Add TypedTree

src/db/fjall_adapter.rs

@@ -12,7 +12,7 @@ use fjall::{
 
 use crate::{
 	open::{Engine, OpenOpt},
-	Db, Error, IDb, ITx, ITxFn, OnCommit, Result, TxError, TxFnResult, TxOpError, TxOpResult,
+	Db, DbError, DbResult, Error, IDb, ITx, ITxFn, OnCommit, TxError, TxFnResult, TxOpError,
 	TxResult, TxValueIter, Value, ValueIter,
 };
 
@@ -20,10 +20,10 @@ pub use fjall;
 
 // --
 
-pub(crate) fn open_db(path: &Path, opt: &OpenOpt) -> Result<Db> {
+pub(crate) fn open_db(path: &Path, opt: &OpenOpt) -> DbResult<Db> {
 	info!("Opening Fjall database at: {}", path.display());
 	if opt.fsync {
-		return Err(Error(
+		return Err(DbError(
 			"metadata_fsync is not supported with the Fjall database engine".into(),
 		));
 	}
@@ -37,21 +37,27 @@ pub(crate) fn open_db(path: &Path, opt: &OpenOpt) -> Result<Db> {
 
 // -- err
 
-impl From<fjall::Error> for Error {
-	fn from(e: fjall::Error) -> Error {
-		Error(format!("fjall: {}", e).into())
+impl From<fjall::Error> for DbError {
+	fn from(e: fjall::Error) -> DbError {
+		DbError(format!("fjall: {}", e).into())
 	}
 }
 
-impl From<fjall::LsmError> for Error {
-	fn from(e: fjall::LsmError) -> Error {
-		Error(format!("fjall lsm_tree: {}", e).into())
+impl From<fjall::LsmError> for DbError {
+	fn from(e: fjall::LsmError) -> DbError {
+		DbError(format!("fjall lsm_tree: {}", e).into())
+	}
+}
+
+impl From<fjall::Error> for Error {
+	fn from(e: fjall::Error) -> Error {
+		Error::Db(DbError::from(e))
 	}
 }
 
 impl From<fjall::Error> for TxOpError {
 	fn from(e: fjall::Error) -> TxOpError {
-		TxOpError(e.into())
+		DbError::from(e).into()
 	}
 }
 
@@ -76,11 +82,11 @@ impl FjallDb {
 	fn get_tree(
 		&self,
 		i: usize,
-	) -> Result<MappedRwLockReadGuard<'_, TransactionalPartitionHandle>> {
+	) -> DbResult<MappedRwLockReadGuard<'_, TransactionalPartitionHandle>> {
 		RwLockReadGuard::try_map(self.trees.read(), |trees: &Vec<_>| {
 			trees.get(i).map(|tup| &tup.1)
 		})
-		.map_err(|_| Error("invalid tree id".into()))
+		.map_err(|_| DbError("invalid tree id".into()))
 	}
 }
 
@@ -89,7 +95,7 @@ impl IDb for FjallDb {
 		"Fjall (EXPERIMENTAL!)".into()
 	}
 
-	fn open_tree(&self, name: &str) -> Result<usize> {
+	fn open_tree(&self, name: &str) -> DbResult<usize> {
 		let mut trees = self.trees.write();
 		let safe_name = encode_name(name)?;
 		if let Some(i) = trees.iter().position(|(name, _)| *name == safe_name) {
@@ -104,15 +110,15 @@ impl IDb for FjallDb {
 		}
 	}
 
-	fn list_trees(&self) -> Result<Vec<String>> {
+	fn list_trees(&self) -> DbResult<Vec<String>> {
 		self.keyspace
 			.list_partitions()
 			.iter()
 			.map(|n| decode_name(n))
-			.collect::<Result<Vec<_>>>()
+			.collect::<DbResult<Vec<_>>>()
 	}
 
-	fn snapshot(&self, base_path: &Path) -> Result<()> {
+	fn snapshot(&self, base_path: &Path) -> DbResult<()> {
 		std::fs::create_dir_all(base_path)?;
 		let path = Engine::Fjall.db_path(base_path);
 
@@ -138,7 +144,7 @@ impl IDb for FjallDb {
 
 	// ----
 
-	fn get(&self, tree_idx: usize, key: &[u8]) -> Result<Option<Value>> {
+	fn get(&self, tree_idx: usize, key: &[u8]) -> DbResult<Option<Value>> {
 		let tree = self.get_tree(tree_idx)?;
 		let tx = self.keyspace.read_tx();
 		let val = tx.get(&tree, key)?;
@@ -148,17 +154,17 @@ impl IDb for FjallDb {
 		}
 	}
 
-	fn approximate_len(&self, tree_idx: usize) -> Result<usize> {
+	fn approximate_len(&self, tree_idx: usize) -> DbResult<usize> {
 		let tree = self.get_tree(tree_idx)?;
 		Ok(tree.approximate_len())
 	}
-	fn is_empty(&self, tree_idx: usize) -> Result<bool> {
+	fn is_empty(&self, tree_idx: usize) -> DbResult<bool> {
 		let tree = self.get_tree(tree_idx)?;
 		let tx = self.keyspace.read_tx();
 		Ok(tx.is_empty(&tree)?)
 	}
 
-	fn insert(&self, tree_idx: usize, key: &[u8], value: &[u8]) -> Result<()> {
+	fn insert(&self, tree_idx: usize, key: &[u8], value: &[u8]) -> DbResult<()> {
 		let tree = self.get_tree(tree_idx)?;
 		let mut tx = self.keyspace.write_tx();
 		tx.insert(&tree, key, value);
@@ -166,7 +172,7 @@ impl IDb for FjallDb {
 		Ok(())
 	}
 
-	fn remove(&self, tree_idx: usize, key: &[u8]) -> Result<()> {
+	fn remove(&self, tree_idx: usize, key: &[u8]) -> DbResult<()> {
 		let tree = self.get_tree(tree_idx)?;
 		let mut tx = self.keyspace.write_tx();
 		tx.remove(&tree, key);
@@ -174,11 +180,11 @@ impl IDb for FjallDb {
 		Ok(())
 	}
 
-	fn clear(&self, tree_idx: usize) -> Result<()> {
+	fn clear(&self, tree_idx: usize) -> DbResult<()> {
 		let mut trees = self.trees.write();
 
 		if tree_idx >= trees.len() {
-			return Err(Error("invalid tree id".into()));
+			return Err(DbError("invalid tree id".into()));
 		}
 		let (name, tree) = trees.remove(tree_idx);
 
@@ -191,13 +197,13 @@ impl IDb for FjallDb {
 		Ok(())
 	}
 
-	fn iter(&self, tree_idx: usize) -> Result<ValueIter<'_>> {
+	fn iter(&self, tree_idx: usize) -> DbResult<ValueIter<'_>> {
 		let tree = self.get_tree(tree_idx)?;
 		let tx = self.keyspace.read_tx();
 		Ok(Box::new(tx.iter(&tree).map(iterator_remap)))
 	}
 
-	fn iter_rev(&self, tree_idx: usize) -> Result<ValueIter<'_>> {
+	fn iter_rev(&self, tree_idx: usize) -> DbResult<ValueIter<'_>> {
 		let tree = self.get_tree(tree_idx)?;
 		let tx = self.keyspace.read_tx();
 		Ok(Box::new(tx.iter(&tree).rev().map(iterator_remap)))
@@ -208,7 +214,7 @@ impl IDb for FjallDb {
 		tree_idx: usize,
 		low: Bound<&'r [u8]>,
 		high: Bound<&'r [u8]>,
-	) -> Result<ValueIter<'_>> {
+	) -> DbResult<ValueIter<'_>> {
 		let tree = self.get_tree(tree_idx)?;
 		let tx = self.keyspace.read_tx();
 		Ok(Box::new(
@@ -221,7 +227,7 @@ impl IDb for FjallDb {
 		tree_idx: usize,
 		low: Bound<&'r [u8]>,
 		high: Bound<&'r [u8]>,
-	) -> Result<ValueIter<'_>> {
+	) -> DbResult<ValueIter<'_>> {
 		let tree = self.get_tree(tree_idx)?;
 		let tx = self.keyspace.read_tx();
 		Ok(Box::new(
@@ -252,9 +258,9 @@ impl IDb for FjallDb {
 			}
 			TxFnResult::DbErr => {
 				tx.tx.rollback();
-				Err(TxError::Db(Error(
-					"(this message will be discarded)".into(),
-				)))
+				Err(TxError::Db(
+					DbError("(this message will be discarded)".into()).into(),
+				))
 			}
 		}
 	}
@@ -268,47 +274,47 @@ struct FjallTx<'a> {
 }
 
 impl<'a> FjallTx<'a> {
-	fn get_tree(&self, i: usize) -> TxOpResult<&TransactionalPartitionHandle> {
+	fn get_tree(&self, i: usize) -> DbResult<&TransactionalPartitionHandle> {
 		self.trees.get(i).map(|tup| &tup.1).ok_or_else(|| {
-			TxOpError(Error(
+			DbError(
 				"invalid tree id (it might have been opened after the transaction started)".into(),
-			))
+			)
 		})
 	}
 }
 
 impl<'a> ITx for FjallTx<'a> {
-	fn get(&self, tree_idx: usize, key: &[u8]) -> TxOpResult<Option<Value>> {
+	fn get(&self, tree_idx: usize, key: &[u8]) -> DbResult<Option<Value>> {
 		let tree = self.get_tree(tree_idx)?;
 		match self.tx.get(tree, key)? {
 			Some(v) => Ok(Some(v.to_vec())),
 			None => Ok(None),
 		}
 	}
-	fn len(&self, tree_idx: usize) -> TxOpResult<usize> {
+	fn len(&self, tree_idx: usize) -> DbResult<usize> {
 		let tree = self.get_tree(tree_idx)?;
 		Ok(self.tx.len(tree)?)
 	}
 
