After connection is drop()ed, it becomes parmanently unable to use

[jjangga0214]

I am using diesel_async.

Let's say I have connections in deadpool.
I want 2 connections in total.

let pool: Pool<AsyncPgConnection> = Pool::builder(deadpool_config)
    .max_size(2) // <== max size is 2
    .build()
    .unwrap();

// share the pool with async thread
let _pool = pool.clone();
tokio::spawn(async move { 
    for i in 0..3 {
        let mut conn = _pool.get().await.unwrap();
        // This works when i == 0 or i == 1, but not when i == 2 
        do_something(&mut conn); 
    }
});

So it seems like drop(conn) is automatically called at the end of each iteration(which is by Rust Compiler), and the Pool becomes out of connections.

I just want the connection when I need, and then return it back to the pool after use.
So I want to get it back to the pool for each iteration.

I hoped drop(conn) make this happen, as like Rc and Arc, but apparently it doesn't.
How can I get it to work?

Thanks!

[bikeshedder]

I'm wondering about that comment:

// This works when i == 0 or i == 1, but not when i == 2 

The for loop for i in 0..2 { ... } will only iterate over 0 and 1. If you meant to write a loop that goes from 0 to 2 (inclusive) you can use for i in 0..=2 {...} instead.

[jjangga0214]

Thanks for the reply. It should have been 0..3 or 0..=2. Just a simple mistake :)

[bikeshedder]

So does this fix your problem or is there some issue within deadpool_diesel?

[jjangga0214]

Actually, the cause was differentl, but it was totally by my subtle mistake. Thank you for the reply anyway!