Simple, small, and flexible task scheduler for Deno, backed by MongoDB.

NOTICE: This library is not 100% ready so use it with caution. 🙏

You will also need a working Mongo database (v3) to point it to.

import { Tachyon } from "https://deno.land/x/[email protected]/mod.ts";

const tachyon = new Tachyon({
  maxConcurrency: 20,
  db: {
    uri: "mongodb://localhost:27017",
    name: "my-db",
    collection: "_tasks",
  }
});

tachyon.define("echo-date", () => {
  console.log(new Date());
});

await tachyon.start();
await tachyon.every(2000, "echo-date");

The available config options can be found here: https://github.com/alexalikiotis/tachyon/blob/master/lib/types.ts#L13

Methods starting with a $ are meant to be used internally by the runtime and not by the user !!!

The define method lets you define the task function that the runtime will execute when called.

tachyon.define("echo-date", () => {
  console.log(new Date());
});

By using the start method you essentially start the task processing by the runtime. (async)

await tachyon.start();

Top level await supported by Deno really gets handy here 🎉

The now method subscribes a task to runtime to run as soon as possible. (async)

tachion.define("print", ({ message }: any) => {
  console.log(message);
});

await achyon.now("print", { message: "Hello, Deno!" });

For available options check here: https://github.com/alexalikiotis/tachyon/blob/master/lib/types.ts#L18

The every method subscribes a recurring task to runtime's task queue. Keep in mind, interval supports only milliseconds for now. (async)

await tachyon.every(2000, "echo-date");

The schedule method allows you to create a task based on a cron syntax (repeated or not). (async)

await tachyon.schedule("* * * * *", "print", { message: "this is a cron based task!" });

Timezones are not supported yet, but there coming eventually!

Although the recommended way to register tasks is with the now, every and schedule methods, there is also the option to create tasks manually. (cool thing is you can chain task methods using this approach)

// create `raw` task
const task = create("send-email", "[email protected]")
  .interval("0 0 * * THU")
  .timeout(10000)
  .retries(2)
  .repeat(true);

await task.save(); // save task to queue

Use the stop method if you want to gracefully shutdown the runtime.

tachyon.stop() // graceful shutdown

makes process-interval undefined and clears the task queue

When the runtime will be ready for processing tasks will emit a ready event.

tachyon.on("ready", () => {
  console.log("tachyon runtime is ready now 🖖");
});

When a task is ready to be processed the runtime will emit the start event with the task instance as a parameter.

tachyon.on("start", (task: Task) => {
  console.log(`task ${task.name} is about to run...`);
});

With the generic start event emitted (for all tasks), the runtime will also emit a start event for the specific task.

tachyon.on("start:echo-date", (task: Task) => {
  console.log(`task ${task.name} is about to run...`);
});

When a task finishes successfully the runtime will emit a success event with the task instance and the task's result as parameters.

tachyon.on("success", (task: Task, result: any) => {
  console.log(`task ${task.name}'s result is ${result}`);
});

Following the pattern from the start event, the runtime will also emit a specific success event for task.

tachyon.on("success:fetch-api", (task: Task, result: any) => {
  console.log(`API response is ${JSON.parse(result)}`);
});

When a task fails the runtime will emit a fail event. (this is the recommended way to handle task errors)

tachyon.on("fail", (task: Task, err: any) => {
  console.log(`task ${task.name} failed with error: ${err}`);
});

Once again there is also a fail event for a specific task. (this is the recommended way to handle task errors)

tachyon.on("fail:fetch-api", (task: Task, result: any) => {
  console.log(`can't fetch API: ${result}`);
});

After a task is run and finishes (success / fail) the runtime will emit a complete event for clean up purposes.

tachyon.on("complete", (task: Task) => {
  console.log(`task ${task.name} completed 😎`);
});

It gets boring now but the runtime will also emit a complete event for targeted tasks.

tachyon.on("complete:fetch-api", (task: Task) => {
  console.log(`task ${task.name} completed 😎`);
});

Pull requests are welcome; My free time is limited but I'll try to review them as soon as possible... ❤️

The MIT License