database: permit to remove coins from DB

src/database/mod.rs

@@ -89,6 +89,9 @@ pub trait DatabaseConnection {
     /// Store new UTxOs. Coins must not already be in database.
     fn new_unspent_coins(&mut self, coins: &[Coin]);
 
+    /// Remove some UTxOs from the database.
+    fn remove_coins(&mut self, coins: &[bitcoin::OutPoint]);
+
     /// Mark a set of coins as being confirmed at a specified height and block time.
     fn confirm_coins(&mut self, outpoints: &[(bitcoin::OutPoint, i32, u32)]);
 
@@ -196,6 +199,10 @@ impl DatabaseConnection for SqliteConn {
         self.new_unspent_coins(coins)
     }
 
+    fn remove_coins(&mut self, outpoints: &[bitcoin::OutPoint]) {
+        self.remove_coins(outpoints)
+    }
+
     fn confirm_coins<'a>(&mut self, outpoints: &[(bitcoin::OutPoint, i32, u32)]) {
         self.confirm_coins(outpoints)
     }

src/database/sqlite/mod.rs

@@ -363,6 +363,21 @@ impl SqliteConn {
         .expect("Database must be available")
     }
 
+    /// Remove a set of coins from the database.
+    pub fn remove_coins(&mut self, outpoints: &[bitcoin::OutPoint]) {
+        db_exec(&mut self.conn, |db_tx| {
+            for outpoint in outpoints {
+                db_tx.execute(
+                    "DELETE FROM coins WHERE txid = ?1 AND vout = ?2",
+                    rusqlite::params![outpoint.txid.to_vec(), outpoint.vout,],
+                )?;
+            }
+
+            Ok(())
+        })
+        .expect("Database must be available")
+    }
+
     /// Mark a set of coins as confirmed.
     pub fn confirm_coins<'a>(
         &mut self,
@@ -705,6 +720,13 @@ mod tests {
             conn.new_unspent_coins(&[coin_a]);
             assert_eq!(conn.coins(CoinType::All)[0].outpoint, coin_a.outpoint);
 
+            // We can also remove it. Say the unconfirmed tx that created it got replaced.
+            conn.remove_coins(&[coin_a.outpoint]);
+            assert!(conn.coins(CoinType::All).is_empty());
+
+            // Add it back for the rest of the test.
+            conn.new_unspent_coins(&[coin_a]);
+
             // We can query it by its outpoint
             let coins = conn.db_coins(&[coin_a.outpoint]);
             assert_eq!(coins.len(), 1);

src/testutils.rs

@@ -220,6 +220,12 @@ impl DatabaseConnection for DummyDatabase {
         }
     }
 
+    fn remove_coins(&mut self, outpoints: &[bitcoin::OutPoint]) {
+        for op in outpoints {
+            self.db.write().unwrap().coins.remove(op);
+        }
+    }
+
     fn confirm_coins<'a>(&mut self, outpoints: &[(bitcoin::OutPoint, i32, u32)]) {
         for (op, height, time) in outpoints {
             let mut db = self.db.write().unwrap();