1 files changed, 142 insertions, 42 deletions
diff --git a/src/db/sqlite_adapter.rs b/src/db/sqlite_adapter.rs
index 3eccfdde..a91b9011 100644
--- a/src/db/sqlite_adapter.rs
+++ b/src/db/sqlite_adapter.rs
@@ -169,10 +169,6 @@ impl IDb for SqliteDb {
 		}
 	}
 
-	fn fast_len(&self, tree: usize) -> Result<Option<usize>> {
-		Ok(Some(self.len(tree)?))
-	}
-
 	fn insert(&self, tree: usize, key: &[u8], value: &[u8]) -> Result<Option<Value>> {
 		let tree = self.get_tree(tree)?;
 		let db = self.db.get()?;
@@ -371,33 +367,64 @@ 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!();
+	fn iter(&self, tree: usize) -> TxOpResult<TxValueIter<'_>> {
+		let tree = self.get_tree(tree)?;
+		let sql = format!("SELECT k, v FROM {} ORDER BY k ASC", tree);
+		TxValueIterator::make(self, &sql, [])
 	}
-	fn iter_rev(&self, _tree: usize) -> TxOpResult<TxValueIter<'_>> {
-		unimplemented!();
+	fn iter_rev(&self, tree: usize) -> TxOpResult<TxValueIter<'_>> {
+		let tree = self.get_tree(tree)?;
+		let sql = format!("SELECT k, v FROM {} ORDER BY k DESC", tree);
+		TxValueIterator::make(self, &sql, [])
 	}
 
 	fn range<'r>(
 		&self,
-		_tree: usize,
-		_low: Bound<&'r [u8]>,
-		_high: Bound<&'r [u8]>,
+		tree: usize,
+		low: Bound<&'r [u8]>,
+		high: Bound<&'r [u8]>,
 	) -> TxOpResult<TxValueIter<'_>> {
-		unimplemented!();
+		let tree = self.get_tree(tree)?;
+
+		let (bounds_sql, params) = bounds_sql(low, high);
+		let sql = format!("SELECT k, v FROM {} {} ORDER BY k ASC", tree, bounds_sql);
+
+		let params = params
+			.iter()
+			.map(|x| x as &dyn rusqlite::ToSql)
+			.collect::<Vec<_>>();
+
+		TxValueIterator::make::<&[&dyn rusqlite::ToSql]>(self, &sql, params.as_ref())
 	}
 	fn range_rev<'r>(
 		&self,
-		_tree: usize,
-		_low: Bound<&'r [u8]>,
-		_high: Bound<&'r [u8]>,
+		tree: usize,
+		low: Bound<&'r [u8]>,
+		high: Bound<&'r [u8]>,
 	) -> TxOpResult<TxValueIter<'_>> {
-		unimplemented!();
+		let tree = self.get_tree(tree)?;
+
+		let (bounds_sql, params) = bounds_sql(low, high);
+		let sql = format!("SELECT k, v FROM {} {} ORDER BY k DESC", tree, bounds_sql);
+
+		let params = params
+			.iter()
+			.map(|x| x as &dyn rusqlite::ToSql)
+			.collect::<Vec<_>>();
+
+		TxValueIterator::make::<&[&dyn rusqlite::ToSql]>(self, &sql, params.as_ref())
 	}
 }
 
-// ----
+// ---- iterators outside transactions ----
+// complicated, they must hold the Statement and Row objects
+// therefore quite some unsafe code (it is a self-referential struct)
 
 struct DbValueIterator<'a> {
 	db: Connection,
@@ -417,17 +444,23 @@ impl<'a> DbValueIterator<'a> {
 		let mut boxed = Box::pin(res);
 		trace!("make iterator with sql: {}", sql);
 
-		unsafe {
-			let db = NonNull::from(&boxed.db);
-			let stmt = db.as_ref().prepare(sql)?;
+		// This unsafe allows us to bypass lifetime checks
+		let db = unsafe { NonNull::from(&boxed.db).as_ref() };
+		let stmt = db.prepare(sql)?;
 
-			let mut_ref: Pin<&mut DbValueIterator<'a>> = Pin::as_mut(&mut boxed);
+		let mut_ref = Pin::as_mut(&mut boxed);
+		// This unsafe allows us to write in a field of the pinned struct
+		unsafe {
 			Pin::get_unchecked_mut(mut_ref).stmt = Some(stmt);
+		}
 
-			let mut stmt = NonNull::from(&boxed.stmt);
-			let iter = stmt.as_mut().as_mut().unwrap().query(args)?;
+		// This unsafe allows us to bypass lifetime checks
+		let stmt = unsafe { NonNull::from(&boxed.stmt).as_mut() };
+		let iter = stmt.as_mut().unwrap().query(args)?;
 