-	fn insert(&mut self, tree_idx: usize, key: &[u8], value: &[u8]) -> TxOpResult<()> {
+	fn insert(&mut self, tree_idx: usize, key: &[u8], value: &[u8]) -> DbResult<()> {
 		let tree = self.get_tree(tree_idx)?.clone();
 		self.tx.insert(&tree, key, value);
 		Ok(())
 	}
-	fn remove(&mut self, tree_idx: usize, key: &[u8]) -> TxOpResult<()> {
+	fn remove(&mut self, tree_idx: usize, key: &[u8]) -> DbResult<()> {
 		let tree = self.get_tree(tree_idx)?.clone();
 		self.tx.remove(&tree, key);
 		Ok(())
 	}
-	fn clear(&mut self, _tree_idx: usize) -> TxOpResult<()> {
+	fn clear(&mut self, _tree_idx: usize) -> DbResult<()> {
 		unimplemented!("LSM tree clearing in cross-partition transaction is not supported")
 	}
 
-	fn iter(&self, tree_idx: usize) -> TxOpResult<TxValueIter<'_>> {
+	fn iter(&self, tree_idx: usize) -> DbResult<TxValueIter<'_>> {
 		let tree = self.get_tree(tree_idx)?.clone();
 		Ok(Box::new(self.tx.iter(&tree).map(iterator_remap_tx)))
 	}
-	fn iter_rev(&self, tree_idx: usize) -> TxOpResult<TxValueIter<'_>> {
+	fn iter_rev(&self, tree_idx: usize) -> DbResult<TxValueIter<'_>> {
 		let tree = self.get_tree(tree_idx)?.clone();
 		Ok(Box::new(self.tx.iter(&tree).rev().map(iterator_remap_tx)))
 	}
@@ -318,7 +324,7 @@ impl<'a> ITx for FjallTx<'a> {
 		tree_idx: usize,
 		low: Bound<&'r [u8]>,
 		high: Bound<&'r [u8]>,
-	) -> TxOpResult<TxValueIter<'_>> {
+	) -> DbResult<TxValueIter<'_>> {
 		let tree = self.get_tree(tree_idx)?;
 		let low = clone_bound(low);
 		let high = clone_bound(high);
@@ -333,7 +339,7 @@ impl<'a> ITx for FjallTx<'a> {
 		tree_idx: usize,
 		low: Bound<&'r [u8]>,
 		high: Bound<&'r [u8]>,
-	) -> TxOpResult<TxValueIter<'_>> {
+	) -> DbResult<TxValueIter<'_>> {
 		let tree = self.get_tree(tree_idx)?;
 		let low = clone_bound(low);
 		let high = clone_bound(high);
@@ -348,14 +354,14 @@ impl<'a> ITx for FjallTx<'a> {
 
 // -- maps fjall's (k, v) to ours
 
-fn iterator_remap(r: fjall::Result<(fjall::Slice, fjall::Slice)>) -> Result<(Value, Value)> {
+fn iterator_remap(r: fjall::Result<(fjall::Slice, fjall::Slice)>) -> DbResult<(Value, Value)> {
 	r.map(|(k, v)| (k.to_vec(), v.to_vec()))
-		.map_err(|e| e.into())
+		.map_err(DbError::from)
 }
 
-fn iterator_remap_tx(r: fjall::Result<(fjall::Slice, fjall::Slice)>) -> TxOpResult<(Value, Value)> {
+fn iterator_remap_tx(r: fjall::Result<(fjall::Slice, fjall::Slice)>) -> DbResult<(Value, Value)> {
 	r.map(|(k, v)| (k.to_vec(), v.to_vec()))
-		.map_err(|e| e.into())
+		.map_err(DbError::from)
 }
 
 // -- utils to deal with Garage's tightness on Bound lifetimes
@@ -378,7 +384,7 @@ fn clone_bound(bound: Bound<&[u8]>) -> ByteVecBound {
 
 // -- utils to encode table names --
 
-fn encode_name(s: &str) -> Result<String> {
+fn encode_name(s: &str) -> DbResult<String> {
 	let base = 'A' as u32;
 
 	let mut ret = String::with_capacity(s.len() + 10);
@@ -392,7 +398,7 @@ fn encode_name(s: &str) -> Result<String> {
 			ret.push(char::from_u32(base + c_hi).unwrap());
 			ret.push(char::from_u32(base + c_lo).unwrap());
 		} else {
-			return Err(Error(
+			return Err(DbError(
 				format!("table name {} could not be safely encoded", s).into(),
 			));
 		}
@@ -400,10 +406,10 @@ fn encode_name(s: &str) -> Result<String> {
 	Ok(ret)
 }
 
-fn decode_name(s: &str) -> Result<String> {
+fn decode_name(s: &str) -> DbResult<String> {
 	use std::convert::TryFrom;
 
-	let errfn = || Error(format!("encoded table name {} is invalid", s).into());
+	let errfn = || DbError(format!("encoded table name {} is invalid", s).into());
 	let c_map = |c: char| {
 		let c = c as u32;
 		let base = 'A' as u32;

src/db/lib.rs

@@ -9,6 +9,7 @@ pub mod lmdb_adapter;
 pub mod sqlite_adapter;
 
 pub mod open;
+pub mod typed;
 
 #[cfg(test)]
 pub mod test;
@@ -23,6 +24,7 @@ use std::sync::Arc;
 use thiserror::Error;
 
 pub use open::*;
+pub use typed::{DbBytes, DbOrdKey, TypedIter, TypedTree, TypedTxIter};
 
 pub(crate) type OnCommit = Vec<Box<dyn FnOnce()>>;
 
@@ -38,21 +40,34 @@ pub struct Transaction<'a> {
 pub struct Tree(Arc<dyn IDb>, usize);
 
 pub type Value = Vec<u8>;
-pub type ValueIter<'a> = Box<dyn std::iter::Iterator<Item = Result<(Value, Value)>> + 'a>;
-pub type TxValueIter<'a> = Box<dyn std::iter::Iterator<Item = TxOpResult<(Value, Value)>> + 'a>;
+pub type ValueIter<'a> = Box<dyn std::iter::Iterator<Item = DbResult<(Value, Value)>> + 'a>;
+pub type TxValueIter<'a> = Box<dyn std::iter::Iterator<Item = DbResult<(Value, Value)>> + 'a>;
 
 // ----
 
 #[derive(Debug, Error)]
-#[error("{0}")]
-pub struct Error(pub Cow<'static, str>);
+#[error("database error: {0}")]
+pub struct DbError(pub Cow<'static, str>);
 
-impl From<std::io::Error> for Error {
-	fn from(e: std::io::Error) -> Error {
-		Error(format!("IO: {}", e).into())
+#[derive(Debug, Error)]
+#[error("decode error: {0}")]
+pub struct DecodeError(pub Cow<'static, str>);
+
+#[derive(Debug, Error)]
+pub enum Error {
+	#[error(transparent)]
+	Db(#[from] DbError),
+	#[error(transparent)]
+	Decode(#[from] DecodeError),
+}
+
+impl From<std::io::Error> for DbError {
+	fn from(e: std::io::Error) -> DbError {
+		DbError(format!("IO: {}", e).into())
 	}
 }
 
+pub type DbResult<T> = std::result::Result<T, DbError>;
 pub type Result<T> = std::result::Result<T, Error>;
 
 #[derive(Debug, Error)]
@@ -60,6 +75,18 @@ pub type Result<T> = std::result::Result<T, Error>;
 pub struct TxOpError(pub(crate) Error);
 pub type TxOpResult<T> = std::result::Result<T, TxOpError>;
 
+impl From<DbError> for TxOpError {
+	fn from(e: DbError) -> TxOpError {
+		TxOpError(e.into())
+	}
+}
+
+impl From<DecodeError> for TxOpError {
+	fn from(e: DecodeError) -> TxOpError {
+		TxOpError(e.into())
+	}
+}
+
 #[derive(Debug)]
 pub enum TxError<E> {
 	Abort(E),
@@ -73,6 +100,12 @@ impl<E> From<TxOpError> for TxError<E> {
 	}
 }
 
