From b942949940b5a0dec8e8640c44a2705a4482a2e4 Mon Sep 17 00:00:00 2001 From: Alex Auvolat Date: Fri, 8 Mar 2024 16:38:01 +0100 Subject: [rm-sled] Implement iterators in sqlite & lmdb transactions with way too much unsafe code --- src/db/lib.rs | 1 + src/db/lmdb_adapter.rs | 48 ++++++++++++------ src/db/sqlite_adapter.rs | 125 +++++++++++++++++++++++++++++++++++++++++------ src/db/test.rs | 49 +++++++++++++++++++ 4 files changed, 195 insertions(+), 28 deletions(-) diff --git a/src/db/lib.rs b/src/db/lib.rs index 5881954d..ff511b5f 100644 --- a/src/db/lib.rs +++ b/src/db/lib.rs @@ -51,6 +51,7 @@ pub type Result = std::result::Result; pub struct TxOpError(pub(crate) Error); pub type TxOpResult = std::result::Result; +#[derive(Debug)] pub enum TxError { Abort(E), Db(Error), diff --git a/src/db/lmdb_adapter.rs b/src/db/lmdb_adapter.rs index 01c360b4..ddfb6ed5 100644 --- a/src/db/lmdb_adapter.rs +++ b/src/db/lmdb_adapter.rs @@ -261,32 +261,42 @@ impl<'a> ITx for LmdbTx<'a> { Ok(()) } - fn iter(&self, _tree: usize) -> TxOpResult> { - unimplemented!("Iterators in transactions not supported with LMDB backend"); + fn iter(&self, tree: usize) -> TxOpResult> { + let tree = *self.get_tree(tree)?; + Ok(Box::new(tree.iter(&self.tx)?.map(tx_iter_item))) } - fn iter_rev(&self, _tree: usize) -> TxOpResult> { - unimplemented!("Iterators in transactions not supported with LMDB backend"); + fn iter_rev(&self, tree: usize) -> TxOpResult> { + let tree = *self.get_tree(tree)?; + Ok(Box::new(tree.rev_iter(&self.tx)?.map(tx_iter_item))) } 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> { - unimplemented!("Iterators in transactions not supported with LMDB backend"); + let tree = *self.get_tree(tree)?; + Ok(Box::new( + tree.range(&self.tx, &(low, high))?.map(tx_iter_item), + )) } 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> { - unimplemented!("Iterators in transactions not supported with LMDB backend"); + let tree = *self.get_tree(tree)?; + Ok(Box::new( + tree.rev_range(&self.tx, &(low, high))?.map(tx_iter_item), + )) } } -// ---- +// ---- iterators outside transactions ---- +// complicated, they must hold the transaction object +// therefore a bit of unsafe code (it is a self-referential struct) type IteratorItem<'a> = heed::Result<( >::DItem, @@ -323,6 +333,7 @@ where I: Iterator> + 'a, { fn drop(&mut self) { + // ensure the iterator is dropped before the RoTxn it references drop(self.iter.take()); } } @@ -342,7 +353,16 @@ where } } -// ---- +// ---- iterators within transactions ---- + +fn tx_iter_item<'a>( + item: std::result::Result<(&'a [u8], &'a [u8]), heed::Error>, +) -> TxOpResult<(Vec, Vec)> { + item.map(|(k, v)| (k.to_vec(), v.to_vec())) + .map_err(|e| TxOpError(Error::from(e))) +} + +// ---- utility ---- #[cfg(target_pointer_width = "64")] pub fn recommended_map_size() -> usize { diff --git a/src/db/sqlite_adapter.rs b/src/db/sqlite_adapter.rs index d1394355..077c1f1b 100644 --- a/src/db/sqlite_adapter.rs +++ b/src/db/sqlite_adapter.rs @@ -369,32 +369,58 @@ impl<'a> ITx for SqliteTx<'a> { Ok(()) } - fn iter(&self, _tree: usize) -> TxOpResult> { - unimplemented!(); + fn iter(&self, tree: usize) -> TxOpResult> { + 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> { - unimplemented!