Properly implement SqliteStorage methods

src/dispatching/dialogue/storage/sqlite_storage.rs

@@ -1,15 +1,14 @@
 use super::{serializer::Serializer, Storage};
 use futures::future::BoxFuture;
 use serde::{de::DeserializeOwned, Serialize};
-use sqlx::sqlite::{SqliteConnectOptions, SqliteConnection};
-use sqlx::{ConnectOptions, Executor};
+use sqlx::sqlite::SqlitePool;
+use sqlx::Executor;
 use std::{
     convert::Infallible,
     fmt::{Debug, Display},
     sync::Arc,
 };
 use thiserror::Error;
-use tokio::sync::Mutex;
 
 // An error returned from [`SqliteStorage`].
 #[derive(Debug, Error)]
@@ -25,20 +24,23 @@ where
 
 // TODO: make JSON serializer to be default
 pub struct SqliteStorage<S> {
-    conn: Mutex<SqliteConnection>,
+    pool: SqlitePool,
     serializer: S,
 }
 
+#[derive(sqlx::FromRow)]
+struct DialogueDBRow {
+    dialogue: Vec<u8>,
+}
+
 impl<S> SqliteStorage<S> {
     pub async fn open(
         path: &str,
         serializer: S,
     ) -> Result<Arc<Self>, SqliteStorageError<Infallible>> {
-        let mut conn =
-            SqliteConnectOptions::new().filename(path).create_if_missing(true).connect().await?;
-
-        // TODO: think about a schema migration mechanism.
-        conn.execute(
+        let pool = SqlitePool::connect(format!("sqlite:{}?mode=rwc", path).as_str()).await?;
+        let mut conn = pool.acquire().await?;
+        sqlx::query(
             r#"
 CREATE TABLE IF NOT EXISTS teloxide_dialogues (
     chat_id BIGINT PRIMARY KEY,
@@ -46,9 +48,26 @@ CREATE TABLE IF NOT EXISTS teloxide_dialogues (
 );
         "#,
         )
+        .execute(&mut conn)
         .await?;
 
-        Ok(Arc::new(Self { conn: Mutex::new(conn), serializer }))
+        Ok(Arc::new(Self { pool, serializer }))
+    }
+}
+
+async fn get_dialogue(
+    pool: &SqlitePool,
+    chat_id: i64,
+) -> Result<Option<Box<Vec<u8>>>, sqlx::Error> {
+    match sqlx::query_as::<_, DialogueDBRow>(
+        "SELECT dialogue FROM teloxide_dialogues WHERE chat_id = ?",
+    )
+    .bind(chat_id)
+    .fetch_optional(pool)
+    .await?
+    {
+        Some(r) => Ok(Some(Box::new(r.dialogue))),
+        _ => Ok(None),
     }
 }
 
@@ -65,14 +84,18 @@ where
         chat_id: i64,
     ) -> BoxFuture<'static, Result<Option<D>, Self::Error>> {
         Box::pin(async move {
-            self.conn
-                .lock()
-                .await
-                .execute(
-                    sqlx::query("DELETE FROM teloxide_dialogues WHERE chat_id = ?").bind(chat_id),
-                )
-                .await?;
-            Ok(None)
+            match get_dialogue(&self.pool, chat_id).await? {
+                None => Ok(None),
+                Some(d) => {
+                    let prev_dialogue =
+                        self.serializer.deserialize(&d).map_err(SqliteStorageError::SerdeError)?;
+                    sqlx::query("DELETE FROM teloxide_dialogues WHERE chat_id = ?")
+                        .bind(chat_id)
+                        .execute(&self.pool)
+                        .await?;
+                    Ok(Some(prev_dialogue))
+                }
+            }
         })
     }
 
@@ -82,23 +105,31 @@ where
         dialogue: D,
     ) -> BoxFuture<'static, Result<Option<D>, Self::Error>> {
         Box::pin(async move {
-            let dialogue =
+            let serialized_dialogue =
                 self.serializer.serialize(&dialogue).map_err(SqliteStorageError::SerdeError)?;
-            self.conn
-                .lock()
-                .await
+            let prev_dialogue = get_dialogue(&self.pool, chat_id).await?;
+
+            self.pool
+                .acquire()
+                .await?
                 .execute(
                     sqlx::query(
                         r#"
-INSERT INTO teloxide_dialogues VALUES (?, ?) WHERE chat_id = ?
-ON CONFLICT(chat_id) DO UPDATE SET dialogue=excluded.dialogue
-                    "#,
+            INSERT INTO teloxide_dialogues VALUES (?, ?) WHERE chat_id = ?
+            ON CONFLICT(chat_id) DO UPDATE SET dialogue=excluded.dialogue
+                                "#,
                     )
                     .bind(chat_id)
-                    .bind(dialogue),
+                    .bind(serialized_dialogue),
                 )
                 .await?;
-            Ok(None)
+
+            Ok(match prev_dialogue {
+                None => None,
+                Some(d) => {
+                    Some(self.serializer.deserialize(&d).map_err(SqliteStorageError::SerdeError)?)
+                }
+            })
         })
     }
 }