db abstraction: make .insert() and .remove() return the old value

1 files changed, 17 insertions, 15 deletions

diff --git a/src/db/lmdb_adapter.rs b/src/db/lmdb_adapter.rs
index d8e5bcd3..9e4306c8 100644
--- a/src/db/lmdb_adapter.rs
+++ b/src/db/lmdb_adapter.rs
@@ -108,27 +108,28 @@ impl IDb for LmdbDb {
 		}
 	}
 
-	fn remove(&self, tree: usize, key: &[u8]) -> Result<bool> {
-		let tree = self.get_tree(tree)?;
-		let mut tx = self.db.write_txn()?;
-		let deleted = tree.delete(&mut tx, key)?;
-		tx.commit()?;
-		Ok(deleted)
-	}
-
 	fn len(&self, tree: usize) -> Result<usize> {
 		let tree = self.get_tree(tree)?;
 		let tx = self.db.read_txn()?;
 		Ok(tree.len(&tx)?.try_into().unwrap())
 	}
 
-	fn insert(&self, tree: usize, key: &[u8], value: &[u8]) -> Result<bool> {
+	fn insert(&self, tree: usize, key: &[u8], value: &[u8]) -> Result<Option<Value>> {
 		let tree = self.get_tree(tree)?;
 		let mut tx = self.db.write_txn()?;
 		let old_val = tree.get(&tx, key)?.map(Vec::from);
 		tree.put(&mut tx, key, value)?;
 		tx.commit()?;
-		Ok(old_val.is_none())
+		Ok(old_val)
+	}
+
+	fn remove(&self, tree: usize, key: &[u8]) -> Result<Option<Value>> {
+		let tree = self.get_tree(tree)?;
+		let mut tx = self.db.write_txn()?;
+		let old_val = tree.get(&tx, key)?.map(Vec::from);
+		tree.delete(&mut tx, key)?;
+		tx.commit()?;
+		Ok(old_val)
 	}
 
 	fn iter(&self, tree: usize) -> Result<ValueIter<'_>> {
@@ -222,16 +223,17 @@ impl<'a, 'db> ITx for LmdbTx<'a, 'db> {
 		unimplemented!(".len() in transaction not supported with LMDB backend")
 	}
 
-	fn insert(&mut self, tree: usize, key: &[u8], value: &[u8]) -> Result<bool> {
+	fn insert(&mut self, tree: usize, key: &[u8], value: &[u8]) -> Result<Option<Value>> {
 		let tree = *self.get_tree(tree)?;
 		let old_val = tree.get(&self.tx, key)?.map(Vec::from);
 		tree.put(&mut self.tx, key, value)?;
-		Ok(old_val.is_none())
+		Ok(old_val)
 	}
-	fn remove(&mut self, tree: usize, key: &[u8]) -> Result<bool> {
+	fn remove(&mut self, tree: usize, key: &[u8]) -> Result<Option<Value>> {
 		let tree = *self.get_tree(tree)?;
-		let deleted = tree.delete(&mut self.tx, key)?;
-		Ok(deleted)
+		let old_val = tree.get(&self.tx, key)?.map(Vec::from);
+		tree.delete(&mut self.tx, key)?;
+		Ok(old_val)
 	}
 
 	fn iter(&self, _tree: usize) -> Result<ValueIter<'_>> {