+impl<E> From<DbError> for TxError<E> {
+	fn from(e: DbError) -> TxError<E> {
+		TxError::Db(e.into())
+	}
+}
+
 pub fn unabort<R, E>(res: TxResult<R, E>) -> TxOpResult<std::result::Result<R, E>> {
 	match res {
 		Ok(v) => Ok(Ok(v)),
@@ -88,12 +121,12 @@ impl Db {
 		self.0.engine()
 	}
 
-	pub fn open_tree<S: AsRef<str>>(&self, name: S) -> Result<Tree> {
+	pub fn open_tree<S: AsRef<str>>(&self, name: S) -> DbResult<Tree> {
 		let tree_id = self.0.open_tree(name.as_ref())?;
 		Ok(Tree(self.0.clone(), tree_id))
 	}
 
-	pub fn list_trees(&self) -> Result<Vec<String>> {
+	pub fn list_trees(&self) -> DbResult<Vec<String>> {
 		self.0.list_trees()
 	}
 
@@ -147,27 +180,28 @@ impl Db {
 		}
 	}
 
-	pub fn snapshot(&self, path: &Path) -> Result<()> {
+	pub fn snapshot(&self, path: &Path) -> DbResult<()> {
 		self.0.snapshot(path)
 	}
 
 	pub fn import(&self, other: &Db) -> Result<()> {
 		let existing_trees = self.list_trees()?;
 		if !existing_trees.is_empty() {
-			return Err(Error(
+			return Err(DbError(
 				format!(
 					"destination database already contains data: {:?}",
 					existing_trees
 				)
 				.into(),
-			));
+			)
+			.into());
 		}
 
 		let tree_names = other.list_trees()?;
 		for name in tree_names {
 			let tree = self.open_tree(&name)?;
 			if !tree.is_empty()? {
-				return Err(Error(format!("tree {} already contains data", name).into()));
+				return Err(DbError(format!("tree {} already contains data", name).into()).into());
 			}
 
 			let ex_tree = other.open_tree(&name)?;
@@ -186,7 +220,7 @@ impl Db {
 			});
 			let total = match tx_res {
 				Err(TxError::Db(e)) => return Err(e),
-				Err(TxError::Abort(e)) => return Err(e),
+				Err(TxError::Abort(e)) => return Err(e.into()),
 				Ok(x) => x,
 			};
 
@@ -204,24 +238,24 @@ impl Tree {
 	}
 
 	#[inline]
-	pub fn get<T: AsRef<[u8]>>(&self, key: T) -> Result<Option<Value>> {
+	pub fn get<T: AsRef<[u8]>>(&self, key: T) -> DbResult<Option<Value>> {
 		self.0.get(self.1, key.as_ref())
 	}
 	#[inline]
-	pub fn approximate_len(&self) -> Result<usize> {
+	pub fn approximate_len(&self) -> DbResult<usize> {
 		self.0.approximate_len(self.1)
 	}
 	#[inline]
-	pub fn is_empty(&self) -> Result<bool> {
+	pub fn is_empty(&self) -> DbResult<bool> {
 		self.0.is_empty(self.1)
 	}
 
 	#[inline]
-	pub fn first(&self) -> Result<Option<(Value, Value)>> {
+	pub fn first(&self) -> DbResult<Option<(Value, Value)>> {
 		self.iter()?.next().transpose()
 	}
 	#[inline]
-	pub fn get_gt<T: AsRef<[u8]>>(&self, from: T) -> Result<Option<(Value, Value)>> {
+	pub fn get_gt<T: AsRef<[u8]>>(&self, from: T) -> DbResult<Option<(Value, Value)>> {
 		if from.as_ref().is_empty() {
 			self.iter()?.next().transpose()
 		} else {
@@ -233,31 +267,31 @@ impl Tree {
 
 	/// Returns the old value if there was one
 	#[inline]
-	pub fn insert<T: AsRef<[u8]>, U: AsRef<[u8]>>(&self, key: T, value: U) -> Result<()> {
+	pub fn insert<T: AsRef<[u8]>, U: AsRef<[u8]>>(&self, key: T, value: U) -> DbResult<()> {
 		self.0.insert(self.1, key.as_ref(), value.as_ref())
 	}
 	/// Returns the old value if there was one
 	#[inline]
-	pub fn remove<T: AsRef<[u8]>>(&self, key: T) -> Result<()> {
+	pub fn remove<T: AsRef<[u8]>>(&self, key: T) -> DbResult<()> {
 		self.0.remove(self.1, key.as_ref())
 	}
 	/// Clears all values from the tree
 	#[inline]
-	pub fn clear(&self) -> Result<()> {
+	pub fn clear(&self) -> DbResult<()> {
 		self.0.clear(self.1)
 	}
 
 	#[inline]
-	pub fn iter(&self) -> Result<ValueIter<'_>> {
+	pub fn iter(&self) -> DbResult<ValueIter<'_>> {
 		self.0.iter(self.1)
 	}
 	#[inline]
-	pub fn iter_rev(&self) -> Result<ValueIter<'_>> {
+	pub fn iter_rev(&self) -> DbResult<ValueIter<'_>> {
 		self.0.iter_rev(self.1)
 	}
 
 	#[inline]
-	pub fn range<K, R>(&self, range: R) -> Result<ValueIter<'_>>
+	pub fn range<K, R>(&self, range: R) -> DbResult<ValueIter<'_>>
 	where
 		K: AsRef<[u8]>,
 		R: RangeBounds<K>,
@@ -267,7 +301,7 @@ impl Tree {
 		self.0.range(self.1, get_bound(sb), get_bound(eb))
 	}
 	#[inline]
-	pub fn range_rev<K, R>(&self, range: R) -> Result<ValueIter<'_>>
+	pub fn range_rev<K, R>(&self, range: R) -> DbResult<ValueIter<'_>>
 	where
 		K: AsRef<[u8]>,
 		R: RangeBounds<K>,
@@ -282,11 +316,11 @@ impl Tree {
 impl<'a> Transaction<'a> {
 	#[inline]
 	pub fn get<T: AsRef<[u8]>>(&self, tree: &Tree, key: T) -> TxOpResult<Option<Value>> {
-		self.tx.get(tree.1, key.as_ref())
+		self.tx.get(tree.1, key.as_ref()).map_err(Into::into)
 	}
 	#[inline]
 	pub fn len(&self, tree: &Tree) -> TxOpResult<usize> {
-		self.tx.len(tree.1)
+		self.tx.len(tree.1).map_err(Into::into)
 	}
 
 	/// Returns the old value if there was one
@@ -297,26 +331,28 @@ impl<'a> Transaction<'a> {
 		key: T,
 		value: U,
 	) -> TxOpResult<()> {
-		self.tx.insert(tree.1, key.as_ref(), value.as_ref())
+		self.tx
+			.insert(tree.1, key.as_ref(), value.as_ref())
+			.map_err(Into::into)
 	}
 	/// Returns the old value if there was one
 	#[inline]
 	pub fn remove<T: AsRef<[u8]>>(&mut self, tree: &Tree, key: T) -> TxOpResult<()> {
-		self.tx.remove(tree.1, key.as_ref())
+		self.tx.remove(tree.1, key.as_ref()).map_err(Into::into)
 	}
 	/// Clears all values in a tree
 	#[inline]
 	pub fn clear(&mut self, tree: &Tree) -> TxOpResult<()> {
-		self.tx.clear(tree.1)
+		self.tx.clear(tree.1).map_err(Into::into)
 	}
 
 	#[inline]
 	pub fn iter(&self, tree: &Tree) -> TxOpResult<TxValueIter<'_>> {
-		self.tx.iter(tree.1)
+		self.tx.iter(tree.1).map_err(Into::into)
 	}
 	#[inline]
 	pub fn iter_rev(&self, tree: &Tree) -> TxOpResult<TxValueIter<'_>> {
-		self.tx.iter_rev(tree.1)
+		self.tx.iter_rev(tree.1).map_err(Into::into)
 	}
 
 	#[inline]
@@ -327,7 +363,9 @@ impl<'a> Transaction<'a> {
 	{
 		let sb = range.start_bound();
 		let eb = range.end_bound();
-		self.tx.range(tree.1, get_bound(sb), get_bound(eb))
+		self.tx
+			.range(tree.1, get_bound(sb), get_bound(eb))
+			.map_err(Into::into)
 	}
 	#[inline]
 	pub fn range_rev<K, R>(&self, tree: &Tree, range: R) -> TxOpResult<TxValueIter<'_>>
@@ -337,7 +375,9 @@ impl<'a> Transaction<'a> {
 	{
 		let sb = range.start_bound();
 		let eb = range.end_bound();
-		self.tx.range_rev(tree.1, get_bound(sb), get_bound(eb))
+		self.tx
+			.range_rev(tree.1, get_bound(sb), get_bound(eb))
+			.map_err(Into::into)
 	}
 
 	#[inline]
@@ -350,60 +390,60 @@ impl<'a> Transaction<'a> {
 
 pub(crate) trait IDb: Send + Sync {
 	fn engine(&self) -> String;
-	fn open_tree(&self, name: &str) -> Result<usize>;
-	fn list_trees(&self) -> Result<Vec<String>>;
-	fn snapshot(&self, path: &Path) -> Result<()>;
+	fn open_tree(&self, name: &str) -> DbResult<usize>;
+	fn list_trees(&self) -> DbResult<Vec<String>>;
+	fn snapshot(&self, path: &Path) -> DbResult<()>;
 
