src/db/lib.rs

@@ -274,6 +274,11 @@ impl<'a> Transaction<'a> {
 	pub fn remove<T: AsRef<[u8]>>(&mut self, tree: &Tree, key: T) -> TxOpResult<Option<Value>> {
 		self.tx.remove(tree.1, key.as_ref())
 	}
+	/// Clears all values in a tree
+	#[inline]
+	pub fn clear(&mut self, tree: &Tree) -> TxOpResult<()> {
+		self.tx.clear(tree.1)
+	}
 
 	#[inline]
 	pub fn iter(&self, tree: &Tree) -> TxOpResult<TxValueIter<'_>> {
@@ -350,6 +355,7 @@ pub(crate) trait ITx {
 
 	fn insert(&mut self, tree: usize, key: &[u8], value: &[u8]) -> TxOpResult<Option<Value>>;
 	fn remove(&mut self, tree: usize, key: &[u8]) -> TxOpResult<Option<Value>>;
+	fn clear(&mut self, tree: usize) -> TxOpResult<()>;
 
 	fn iter(&self, tree: usize) -> TxOpResult<TxValueIter<'_>>;
 	fn iter_rev(&self, tree: usize) -> TxOpResult<TxValueIter<'_>>;

src/db/lmdb_adapter.rs

@@ -238,8 +238,9 @@ impl<'a> ITx for LmdbTx<'a> {
 			None => Ok(None),
 		}
 	}
-	fn len(&self, _tree: usize) -> TxOpResult<usize> {
+	fn len(&self, tree: usize) -> TxOpResult<usize> {
-		unimplemented!(".len() in transaction not supported with LMDB backend")
+		let tree = self.get_tree(tree)?;
+		Ok(tree.len(&self.tx)? as usize)
 	}
 
 	fn insert(&mut self, tree: usize, key: &[u8], value: &[u8]) -> TxOpResult<Option<Value>> {
@@ -254,6 +255,11 @@ impl<'a> ITx for LmdbTx<'a> {
 		tree.delete(&mut self.tx, key)?;
 		Ok(old_val)
 	}
+	fn clear(&mut self, tree: usize) -> TxOpResult<()> {
+		let tree = *self.get_tree(tree)?;
+		tree.clear(&mut self.tx)?;
+		Ok(())
+	}
 
 	fn iter(&self, _tree: usize) -> TxOpResult<TxValueIter<'_>> {
 		unimplemented!("Iterators in transactions not supported with LMDB backend");

src/db/sqlite_adapter.rs

@@ -363,6 +363,11 @@ impl<'a> ITx for SqliteTx<'a> {
 
 		Ok(old_val)
 	}
+	fn clear(&mut self, tree: usize) -> TxOpResult<()> {
+		let tree = self.get_tree(tree)?;
+		self.tx.execute(&format!("DELETE FROM {}", tree), [])?;
+		Ok(())
+	}
 
 	fn iter(&self, _tree: usize) -> TxOpResult<TxValueIter<'_>> {
 		unimplemented!();