Crate taskwait 

This library provides facility to wait on multiple spawned async tasks. It is runtime agnostic.

Adding and waiting on tasks

use taskwait::TaskGroup;
 
#[tokio::main]
async fn main() {
    let tg = TaskGroup::new();
    for _ in 0..10 {
        tg.add();
        let tg_c = tg.clone();
        tokio::spawn(async move{
            //...
            tg_c.done();
        });
    }
    tg.wait().await;
}

Note: User must ensure that call to done() made above is made in both success & error code path.

Using add_work

This example uses add_work() which creates a Work object. When it goes out of scope done() is is automatically called.

use taskwait::TaskGroup;
 
#[tokio::main]
async fn main() {
    let tg = TaskGroup::new();
    for _ in 0..10 {
        let work = tg.add_work(1);
        tokio::spawn(async move{
            let _work = work; // done() will be called when this is dropped
            //...
        });
    }
 
    tg.wait().await;
}

Reusing the taskgroup

The following shows how the same task group can be reused to achieve checkpointing

use taskwait::{TaskGroup, Work};

async fn multiple_tasks(tg: TaskGroup, count: usize) {
    for _ in 0..count {
        let work = tg.add_work(1);
        tokio::spawn(async move {
            let _work = work;
            // .. do something
        });
    }
}
 
#[tokio::main]
async fn main() {
    let tg = TaskGroup::new();
    // Spawn 100 tasks 
    tokio::spawn(multiple_tasks(tg.clone(), 100));
    // Let the first 100 complete first.
    tg.wait().await;
     
    // Spawn 2nd batch
    tokio::spawn(multiple_tasks(tg.clone(), 100));
    // Now wait for 2nd batch
    tg.wait().await; // Wait for the next 100
}

Structs

TaskGroup

Group of tasks to be waited on.

WaitFuture

Future to wait for the counter to become 0 or -ve.

Work

Represents a work or task.