How can I get the current time in milliseconds?

Question

How can I get the current time in milliseconds like I can in Java?

System.currentTimeMillis()

Answer 1

Since Rust 1.8, you do not need to use a crate. Instead, you can use SystemTime and UNIX_EPOCH:

use std::time::{SystemTime, UNIX_EPOCH};

fn main() {
    let start = SystemTime::now();
    let since_the_epoch = start
        .duration_since(UNIX_EPOCH)
        .expect("Time went backwards");
    println!("{:?}", since_the_epoch);
}

If you need exactly milliseconds, you can convert the Duration.

Rust 1.33

let in_ms = since_the_epoch.as_millis();

Rust 1.27

let in_ms = since_the_epoch.as_secs() as u128 * 1000 + 
            since_the_epoch.subsec_millis() as u128;

Rust 1.8

let in_ms = since_the_epoch.as_secs() * 1000 +
            since_the_epoch.subsec_nanos() as u64 / 1_000_000;

Answer 2

If you just want to do simple timings with the milliseconds, you can use std::time::Instant like this:

use std::time::Instant;

fn main() {
    let start = Instant::now();

    // do stuff

    let elapsed = start.elapsed();

    // Debug format
    println!("Debug: {:?}", elapsed); 

    // Format as milliseconds rounded down
    // Since Rust 1.33:
    println!("Millis: {} ms", elapsed.as_millis());

    // Before Rust 1.33:
    println!("Millis: {} ms",
             (elapsed.as_secs() * 1_000) + (elapsed.subsec_nanos() / 1_000_000) as u64);
}

Output:

Debug: 10.93993ms
Millis: 10 ms
Millis: 10 ms

Answer 3

You can use the time crate:

extern crate time;

fn main() {
    println!("{}", time::now());
}

It returns a Tm which you can get whatever precision you want.

Answer 4

I've found a clear solution with chrono in coinnect:

use chrono::prelude::*;

pub fn get_unix_timestamp_ms() -> i64 {
    let now = Utc::now();
    now.timestamp_millis()
}

pub fn get_unix_timestamp_us() -> i64 {
    let now = Utc::now();
    now.timestamp_nanos()
}

Answer 5

As @Shepmaster mentioned, this is the equivalent of Java's System.currentTimeMillis() in Rust.

use std::time::{SystemTime, UNIX_EPOCH};

fn get_epoch_ms() -> u128 {
    SystemTime::now()
        .duration_since(UNIX_EPOCH)
        .unwrap()
        .as_millis()
}

Answer 6

extern crate time;

fn timestamp() -> f64 {
    let timespec = time::get_time();
    // 1459440009.113178
    let mills: f64 = timespec.sec as f64 + (timespec.nsec as f64 / 1000.0 / 1000.0 / 1000.0);
    mills
}

fn main() {
    let ts = timestamp();
    println!("Time Stamp: {:?}", ts);
}

Rust Playground

Answer 7

System.currentTimeMillis() in Java returns the difference in milliseconds between the current time and midnight, January 1, 1970.

In Rust we have time::get_time() which returns a Timespec with the current time as seconds and the offset in nanoseconds since midnight, January 1, 1970.

Example (using Rust 1.13):

extern crate time; //Time library

fn main() {
    //Get current time
    let current_time = time::get_time();

    //Print results
    println!("Time in seconds {}\nOffset in nanoseconds {}",
             current_time.sec, 
             current_time.nsec);

    //Calculate milliseconds
    let milliseconds = (current_time.sec as i64 * 1000) + 
                       (current_time.nsec as i64 / 1000 / 1000);

    println!("System.currentTimeMillis(): {}", milliseconds);
}

Reference: Time crate, System.currentTimeMillis()

Answer 8

There seems to be a simple one-liner that yields a u128, which is pretty close to what a java long is.

let timestamp = std::time::UNIX_EPOCH.elapsed().unwrap().as_millis()

The docs do warn about clock drifting related to SystemTime objects, but I think this does not apply here, given we're checking against a point in time way back.