-	fn get(&self, tree: usize, key: &[u8]) -> Result<Option<Value>>;
-	fn approximate_len(&self, tree: usize) -> Result<usize>;
-	fn is_empty(&self, tree: usize) -> Result<bool>;
+	fn get(&self, tree: usize, key: &[u8]) -> DbResult<Option<Value>>;
+	fn approximate_len(&self, tree: usize) -> DbResult<usize>;
+	fn is_empty(&self, tree: usize) -> DbResult<bool>;
 
-	fn insert(&self, tree: usize, key: &[u8], value: &[u8]) -> Result<()>;
-	fn remove(&self, tree: usize, key: &[u8]) -> Result<()>;
-	fn clear(&self, tree: usize) -> Result<()>;
+	fn insert(&self, tree: usize, key: &[u8], value: &[u8]) -> DbResult<()>;
+	fn remove(&self, tree: usize, key: &[u8]) -> DbResult<()>;
+	fn clear(&self, tree: usize) -> DbResult<()>;
 
-	fn iter(&self, tree: usize) -> Result<ValueIter<'_>>;
-	fn iter_rev(&self, tree: usize) -> Result<ValueIter<'_>>;
+	fn iter(&self, tree: usize) -> DbResult<ValueIter<'_>>;
+	fn iter_rev(&self, tree: usize) -> DbResult<ValueIter<'_>>;
 
 	fn range<'r>(
 		&self,
 		tree: usize,
 		low: Bound<&'r [u8]>,
 		high: Bound<&'r [u8]>,
-	) -> Result<ValueIter<'_>>;
+	) -> DbResult<ValueIter<'_>>;
 	fn range_rev<'r>(
 		&self,
 		tree: usize,
 		low: Bound<&'r [u8]>,
 		high: Bound<&'r [u8]>,
-	) -> Result<ValueIter<'_>>;
+	) -> DbResult<ValueIter<'_>>;
 
 	fn transaction(&self, f: &dyn ITxFn) -> TxResult<OnCommit, ()>;
 }
 
 pub(crate) trait ITx {
-	fn get(&self, tree: usize, key: &[u8]) -> TxOpResult<Option<Value>>;
-	fn len(&self, tree: usize) -> TxOpResult<usize>;
+	fn get(&self, tree: usize, key: &[u8]) -> DbResult<Option<Value>>;
+	fn len(&self, tree: usize) -> DbResult<usize>;
 
-	fn insert(&mut self, tree: usize, key: &[u8], value: &[u8]) -> TxOpResult<()>;
-	fn remove(&mut self, tree: usize, key: &[u8]) -> TxOpResult<()>;
-	fn clear(&mut self, tree: usize) -> TxOpResult<()>;
+	fn insert(&mut self, tree: usize, key: &[u8], value: &[u8]) -> DbResult<()>;
+	fn remove(&mut self, tree: usize, key: &[u8]) -> DbResult<()>;
+	fn clear(&mut self, tree: usize) -> DbResult<()>;
 
-	fn iter(&self, tree: usize) -> TxOpResult<TxValueIter<'_>>;
-	fn iter_rev(&self, tree: usize) -> TxOpResult<TxValueIter<'_>>;
+	fn iter(&self, tree: usize) -> DbResult<TxValueIter<'_>>;
+	fn iter_rev(&self, tree: usize) -> DbResult<TxValueIter<'_>>;
 
 	fn range<'r>(
 		&self,
 		tree: usize,
 		low: Bound<&'r [u8]>,
 		high: Bound<&'r [u8]>,
-	) -> TxOpResult<TxValueIter<'_>>;
+	) -> DbResult<TxValueIter<'_>>;
 	fn range_rev<'r>(
 		&self,
 		tree: usize,
 		low: Bound<&'r [u8]>,
 		high: Bound<&'r [u8]>,
-	) -> TxOpResult<TxValueIter<'_>>;
+	) -> DbResult<TxValueIter<'_>>;
 }
 
 pub(crate) trait ITxFn {

src/db/lmdb_adapter.rs

@@ -14,7 +14,7 @@ type Database = heed::Database<Bytes, Bytes>;
 
 use crate::{
 	open::{Engine, OpenOpt},
-	Db, Error, IDb, ITx, ITxFn, OnCommit, Result, TxError, TxFnResult, TxOpError, TxOpResult,
+	Db, DbError, DbResult, Error, IDb, ITx, ITxFn, OnCommit, TxError, TxFnResult, TxOpError,
 	TxResult, TxValueIter, Value, ValueIter,
 };
 
@@ -22,10 +22,10 @@ pub use heed;
 
 // ---- top-level open function
 
-pub(crate) fn open_db(path: &PathBuf, opt: &OpenOpt) -> Result<Db> {
+pub(crate) fn open_db(path: &PathBuf, opt: &OpenOpt) -> DbResult<Db> {
 	info!("Opening LMDB database at: {}", path.display());
 	if let Err(e) = std::fs::create_dir_all(path) {
-		return Err(Error(
+		return Err(DbError(
 			format!("Unable to create LMDB data directory: {}", e).into(),
 		));
 	}
@@ -48,7 +48,7 @@ pub(crate) fn open_db(path: &PathBuf, opt: &OpenOpt) -> Result<Db> {
 		env_builder.open(path)
 	};
 	match open_res {
-		Err(heed::Error::Io(e)) if e.kind() == std::io::ErrorKind::OutOfMemory => Err(Error(
+		Err(heed::Error::Io(e)) if e.kind() == std::io::ErrorKind::OutOfMemory => Err(DbError(
 			"OutOfMemory error while trying to open LMDB database. This can happen \
                 if your operating system is not allowing you to use sufficient virtual \
                 memory address space. Please check that no limit is set (ulimit -v). \
@@ -56,22 +56,28 @@ pub(crate) fn open_db(path: &PathBuf, opt: &OpenOpt) -> Result<Db> {
                 On 32-bit machines, you should probably switch to another database engine."
 				.into(),
 		)),
-		Err(e) => Err(Error(format!("Cannot open LMDB database: {}", e).into())),
+		Err(e) => Err(DbError(format!("Cannot open LMDB database: {}", e).into())),
 		Ok(db) => Ok(LmdbDb::init(db)),
 	}
 }
 
 // -- err
 
+impl From<heed::Error> for DbError {
+	fn from(e: heed::Error) -> DbError {
+		DbError(format!("LMDB: {}", e).into())
+	}
+}
+
 impl From<heed::Error> for Error {
 	fn from(e: heed::Error) -> Error {
-		Error(format!("LMDB: {}", e).into())
+		DbError::from(e).into()
 	}
 }
 
 impl From<heed::Error> for TxOpError {
 	fn from(e: heed::Error) -> TxOpError {
-		TxOpError(e.into())
+		DbError::from(e).into()
 	}
 }
 
@@ -91,14 +97,14 @@ impl LmdbDb {
 		Db(Arc::new(s))
 	}
 
-	fn get_tree(&self, i: usize) -> Result<Database> {
+	fn get_tree(&self, i: usize) -> DbResult<Database> {
 		self.trees
 			.read()
 			.unwrap()
 			.0
 			.get(i)
 			.cloned()
-			.ok_or_else(|| Error("invalid tree id".into()))
+			.ok_or_else(|| DbError("invalid tree id".into()))
 	}
 }
 
@@ -107,7 +113,7 @@ impl IDb for LmdbDb {
 		"LMDB (using Heed crate)".into()
 	}
 
-	fn open_tree(&self, name: &str) -> Result<usize> {
+	fn open_tree(&self, name: &str) -> DbResult<usize> {
 		let mut trees = self.trees.write().unwrap();
 		if let Some(i) = trees.1.get(name) {
 			Ok(*i)
@@ -122,7 +128,7 @@ impl IDb for LmdbDb {
 		}
 	}
 
-	fn list_trees(&self) -> Result<Vec<String>> {
+	fn list_trees(&self) -> DbResult<Vec<String>> {
 		let rtxn = self.db.read_txn()?;
 		let tree0 = match self
 			.db
@@ -153,7 +159,7 @@ impl IDb for LmdbDb {
 		Ok(ret2)
 	}
 
-	fn snapshot(&self, base_path: &Path) -> Result<()> {
+	fn snapshot(&self, base_path: &Path) -> DbResult<()> {
 		std::fs::create_dir_all(base_path)?;
 		let path = Engine::Lmdb.db_path(base_path);
 		self.db
@@ -163,7 +169,7 @@ impl IDb for LmdbDb {
 
 	// ----
 
-	fn get(&self, tree: usize, key: &[u8]) -> Result<Option<Value>> {
+	fn get(&self, tree: usize, key: &[u8]) -> DbResult<Option<Value>> {
 		let tree = self.get_tree(tree)?;
 
 		let tx = self.db.read_txn()?;
@@ -174,18 +180,18 @@ impl IDb for LmdbDb {
 		}
 	}
 
