update rusqlite and r2d2_sqlite in async_db and r2d2 (#148)

* upgrade rusqlite to 0.18

* add note about async_db blocking and running in thread pool

* idiomatic async_db

- DRY
- Iterator::collect + return type
- note about why we are sleeping

* remove r2d2/test.db

async_db/Cargo.toml

@@ -14,7 +14,7 @@ failure = "0.1.1"
 futures = "0.3.1"
 num_cpus = "1.10.0"
 r2d2 = "0.8.2"
-r2d2_sqlite = "0.8.0"
-rusqlite = "0.16"
+r2d2_sqlite = "0.10"
+rusqlite = "0.18"
 serde = { version = "1.0", features = ["derive"] }
 serde_json = "1.0"

async_db/src/db.rs

@@ -3,12 +3,13 @@ use failure::Error;
 use futures::{Future, TryFutureExt};
 use r2d2;
 use r2d2_sqlite;
-use rusqlite::NO_PARAMS;
+use rusqlite::{Statement, NO_PARAMS};
 use serde::{Deserialize, Serialize};
 use std::{thread::sleep, time::Duration};
 
 pub type Pool = r2d2::Pool<r2d2_sqlite::SqliteConnectionManager>;
 pub type Connection = r2d2::PooledConnection<r2d2_sqlite::SqliteConnectionManager>;
+type WeatherAggResult = Result<Vec<WeatherAgg>, rusqlite::Error>;
 
 #[derive(Debug, Serialize, Deserialize)]
 pub enum WeatherAgg {
@@ -28,115 +29,96 @@ pub fn execute(
     query: Queries,
 ) -> impl Future<Output = Result<Vec<WeatherAgg>, AWError>> {
     let pool = pool.clone();
-    web::block(move || 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()?),
+    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)
     })
     .map_err(AWError::from)
 }
 
-fn get_hottest_years(conn: Connection) -> Result<Vec<WeatherAgg>, Error> {
-    let stmt = "
+fn get_hottest_years(conn: Connection) -> WeatherAggResult {
+    let stmt = conn.prepare(
+        "
     SELECT cast(strftime('%Y', date) as int) as theyear,
             sum(tmax) as total
         FROM nyc_weather
         WHERE tmax <> 'TMAX'
         GROUP BY theyear
-        ORDER BY total DESC LIMIT 10;";
+        ORDER BY total DESC LIMIT 10",
+    )?;
 
-    let mut prep_stmt = conn.prepare(stmt)?;
-    let annuals = prep_stmt
-        .query_map(NO_PARAMS, |row| WeatherAgg::AnnualAgg {
-            year: row.get(0),
-            total: row.get(1),
-        })
-        .and_then(|mapped_rows| {
-            Ok(mapped_rows
-                .map(|row| row.unwrap())
-                .collect::<Vec<WeatherAgg>>())
-        })?;
-
-    sleep(Duration::from_secs(2)); //see comments at top of main.rs
-
-    Ok(annuals)
+    get_rows_as_annual_agg(stmt)
 }
 
-fn get_coldest_years(conn: Connection) -> Result<Vec<WeatherAgg>, Error> {
-    let stmt = "
+fn get_coldest_years(conn: Connection) -> WeatherAggResult {
+    let stmt = conn.prepare(
+        "
         SELECT cast(strftime('%Y', date) as int) as theyear,
                 sum(tmax) as total
         FROM nyc_weather
         WHERE tmax <> 'TMAX'
         GROUP BY theyear
-        ORDER BY total ASC LIMIT 10;";
+        ORDER BY total ASC LIMIT 10",
+    )?;
 
-    let mut prep_stmt = conn.prepare(stmt)?;
-    let annuals = prep_stmt
-        .query_map(NO_PARAMS, |row| WeatherAgg::AnnualAgg {
-            year: row.get(0),
-            total: row.get(1),
-        })
-        .and_then(|mapped_rows| {
-            Ok(mapped_rows
-                .map(|row| row.unwrap())
-                .collect::<Vec<WeatherAgg>>())
-        })?;
-
-    sleep(Duration::from_secs(2)); //see comments at top of main.rs
-
-    Ok(annuals)
+    get_rows_as_annual_agg(stmt)
 }
 
