wip

5 files changed, 124 insertions, 87 deletions

diff --git a/src/commands/meme/create.rs b/src/commands/meme/create.rs
index 2cd9465..160de7b 100644
--- a/src/commands/meme/create.rs
+++ b/src/commands/meme/create.rs
@@ -72,7 +72,7 @@ pub async fn addmeme(ctx: &Context, msg: &Message, args: Args) -> CommandResult
 
     if let Some(att) = image {
         let data = att.download().await?;
-        image_id = Some(Image::create(&mut conn, &att.filename, data, msg.author.id.get())?);
+        image_id = Some(Image::create(&mut conn, &att.filename, data, msg.author.id.get()).await?);
     };
 
     let save_result = NewMeme {
@@ -83,6 +83,7 @@ pub async fn addmeme(ctx: &Context, msg: &Message, args: Args) -> CommandResult
         metadata_id: 0,
     }
     .save(&mut conn, msg.author.id.get())
+    .await
     .map(|_| {});
 
     use diesel::result::DatabaseErrorKind;
@@ -182,7 +183,7 @@ pub async fn addaudiomeme(ctx: &Context, msg: &Message, args: Args) -> CommandRe
 
     if let Ok(att) = image_att {
         let data = att.download().await?;
-        image_id = Image::create(&mut conn, &att.filename, data, msg.author.id.get())?.pipe(Some);
+        image_id = Image::create(&mut conn, &att.filename, data, msg.author.id.get())?.await.pipe(Some);
     }
 
     let mut audio_data = Vec::new();
@@ -196,7 +197,7 @@ pub async fn addaudiomeme(ctx: &Context, msg: &Message, args: Args) -> CommandRe
             .await;
     }
 
-    let audio_id = Audio::create(&mut conn, audio_data, msg.author.id.get())?;
+    let audio_id = Audio::create(&mut conn, audio_data, msg.author.id.get()).await?;
 
     let save_result = NewMeme {
         title,
@@ -206,6 +207,7 @@ pub async fn addaudiomeme(ctx: &Context, msg: &Message, args: Args) -> CommandRe
         metadata_id: 0,
     }
     .save(&mut conn, msg.author.id.get())
+    .await
     .map(|_| {});
 
     use diesel::result::DatabaseErrorKind;
diff --git a/src/commands/meme/history.rs b/src/commands/meme/history.rs
index e2953d1..e5b3d33 100644
--- a/src/commands/meme/history.rs
+++ b/src/commands/meme/history.rs
@@ -60,7 +60,7 @@ static CLEAN_DATE_FORMAT: &str = "%b %-e %Y";
 pub async fn wat(ctx: &Context, msg: &Message, _: Args) -> CommandResult {
     let mut conn = connection()?;
 
-    let record = match InvocationRecord::last(&mut conn) {
+    let record = match InvocationRecord::last(&mut conn).await {
         Ok(x) => x,
         Err(e) => {
             if let Some(NotFound) = e.downcast_ref::<DieselError>() {
@@ -75,11 +75,11 @@ pub async fn wat(ctx: &Context, msg: &Message, _: Args) -> CommandResult {
         },
     };
 
-    let meme = Meme::find(&mut conn, record.meme_id);
+    let meme = Meme::find(&mut conn, record.meme_id).await;
 
     match meme {
         Ok(ref meme) => {
-            let metadata = Metadata::find(&mut conn, meme.metadata_id)?;
+            let metadata = Metadata::find(&mut conn, meme.metadata_id).await?;
             let author = CONFIG.discord.guild().member(&ctx, metadata.created_by as u64).await?;
 
             util::send(
@@ -125,7 +125,7 @@ pub async fn history(ctx: &Context, msg: &Message, mut args: Args) -> CommandRes
 
     let records = {
         let mut conn = connection()?;
-        InvocationRecord::last_n(&mut conn, n)?
+        InvocationRecord::last_n(&mut conn, n).await?
     };
 
     if records.is_empty() {
@@ -150,7 +150,9 @@ pub async fn history(ctx: &Context, msg: &Message, mut args: Args) -> CommandRes
                 ""
             };
 
-            let meme = Meme::find(&mut conn, rec.meme_id).and_then(|meme| {
+            let meme = Meme::find(&mut conn, rec.meme_id).await;
+            
+            .and_then(|meme| {
                 Metadata::find(&mut conn, meme.metadata_id).map(|metadata| (metadata, meme))
             });
 