-	fn approximate_len(&self, tree: usize) -> Result<usize> {
+	fn approximate_len(&self, tree: usize) -> DbResult<usize> {
 		let tree = self.get_tree(tree)?;
 		let tx = self.db.read_txn()?;
 		Ok(tree.len(&tx)?.try_into().unwrap())
 	}
-	fn is_empty(&self, tree: usize) -> Result<bool> {
+	fn is_empty(&self, tree: usize) -> DbResult<bool> {
 		let tree = self.get_tree(tree)?;
 		let tx = self.db.read_txn()?;
 		Ok(tree.is_empty(&tx)?)
 	}
 
-	fn insert(&self, tree: usize, key: &[u8], value: &[u8]) -> Result<()> {
+	fn insert(&self, tree: usize, key: &[u8], value: &[u8]) -> DbResult<()> {
 		let tree = self.get_tree(tree)?;
 		let mut tx = self.db.write_txn()?;
 		tree.put(&mut tx, key, value)?;
@@ -193,7 +199,7 @@ impl IDb for LmdbDb {
 		Ok(())
 	}
 
-	fn remove(&self, tree: usize, key: &[u8]) -> Result<()> {
+	fn remove(&self, tree: usize, key: &[u8]) -> DbResult<()> {
 		let tree = self.get_tree(tree)?;
 		let mut tx = self.db.write_txn()?;
 		tree.delete(&mut tx, key)?;
@@ -201,7 +207,7 @@ impl IDb for LmdbDb {
 		Ok(())
 	}
 
-	fn clear(&self, tree: usize) -> Result<()> {
+	fn clear(&self, tree: usize) -> DbResult<()> {
 		let tree = self.get_tree(tree)?;
 		let mut tx = self.db.write_txn()?;
 		tree.clear(&mut tx)?;
@@ -209,14 +215,14 @@ impl IDb for LmdbDb {
 		Ok(())
 	}
 
-	fn iter(&self, tree: usize) -> Result<ValueIter<'_>> {
+	fn iter(&self, tree: usize) -> DbResult<ValueIter<'_>> {
 		let tree = self.get_tree(tree)?;
 		let tx = self.db.read_txn()?;
 		// Safety: the cloture does not store its argument anywhere,
 		unsafe { TxAndIterator::make(tx, |tx| Ok(tree.iter(tx)?)) }
 	}
 
-	fn iter_rev(&self, tree: usize) -> Result<ValueIter<'_>> {
+	fn iter_rev(&self, tree: usize) -> DbResult<ValueIter<'_>> {
 		let tree = self.get_tree(tree)?;
 		let tx = self.db.read_txn()?;
 		// Safety: the cloture does not store its argument anywhere,
@@ -228,7 +234,7 @@ impl IDb for LmdbDb {
 		tree: usize,
 		low: Bound<&'r [u8]>,
 		high: Bound<&'r [u8]>,
-	) -> Result<ValueIter<'_>> {
+	) -> DbResult<ValueIter<'_>> {
 		let tree = self.get_tree(tree)?;
 		let tx = self.db.read_txn()?;
 		// Safety: the cloture does not store its argument anywhere,
@@ -239,7 +245,7 @@ impl IDb for LmdbDb {
 		tree: usize,
 		low: Bound<&'r [u8]>,
 		high: Bound<&'r [u8]>,
-	) -> Result<ValueIter<'_>> {
+	) -> DbResult<ValueIter<'_>> {
 		let tree = self.get_tree(tree)?;
 		let tx = self.db.read_txn()?;
 		// Safety: the cloture does not store its argument anywhere,
@@ -271,9 +277,9 @@ impl IDb for LmdbDb {
 			}
 			TxFnResult::DbErr => {
 				tx.tx.abort();
-				Err(TxError::Db(Error(
-					"(this message will be discarded)".into(),
-				)))
+				Err(TxError::Db(
+					DbError("(this message will be discarded)".into()).into(),
+				))
 			}
 		}
 	}
@@ -287,49 +293,49 @@ struct LmdbTx<'a> {
 }
 
 impl<'a> LmdbTx<'a> {
-	fn get_tree(&self, i: usize) -> TxOpResult<&Database> {
+	fn get_tree(&self, i: usize) -> DbResult<&Database> {
 		self.trees.get(i).ok_or_else(|| {
-			TxOpError(Error(
+			DbError(
 				"invalid tree id (it might have been opened after the transaction started)".into(),
-			))
+			)
 		})
 	}
 }
 
 impl<'a> ITx for LmdbTx<'a> {
-	fn get(&self, tree: usize, key: &[u8]) -> TxOpResult<Option<Value>> {
+	fn get(&self, tree: usize, key: &[u8]) -> DbResult<Option<Value>> {
 		let tree = self.get_tree(tree)?;
 		match tree.get(&self.tx, key)? {
 			Some(v) => Ok(Some(v.to_vec())),
 			None => Ok(None),
 		}
 	}
-	fn len(&self, tree: usize) -> TxOpResult<usize> {
+	fn len(&self, tree: usize) -> DbResult<usize> {
 		let tree = self.get_tree(tree)?;
 		Ok(tree.len(&self.tx)? as usize)
 	}
 
-	fn insert(&mut self, tree: usize, key: &[u8], value: &[u8]) -> TxOpResult<()> {
+	fn insert(&mut self, tree: usize, key: &[u8], value: &[u8]) -> DbResult<()> {
 		let tree = *self.get_tree(tree)?;
 		tree.put(&mut self.tx, key, value)?;
 		Ok(())
 	}
-	fn remove(&mut self, tree: usize, key: &[u8]) -> TxOpResult<()> {
+	fn remove(&mut self, tree: usize, key: &[u8]) -> DbResult<()> {
 		let tree = *self.get_tree(tree)?;
 		tree.delete(&mut self.tx, key)?;
 		Ok(())
 	}
-	fn clear(&mut self, tree: usize) -> TxOpResult<()> {
+	fn clear(&mut self, tree: usize) -> DbResult<()> {
 		let tree = *self.get_tree(tree)?;
 		tree.clear(&mut self.tx)?;
 		Ok(())
 	}
 
-	fn iter(&self, tree: usize) -> TxOpResult<TxValueIter<'_>> {
+	fn iter(&self, tree: usize) -> DbResult<TxValueIter<'_>> {
 		let tree = *self.get_tree(tree)?;
 		Ok(Box::new(tree.iter(&self.tx)?.map(tx_iter_item)))
 	}
-	fn iter_rev(&self, tree: usize) -> TxOpResult<TxValueIter<'_>> {
+	fn iter_rev(&self, tree: usize) -> DbResult<TxValueIter<'_>> {
 		let tree = *self.get_tree(tree)?;
 		Ok(Box::new(tree.rev_iter(&self.tx)?.map(tx_iter_item)))
 	}
@@ -339,7 +345,7 @@ impl<'a> ITx for LmdbTx<'a> {
 		tree: usize,
 		low: Bound<&'r [u8]>,
 		high: Bound<&'r [u8]>,
-	) -> TxOpResult<TxValueIter<'_>> {
+	) -> DbResult<TxValueIter<'_>> {
 		let tree = *self.get_tree(tree)?;
 		Ok(Box::new(
 			tree.range(&self.tx, &(low, high))?.map(tx_iter_item),
@@ -350,7 +356,7 @@ impl<'a> ITx for LmdbTx<'a> {
 		tree: usize,
 		low: Bound<&'r [u8]>,
 		high: Bound<&'r [u8]>,
-	) -> TxOpResult<TxValueIter<'_>> {
+	) -> DbResult<TxValueIter<'_>> {
 		let tree = *self.get_tree(tree)?;
 		Ok(Box::new(
 			tree.rev_range(&self.tx, &(low, high))?.map(tx_iter_item),
@@ -386,9 +392,9 @@ where
 	}
 
 	/// Safety: iterfun must not store its argument anywhere but in its result.
-	unsafe fn make<F>(tx: RoTxn<'a, WithTls>, iterfun: F) -> Result<ValueIter<'a>>
+	unsafe fn make<F>(tx: RoTxn<'a, WithTls>, iterfun: F) -> DbResult<ValueIter<'a>>
 	where
-		F: FnOnce(&'a RoTxn<'a>) -> Result<I>,
+		F: FnOnce(&'a RoTxn<'a>) -> DbResult<I>,
 	{
 		let res = TxAndIterator {
 			tx,
@@ -436,13 +442,13 @@ impl<'a, I> Iterator for TxAndIteratorPin<'a, I>
 where
 	I: Iterator<Item = IteratorItem<'a>> + 'a,
 {
-	type Item = Result<(Value, Value)>;
+	type Item = DbResult<(Value, Value)>;
 
 	fn next(&mut self) -> Option<Self::Item> {
 		let mut_ref = Pin::as_mut(&mut self.0);
 		let next = mut_ref.iter().as_mut()?.next()?;
 		let res = match next {
-			Err(e) => Err(e.into()),
+			Err(e) => Err(DbError::from(e)),
 			Ok((k, v)) => Ok((k.to_vec(), v.to_vec())),
 		};
 		Some(res)
@@ -453,9 +459,9 @@ where
 
 fn tx_iter_item<'a>(
 	item: std::result::Result<(&'a [u8], &'a [u8]), heed::Error>,
-) -> TxOpResult<(Vec<u8>, Vec<u8>)> {
+) -> DbResult<(Vec<u8>, Vec<u8>)> {
 	item.map(|(k, v)| (k.to_vec(), v.to_vec()))
-		.map_err(|e| TxOpError(Error::from(e)))
+		.map_err(DbError::from)
 }
 