-fn get_hottest_months(conn: Connection) -> Result<Vec<WeatherAgg>, Error> {
-    let stmt = "SELECT cast(strftime('%Y', date) as int) as theyear,
+fn get_rows_as_annual_agg(mut statement: Statement) -> WeatherAggResult {
+    statement
+        .query_map(NO_PARAMS, |row| {
+            Ok(WeatherAgg::AnnualAgg {
+                year: row.get(0)?,
+                total: row.get(1)?,
+            })
+        })
+        .and_then(Iterator::collect)
+}
+
+fn get_hottest_months(conn: Connection) -> WeatherAggResult {
+    let stmt = conn.prepare(
+        "SELECT cast(strftime('%Y', date) as int) as theyear,
                 cast(strftime('%m', date) as int) as themonth,
                 sum(tmax) as total
         FROM nyc_weather
         WHERE tmax <> 'TMAX'
         GROUP BY theyear, themonth
-        ORDER BY total DESC LIMIT 10;";
+        ORDER BY total DESC LIMIT 10",
+    )?;
 
-    let mut prep_stmt = conn.prepare(stmt)?;
-    let annuals = prep_stmt
-        .query_map(NO_PARAMS, |row| WeatherAgg::MonthAgg {
-            year: row.get(0),
-            month: row.get(1),
-            total: row.get(2),
-        })
-        .and_then(|mapped_rows| {
-            Ok(mapped_rows
-                .map(|row| row.unwrap())
-                .collect::<Vec<WeatherAgg>>())
-        })?;
-
-    sleep(Duration::from_secs(2)); //see comments at top of main.rs
-    Ok(annuals)
+    get_rows_as_month_agg(stmt)
 }
 
-fn get_coldest_months(conn: Connection) -> Result<Vec<WeatherAgg>, Error> {
-    let stmt = "SELECT cast(strftime('%Y', date) as int) as theyear,
+fn get_coldest_months(conn: Connection) -> WeatherAggResult {
+    let stmt = conn.prepare(
+        "SELECT cast(strftime('%Y', date) as int) as theyear,
                 cast(strftime('%m', date) as int) as themonth,
                 sum(tmax) as total
         FROM nyc_weather
         WHERE tmax <> 'TMAX'
         GROUP BY theyear, themonth
-        ORDER BY total ASC LIMIT 10;";
+        ORDER BY total ASC LIMIT 10",
+    )?;
 
-    let mut prep_stmt = conn.prepare(stmt)?;
-    let annuals = prep_stmt
-        .query_map(NO_PARAMS, |row| WeatherAgg::MonthAgg {
-            year: row.get(0),
-            month: row.get(1),
-            total: row.get(2),
-        })
-        .and_then(|mapped_rows| {
-            Ok(mapped_rows
-                .map(|row| row.unwrap())
-                .collect::<Vec<WeatherAgg>>())
-        })?;
-
-    sleep(Duration::from_secs(2)); //see comments at top of main.rs
-    Ok(annuals)
+    get_rows_as_month_agg(stmt)
+}
+
+fn get_rows_as_month_agg(mut statement: Statement) -> WeatherAggResult {
+    statement
+        .query_map(NO_PARAMS, |row| {
+            Ok(WeatherAgg::MonthAgg {
+                year: row.get(0)?,
+                month: row.get(1)?,
+                total: row.get(2)?,
+            })
+        })
+        .and_then(Iterator::collect)
 }

async_db/src/main.rs

@@ -1,6 +1,7 @@
 /* Actix-Web Asynchronous Database Example
 
-This project illustrates two examples:
+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

r2d2/Cargo.toml

@@ -13,5 +13,5 @@ env_logger = "0.6"
 uuid = { version = "0.8", features = ["v4"] }
 
 r2d2 = "0.8"
-r2d2_sqlite = "0.8"
-rusqlite = "0.16"
+r2d2_sqlite = "0.10"
+rusqlite = "0.18"