@@ -214,7 +216,7 @@ pub async fn stats(ctx: &Context, msg: &Message, _: Args) -> CommandResult {
     };
 
     let mut conn = connection()?;
-    let stats = db::stats(&mut conn)?;
+    let stats = db::stats(&mut conn).await?;
 
     debug!("reporting stats");
 
diff --git a/src/commands/meme/mod.rs b/src/commands/meme/mod.rs
index c40e80a..b5a3c98 100644
--- a/src/commands/meme/mod.rs
+++ b/src/commands/meme/mod.rs
@@ -1,4 +1,4 @@
-use diesel::PgConnection;
+use diesel_async::AsyncPgConnection;
 use log::debug;
 use rand::random;
 use serenity::{
@@ -70,7 +70,7 @@ struct Memes;
 async fn send_meme(
     ctx: &Context,
     t: &Meme,
-    conn: &mut PgConnection,
+    conn: &mut AsyncPgConnection,
     msg: &Message,
 ) -> CommandResult {
     let should_tts =
diff --git a/src/db/mod.rs b/src/db/mod.rs
index e7ff17f..04f2239 100644
--- a/src/db/mod.rs
+++ b/src/db/mod.rs
@@ -11,24 +11,13 @@ use chrono::{
 };
 use diesel::{
     prelude::*,
-    r2d2::{
-        ConnectionManager,
-        ManageConnection,
-    },
     NotFound,
 };
-
-use postgres::Client as RawPgConn;
-use r2d2_postgres::{
-    postgres::{
-        Config,
-        NoTls,
-    },
-    PostgresConnectionManager as RawPgConnMgr,
-};
-
+use diesel_async::pooled_connection::AsyncDieselConnectionManager;
+use tokio_postgres::Client as RawPgConn;
 use anyhow::anyhow;
-use diesel_migrations::MigrationHarness;
+use diesel_async::pooled_connection::deadpool::Pool;
+use deadpool_postgres::{Pool as RawPgConnMgr, PoolConfig};
 use lazy_static::lazy_static;
 
 use crate::{
@@ -42,47 +31,62 @@ use self::schema::*;
 mod models;
 mod schema;
 
-const MIGRATIONS: diesel_migrations::EmbeddedMigrations = diesel_migrations::embed_migrations!();
-static MIGRATE: std::sync::Once = std::sync::Once::new();
+const MIGRATIONS: diesel_async_migrations::EmbeddedMigrations = diesel_async_migrations::embed_migrations!();
+static MIGRATE: tokio::sync::OnceCell<()> = tokio::sync::OnceCell::new();
 
 lazy_static! {
     static ref DB_URL: String =
         env::var("DATABASE_URL").expect("no database url in environment");
     static ref DB_CONFIG: Config = Config::from_str(&DB_URL).expect("parsing db url as config");
-    static ref CONN_MGR: ConnectionManager<PgConnection> = ConnectionManager::new(DB_URL.clone());
-    static ref RAW_CONN_MGR: RawPgConnMgr<NoTls> = RawPgConnMgr::new(DB_CONFIG.clone(), NoTls);
+
+    static ref POOL: diesel_async::pooled_connection::deadpool::Pool<AsyncDieselConnectionManager<AsyncPgConnection>> = {
+        let cfg = AsyncDieselConnectionManager::new(DB_URL.clone());
+        let pool = Pool::builder(cfg).build().unwrap();
+
+        pool
+    };
+
+    static ref RAW_CONN_MGR: RawPgConnMgr = {
+        deadpool_postgres::Config::builder(tokio_postgres::NoTls).expect("failed to init config")
+            .config(PoolConfig::new(8))
+            .build().expect("failed to build pool")
+    };
 }
 
