Question: Reproduce, Random and Time

[violin0622]

I read the examples and tests code in turmoil but still have some puzzle:

1. In the similar project MadSim , there is a "Test Seed" for every run to generate a deterministic time and random number, so users can use same seed to get exactly same result. Can turmoil do something like this? and how ?

BTW, I thought it was Sim::epoch() to do this, but I got different result by every run in code below:

use rand::SeedableRng;
use std::time::SystemTime;
use turmoil::{Builder, Result};

fn main() {
    println!("Hello, world!");
}

#[test]
fn test_main() -> Result {
    let mut sim = Builder::new()
        .epoch(SystemTime::UNIX_EPOCH)
        .rng(rand::rngs::StdRng::seed_from_u64(10))
        .build();

    sim.client("host", async {
        println!("Hello world!");

// now() is diffferent in every run . And there seems no API in turmoil to mock time.
        println!("now: {:?}", std::time::Instant::now());
        Ok(())
    });
    sim.run()
}

2. Can turmoil simulate IO other than network? (for example, Disk IO )

[mcches]

For 1. you've got the rng and epoch setup correctly, but unfortunately we aren't tied tightly into tokio yet for Instant to work, note you are using std::time not tokio::time as well. The tokio Instant's elapsed() will work correctly, and we also expose the total elapsed() time in each host for building more accurate simulated clocks across host restarts.

For 2. we haven't built IO yet, but that is something we'd like to include: #15

[violin0622]

For 1. you've got the rng and epoch setup correctly, but unfortunately we aren't tied tightly into tokio yet for Instant to work, note you are using std::time not tokio::time as well. The tokio Instant's elapsed() will work correctly, and we also expose the total elapsed() time in each host for building more accurate simulated clocks across host restarts.

Thx, I found turmoil::elapsed(), it works as alternatives of now() . But when I want to sleep(duration), without an mock API like turmoil:sleep() , how do I sleep a logical duration rather than realistic duration ?

[mcches]

Thx, I found turmoil::elapsed(), it works as alternatives of now() . But when I want to sleep(duration), without an mock API like turmoil:sleep() , how do I sleep a logical duration rather than realistic duration ?

tokio::time::sleep works on logical time as each host's runtime is paused.

See: https://docs.rs/tokio/latest/tokio/runtime/struct.Builder.html#method.start_paused
See: https://github.com/tokio-rs/turmoil/blob/main/src/rt.rs#L112

[violin0622]

Good !