src/external/database/sql/backend.rs

@@ -2,11 +2,11 @@
 
 use std::path::PathBuf;
 
-use rusqlite::{self, CachedStatement, Connection, Params, Statement};
+use rusqlite::{self, CachedStatement, Connection, Params, Statement, Transaction};
 
 use crate::external::database::{
     serde::serialize::{SerializeAlbum, SerializeArtist, SerializeDatabase},
-    sql::{Error, ISqlDatabaseBackend},
+    sql::{Error, ISqlDatabaseBackend, ISqlTransactionBackend},
 };
 
 /// SQLite database backend that uses SQLite as the implementation.
@@ -14,6 +14,10 @@ pub struct SqlDatabaseSqliteBackend {
     conn: Connection,
 }
 
+pub struct SqlTransactionSqliteBackend<'conn> {
+    tx: Transaction<'conn>,
+}
+
 impl SqlDatabaseSqliteBackend {
     /// Create a [`SqlDatabaseSqliteBackend`] that will read/write to the provided database.
     pub fn new<P: Into<PathBuf>>(path: P) -> Result<Self, Error> {
@@ -21,15 +25,17 @@ impl SqlDatabaseSqliteBackend {
             conn: Connection::open(path.into()).map_err(|err| Error::OpenError(err.to_string()))?,
         })
     }
+}
 
+impl<'conn> SqlTransactionSqliteBackend<'conn> {
     fn prepare(&self, sql: &str) -> Result<Statement, Error> {
-        self.conn
+        self.tx
             .prepare(sql)
             .map_err(|err| Error::StmtError(err.to_string()))
     }
 
     fn prepare_cached(&self, sql: &str) -> Result<CachedStatement, Error> {
-        self.conn
+        self.tx
             .prepare_cached(sql)
             .map_err(|err| Error::StmtError(err.to_string()))
     }
@@ -47,15 +53,22 @@ impl From<serde_json::Error> for Error {
     }
 }
 
-impl ISqlDatabaseBackend for SqlDatabaseSqliteBackend {
-    fn begin_transaction(&self) -> Result<(), Error> {
-        let mut stmt = self.prepare_cached("BEGIN TRANSACTION;")?;
-        Self::execute(&mut stmt, ())
-    }
+impl<'conn> ISqlDatabaseBackend<'conn> for SqlDatabaseSqliteBackend {
+    type Tx = SqlTransactionSqliteBackend<'conn>;
 
-    fn commit_transaction(&self) -> Result<(), Error> {
-        let mut stmt = self.prepare_cached("COMMIT;")?;
-        Self::execute(&mut stmt, ())
+    fn transaction(&'conn mut self) -> Result<Self::Tx, Error> {
+        self.conn
+            .transaction()
+            .map(|tx| SqlTransactionSqliteBackend { tx })
+            .map_err(|err| Error::OpenError(err.to_string()))
+    }
+}
+
+impl<'conn> ISqlTransactionBackend for SqlTransactionSqliteBackend<'conn> {
+    fn commit(self) -> Result<(), Error> {
+        self.tx
+            .commit()
+            .map_err(|err| Error::ExecError(err.to_string()))
     }
 
     fn create_database_metadata_table(&self) -> Result<(), Error> {
@@ -85,7 +98,7 @@ impl ISqlDatabaseBackend for SqlDatabaseSqliteBackend {
         Self::execute(&mut stmt, ())
     }
 
-    fn drop_artists_table(&self) -> Result<(),Error> {
+    fn drop_artists_table(&self) -> Result<(), Error> {
         let mut stmt = self.prepare_cached("DROP TABLE artists")?;
         Self::execute(&mut stmt, ())
     }
@@ -109,7 +122,7 @@ impl ISqlDatabaseBackend for SqlDatabaseSqliteBackend {
         Self::execute(&mut stmt, ())
     }
 
-    fn drop_albums_table(&self) -> Result<(),Error> {
+    fn drop_albums_table(&self) -> Result<(), Error> {
         let mut stmt = self.prepare_cached("DROP TABLE albums")?;
         Self::execute(&mut stmt, ())
     }

src/external/database/sql/mod.rs

@@ -16,13 +16,18 @@ use crate::{
 };
 