 // ---- utility ----

src/db/open.rs

@@ -1,6 +1,6 @@
 use std::path::{Path, PathBuf};
 
-use crate::{Db, Error, Result};
+use crate::{Db, DbError, Error, Result};
 
 /// List of supported database engine types
 ///
@@ -49,14 +49,14 @@ impl std::str::FromStr for Engine {
 			"lmdb" | "heed" => Ok(Self::Lmdb),
 			"sqlite" | "sqlite3" | "rusqlite" => Ok(Self::Sqlite),
             "fjall" => Ok(Self::Fjall),
-			"sled" => Err(Error("Sled is no longer supported as a database engine. Converting your old metadata db can be done using an older Garage binary (e.g. v0.9.4).".into())),
-			kind => Err(Error(
+			"sled" => Err(DbError("Sled is no longer supported as a database engine. Converting your old metadata db can be done using an older Garage binary (e.g. v0.9.4).".into()).into()),
+			kind => Err(DbError(
 				format!(
 					"Invalid DB engine: {} (options are: lmdb, sqlite, fjall)",
 					kind
 				)
 				.into(),
-			)),
+			).into()),
 		}
 	}
 }
@@ -72,22 +72,23 @@ pub fn open_db(path: &PathBuf, engine: Engine, opt: &OpenOpt) -> Result<Db> {
 	match engine {
 		// ---- Sqlite DB ----
 		#[cfg(feature = "sqlite")]
-		Engine::Sqlite => crate::sqlite_adapter::open_db(path, opt),
+		Engine::Sqlite => Ok(crate::sqlite_adapter::open_db(path, opt)?),
 
 		// ---- LMDB DB ----
 		#[cfg(feature = "lmdb")]
-		Engine::Lmdb => crate::lmdb_adapter::open_db(path, opt),
+		Engine::Lmdb => Ok(crate::lmdb_adapter::open_db(path, opt)?),
 
 		// ---- Fjall DB ----
 		#[cfg(feature = "fjall")]
-		Engine::Fjall => crate::fjall_adapter::open_db(path, opt),
+		Engine::Fjall => Ok(crate::fjall_adapter::open_db(path, opt)?),
 
 		// Pattern is unreachable when all supported DB engines are compiled into binary. The allow
 		// attribute is added so that we won't have to change this match in case stop building
 		// support for one or more engines by default.
 		#[allow(unreachable_patterns)]
-		engine => Err(Error(
+		engine => Err(DbError(
 			format!("DB engine support not available in this build: {}", engine).into(),
-		)),
+		)
+		.into()),
 	}
 }

src/db/sqlite_adapter.rs

@@ -12,7 +12,7 @@ use rusqlite::{params, Rows, Statement, Transaction};
 
 use crate::{
 	open::{Engine, OpenOpt},
-	Db, Error, IDb, ITx, ITxFn, OnCommit, Result, TxError, TxFnResult, TxOpError, TxOpResult,
+	Db, DbError, DbResult, Error, IDb, ITx, ITxFn, OnCommit, TxError, TxFnResult, TxOpError,
 	TxResult, TxValueIter, Value, ValueIter,
 };
 
@@ -20,7 +20,7 @@ pub use rusqlite;
 
 // ---- top-level open function
 
-pub(crate) fn open_db(path: &PathBuf, opt: &OpenOpt) -> Result<Db> {
+pub(crate) fn open_db(path: &PathBuf, opt: &OpenOpt) -> DbResult<Db> {
 	info!("Opening Sqlite database at: {}", path.display());
 	let manager = r2d2_sqlite::SqliteConnectionManager::file(path);
 	SqliteDb::open(manager, opt.fsync)
@@ -32,21 +32,33 @@ type Connection = r2d2::PooledConnection<SqliteConnectionManager>;
 
 // --- err
 
+impl From<rusqlite::Error> for DbError {
+	fn from(e: rusqlite::Error) -> DbError {
+		DbError(format!("Sqlite: {}", e).into())
+	}
+}
+
 impl From<rusqlite::Error> for Error {
 	fn from(e: rusqlite::Error) -> Error {
-		Error(format!("Sqlite: {}", e).into())
+		DbError::from(e).into()
+	}
+}
+
+impl From<r2d2::Error> for DbError {
+	fn from(e: r2d2::Error) -> DbError {
+		DbError(format!("Sqlite: {}", e).into())
 	}
 }
 
 impl From<r2d2::Error> for Error {
 	fn from(e: r2d2::Error) -> Error {
-		Error(format!("Sqlite: {}", e).into())
+		DbError::from(e).into()
 	}
 }
 
 impl From<rusqlite::Error> for TxOpError {
 	fn from(e: rusqlite::Error) -> TxOpError {
-		TxOpError(e.into())
+		DbError::from(e).into()
 	}
 }
 
@@ -62,7 +74,7 @@ pub struct SqliteDb {
 }
 
 impl SqliteDb {
-	pub fn open(manager: SqliteConnectionManager, sync_mode: bool) -> Result<Db> {
+	pub fn open(manager: SqliteConnectionManager, sync_mode: bool) -> DbResult<Db> {
 		let manager = manager.with_init(move |db| {
 			db.pragma_update(None, "journal_mode", "WAL")?;
 			if sync_mode {
@@ -82,16 +94,16 @@ impl SqliteDb {
 }
 
 impl SqliteDb {
-	fn get_tree(&self, i: usize) -> Result<Arc<str>> {
+	fn get_tree(&self, i: usize) -> DbResult<Arc<str>> {
 		self.trees
 			.read()
 			.unwrap()
 			.get(i)
 			.cloned()
-			.ok_or_else(|| Error("invalid tree id".into()))
+			.ok_or_else(|| DbError("invalid tree id".into()))
 	}
 
-	fn internal_get(&self, db: &Connection, tree: &str, key: &[u8]) -> Result<Option<Value>> {
+	fn internal_get(&self, db: &Connection, tree: &str, key: &[u8]) -> DbResult<Option<Value>> {
 		let mut stmt = db.prepare(&format!("SELECT v FROM {} WHERE k = ?1", tree))?;
 		let mut res_iter = stmt.query([key])?;
 		match res_iter.next()? {
@@ -106,7 +118,7 @@ impl IDb for SqliteDb {
 		format!("sqlite3 v{} (using rusqlite crate)", rusqlite::version())
 	}
 
-	fn open_tree(&self, name: &str) -> Result<usize> {
+	fn open_tree(&self, name: &str) -> DbResult<usize> {
 		let name = format!("tree_{}", name.replace(':', "_COLON_"));
 		let mut trees = self.trees.write().unwrap();
 
@@ -133,7 +145,7 @@ impl IDb for SqliteDb {
 		}
 	}
 
-	fn list_trees(&self) -> Result<Vec<String>> {
+	fn list_trees(&self) -> DbResult<Vec<String>> {
 		let mut trees = vec![];
 
 		let db = self.db.get()?;
@@ -150,13 +162,13 @@ impl IDb for SqliteDb {
 		Ok(trees)
 	}
 
-	fn snapshot(&self, base_path: &Path) -> Result<()> {
+	fn snapshot(&self, base_path: &Path) -> DbResult<()> {
 		std::fs::create_dir_all(base_path)?;
 		let path = Engine::Sqlite
 			.db_path(base_path)
 			.into_os_string()
 			.into_string()
-			.map_err(|_| Error("invalid sqlite path string".into()))?;
+			.map_err(|_| DbError("invalid sqlite path string".into()))?;
 
 		info!("Start sqlite VACUUM INTO `{}`", path);
 		self.db.get()?.execute("VACUUM INTO ?1", params![path])?;
@@ -167,12 +179,12 @@ impl IDb for SqliteDb {
 
 	// ----
 
-	fn get(&self, tree: usize, key: &[u8]) -> Result<Option<Value>> {
+	fn get(&self, tree: usize, key: &[u8]) -> DbResult<Option<Value>> {
 		let tree = self.get_tree(tree)?;
 		self.internal_get(&self.db.get()?, &tree, key)
 	}
 
-	fn approximate_len(&self, tree: usize) -> Result<usize> {
+	fn approximate_len(&self, tree: usize) -> DbResult<usize> {
 		let tree = self.get_tree(tree)?;
 		let db = self.db.get()?;
 
@@ -184,11 +196,11 @@ impl IDb for SqliteDb {
 		}
 	}
 
-	fn is_empty(&self, tree: usize) -> Result<bool> {
+	fn is_empty(&self, tree: usize) -> DbResult<bool> {
 		Ok(self.approximate_len(tree)? == 0)
 	}
 
