nim-ffi/examples/timer/rust_client/src/main.rs

// Rust client for the my_timer shared library built with nim-ffi + chronos.
//
// This file uses the generated `my_timer` crate, which wraps all the raw FFI
// boilerplate (extern "C" declarations, callback machinery, CBOR encode/decode).
//
// To regenerate the `rust_bindings` crate:
//   nimble genbindings_rust
use std::time::Duration;
use my_timer::{
    EchoRequest, JobSpec, MyTimerCtx, RetryPolicy, ScheduleConfig, TimerConfig,
};

fn main() {
    let timeout = Duration::from_secs(5);

    // ── 1. Create the timer service ────────────────────────────────────────
    let ctx = MyTimerCtx::create(TimerConfig { name: "demo".into() }, timeout)
        .expect("my_timer_create failed");
    println!("[1] Context created");

    // ── 2. Sync call: version ──────────────────────────────────────────────
    let version = ctx.version().expect("my_timer_version failed");
    println!("[2] Version (sync call, callback fired inline): {version}");

    // ── 3. Async call: echo (200 ms delay) ────────────────────────────────
    let echo = ctx
        .echo(EchoRequest {
            message: "hello from Rust".into(),
            delay_ms: 200,
        })
        .expect("my_timer_echo failed");
    println!(
        "[3] Echo (async, 200 ms chronos delay): echoed={}, timerName={}",
        echo.echoed, echo.timer_name
    );

    // ── 4. A second echo ──────────────────────────────────────────────────
    let echo2 = ctx
        .echo(EchoRequest {
            message: "second request".into(),
            delay_ms: 50,
        })
        .expect("second my_timer_echo failed");
    println!("[4] Echo: echoed={}, timerName={}", echo2.echoed, echo2.timer_name);

    // ── 5. Call with three complex parameters ─────────────────────────────
    // Each param is its own first-class Rust struct generated by the
    // bindings. The nim-ffi macro packs all three into one CBOR envelope on
    // the wire — from the caller's perspective, this is just a typed call.
    let schedule = ctx
        .schedule(
            JobSpec {
                name: "nightly-rollup".into(),
                payload: vec!["rollup".into(), "v2".into()],
                priority: 10,
            },
            RetryPolicy {
                max_attempts: 3,
                backoff_ms: 500,
                retry_on: vec!["timeout".into(), "5xx".into()],
            },
            ScheduleConfig {
                start_at_ms: 1_000,
                interval_ms: 15_000,
                jitter: Some(250),
            },
        )
        .expect("my_timer_schedule failed");
    println!(
        "[5] Schedule (3 complex params): jobId={}, willRunCount={}, firstRunAtMs={}, effectiveBackoffMs={}",
        schedule.job_id,
        schedule.will_run_count,
        schedule.first_run_at_ms,
        schedule.effective_backoff_ms,
    );

    println!("\nDone. The Nim FFI thread and watchdog are still running.");
    println!("(In a real app, call my_timer_destroy to join them gracefully.)");
}