Background task processing library for Rust. It uses Postgres DB as a task queue.
Here are some of the fang's key features:
- Async and threaded workers.
Workers can be started in threads (threaded workers) or
tokio
tasks (async workers) - Scheduled tasks. Tasks can be scheduled at any time in the future
- Periodic (CRON) tasks. Tasks can be scheduled using cron expressions
- Unique tasks. Tasks are not duplicated in the queue if they are unique
- Single-purpose workers. Tasks are stored in a single table but workers can execute only tasks of the specific type
- Retries. Tasks can be retried with a custom backoff mode
- Add this to your Cargo.toml
[dependencies]
fang = { version = "0.10.3" , features = ["blocking"], default-features = false }
[dependencies]
fang = { version = "0.10.3" , features = ["asynk"], default-features = false }
fang = { version = "0.10.3" }
Supports rustc 1.62+
- Create the
fang_tasks
table in the Postgres database. The migration can be found in the migrations directory.
Every task should implement the fang::Runnable
trait which is used by fang
to execute it.
use fang::Error;
use fang::Runnable;
use fang::typetag;
use fang::PgConnection;
use fang::serde::{Deserialize, Serialize};
#[derive(Serialize, Deserialize)]
#[serde(crate = "fang::serde")]
struct MyTask {
pub number: u16,
}
#[typetag::serde]
impl Runnable for MyTask {
fn run(&self, _queue: &dyn Queueable) -> Result<(), Error> {
println!("the number is {}", self.number);
Ok(())
}
// If `uniq` is set to true and the task is already in the storage, it won't be inserted again
// The existing record will be returned for for any insertions operaiton
fn uniq(&self) -> bool {
true
}
// This will be useful if you want to filter tasks.
// the default value is `common`
fn task_type(&self) -> String {
"my_task".to_string()
}
// This will be useful if you would like to schedule tasks.
// default value is None (the task is not scheduled, it's just executed as soon as it's inserted)
fn cron(&self) -> Option<Scheduled> {
let expression = "0/20 * * * Aug-Sep * 2022/1";
Some(Scheduled::CronPattern(expression.to_string()))
}
// the maximum number of retries. Set it to 0 to make it not retriable
// the default value is 20
fn max_retries(&self) -> i32 {
20
}
// backoff mode for retries
fn backoff(&self, attempt: u32) -> u32 {
u32::pow(2, attempt)
}
}
As you can see from the example above, the trait implementation has #[typetag::serde]
attribute which is used to deserialize the task.
The second parameter of the run
function is a struct that implements fang::Queueable
. You can re-use it to manipulate the task queue, for example, to add a new job during the current job's execution. If you don't need it, just ignore it.
Every task should implement fang::AsyncRunnable
trait which is used by fang
to execute it.
Be careful not to call two implementations of the AsyncRunnable trait with the same name, because it will cause a failure in the typetag
crate.
use fang::AsyncRunnable;
use fang::asynk::async_queue::AsyncQueueable;
use fang::serde::{Deserialize, Serialize};
use fang::async_trait;
#[derive(Serialize, Deserialize)]
#[serde(crate = "fang::serde")]
struct AsyncTask {
pub number: u16,
}
#[typetag::serde]
#[async_trait]
impl AsyncRunnable for AsyncTask {
async fn run(&self, _queueable: &mut dyn AsyncQueueable) -> Result<(), Error> {
Ok(())
}
// this func is optional
// Default task_type is common
fn task_type(&self) -> String {
"my-task-type".to_string()
}
// If `uniq` is set to true and the task is already in the storage, it won't be inserted again
// The existing record will be returned for for any insertions operaiton
fn uniq(&self) -> bool {
true
}
// This will be useful if you would like to schedule tasks.
// default value is None (the task is not scheduled, it's just executed as soon as it's inserted)
fn cron(&self) -> Option<Scheduled> {
let expression = "0/20 * * * Aug-Sep * 2022/1";
Some(Scheduled::CronPattern(expression.to_string()))
}
// the maximum number of retries. Set it to 0 to make it not retriable
// the default value is 20
fn max_retries(&self) -> i32 {
20
}
// backoff mode for retries
fn backoff(&self, attempt: u32) -> u32 {
u32::pow(2, attempt)
}
}
In both modules, tasks can be scheduled to be executed once. Use Scheduled::ScheduleOnce
enum variant.
Datetimes and cron patterns are interpreted in the UTC timezone. So you should introduce the offset to schedule in a different timezone.