-	fn insert(&self, tree: usize, key: &[u8], value: &[u8]) -> Result<()> {
+	fn insert(&self, tree: usize, key: &[u8], value: &[u8]) -> DbResult<()> {
 		let tree = self.get_tree(tree)?;
 		let db = self.db.get()?;
 		let lock = self.write_lock.lock();
@@ -206,7 +218,7 @@ impl IDb for SqliteDb {
 		Ok(())
 	}
 
-	fn remove(&self, tree: usize, key: &[u8]) -> Result<()> {
+	fn remove(&self, tree: usize, key: &[u8]) -> DbResult<()> {
 		let tree = self.get_tree(tree)?;
 		let db = self.db.get()?;
 		let lock = self.write_lock.lock();
@@ -217,7 +229,7 @@ impl IDb for SqliteDb {
 		Ok(())
 	}
 
-	fn clear(&self, tree: usize) -> Result<()> {
+	fn clear(&self, tree: usize) -> DbResult<()> {
 		let tree = self.get_tree(tree)?;
 		let db = self.db.get()?;
 		let lock = self.write_lock.lock();
@@ -228,13 +240,13 @@ impl IDb for SqliteDb {
 		Ok(())
 	}
 
-	fn iter(&self, tree: usize) -> Result<ValueIter<'_>> {
+	fn iter(&self, tree: usize) -> DbResult<ValueIter<'_>> {
 		let tree = self.get_tree(tree)?;
 		let sql = format!("SELECT k, v FROM {} ORDER BY k ASC", tree);
 		DbValueIterator::make(self.db.get()?, &sql, [])
 	}
 
-	fn iter_rev(&self, tree: usize) -> Result<ValueIter<'_>> {
+	fn iter_rev(&self, tree: usize) -> DbResult<ValueIter<'_>> {
 		let tree = self.get_tree(tree)?;
 		let sql = format!("SELECT k, v FROM {} ORDER BY k DESC", tree);
 		DbValueIterator::make(self.db.get()?, &sql, [])
@@ -245,7 +257,7 @@ impl IDb for SqliteDb {
 		tree: usize,
 		low: Bound<&'r [u8]>,
 		high: Bound<&'r [u8]>,
-	) -> Result<ValueIter<'_>> {
+	) -> DbResult<ValueIter<'_>> {
 		let tree = self.get_tree(tree)?;
 
 		let (bounds_sql, params) = bounds_sql(low, high);
@@ -263,7 +275,7 @@ impl IDb for SqliteDb {
 		tree: usize,
 		low: Bound<&'r [u8]>,
 		high: Bound<&'r [u8]>,
-	) -> Result<ValueIter<'_>> {
+	) -> DbResult<ValueIter<'_>> {
 		let tree = self.get_tree(tree)?;
 
 		let (bounds_sql, params) = bounds_sql(low, high);
@@ -300,9 +312,9 @@ impl IDb for SqliteDb {
 			}
 			TxFnResult::DbErr => {
 				tx.tx.rollback().map_err(Error::from).map_err(TxError::Db)?;
-				Err(TxError::Db(Error(
-					"(this message will be discarded)".into(),
-				)))
+				Err(TxError::Db(
+					DbError("(this message will be discarded)".into()).into(),
+				))
 			}
 		};
 
@@ -320,15 +332,15 @@ struct SqliteTx<'a> {
 }
 
 impl<'a> SqliteTx<'a> {
-	fn get_tree(&self, i: usize) -> TxOpResult<&'_ str> {
+	fn get_tree(&self, i: usize) -> DbResult<&'_ str> {
 		self.trees.get(i).map(Arc::as_ref).ok_or_else(|| {
-			TxOpError(Error(
+			DbError(
 				"invalid tree id (it might have been opened after the transaction started)".into(),
-			))
+			)
 		})
 	}
 
-	fn internal_get(&self, tree: &str, key: &[u8]) -> TxOpResult<Option<Value>> {
+	fn internal_get(&self, tree: &str, key: &[u8]) -> DbResult<Option<Value>> {
 		let mut stmt = self
 			.tx
 			.prepare(&format!("SELECT v FROM {} WHERE k = ?1", tree))?;
@@ -341,11 +353,11 @@ impl<'a> SqliteTx<'a> {
 }
 
 impl<'a> ITx for SqliteTx<'a> {
-	fn get(&self, tree: usize, key: &[u8]) -> TxOpResult<Option<Value>> {
+	fn get(&self, tree: usize, key: &[u8]) -> DbResult<Option<Value>> {
 		let tree = self.get_tree(tree)?;
 		self.internal_get(tree, key)
 	}
-	fn len(&self, tree: usize) -> TxOpResult<usize> {
+	fn len(&self, tree: usize) -> DbResult<usize> {
 		let tree = self.get_tree(tree)?;
 		let mut stmt = self.tx.prepare(&format!("SELECT COUNT(*) FROM {}", tree))?;
 		let mut res_iter = stmt.query([])?;
@@ -355,30 +367,30 @@ impl<'a> ITx for SqliteTx<'a> {
 		}
 	}
 
-	fn insert(&mut self, tree: usize, key: &[u8], value: &[u8]) -> TxOpResult<()> {
+	fn insert(&mut self, tree: usize, key: &[u8], value: &[u8]) -> DbResult<()> {
 		let tree = self.get_tree(tree)?;
 		let sql = format!("INSERT OR REPLACE INTO {} (k, v) VALUES (?1, ?2)", tree);
 		self.tx.execute(&sql, params![key, value])?;
 		Ok(())
 	}
-	fn remove(&mut self, tree: usize, key: &[u8]) -> TxOpResult<()> {
+	fn remove(&mut self, tree: usize, key: &[u8]) -> DbResult<()> {
 		let tree = self.get_tree(tree)?;
 		self.tx
 			.execute(&format!("DELETE FROM {} WHERE k = ?1", tree), params![key])?;
 		Ok(())
 	}
-	fn clear(&mut self, tree: usize) -> TxOpResult<()> {
+	fn clear(&mut self, tree: usize) -> DbResult<()> {
 		let tree = self.get_tree(tree)?;
 		self.tx.execute(&format!("DELETE FROM {}", tree), [])?;
 		Ok(())
 	}
 
-	fn iter(&self, tree: usize) -> TxOpResult<TxValueIter<'_>> {
+	fn iter(&self, tree: usize) -> DbResult<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<'_>> {
+	fn iter_rev(&self, tree: usize) -> DbResult<TxValueIter<'_>> {
 		let tree = self.get_tree(tree)?;
 		let sql = format!("SELECT k, v FROM {} ORDER BY k DESC", tree);
 		TxValueIterator::make(self, &sql, [])
@@ -389,7 +401,7 @@ impl<'a> ITx for SqliteTx<'a> {
 		tree: usize,
 		low: Bound<&'r [u8]>,
 		high: Bound<&'r [u8]>,
-	) -> TxOpResult<TxValueIter<'_>> {
+	) -> DbResult<TxValueIter<'_>> {
 		let tree = self.get_tree(tree)?;
 
 		let (bounds_sql, params) = bounds_sql(low, high);
@@ -407,7 +419,7 @@ impl<'a> ITx for SqliteTx<'a> {
 		tree: usize,
 		low: Bound<&'r [u8]>,
 		high: Bound<&'r [u8]>,
-	) -> TxOpResult<TxValueIter<'_>> {
+	) -> DbResult<TxValueIter<'_>> {
 		let tree = self.get_tree(tree)?;
 
 		let (bounds_sql, params) = bounds_sql(low, high);
@@ -439,7 +451,7 @@ impl DbValueIterator {
 		db: Connection,
 		sql: &str,
 		args: P,
-	) -> Result<ValueIter<'res>> {
+	) -> DbResult<ValueIter<'res>> {
 		let res = DbValueIterator {
 			db,
 			stmt: None,
@@ -484,7 +496,7 @@ impl Drop for DbValueIterator {
 struct DbValueIteratorPin(Pin<Box<DbValueIterator>>);
 
 impl Iterator for DbValueIteratorPin {
-	type Item = Result<(Value, Value)>;
+	type Item = DbResult<(Value, Value)>;
 
 	fn next(&mut self) -> Option<Self::Item> {
 		let mut_ref = Pin::as_mut(&mut self.0);
@@ -509,7 +521,7 @@ impl<'a> TxValueIterator<'a> {
 		tx: &'a SqliteTx<'a>,
 		sql: &str,
 		args: P,
-	) -> TxOpResult<TxValueIter<'a>> {
+	) -> DbResult<TxValueIter<'a>> {
 		let stmt = tx.tx.prepare(sql)?;
 		let res = TxValueIterator {
 			stmt,
@@ -543,7 +555,7 @@ impl<'a> Drop for TxValueIterator<'a> {
 struct TxValueIteratorPin<'a>(Pin<Box<TxValueIterator<'a>>>);
 
 impl<'a> Iterator for TxValueIteratorPin<'a> {
-	type Item = TxOpResult<(Value, Value)>;
+	type Item = DbResult<(Value, Value)>;
 
 	fn next(&mut self) -> Option<Self::Item> {
 		let mut_ref = Pin::as_mut(&mut self.0);

