops package: Supports functions for converting system time into UTC format, local timezone, and fixed timezones.

For Rust canisters:

• time:

• datetimeutils:

Converting Unix timestamps to DateTime format

The nanosecond format that system time is returned in uses the Unix timestamp format, which is simply the total number of nanoseconds, such as 1721402551. DateTime format uses the structure YYYY-MM-DD HH:MM:SS.

Below are examples showing how to convert Unix timestamps to DateTime format.

Motoko

import Time "mo:time/time";
import DateTime "mo:datetime/DateTime";
import Debug "mo:base/Debug";

actor {
    let now = Time.now();
    let dateTime = DateTime.DateTime(now);

    Debug.print(dateTime.toText());
};

Rust

use crate::types::utils::CalendarDate;
use time::{Duration, OffsetDateTime};

pub fn calendar_date(timestamp: &u64) -> CalendarDate {
    CalendarDate::from(&to_date(timestamp).to_calendar_date())
}

You can also convert Unix time to an OffsetDateTime format:

use crate::types::utils::CalendarDate;
use time::{Duration, OffsetDateTime};

fn to_date(timestamp: &u64) -> OffsetDateTime {
    let nanoseconds = *timestamp as i64;
    let seconds = nanoseconds / 1_000_000_000;
    let nanos_remainder = nanoseconds % 1_000_000_000;

    OffsetDateTime::from_unix_timestamp(seconds).unwrap() + Duration::nanoseconds(nanos_remainder)
}

Calculating the time between two timestamps

For some applications, it may be useful to calculate the time that has passed between two timestamps. Below is an example canister written in Motoko that demonstrates how to use timers to generate two timestamps, then creates a function that can be used to calculate the difference:

import Debug "mo:base/Debug";
import { setTimer; recurringTimer } = "mo:base/Timer";
import Time "mo:time/time";
import DateTime "mo:datetime/DateTime";
import Int "mo:base/Int";

actor Alarm {

  let N1 = 10;
  let N2 = 13;

  var now1 = Time.now();
  var now2 = Time.now();

  private func time1() : async () {
    var now1 = Time.now();
    Debug.print(debug_show(now1));
  };

  private func time2() : async () {
    var now2 = Time.now();
    Debug.print(debug_show(now2));
  };

  ignore setTimer<system>(#seconds N1,
    func () : async () {
      ignore recurringTimer<system>(#seconds N1, time1);
      var now1 = Time.now();
  });

  ignore setTimer<system>(#seconds N1,
    func () : async () {
      ignore recurringTimer<system>(#seconds N2, time2);
      var now2 = Time.now();
  });

  public query func calculate(now1 : Int, now2 : Int) : async Int {
    return (now2 - now1);
  };
}

This canister deploys two reoccurring timers: one every 10 seconds and one every 13 seconds. Alter these values to fit your application's requirements.

Once deployed, the timestamps for each timer will be printed to the terminal:

2024-07-19 20:55:43.012377 UTC: [Canister bd3sg-teaaa-aaaaa-qaaba-cai] +1_721_422_543_012_377_000
2024-07-19 20:55:45.633980 UTC: [Canister bd3sg-teaaa-aaaaa-qaaba-cai] +1_721_422_545_633_980_000

Then, call the canister's calculate method and pass these two timestamps:

dfx canister call test23_backend calculate

Pass in the two timestamps in nanoseconds:

1_721_422_543_012_377_000
1_721_422_545_633_980_000

The difference between these two, in nanoseconds, will be returned:

(2_621_603_000 : int)

References

• [Motoko Time documentation]

• time Mops package

• dateTime Mops package

• Rust time documentation

• Rust datetimeutils documentation

• [Azle Time documentation]

• [Kybra Time documentation]

• time