Skedgy - Asynchronous Task Scheduler

Skedgy is a lightweight, asynchronous task scheduler written in Rust. It allows you to schedule tasks to run at specific times, after certain delays, or based on cron expressions. Built on top of tokio, Skedgy is designed for efficient, non-blocking execution, making it an excellent choice for Rust applications that require scheduled task management.

Features

• Run Tasks at a Specific Time: Schedule tasks to execute at any DateTime<Utc>.
• Run Tasks After a Delay: Schedule tasks to run after a specified Duration.
• Cron Scheduling: Use cron expressions for recurring tasks.
• Asynchronous Execution: Built with tokio for seamless async integration.
• Dynamic Task Management: Add, remove, and manage tasks at runtime.
• Dependency Injection: Inject dependencies into tasks for easy access to shared resources.

Installation

Add Skedgy to your Cargo.toml:

[dependencies]
skedgy = "0.0.3"

Or use Cargo to add it directly:

cargo add skedgy

Usage

Basic Example

use skedgy::{task, Skedgy};
use std::error::Error;
use std::time::Duration;

#[task]
async fn delayed_hello() {
    println!("Hello!");
}

#[tokio::main]
async fn main() -> Result<(), Box<dyn Error>> {
    let skedgy = Skedgy::builder().build();

    skedgy
        .duration(Duration::from_secs(5))
        .task(delayed_hello::new())
        .await?;

    // Keep the main task alive to allow the scheduled task to execute
    tokio::time::sleep(Duration::from_secs(6)).await;
    Ok(())
}

Scheduling in a duration

skedgy
    .duration(Duration::from_secs(5))
    .task(delayed_hello::new())
    .await
    .expect("Failed to schedule task");

Scheduling at a specific time

use chrono::{DateTime, Utc};

skedgy
    .datetime(chrono::Utc::now() + chrono::Duration::seconds(5))
    .task(delayed_hello::new())
    .await
    .expect("Failed to schedule task");

Scheduling with Cron Expressions

// Schedule a recurring task using a cron expression
skedgy
    .named("cron_task")
    .cron("0/5 * * * * * *") // Every 5 seconds
    .task(delayed_hello::new())
    .await
    .expect("Failed to schedule cron task");

Removing a Scheduled Task

// Remove a scheduled task by name
skedgy
    .remove("my_task")
    .await
    .expect("Failed to remove task");

Adding dependencies to tasks

This can be useful if you want tasks to be able to acces some 'global' state, such as a database connection or a channel to send messages to. You can only provide one dependency per type, so if you need multiple instances of the same type, I suggest wrapping them in a struct.

use async_channel::Sender;
use skedgy::{task, Dep, Skedgy};
use std::error::Error;
use std::time::Duration;

#[task]
async fn send_delayed_message(message: String, sender: Dep<Sender<String>>) {
    let _ = sender.inner().send(message.clone()).await;
}

#[tokio::main]
async fn main() -> Result<(), Box<dyn Error>> {
    let (sender, receiver) = async_channel::unbounded::<String>();
    let skedgy = Skedgy::builder()
        .manage(sender) // Add the sender to the dependency manager
        .build();

    skedgy
        .duration(Duration::from_secs(5))
        .task(send_delayed_message::new("Hello!".to_string()))
        .await?;

    let message = receiver.recv().await.unwrap();
    println!("Received message: {}", message);

    Ok(())
}

In this example the send_delayed_message task has a dependency on a Sender<String>. The sender is added to the dependency manager when the Skedgy instance is created. The procedural macro expands send_delayed_message out to the following code:

pub(crate) mod send_delayed_message {
    use super::*;
    use skedgy::BoxFuture;
    use skedgy::DependencyStore;
    use skedgy::Task;
    pub fn new(message: String) -> SendDelayedMessage {
        SendDelayedMessage { message: message }
    }
    pub struct SendDelayedMessage {
        message: String,
    }
    impl SendDelayedMessage {
        pub fn new(message: String) -> Self {
            Self { message: message }
        }
        pub async fn execute(&self, sender: impl Into<Dep<Sender<String>>>) -> () {
            let message = &self.message;
            let sender = sender.into();
            {
                let _ = sender.inner().send(message.clone()).await;
            }
        }
    }
    impl Task for SendDelayedMessage {
        fn run(&self, dep_store: &DependencyStore) -> BoxFuture<'_, ()> {
            let sender = dep_store.get::<Sender<String>>().unwrap();
            Box::pin(async move {
                self.execute(sender).await;
            })
        }
    }
}

Contributing

Contributions are welcome! Please follow these steps:

1. Fork the repository.
2. Create a new branch for your feature or bug fix.
3. Write your code and include tests.
4. Submit a pull request.

Please ensure your code adheres to the existing style and includes appropriate documentation.

License

This project is licensed under the MIT License. See the LICENSE file for details.