src/db/typed.rs

@@ -0,0 +1,241 @@
+use std::marker::PhantomData;
+use std::ops::{Bound, RangeBounds};
+
+// Todo: some parts of this code, notably around ranges are never used but are here to prepare
+// the migration of the parts of the codebase that still use untyped trees. At one point, this
+// migration should be done or these functions deleted.
+
+use super::{
+	DbResult, DecodeError, Error, Result, Transaction, Tree, TxOpError, TxOpResult, TxValueIter,
+	ValueIter,
+};
+
+pub use super::Db;
+
+pub trait DbBytes: Sized {
+	fn encode(&self) -> Vec<u8>;
+	fn decode(bytes: &[u8]) -> std::result::Result<Self, DecodeError>;
+}
+
+/// Subtrait of [`DbBytes`] for types used as tree keys with operations where order matters
+/// (`get_gt`, range, etc...).
+///
+/// Implementors must guarantee that the byte encoding is order-preserving:
+/// for any `a, b: Self`, `a.cmp(&b) == a.encode().cmp(&b.encode())`.
+pub trait DbOrdKey: DbBytes + Ord {}
+
+#[derive(Clone)]
+pub struct TypedTree<K, V> {
+	inner: Tree,
+	_phantom: PhantomData<[(K, V)]>,
+}
+
+impl<K: DbBytes, V: DbBytes> TypedTree<K, V> {
+	pub fn new(tree: Tree) -> Self {
+		Self {
+			inner: tree,
+			_phantom: PhantomData,
+		}
+	}
+
+	pub fn db(&self) -> Db {
+		self.inner.db()
+	}
+
+	pub fn untyped(&self) -> &Tree {
+		&self.inner
+	}
+
+	pub fn get(&self, key: &K) -> Result<Option<V>> {
+		self.inner
+			.get(key.encode())?
+			.map(|v| V::decode(&v).map_err(Error::from))
+			.transpose()
+	}
+
+	pub fn approximate_len(&self) -> DbResult<usize> {
+		self.inner.approximate_len()
+	}
+
+	pub fn is_empty(&self) -> DbResult<bool> {
+		self.inner.is_empty()
+	}
+
+	pub fn insert(&self, key: &K, value: &V) -> DbResult<()> {
+		self.inner.insert(key.encode(), value.encode())
+	}
+
+	pub fn remove(&self, key: &K) -> DbResult<()> {
+		self.inner.remove(key.encode())
+	}
+
+	pub fn clear(&self) -> DbResult<()> {
+		self.inner.clear()
+	}
+
+	pub fn tx_get(&self, tx: &Transaction<'_>, key: &K) -> TxOpResult<Option<V>> {
+		tx.get(&self.inner, key.encode())?
+			.map(|v| V::decode(&v).map_err(TxOpError::from))
+			.transpose()
+	}
+
+	pub fn tx_insert(&self, tx: &mut Transaction<'_>, key: &K, value: &V) -> TxOpResult<()> {
+		tx.insert(&self.inner, key.encode(), value.encode())
+	}
+
+	pub fn tx_remove(&self, tx: &mut Transaction<'_>, key: &K) -> TxOpResult<()> {
+		tx.remove(&self.inner, key.encode())
+	}
+
+	pub fn tx_clear(&self, tx: &mut Transaction<'_>) -> TxOpResult<()> {
+		tx.clear(&self.inner)
+	}
+}
+
+impl<K: DbOrdKey, V: DbBytes> TypedTree<K, V> {
+	pub fn first(&self) -> Result<Option<(K, V)>> {
+		self.iter()?.next().transpose()
+	}
+
+	pub fn get_gt(&self, from: &K) -> Result<Option<(K, V)>> {
+		self.inner
+			.get_gt(from.encode())?
+			.map(|(k, v)| {
+				Ok((
+					K::decode(&k).map_err(Error::from)?,
+					V::decode(&v).map_err(Error::from)?,
+				))
+			})
+			.transpose()
+	}
+
+	pub fn iter(&self) -> Result<TypedIter<'_, K, V>> {
+		Ok(TypedIter::new(self.inner.iter()?))
+	}
+
+	pub fn iter_rev(&self) -> Result<TypedIter<'_, K, V>> {
+		Ok(TypedIter::new(self.inner.iter_rev()?))
+	}
+
+	pub fn range<R: RangeBounds<K>>(&self, range: R) -> Result<TypedIter<'_, K, V>> {
+		Ok(TypedIter::new(self.inner.range(encode_range(range))?))
+	}
+
+	pub fn range_rev<R: RangeBounds<K>>(&self, range: R) -> Result<TypedIter<'_, K, V>> {
+		Ok(TypedIter::new(self.inner.range_rev(encode_range(range))?))
+	}
+
+	pub fn tx_iter<'t>(&self, tx: &'t Transaction<'_>) -> TxOpResult<TypedTxIter<'t, K, V>> {
+		Ok(TypedTxIter::new(tx.iter(&self.inner)?))
+	}
+
+	pub fn tx_iter_rev<'t>(&self, tx: &'t Transaction<'_>) -> TxOpResult<TypedTxIter<'t, K, V>> {
+		Ok(TypedTxIter::new(tx.iter_rev(&self.inner)?))
+	}
+
+	pub fn tx_range<'t, R: RangeBounds<K>>(
+		&self,
+		tx: &'t Transaction<'_>,
+		range: R,
+	) -> TxOpResult<TypedTxIter<'t, K, V>> {
+		Ok(TypedTxIter::new(
+			tx.range(&self.inner, encode_range(range))?,
+		))
+	}
+
+	pub fn tx_range_rev<'t, R: RangeBounds<K>>(
+		&self,
+		tx: &'t Transaction<'_>,
+		range: R,
+	) -> TxOpResult<TypedTxIter<'t, K, V>> {
+		Ok(TypedTxIter::new(
+			tx.range_rev(&self.inner, encode_range(range))?,
+		))
+	}
+}
+
+impl<K: DbBytes, V: DbBytes> From<Tree> for TypedTree<K, V> {
+	fn from(tree: Tree) -> Self {
+		Self::new(tree)
+	}
+}
+
+impl Db {
+	pub fn open_typed_tree<K: DbBytes, V: DbBytes, S: AsRef<str>>(
+		&self,
+		name: S,
+	) -> DbResult<TypedTree<K, V>> {
+		Ok(TypedTree::new(self.open_tree(name)?))
+	}
+}
+
+pub struct TypedIter<'a, K, V> {
+	inner: ValueIter<'a>,
+	_phantom: PhantomData<(K, V)>,
+}
+
+impl<'a, K, V> TypedIter<'a, K, V> {
+	fn new(inner: ValueIter<'a>) -> Self {
+		Self {
+			inner,
+			_phantom: PhantomData,
+		}
+	}
+}
+
+impl<K: DbOrdKey, V: DbBytes> Iterator for TypedIter<'_, K, V> {
+	type Item = Result<(K, V)>;
+
+	fn next(&mut self) -> Option<Self::Item> {
+		self.inner.next().map(|res| {
+			let (k, v) = res?;
+			Ok((
+				K::decode(&k).map_err(Error::from)?,
+				V::decode(&v).map_err(Error::from)?,
+			))
+		})
+	}
+}
+
+pub struct TypedTxIter<'a, K, V> {
+	inner: TxValueIter<'a>,
+	_phantom: PhantomData<(K, V)>,
+}
+
+impl<'a, K, V> TypedTxIter<'a, K, V> {
+	fn new(inner: TxValueIter<'a>) -> Self {
+		Self {
+			inner,
+			_phantom: PhantomData,
+		}
+	}
+}
+
+impl<K: DbOrdKey, V: DbBytes> Iterator for TypedTxIter<'_, K, V> {
+	type Item = TxOpResult<(K, V)>;
+
+	fn next(&mut self) -> Option<Self::Item> {
+		self.inner.next().map(|res| {
+			let (k, v) = res?;
+			Ok((
+				K::decode(&k).map_err(TxOpError::from)?,
+				V::decode(&v).map_err(TxOpError::from)?,
+			))
+		})
+	}
+}
+
+fn encode_range<K: DbOrdKey, R: RangeBounds<K>>(range: R) -> (Bound<Vec<u8>>, Bound<Vec<u8>>) {
+	(
+		encode_bound(range.start_bound()),
+		encode_bound(range.end_bound()),
+	)
+}
+
+fn encode_bound<K: DbOrdKey>(bound: Bound<&K>) -> Bound<Vec<u8>> {
+	match bound {
+		Bound::Included(k) => Bound::Included(k.encode()),
+		Bound::Excluded(k) => Bound::Excluded(k.encode()),
+		Bound::Unbounded => Bound::Unbounded,
+	}
+}

src/garage/cli/local/convert_db.rs

@@ -49,7 +49,7 @@ pub struct OpenLmdbOpt {
 
 pub(crate) fn do_conversion(args: ConvertDbOpt) -> Result<()> {
 	if args.input_engine == args.output_engine {
-		return Err(Error("input and output database engine must differ".into()));
+		return Err(DbError("input and output database engine must differ".into()).into());
 	}
 
 	let opt = OpenOpt {