 #[inline]
-pub fn connection() -> Result<PgConnection> {
-    CONN_MGR
-        .connect()
-        .map(|mut conn| {
-            MIGRATE.call_once(|| {
-                log::info!("running migrations");
-                conn.run_pending_migrations(MIGRATIONS).expect("failed running migrations");
-                log::info!("migrations complete");
-            });
+pub async fn connection() -> Result<AsyncPgConnection> {
+    let pool: &Pool<AsyncDieselConnectionManager<_>> = POOL;
+
+    pool.get()
+        .then(|mut conn| async move {
+            if let Ok(conn) = conn {
+                MIGRATE.get_or_init(|| async move {
+                    log::info!("running migrations");
+                    MIGRATIONS.run_pending_migrations(&mut conn).await.expect("failed running migrations");
+                    log::info!("migrations complete");
+                }).await;
+            }
 
             conn
         })
+        .await
         .map_err(Error::from)
 }
 
 #[inline]
-fn raw_connection() -> Result<RawPgConn> {
+async fn raw_connection() -> Result<tokio_postgres::Client> {
     // HACK
-    if !MIGRATE.is_completed() {
-        connection()?;
+    if !MIGRATE.initialized() {
+        connection().await?;
     }
 
     RAW_CONN_MGR.connect().map_err(Error::from)
 }
 
-pub fn find_meme<T: AsRef<str>>(conn: &mut PgConnection, search: T) -> Result<Meme> {
+pub async fn find_meme<T: AsRef<str>>(conn: &mut AsyncPgConnection, search: T) -> Result<Meme> {
     let search = search.as_ref();
 
-    let mut meme = memes::table.filter(memes::title.eq(search)).limit(1).first::<Meme>(conn);
+    let mut meme = memes::table.filter(memes::title.eq(search)).limit(1).first::<Meme>(conn).await;
 
     if let Err(NotFound) = meme {
         let format_search = format!("%{}%", search);
@@ -90,18 +94,18 @@ pub fn find_meme<T: AsRef<str>>(conn: &mut PgConnection, search: T) -> Result<Me
         meme = memes::table
             .filter(memes::title.ilike(&format_search).or(memes::content.ilike(&format_search)))
             .limit(1)
-            .first::<Meme>(conn);
+            .first::<Meme>(conn).await;
     }
 
     meme.map_err(Error::from)
 }
 
-pub fn query_meme<T: AsRef<str>>(
+pub async fn query_meme<T: AsRef<str>>(
     search: T,
     user_id: Option<u64>,
     age_desc: bool,
 ) -> Result<Vec<(Meme, Metadata)>> {
-    let mut raw_conn = raw_connection()?;
+    let mut raw_conn = raw_connection().await?;
 
     let search = format!("%{}%", search.as_ref());
 
@@ -123,7 +127,7 @@ pub fn query_meme<T: AsRef<str>>(
             },
         ),
         &[&search, &(user_id.unwrap_or(0) as i64), &user_id.is_none()],
-    )?;
+    ).await?;
 
     let result = rows
         .iter()
@@ -150,21 +154,21 @@ pub fn query_meme<T: AsRef<str>>(
     Ok(result)
 }
 
-pub fn delete_meme<T: AsRef<str>>(
-    conn: &mut PgConnection,
+pub async fn delete_meme<T: AsRef<str>>(
+    conn: &mut AsyncPgConnection,
     search: T,
     deleted_by: u64,
 ) -> Result<()> {
     conn.transaction::<(), Error, _>(|tx| {
-        let deleted = memes::table.filter(memes::title.eq(search.as_ref())).first::<Meme>(tx)?;
+        let deleted = memes::table.filter(memes::title.eq(search.as_ref())).first::<Meme>(tx).await?;
 
-        diesel::delete(memes::table).filter(memes::id.eq(deleted.id)).execute(tx)?;
+        diesel::delete(memes::table).filter(memes::id.eq(deleted.id)).execute(tx).await?;
 
         if let Some(image_id) = deleted.image_id {
-            let count = memes::table.filter(memes::image_id.eq(image_id)).count().execute(tx)?;
+            let count = memes::table.filter(memes::image_id.eq(image_id)).count().execute(tx).await?;
 
             if count == 0 {
-                diesel::delete(images::table).filter(images::id.eq(image_id)).execute(tx)?;
+                diesel::delete(images::table).filter(images::id.eq(image_id)).execute(tx).await?;
             }
         }
 
@@ -172,10 +176,10 @@ pub fn delete_meme<T: AsRef<str>>(
             let count = memes::table
                 .select(::diesel::dsl::count_star())
                 .filter(memes::audio_id.eq(audio_id))
-                .execute(tx)?;
+                .execute(tx).await?;
 
             if count == 0 {
-                diesel::delete(audio::table).filter(audio::id.eq(audio_id)).execute(tx)?;
+                diesel::delete(audio::table).filter(audio::id.eq(audio_id)).execute(tx).await?;
             }
         }
 
