Time

System time utilities and timers.

The following example illustrates using the system time:

import Int = "mo:core/Int";
import Time = "mo:core/Time";

persistent actor {
  var lastTime = Time.now();

  public func greet(name : Text) : async Text {
    let now = Time.now();
    let elapsedSeconds = (now - lastTime) / 1000_000_000;
    lastTime := now;
    return "Hello, " # name # "!" #
      " I was last called " # Int.toText(elapsedSeconds) # " seconds ago";
   };
};

Note: If moc is invoked with -no-timer, the importing will fail. Note: The resolution of the timers is in the order of the block rate,

  so durations should be chosen well above that. For frequent
  canister wake-ups the heartbeat mechanism should be considered.

type Time = Types.Time

System time is represent as nanoseconds since 1970-01-01.

type Duration = Types.Duration

Quantity of time expressed in #days, #hours, #minutes, #seconds, #milliseconds, or #nanoseconds.

public func now() : Time

Current system time given as nanoseconds since 1970-01-01. The system guarantees that:

The system times of different canisters are unrelated, and calls from one canister to another may appear to travel "backwards in time"

Note: While an implementation will likely try to keep the system time close to the real time, this is not formally guaranteed.

type TimerId = Nat

public func toNanoseconds(duration : Duration) : Nat