Example:
If your timezone is UTC + 2 and you want to schedule at 11:00:
let expression = "0 0 9 * * * *";
To enqueue a task use Queue::enqueue_task
use fang::Queue;
// create a r2d2 pool
// create a fang queue
let queue = Queue::builder().connection_pool(pool).build();
let task_inserted = queue.insert_task(&MyTask::new(1)).unwrap();
To enqueue a task use AsyncQueueable::insert_task
.
For Postgres backend.
use fang::asynk::async_queue::AsyncQueue;
use fang::NoTls;
use fang::AsyncRunnable;
// Create an AsyncQueue
let max_pool_size: u32 = 2;
let mut queue = AsyncQueue::builder()
// Postgres database url
.uri("postgres://postgres:postgres@localhost/fang")
// Max number of connections that are allowed
.max_pool_size(max_pool_size)
.build();
// Always connect first in order to perform any operation
queue.connect(NoTls).await.unwrap();
As an easy example, we are using NoTls type. If for some reason you would like to encrypt Postgres requests, you can use openssl or native-tls.
// AsyncTask from the first example
let task = AsyncTask { 8 };
let task_returned = queue
.insert_task(&task as &dyn AsyncRunnable)
.await
.unwrap();
Every worker runs in a separate thread. In case of panic, they are always restarted.
Use WorkerPool
to start workers. Use WorkerPool::builder
to create your worker pool and run tasks.
use fang::WorkerPool;
use fang::Queue;
// create a Queue
let mut worker_pool = WorkerPool::<Queue>::builder()
.queue(queue)
.number_of_workers(3_u32)
// if you want to run tasks of the specific kind
.task_type("my_task_type")
.build();
worker_pool.start();
Every worker runs in a separate tokio
task. In case of panic, they are always restarted.
Use AsyncWorkerPool
to start workers.
use fang::asynk::async_worker_pool::AsyncWorkerPool;
// Need to create a queue
// Also insert some tasks
let mut pool: AsyncWorkerPool<AsyncQueue<NoTls>> = AsyncWorkerPool::builder()
.number_of_workers(max_pool_size)
.queue(queue.clone())
// if you want to run tasks of the specific kind
.task_type("my_task_type")
.build();
pool.start().await;
Check out:
- Simple Worker Example - simple worker example
- Simple Cron Worker Example - simple worker example
- Simple Async Worker Example - simple async worker example
- Simple Cron Async Worker Example - simple async worker example
- El Monitorro - telegram feed reader. It uses the Fang's blocking module to synchronize feeds and deliver updates to users.
- weather_bot_rust - A bot that provides weather info. It uses the Fang's asynk module to process updates from Telegram users and schedule weather info.
Just use TypeBuilder
for WorkerPool
.
Just use TypeBuilder
for AsyncWorkerPool
.
By default, all successfully finished tasks are removed from the DB, failed tasks aren't.
There are three retention modes you can use:
pub enum RetentionMode {
KeepAll, // doesn't remove tasks
RemoveAll, // removes all tasks
RemoveFinished, // default value
}
Set retention mode with worker pools TypeBuilder
in both modules.
You can use use SleepParams
to configure sleep values:
pub struct SleepParams {
pub sleep_period: Duration, // default value is 5 seconds
pub max_sleep_period: Duration, // default value is 15 seconds
pub min_sleep_period: Duration, // default value is 5 seconds
pub sleep_step: Duration, // default value is 5 seconds
}
If there are no tasks in the DB, a worker sleeps for sleep_period
and each time this value increases by sleep_step
until it reaches max_sleep_period
. min_sleep_period
is the initial value for sleep_period
. All values are in seconds.
Use set_sleep_params
to set it:
let sleep_params = SleepParams {
sleep_period: Duration::from_secs(2),
max_sleep_period: Duration::from_secs(6),
min_sleep_period: Duration::from_secs(2),
sleep_step: Duration::from_secs(1),
};
Set sleep params with worker pools TypeBuilder
in both modules.
- Fork it!
- Create your feature branch (
git checkout -b my-new-feature
) - Commit your changes (
git commit -am 'Add some feature'
) - Push to the branch (
git push origin my-new-feature
) - Create a new Pull Request
- Install diesel_cli.
cargo install diesel_cli
-
Install docker on your machine.
-
Run a Postgres docker container. (See in Makefile.)
make db
- Run the migrations
make diesel
- Run tests
make tests
- Run dirty//long tests, DB must be recreated afterwards.
make ignored
- Kill the docker container
make stop
-
Ayrat Badykov (@ayrat555)
-
Pepe Márquez (@pxp9)