@@ -185,16 +189,16 @@ pub fn delete_meme<T: AsRef<str>>(
             meme_id:     deleted.id,
         };
 
-        let _ = diesel::insert_into(tombstones::table).values(&tombstone).execute(tx)?;
+        let _ = diesel::insert_into(tombstones::table).values(&tombstone).execute(tx).await?;
 
         Ok(())
     })
 }
 
-pub fn rare_meme(conn: &mut PgConnection, audio: bool) -> Result<Meme> {
+pub async fn rare_meme(conn: &mut AsyncPgConnection, audio: bool) -> Result<Meme> {
     use rand::prelude::*;
 
-    let mut raw_conn = raw_connection()?;
+    let mut raw_conn = raw_connection().await?;
 
     let rows = raw_conn.query(
         r#"
@@ -229,7 +233,7 @@ pub fn rare_meme(conn: &mut PgConnection, audio: bool) -> Result<Meme> {
     LIMIT 100;
     "#,
         &[&!audio, &audio],
-    )?;
+    ).await?;
 
     let elems = rows
         .iter()
@@ -249,10 +253,10 @@ pub fn rare_meme(conn: &mut PgConnection, audio: bool) -> Result<Meme> {
         .ok_or_else(|| anyhow!("couldn't locate meme satisfying target probability"))?
         .0;
 
-    Meme::find(conn, meme_id)
+    Meme::find(conn, meme_id).await
 }
 
-pub fn rand_meme(conn: &mut PgConnection, audio: bool) -> Result<Meme> {
+pub async fn rand_meme(conn: &mut AsyncPgConnection, audio: bool) -> Result<Meme> {
     use rand::{
         seq::SliceRandom,
         thread_rng,
@@ -268,21 +272,23 @@ pub fn rand_meme(conn: &mut PgConnection, audio: bool) -> Result<Meme> {
                     .or(memes::audio_id.is_not_null()),
             )
             .load(conn)
+            .await
             .map_err(Error::from)?
     } else {
         memes::table
             .select(memes::id)
             .filter(memes::content.is_not_null().or(memes::image_id.is_not_null()))
             .load(conn)
+            .await
             .map_err(Error::from)?
     };
 
     let id = ids.choose(&mut thread_rng()).ok_or_else(|| anyhow!("couldn't load meme"))?;
 
-    memes::table.find(id).first::<Meme>(conn).map_err(Error::from)
+    memes::table.find(id).first::<Meme>(conn).await.map_err(Error::from)
 }
 
-pub fn rand_audio_meme(conn: &mut PgConnection) -> Result<Meme> {
+pub async fn rand_audio_meme(conn: &mut AsyncPgConnection) -> Result<Meme> {
     use rand::{
         seq::SliceRandom,
         thread_rng,
@@ -292,14 +298,15 @@ pub fn rand_audio_meme(conn: &mut PgConnection) -> Result<Meme> {
         .select(memes::id)
         .filter(memes::audio_id.is_not_null())
         .load(conn)
+        .await
         .map_err(Error::from)?;
 
     let id = ids.choose(&mut thread_rng()).ok_or_else(|| anyhow!("couldn't load audio meme"))?;
 
-    memes::table.find(id).first::<Meme>(conn).map_err(Error::from)
+    memes::table.find(id).first::<Meme>(conn).await.map_err(Error::from)
 }
 
-pub fn rand_silent_meme(conn: &mut PgConnection) -> Result<Meme> {
+pub async fn rand_silent_meme(conn: &mut AsyncPgConnection) -> Result<Meme> {
     use rand::{
         seq::SliceRandom,
         thread_rng,
@@ -309,11 +316,12 @@ pub fn rand_silent_meme(conn: &mut PgConnection) -> Result<Meme> {
         .select(memes::id)
         .filter(memes::audio_id.is_null())
         .load(conn)
+        .await
         .map_err(Error::from)?;
 
     let id = ids.choose(&mut thread_rng()).ok_or_else(|| anyhow!("couldn't load audio meme"))?;
 
-    memes::table.find(id).first::<Meme>(conn).map_err(Error::from)
+    memes::table.find(id).first::<Meme>(conn).await.map_err(Error::from)
 }
 
 #[derive(Debug, Clone)]
@@ -347,7 +355,7 @@ pub struct Stats {
     pub most_popular_meme_overall_count: usize,
 }
 