 /// Trait for the SQL database backend.
-#[cfg_attr(test, automock)]
-pub trait ISqlDatabaseBackend {
-    /// Begin an SQL transaction.
-    fn begin_transaction(&self) -> Result<(), Error>;
+pub trait ISqlDatabaseBackend<'conn> {
+    type Tx: ISqlTransactionBackend + 'conn;
 
-    /// Commit ongoing transaction.
-    fn commit_transaction(&self) -> Result<(), Error>;
+    /// Begin an SQL transaction.
+    fn transaction(&'conn mut self) -> Result<Self::Tx, Error>;
+}
+
+/// Trait for the SQL database backend.
+#[cfg_attr(test, automock)]
+pub trait ISqlTransactionBackend {
+    /// Commit transaction.
+    fn commit(self) -> Result<(), Error>;
 
     /// Create the database metadata table (if needed).
     fn create_database_metadata_table(&self) -> Result<(), Error>;
@@ -95,65 +100,57 @@ pub struct SqlDatabase<SDB> {
     backend: SDB,
 }
 
-impl<SDB: ISqlDatabaseBackend> SqlDatabase<SDB> {
+impl<SDB: for<'c> ISqlDatabaseBackend<'c>> SqlDatabase<SDB> {
     /// Create a new SQL database with the provided backend, e.g.
     /// [`backend::SqlDatabaseSqliteBackend`].
     pub fn new(backend: SDB) -> Result<Self, Error> {
-        let db = SqlDatabase { backend };
-        db.begin_transaction()?;
-        db.create_tables()?;
-        db.commit_transaction()?;
+        let mut db = SqlDatabase { backend };
+        let tx = db.backend.transaction()?;
+        Self::create_tables(&tx)?;
+        tx.commit()?;
         Ok(db)
     }
 
-    fn begin_transaction(&self) -> Result<(), Error> {
-        self.backend.begin_transaction()
-    }
-
-    fn commit_transaction(&self) -> Result<(), Error> {
-        self.backend.commit_transaction()
-    }
-
-    fn create_tables(&self) -> Result<(), Error> {
-        self.backend.create_database_metadata_table()?;
-        self.backend.create_artists_table()?;
-        self.backend.create_albums_table()?;
+    fn create_tables<Tx: ISqlTransactionBackend>(tx: &Tx) -> Result<(), Error> {
+        tx.create_database_metadata_table()?;
+        tx.create_artists_table()?;
+        tx.create_albums_table()?;
         Ok(())
     }
 
-    fn drop_tables(&self) -> Result<(), Error> {
-        self.backend.drop_database_metadata_table()?;
-        self.backend.drop_artists_table()?;
-        self.backend.drop_albums_table()?;
+    fn drop_tables<Tx: ISqlTransactionBackend>(tx: &Tx) -> Result<(), Error> {
+        tx.drop_database_metadata_table()?;
+        tx.drop_artists_table()?;
+        tx.drop_albums_table()?;
         Ok(())
     }
 }
 
-impl<SDB: ISqlDatabaseBackend> IDatabase for SqlDatabase<SDB> {
+impl<SDB: for<'c> ISqlDatabaseBackend<'c>> IDatabase for SqlDatabase<SDB> {
     fn load(&self) -> Result<Collection, LoadError> {
         Ok(vec![])
     }
 
     fn save(&mut self, collection: &Collection) -> Result<(), SaveError> {
         let database: SerializeDatabase = collection.into();
-        self.begin_transaction()?;
+        let tx = self.backend.transaction()?;
 
-        self.drop_tables()?;
-        self.create_tables()?;
+        Self::drop_tables(&tx)?;
+        Self::create_tables(&tx)?;
 
-        self.backend.insert_database_version(&database)?;
+        tx.insert_database_version(&database)?;
         match database {
             SerializeDatabase::V20250103(artists) => {
                 for artist in artists.iter() {
-                    self.backend.insert_artist(artist)?;
+                    tx.insert_artist(artist)?;
                     for album in artist.albums.iter() {
-                        self.backend.insert_album(artist.name, album)?;
+                        tx.insert_album(artist.name, album)?;
                     }
                 }
             }
         }
 
-        self.commit_transaction()?;
+        tx.commit()?;
         Ok(())
     }
 }