-			let mut_ref: Pin<&mut DbValueIterator<'a>> = Pin::as_mut(&mut boxed);
+		let mut_ref = Pin::as_mut(&mut boxed);
+		// This unsafe allows us to write in a field of the pinned struct
+		unsafe {
 			Pin::get_unchecked_mut(mut_ref).iter = Some(iter);
 		}
 
@@ -449,28 +482,73 @@ impl<'a> Iterator for DbValueIteratorPin<'a> {
 	type Item = Result<(Value, Value)>;
 
 	fn next(&mut self) -> Option<Self::Item> {
-		let next = unsafe {
-			let mut_ref: Pin<&mut DbValueIterator<'a>> = Pin::as_mut(&mut self.0);
-			Pin::get_unchecked_mut(mut_ref).iter.as_mut()?.next()
-		};
-		let row = match next {
-			Err(e) => return Some(Err(e.into())),
-			Ok(None) => return None,
-			Ok(Some(r)) => r,
-		};
-		let k = match row.get::<_, Vec<u8>>(0) {
-			Err(e) => return Some(Err(e.into())),
-			Ok(x) => x,
-		};
-		let v = match row.get::<_, Vec<u8>>(1) {
-			Err(e) => return Some(Err(e.into())),
-			Ok(y) => y,
+		let mut_ref = Pin::as_mut(&mut self.0);
+		// This unsafe allows us to mutably access the iterator field
+		let next = unsafe { Pin::get_unchecked_mut(mut_ref).iter.as_mut()?.next() };
+		iter_next_row(next)
+	}
+}
+
+// ---- iterators within transactions ----
+// it's the same except we don't hold a mutex guard,
+// only a Statement and a Rows object
+
+struct TxValueIterator<'a> {
+	stmt: Statement<'a>,
+	iter: Option<Rows<'a>>,
+	_pin: PhantomPinned,
+}
+
+impl<'a> TxValueIterator<'a> {
+	fn make<P: rusqlite::Params>(
+		tx: &'a SqliteTx<'a>,
+		sql: &str,
+		args: P,
+	) -> TxOpResult<TxValueIter<'a>> {
+		let stmt = tx.tx.prepare(sql)?;
+		let res = TxValueIterator {
+			stmt,
+			iter: None,
+			_pin: PhantomPinned,
 		};
-		Some(Ok((k, v)))
+		let mut boxed = Box::pin(res);
+		trace!("make iterator with sql: {}", sql);
+
+		// This unsafe allows us to bypass lifetime checks
+		let stmt = unsafe { NonNull::from(&boxed.stmt).as_mut() };
+		let iter = stmt.query(args)?;
+
+		let mut_ref = Pin::as_mut(&mut boxed);
+		// This unsafe allows us to write in a field of the pinned struct
+		unsafe {
+			Pin::get_unchecked_mut(mut_ref).iter = Some(iter);
+		}
+
+		Ok(Box::new(TxValueIteratorPin(boxed)))
 	}
 }
 
-// ----
+impl<'a> Drop for TxValueIterator<'a> {
+	fn drop(&mut self) {
+		trace!("drop iter");
+		drop(self.iter.take());
+	}
+}
+
+struct TxValueIteratorPin<'a>(Pin<Box<TxValueIterator<'a>>>);
+
+impl<'a> Iterator for TxValueIteratorPin<'a> {
+	type Item = TxOpResult<(Value, Value)>;
+
+	fn next(&mut self) -> Option<Self::Item> {
+		let mut_ref = Pin::as_mut(&mut self.0);
+		// This unsafe allows us to mutably access the iterator field
+		let next = unsafe { Pin::get_unchecked_mut(mut_ref).iter.as_mut()?.next() };
+		iter_next_row(next)
+	}
+}
+
+// ---- utility ----
 
 fn bounds_sql<'r>(low: Bound<&'r [u8]>, high: Bound<&'r [u8]>) -> (String, Vec<Vec<u8>>) {
 	let mut sql = String::new();
@@ -510,3 +588,25 @@ fn bounds_sql<'r>(low: Bound<&'r [u8]>, high: Bound<&'r [u8]>) -> (String, Vec<V
 
 	(sql, params)
 }
+
+fn iter_next_row<E>(
+	next_row: rusqlite::Result<Option<&rusqlite::Row>>,
+) -> Option<std::result::Result<(Value, Value), E>>
+where
+	E: From<rusqlite::Error>,
+{
+	let row = match next_row {
+		Err(e) => return Some(Err(e.into())),
+		Ok(None) => return None,
+		Ok(Some(r)) => r,
+	};
+	let k = match row.get::<_, Vec<u8>>(0) {
+		Err(e) => return Some(Err(e.into())),
+		Ok(x) => x,
+	};
+	let v = match row.get::<_, Vec<u8>>(1) {
+		Err(e) => return Some(Err(e.into())),
+		Ok(y) => y,
+	};
+	Some(Ok((k, v)))
+}