Add support for Pool::get with timeout

[bikeshedder]

I currently wonder if it should be part of the core of deadpool:

Adding a timeout to the Pool::get function should be as simple as wrapping the call in one of the following two:

• https://docs.rs/tokio/0.2.2/tokio/time/fn.timeout.html
• https://docs.rs/async-std/1.2.0/async_std/future/fn.timeout.html

There is little to be gained when using Pool::get_timeout() over timeout(Pool::get()), is there?

[bikeshedder]

I currently wonder wether I should add a get_timeout function which allows specifying multiple timeouts:

async fn get_timeout(&self,
    create_timeout: Option(Duration),
    wait_timeout: Option(Duration),
    recycle_timeout: Option(Duration))

• create_timeout is the maximum time spent when creating a new connection
• wait_timeout is the maximum time spent when waiting for a connection to become available in the pool.
• recycle_timeout is the maximum time spent recycling an existing connection

For most applications I guess wait_timeout and an overall timeout would suffice so I wonder if create_timeout and recycle_timeout is even needed.

[nihiluis]

I think this feature was only added to managed pools?

I think this would be beneficial for unmanaged ones too. Or do you not think so? If so, why?

[bikeshedder]

Unmanaged pools don't recycle and create new objects. Thus only wait_timeout makes any sense. Right now this can already be achieved by calling tokio::time::timeout(std::time::Duration::from_secs(5), pool.get()). It might make sense to add this as a configuration option to the pool nonetheless. It will require the pool.get() method to return a Result<T, PoolError> instead of T.

Feel free to open a new issue so we can discuss this.

[ansjsun]

my lib not use tokio . use async-st, when add this config
it has err:

thread 'main' panicked at 'there is no timer running, must be called from the context of Tokio runtime', /Users/sunjian11/.cargo/registry/src/github.com-1ecc6299db9ec823/tokio-0.2.21/src/time/driver/handle.rs:24:9

@bikeshedder

[bikeshedder]

That's a bummer. I thought tokio::time::timeout was runtime agnostic. It seams that this is not the case.

Could you please open a new issue regarding this issue? I don't use async-std myself at the moment that's why I didn't notice that.