3 unstable releases
0.2.1 | Jun 24, 2024 |
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0.2.0 | Jun 24, 2024 |
0.1.0 | Jun 18, 2024 |
#416 in Asynchronous
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20KB
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Asynchronous Deferred Calls
This crate implements the Active Object design pattern.
The entry point of this crate is Dispatcher
, which wraps an Arc<Lock<T>>
.
Note: Lock can be RwLock
or Mutex
from the async-lock
crate.
Dispatcher
The Dispatcher
allows you to create Caller
s for some methods on T
.
You can then schedule deferred calls to these methods via these Caller
s.
Dispatcher
implements Future
; You must await this future for calls to
actually be dispatched.
Caller
When you create a Caller
for a method of T
using Dispatcher
, a background
task is created, waiting for you to schedule deferred calls via the Caller
. When
a call is scheduled, the background task will lock the RwLock
or Mutex
and call
the method on the locked T
instance.
Compatible T
methods
The methods must:
- be asynchronous
- return an implementer of
ReturnType
They can take self
mutably or immutably.
Note: you can use a freestanding function instead of a method if the first parameter
of that function is &T
or &mut T
.
Summoner
if the method's last parameter is an async_channel::Sender
, you can turn your Caller
into
a Summoner
, which makes it easy to wait for a reply when you schedule a call.
Example
use async_defer::{*, async_channel::Sender, async_lock::RwLock};
use std::time::{Instant, Duration};
use std::sync::Arc;
// An example object which will be modified in deferred calls
struct Subject;
impl Subject {
async fn print(&mut self, msg: String) -> Result<(), String> {
println!("msg: {}", msg);
Ok(())
}
async fn ping_pong(&self, payload: u8, reply: Sender<u8>) -> Result<(), String> {
let _ = reply.send(payload).await;
Ok(())
}
}
let world = Arc::new(RwLock::new(Subject));
let mut dispatcher = Dispatcher::new(world);
let deferred_print = dispatcher.listen_mut_1(Subject::print);
let deferred_ping_pong = dispatcher.listen_ref_2(Subject::ping_pong);
async {
deferred_print.call("Hello World".to_string()).await;
let later = Instant::now() + Duration::from_secs(5);
deferred_print.call_later(later, "Hello World".to_string()).await;
// `ping_pong` has a reply parameter,
// allowing us to create a `Summoner`.
let summoner = deferred_ping_pong.summoner();
let rep = summoner.summon(5).await;
println!("reply: {}", rep);
};
In this example, two background tasks are created, one for each method of Subject
.
The ping_pong
method's last parameter is a Sender, allowing us to "summon" the method.
Dependencies
~3–12MB
~137K SLoC