feat: add database connection pooling

src/commands/users.rs

@@ -16,7 +16,7 @@ pub async fn register(
     };
 
     {
-        let mut conn = ctx.data().conn.lock().unwrap();
+        let mut conn = ctx.data().pool.get()?;
         user_insert(&mut conn, &user);
     }
 
@@ -26,7 +26,7 @@ pub async fn register(
 #[poise::command(prefix_command, slash_command)]
 pub async fn registered(ctx: Context<'_>) -> Result<(), Error> {
     let users = {
-        let mut conn = ctx.data().conn.lock().unwrap();
+        let mut conn = ctx.data().pool.get()?;
         user_all(&mut conn)
     };
 

src/main.rs

@@ -6,6 +6,8 @@ use diesel::Connection;
 use poise::serenity_prelude as serenity;
 use std::sync::Mutex;
 use std::{env::var, time::Duration};
+use diesel::r2d2::{ConnectionManager, Pool};
+use diesel::sqlite::SqliteConnection;
 
 // Types used by all command functions
 type Error = Box<dyn std::error::Error + Send + Sync>;
@@ -14,7 +16,7 @@ type Context<'a> = poise::Context<'a, Data, Error>;
 // Custom user data passed to all command functions
 pub struct Data {
     client: AffluencesClient,
-    conn: Mutex<diesel::sqlite::SqliteConnection>,
+    pool: Pool<ConnectionManager<SqliteConnection>>
 }
 
 async fn on_error(error: poise::FrameworkError<'_, Data, Error>) {
@@ -34,6 +36,12 @@ async fn on_error(error: poise::FrameworkError<'_, Data, Error>) {
     }
 }
 
+fn db_connection_pool(url: &str) -> Pool<ConnectionManager<SqliteConnection>> {
+    let manager = ConnectionManager::new(url);
+
+    Pool::builder().test_on_check_out(true).build(manager).expect("oops")
+}
+
 #[tokio::main]
 async fn main() {
     // FrameworkOptions contains all of poise's configuration option in one struct
@@ -95,9 +103,7 @@ async fn main() {
                 poise::builtins::register_globally(ctx, &framework.options().commands).await?;
                 Ok(Data {
                     client: AffluencesClient::new(),
-                    conn: Mutex::new(
-                        diesel::sqlite::SqliteConnection::establish("affy.db").unwrap(),
-                    ),
+                    pool: db_connection_pool("affy.db")
                 })
             })
         })