Add bb8 + postgresql example

Cargo.toml

@@ -49,7 +49,10 @@ serde_derive = "1.0"
 handlebars = "4.0"
 tokio = { version = "1.0", features = ["macros", "rt-multi-thread", "io-util"] }
 tokio-stream = { version = "0.1.1", features = ["net"] }
+tokio-postgres = "0.7"
 listenfd = "0.3"
+bb8 = "0.7"
+bb8-postgres = "0.7"
 
 [features]
 default = ["multipart", "websocket", "trace-log", "http2"]

examples/postgres.rs

@@ -0,0 +1,49 @@
+#![deny(warnings)]
+
+use bb8::{Pool, RunError};
+use bb8_postgres::PostgresConnectionManager;
+use std::{convert::Infallible, str::FromStr};
+use tokio_postgres::{config::Config, NoTls};
+use warp::{reject::Reject, Filter, Rejection};
+
+type ConnectionPool = Pool<PostgresConnectionManager<NoTls>>;
+
+#[derive(Debug)]
+struct ConnectionError(RunError<tokio_postgres::Error>);
+
+impl Reject for ConnectionError {}
+
+fn with_pool(
+    pool: ConnectionPool,
+) -> impl Filter<Extract = (ConnectionPool,), Error = Infallible> + Clone {
+    warp::any().map(move || pool.clone())
+}
+
+async fn index_handler(pool: ConnectionPool) -> Result<String, Rejection> {
+    let connection = pool.get().await.map_err(|e| ConnectionError(e.into()))?;
+    let stmt = connection
+        .prepare("SELECT 1")
+        .await
+        .map_err(|e| ConnectionError(e.into()))?;
+    let row = connection
+        .query_one(&stmt, &[])
+        .await
+        .map_err(|e| ConnectionError(e.into()))?;
+    Ok(row.get::<usize, i32>(0).to_string())
+}
+
+#[tokio::main]
+async fn main() {
+    // The simplest way to start the DB is using Docker:
+    // docker run --name postgres -e POSTGRES_PASSWORD=postgres -p 5432:5432 -d postgres
+    let config = Config::from_str("postgresql://postgres:postgres@localhost:5432").unwrap();
+    let manager = PostgresConnectionManager::new(config, NoTls);
+    let pool = match Pool::builder().build(manager).await {
+        Ok(pool) => pool,
+        Err(e) => panic!("Pool builder error: {:?}", e),
+    };
+    let routes = warp::any()
+        .and(with_pool(pool.clone()))
+        .and_then(index_handler);
+    warp::serve(routes).run(([127, 0, 0, 1], 3030)).await;
+}