# sched-callback
A scheduler that executes async callback at certain point.

## Overview
- Works on tokio runtime.
- Lightweight scheduler that only one task is executed in one task queue.

## Usage
Create scheduler using `queue::SchedQueue`
```rust,no_run
let sq = SchedQueue::new();
```

Callback type:
```rust,no_run
type Callback = Box<dyn Fn() -> Pin<Box<dyn Future<Output = ()> + Send + 'static>> + Send + 'static>;
````

Add task with callback.
Callback will be triggered 1 second after the task is added, and will be rescheduled for 10 times after the callback has been triggered.
```rust,no_run
sq.add(Task::new(SchedType::Delay(Duration::from_secs(1), 10), Box::new(move || {
    Box::pin(async move {
        println!("hello world");
    })
}))).await;
````

Two types of task can be added to queue. `SchedType::Timestamp(SystemTime)` specifies the exact
timestamp that the callback will be triggered at. `SchedType::Delay(Duration, usize)` specifies
when the callback will be triggered after the task is added and how many times will it be
rescheduled.