Provides r2d2 support to allow connection pooling with Diesel.
```rust extern crate r2d2; extern crate r2d2_diesel; extern crate diesel;
use std::thread; use diesel::*; use r2d2_diesel::ConnectionManager;
fn main() { let config = r2d2::Config::default(); let manager = ConnectionManager::new("postgres://localhost"); let pool = r2d2::Pool::new(config, manager).unwrap();
for i in 0..10i32 {
let pool = pool.clone();
thread::spawn(move || {
let conn = pool.get().unwrap();
// Do exciting stuff with the connection!
});
}
}