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@sean3z
Created March 18, 2018 04:55
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Connection Pooling for Rust/Diesel
use std::ops::Deref;
use rocket::http::Status;
use rocket::request::{self, FromRequest};
use rocket::{Request, State, Outcome};
use r2d2;
use r2d2_diesel::ConnectionManager;
use diesel::mysql::MysqlConnection;
pub type Pool = r2d2::Pool<ConnectionManager<MysqlConnection>>;
static DATABASE_URL: &'static str = env!("DATABASE_URL");
pub fn connect() -> Pool {
let manager = ConnectionManager::<MysqlConnection>::new(DATABASE_URL);
r2d2::Pool::builder().build(manager).expect("Failed to create pool")
}
// Connection request guard type: a wrapper around an r2d2 pooled connection.
pub struct Connection(pub r2d2::PooledConnection<ConnectionManager<MysqlConnection>>);
/// Attempts to retrieve a single connection from the managed database pool. If
/// no pool is currently managed, fails with an `InternalServerError` status. If
/// no connections are available, fails with a `ServiceUnavailable` status.
impl<'a, 'r> FromRequest<'a, 'r> for Connection {
type Error = ();
fn from_request(request: &'a Request<'r>) -> request::Outcome<Connection, ()> {
let pool = request.guard::<State<Pool>>()?;
match pool.get() {
Ok(conn) => Outcome::Success(Connection(conn)),
Err(_) => Outcome::Failure((Status::ServiceUnavailable, ()))
}
}
}
// For the convenience of using an &Connection as an &SqliteConnection.
impl Deref for Connection {
type Target = MysqlConnection;
fn deref(&self) -> &Self::Target {
&self.0
}
}
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