database.rs

use std::env;
use std::time::Duration;
use postgres::tls::openssl::OpenSsl;
use r2d2::{self, PooledConnection};
use r2d2_postgres::{TlsMode, PostgresConnectionManager};
use rocket::Request;
use rocket::request::{Outcome, FromRequest};
use rocket::Outcome::{Success, Failure};
use rocket::http::Status;

use error::Error;

lazy_static! {
  static ref DB_POOL: r2d2::Pool<PostgresConnectionManager> = {
    let database_url = env::var("DATABASE_URL").expect("Find DATABASE_URL environment variable");

    let config = r2d2::Config::builder()
      .pool_size(10)
      .connection_timeout(Duration::from_secs(5))
      .build();

    let manager = PostgresConnectionManager::new(
      database_url,
      TlsMode::Prefer(Box::new(OpenSsl::new().unwrap()))
    ).unwrap();

    r2d2::Pool::new(config, manager).expect("Create database pool")
  };
}

pub struct DBConnection(PooledConnection<PostgresConnectionManager>);

impl DBConnection {
  pub fn get(&self) -> &PooledConnection<PostgresConnectionManager> {
    &self.0
  }
}

impl<'a, 'r> FromRequest<'a, 'r> for DBConnection {
  type Error = Error;

  fn from_request(_: &'a Request<'r>) -> Outcome<Self, Self::Error> {
    match DB_POOL.get() {
      Ok(conn) => Success(DBConnection(conn)),
      Err(e) => Failure((Status::InternalServerError, Error::from(e))),
    }
  }
}

/*
And then from a controller:
#[get("/")]
fn bla(conn: DBConnection) -> &'static str {
  // conn.get().execute(blablabla)
  ...
}
*/