fix db/basic

database_interactions/basic/.gitignore

@@ -0,0 +1,2 @@
+weather.db
+weather.db-*

database_interactions/basic/Cargo.toml

@@ -4,13 +4,13 @@ version = "1.0.0"
 edition = "2021"
 
 [dependencies]
-actix-web = "4.0.0-rc.1"
-env_logger = "0.9.0"
-failure = "0.1.7"
-futures = "0.3.1"
-num_cpus = "1.13"
-r2d2 = "0.8.2"
-r2d2_sqlite = "0.18.0"
-rusqlite = "0.25.4"
-serde = { version = "1.0", features = ["derive"] }
-serde_json = "1.0"
+actix-web = "4.0.0-rc.2"
+
+env_logger = "0.9"
+futures-util = { version = "0.3", default-features = false, features = ["std"] }
+log = "0.4"
+r2d2 = "0.8"
+r2d2_sqlite = "0.19"
+rusqlite = "0.26"
+serde = { version = "1", features = ["derive"] }
+serde_json = "1"

database_interactions/basic/src/db.rs

@@ -1,5 +1,4 @@
-use actix_web::{error::InternalError, http::StatusCode, web};
-use failure::Error;
+use actix_web::{error, web, Error};
 use rusqlite::Statement;
 use serde::{Deserialize, Serialize};
 use std::{thread::sleep, time::Duration};
@@ -22,26 +21,26 @@ pub enum Queries {
     GetTopTenColdestMonths,
 }
 
-pub async fn execute(
-    pool: &Pool,
-    query: Queries,
-) -> Result<Vec<WeatherAgg>, InternalError<Error>> {
+pub async fn execute(pool: &Pool, query: Queries) -> Result<Vec<WeatherAgg>, Error> {
     let pool = pool.clone();
+
+    let conn = web::block(move || pool.get())
+        .await?
+        .map_err(error::ErrorInternalServerError)?;
+
     web::block(move || {
         // simulate an expensive query, see comments at top of main.rs
         sleep(Duration::from_secs(2));
 
-        let result = match query {
-            Queries::GetTopTenHottestYears => get_hottest_years(pool.get()?),
-            Queries::GetTopTenColdestYears => get_coldest_years(pool.get()?),
-            Queries::GetTopTenHottestMonths => get_hottest_months(pool.get()?),
-            Queries::GetTopTenColdestMonths => get_coldest_months(pool.get()?),
-        };
-        result.map_err(Error::from)
+        match query {
+            Queries::GetTopTenHottestYears => get_hottest_years(conn),
+            Queries::GetTopTenColdestYears => get_coldest_years(conn),
+            Queries::GetTopTenHottestMonths => get_hottest_months(conn),
+            Queries::GetTopTenColdestMonths => get_coldest_months(conn),
+        }
     })
-    .await
-    .unwrap()
-    .map_err(|e| InternalError::new(e, StatusCode::INTERNAL_SERVER_ERROR))
+    .await?
+    .map_err(error::ErrorInternalServerError)
 }
 
 fn get_hottest_years(conn: Connection) -> WeatherAggResult {

database_interactions/basic/src/main.rs

@@ -1,28 +1,27 @@
-/* Actix-Web Asynchronous Database Example
+//! Actix Web Asynchronous Database Example
+//!
+//! This project illustrates expensive and blocking database requests that runs
+//! in a thread-pool using `web::block` with two examples:
+//!
+//!     1. An asynchronous handler that executes 4 queries in *sequential order*,
+//!        collecting the results and returning them as a single serialized json object
+//!
+//!     2. An asynchronous handler that executes 4 queries in *parallel*,
+//!        collecting the results and returning them as a single serialized json object
+//!
+//!     Note: The use of sleep(Duration::from_secs(2)); in db.rs is to make performance
+//!           improvement with parallelism more obvious.
 
-This project illustrates expensive and blocking database requests that runs
-in a thread-pool using `web::block` with two examples:
-
-    1. An asynchronous handler that executes 4 queries in *sequential order*,
-       collecting the results and returning them as a single serialized json object
-
-    2. An asynchronous handler that executes 4 queries in *parallel*,
-       collecting the results and returning them as a single serialized json object
-
-    Note: The use of sleep(Duration::from_secs(2)); in db.rs is to make performance
-          improvement with parallelism more obvious.
- */
 use std::io;
 
 use actix_web::{middleware, web, App, Error as AWError, HttpResponse, HttpServer};
-use futures::future::join_all;
+use futures_util::future::join_all;
 use r2d2_sqlite::{self, SqliteConnectionManager};
 
 mod db;
 use db::{Pool, Queries};
 
 /// Version 1: Calls 4 queries in sequential order, as an asynchronous handler
-#[allow(clippy::eval_order_dependence)] // it's FP?
 async fn asyncio_weather(db: web::Data<Pool>) -> Result<HttpResponse, AWError> {
     let result = vec![
         db::execute(&db, Queries::GetTopTenHottestYears).await?,
@@ -50,14 +49,15 @@ async fn parallel_weather(db: web::Data<Pool>) -> Result<HttpResponse, AWError>
 
 #[actix_web::main]
 async fn main() -> io::Result<()> {
-    std::env::set_var("RUST_LOG", "actix_web=info");
-    env_logger::init();
+    env_logger::init_from_env(env_logger::Env::new().default_filter_or("info"));
 
-    // Start N db executor actors (N = number of cores avail)
+    // connect to SQLite DB
     let manager = SqliteConnectionManager::file("weather.db");
     let pool = Pool::new(manager).unwrap();
 
-    // Start http server
+    log::info!("starting HTTP server at http://localhost:8080");
+
+    // start HTTP server
     HttpServer::new(move || {
         App::new()
             // store db pool as Data object
@@ -71,7 +71,8 @@ async fn main() -> io::Result<()> {
                     .route(web::get().to(parallel_weather)),
             )
     })
-    .bind("127.0.0.1:8080")?
+    .bind(("127.0.0.1", 8080))?
+    .workers(2)
     .run()
     .await
 }