-pub fn stats(conn: &mut PgConnection) -> Result<Stats> {
+pub async fn stats(conn: &mut AsyncPgConnection) -> Result<Stats> {
     use chrono::{
         NaiveDate,
         NaiveDateTime,
@@ -373,36 +381,41 @@ pub fn stats(conn: &mut PgConnection) -> Result<Stats> {
         .select(count(memes::image_id))
         .filter(memes::image_id.is_not_null())
         .first(conn)
+        .await
         .map_err(Error::from)?;
 
     let audio_count: i64 = memes::table
         .select(count(memes::audio_id))
         .filter(memes::audio_id.is_not_null())
         .first(conn)
+        .await
         .map_err(Error::from)?;
 
     let started_recording: NaiveDateTime = invocation_records::table
         .select(invocation_records::time)
         .order(invocation_records::time)
         .first(conn)
+        .await
         .map_err(Error::from)?;
 
     let started_recording = to_utc(started_recording);
 
     let total_meme_invocations: i64 =
-        invocation_records::table.select(count_star()).first(conn).map_err(Error::from)?;
+        invocation_records::table.select(count_star()).first(conn).await.map_err(Error::from)?;
 
     let audio_meme_invocations: i64 = invocation_records::table
         .inner_join(memes::table)
         .select(count_star())
         .filter(memes::audio_id.is_not_null())
         .first(conn)
+        .await
         .map_err(Error::from)?;
 
     let random_meme_invocations: i64 = invocation_records::table
         .select(count_star())
         .filter(invocation_records::random.eq(true))
         .first(conn)
+        .await
         .map_err(Error::from)?;
 
     let mut raw_conn = raw_connection()?;
diff --git a/src/db/models.rs b/src/db/models.rs
index bba25a2..f7bbf8e 100644
--- a/src/db/models.rs
+++ b/src/db/models.rs
@@ -5,6 +5,7 @@ use diesel::{
     Insertable,
     Queryable,
 };
+use diesel_async::{AsyncPgConnection, RunQueryDsl};
 use sha1::Digest;
 
 use crate::{
@@ -25,18 +26,27 @@ pub struct Meme {
 }
 
 impl Meme {
-    pub fn image(&self, conn: &mut PgConnection) -> Option<Result<Image>> {
+    pub async fn image(&self, conn: &mut AsyncPgConnection) -> Option<Result<Image>> {
         self.image_id
-            .map(|x: i32| images::table.filter(images::id.eq(x)).first(conn).map_err(Error::from))
+            .map(|x: i32| images::table.filter(images::id.eq(x))
+                .first(conn)
+                .await
+                .map_err(Error::from))
     }
 
-    pub fn audio(&self, conn: &mut PgConnection) -> Option<Result<Audio>> {
+    pub async fn audio(&self, conn: &mut AsyncPgConnection) -> Option<Result<Audio>> {
         self.audio_id
-            .map(|x: i32| audio::table.filter(audio::id.eq(x)).first(conn).map_err(Error::from))
+            .map(|x: i32| audio::table.filter(audio::id.eq(x))
+                .first(conn)
+                .await
+                .map_err(Error::from))
     }
 
-    pub fn find(conn: &mut PgConnection, id: i32) -> Result<Meme> {
-        memes::table.find(id).get_result(conn).map_err(Error::from)
+    pub async fn find(conn: &mut AsyncPgConnection, id: i32) -> Result<Meme> {
+        memes::table.find(id)
+            .get_result(conn)
+            .await
+            .map_err(Error::from)
     }
 }
 
@@ -51,7 +61,7 @@ pub struct NewMeme {
 }
 
 impl NewMeme {
-    pub fn save(mut self, conn: &mut PgConnection, by_user: u64) -> Result<Meme> {
+    pub async fn save(mut self, conn: &mut AsyncPgConnection, by_user: u64) -> Result<Meme> {
         let metadata = Metadata::create(conn, by_user)?;
 
         self.metadata_id = metadata.id;
@@ -59,6 +69,7 @@ impl NewMeme {
         diesel::insert_into(memes::table)
             .values(&self)
             .get_result::<Meme>(conn)
+            .await
             .map_err(Error::from)
     }
 }
@@ -73,7 +84,7 @@ pub struct Audio {
 }
 