(); + fn iter_rev(&self, tree: usize) -> TxOpResult> { + 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> { - 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::>(); + + 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> { - 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::>(); + + 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: MutexGuard<'a, SqliteDbInner>, @@ -471,7 +497,78 @@ impl<'a> Iterator for DbValueIteratorPin<'a> { } } -// ---- +// ---- 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>, + _pin: PhantomPinned, +} + +impl<'a> TxValueIterator<'a> { + fn make( + tx: &'a SqliteTx<'a>, + sql: &str, + args: P, + ) -> TxOpResult> { + let stmt = tx.tx.prepare(sql)?; + let res = TxValueIterator { + stmt, + iter: None, + _pin: PhantomPinned, + }; + let mut boxed = Box::pin(res); + trace!("make iterator with sql: {}", sql); + + unsafe { + let mut stmt = NonNull::from(&boxed.stmt); + let iter = stmt.as_mut().query(args)?; + + let mut_ref: Pin<&mut TxValueIterator<'a>> = Pin::as_mut(&mut boxed); + 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>>); + +impl<'a> Iterator for TxValueIteratorPin<'a> { + type Item = TxOpResult<(Value, Value)>; + + fn next(&mut self) -> Option { + let next = unsafe { + let mut_ref: Pin<&mut TxValueIterator<'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>(0) { + Err(e) => return Some(Err(e.into())), + Ok(x) => x, + }; + let v = match row.get::<_, Vec>(1) { + Err(e) => return Some(Err(e.into())), + Ok(y) => y, + }; + Some(Ok((k, v))) + } +} + +// ---- utility ---- fn bounds_sql<'r>(low: Bound<&'r [u8]>, high: Bound<&'r [u8]>) -> (String, Vec>) { let mut sql = String::new(); diff --git a/src/db/test.rs b/src/db/test.rs index d4c875f0..3add89fb 100644 --- a/src/db/test.rs +++ b/src/db/test.rs @@ -10,8 +10,13 @@ fn test_suite(db: Db) { let vb: &[u8] = &b"plip"[..]; let vc: &[u8] = &b"plup"[..]; + // ---- test simple insert/delete ---- + assert!(tree.insert(ka, va).unwrap().is_none()); assert_eq!(tree.get(ka).unwrap().unwrap(), va); + assert_eq!(tree.len().unwrap(), 1); + + // ---- test transaction logic ---- let res = db.transaction::<_, (), _>(|tx| { assert_eq!(tx.get(&tree, ka).unwrap().unwrap(), va); @@ -37,6 +42,8 @@ fn test_suite(db: Db) { assert!(matches!(res, Err(TxError::Abort(42)))); assert_eq!(tree.get(ka).unwrap().unwrap(), vb); + // ---- test iteration outside of transactions ---- + let mut iter = tree.iter().unwrap(); let next = iter.next().unwrap().unwrap(); assert_eq!((next.0.as_ref(), next.1.as_ref()), (ka, vb)); @@ -73,6 +80,48 @@ fn test_suite(db: Db) { assert_eq!((next.0.as_ref(), next.1.as_ref()), (ka, vb)); assert!(iter.next().is_none()); drop(iter); + + // ---- test iteration within transactions ---- + + db.transaction::<_, (), _>(|tx| { + let mut iter = tx.iter(&tree).unwrap(); + let next = iter.next().unwrap().unwrap(); + assert_eq!((next.0.as_ref(), next.1.as_ref()), (ka, vb)); + let next = iter.next().unwrap().unwrap(); + assert_eq!((next.0.as_ref(), next.1.as_ref()), (kb, vc)); + assert!(iter.next().is_none()); + Ok(()) + }) + .unwrap(); + + db.transaction::<_, (), _>(|tx| { + let mut iter = tx.range(&tree, kint..).unwrap(); + let next = iter.next().unwrap().unwrap(); + assert_eq!((next.0.as_ref(), next.1.as_ref()), (kb, vc)); + assert!(iter.next().is_none()); + Ok(()) + }) + .unwrap(); + + db.transaction::<_, (), _>(|tx| { + let mut iter = tx.range_rev(&tree, ..kint).unwrap(); + let next = iter.next().unwrap().unwrap(); + assert_eq!((next.0.as_ref(), next.1.as_ref()), (ka, vb)); + assert!(iter.next().is_none()); + Ok(()) + }) + .unwrap(); + + db.transaction::<_, (), _>(|tx| { + let mut iter = tx.iter_rev(&tree).unwrap(); + let next = iter.next().unwrap().unwrap(); + assert_eq!((next.0.as_ref(), next.1.as_ref()), (kb, vc)); + let next = iter.next().unwrap().unwrap(); + assert_eq!((next.0.as_ref(), next.1.as_ref()), (ka, vb)); + assert!(iter.next().is_none()); + Ok(()) + }) + .unwrap(); } #[test] -- cgit v1.2.3