 impl Audio {
-    pub fn create(conn: &mut PgConnection, data: Vec<u8>, by_user: u64) -> Result<i32> {
+    pub fn create(conn: &mut AsyncPgConnection, data: Vec<u8>, by_user: u64) -> Result<i32> {
         let mut data_hash = ::sha1::Sha1::new();
         data_hash.update(&data);
         let data_hash = data_hash.finalize().to_vec();
@@ -81,7 +92,8 @@ impl Audio {
         let id = audio::table
             .select(audio::id)
             .filter(audio::data_hash.eq(&data_hash))
-            .get_results::<i32>(conn)?;
+            .get_results::<i32>(conn)
+            .await?;
 
         if let Some(id) = id.first() {
             return Ok(*id);
@@ -99,6 +111,7 @@ impl Audio {
             .values(&new_audio)
             .returning(audio::id)
             .get_result(conn)
+            .await
             .map_err(Error::from)
     }
 }
@@ -123,7 +136,7 @@ pub struct Image {
 
 impl Image {
     pub fn create(
-        conn: &mut PgConnection,
+        conn: &mut AsyncPgConnection,
         filename: &str,
         data: Vec<u8>,
         by_user: u64,
@@ -135,7 +148,8 @@ impl Image {
         let id = images::table
             .select(images::id)
             .filter(images::data_hash.eq(&data_hash))
-            .get_results::<i32>(conn)?;
+            .get_results::<i32>(conn)
+            .await?;
 
         if let Some(id) = id.first() {
             return Ok(*id);
@@ -154,6 +168,7 @@ impl Image {
             .values(&new_image)
             .returning(images::id)
             .get_result(conn)
+            .await
             .map_err(Error::from)
     }
 }
@@ -176,17 +191,18 @@ pub struct Metadata {
 }
 
 impl Metadata {
-    pub fn create(conn: &mut PgConnection, by_user: u64) -> Result<Metadata> {
+    pub fn create(conn: &mut AsyncPgConnection, by_user: u64) -> Result<Metadata> {
         diesel::insert_into(metadata::table)
             .values(&NewMetadata {
                 created_by: by_user as i64,
             })
             .get_result::<Metadata>(conn)
+            .await
             .map_err(Error::from)
     }
 
-    pub fn find(conn: &mut PgConnection, id: i32) -> Result<Metadata> {
-        metadata::table.find(id).get_result::<Metadata>(conn).map_err(Error::from)
+    pub fn find(conn: &mut AsyncPgConnection, id: i32) -> Result<Metadata> {
+        metadata::table.find(id).get_result::<Metadata>(conn).await.map_err(Error::from)
     }
 }
 
@@ -206,13 +222,14 @@ pub struct AuditRecord {
 }
 
 impl AuditRecord {
-    pub fn create(conn: &mut PgConnection, metadata: i32, by_user: u64) -> Result<AuditRecord> {
+    pub fn create(conn: &mut AsyncPgConnection, metadata: i32, by_user: u64) -> Result<AuditRecord> {
         diesel::insert_into(audit_records::table)
             .values(&NewAuditRecord {
                 updated_by:  by_user as i64,
                 metadata_id: metadata,
             })
             .get_result::<AuditRecord>(conn)
+            .await
             .map_err(Error::from)
     }
 }
@@ -264,7 +281,7 @@ pub struct NewInvocationRecord {
 
 impl InvocationRecord {
     pub fn create(
-        conn: &mut PgConnection,
+        conn: &mut AsyncPgConnection,
         user_id: u64,
         message_id: u64,
         meme_id: i32,
@@ -278,21 +295,24 @@ impl InvocationRecord {
                 random,
             })
             .get_result::<InvocationRecord>(conn)
+            .await
             .map_err(Error::from)
     }
 
-    pub fn last(conn: &mut PgConnection) -> Result<Self> {
+    pub fn last(conn: &mut AsyncPgConnection) -> Result<Self> {
         invocation_records::table
             .order(invocation_records::time.desc())
             .first(conn)
+            .await
             .map_err(Error::from)
     }
 
-    pub fn last_n(conn: &mut PgConnection, n: usize) -> Result<Vec<Self>> {
+    pub fn last_n(conn: &mut AsyncPgConnection, n: usize) -> Result<Vec<Self>> {
         invocation_records::table
             .order(invocation_records::time.desc())
             .limit(n as i64)
             .load(conn)
+            .await
             .map_err(Error::from)
     }
 }