Sqlite iter with unsafe code

Cargo.lock

@@ -2,12 +2,6 @@
 # It is not intended for manual editing.
 version = 3
 
-[[package]]
-name = "Inflector"
-version = "0.11.4"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "fe438c63458706e03479442743baae6c88256498e6431708f6dfc520a26515d3"
-
 [[package]]
 name = "ahash"
 version = "0.7.6"
@@ -28,12 +22,6 @@ dependencies = [
  "memchr",
 ]
 
-[[package]]
-name = "aliasable"
-version = "0.1.3"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "250f629c0161ad8107cf89319e990051fae62832fd343083bea452d93e2205fd"
-
 [[package]]
 name = "anyhow"
 version = "1.0.56"
@@ -1028,7 +1016,6 @@ version = "0.8.0"
 dependencies = [
  "err-derive 0.3.1",
  "mktemp",
- "ouroboros",
  "rusqlite",
  "sled",
 ]
@@ -2211,30 +2198,6 @@ version = "6.0.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "029d8d0b2f198229de29dca79676f2738ff952edf3fde542eb8bf94d8c21b435"
 
-[[package]]
-name = "ouroboros"
-version = "0.15.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "9f31a3b678685b150cba82b702dcdc5e155893f63610cf388d30cd988d4ca2bf"
-dependencies = [
- "aliasable",
- "ouroboros_macro",
- "stable_deref_trait",
-]
-
-[[package]]
-name = "ouroboros_macro"
-version = "0.15.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "084fd65d5dd8b3772edccb5ffd1e4b7eba43897ecd0f9401e330e8c542959408"
-dependencies = [
- "Inflector",
- "proc-macro-error",
- "proc-macro2",
- "quote",
- "syn",
-]
-
 [[package]]
 name = "parking_lot"
 version = "0.11.2"
@@ -3104,12 +3067,6 @@ version = "0.9.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "511254be0c5bcf062b019a6c89c01a664aa359ded62f78aa72c6fc137c0590e5"
 
-[[package]]
-name = "stable_deref_trait"
-version = "1.2.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "a8f112729512f8e442d81f95a8a7ddf2b7c6b8a1a6f509a95864142b30cab2d3"
-
 [[package]]
 name = "static_init"
 version = "1.0.2"

src/block/manager.rs

@@ -547,9 +547,7 @@ impl BlockManager {
 	// - Ok(false) -> no block was processed, but we are ready for the next iteration
 	// - Err(_) -> a Sled error occurred when reading/writing from resync_queue/resync_errors
 	async fn resync_iter(&self, must_exit: &mut watch::Receiver<bool>) -> Result<bool, db::Error> {
-		if let Some(first_pair_res) = self.resync_queue.iter()?.next() {
+		if let Some((time_bytes, hash_bytes)) = self.resync_get_next()? {
-			let (time_bytes, hash_bytes) = first_pair_res?;
-
 			let time_msec = u64::from_be_bytes(time_bytes[0..8].try_into().unwrap());
 			let now = now_msec();
 
@@ -642,6 +640,16 @@ impl BlockManager {
 		}
 	}
 
+	fn resync_get_next(&self) -> Result<Option<(Vec<u8>, Vec<u8>)>, db::Error> {
+		match self.resync_queue.iter()?.next() {
+			None => Ok(None),
+			Some(v) => {
+				let (time_bytes, hash_bytes) = v?;
+				Ok(Some((time_bytes.into_owned(), hash_bytes.into_owned())))
+			}
+		}
+	}
+
 	async fn resync_block(&self, hash: &Hash) -> Result<(), Error> {
 		let BlockStatus { exists, needed } = self
 			.mutation_lock

src/db/Cargo.toml

@@ -15,7 +15,6 @@ path = "lib.rs"
 
 [dependencies]
 err-derive = "0.3"
-ouroboros = "0.15"
 
 sled = "0.34"
 rusqlite = "0.27"

src/db/lib.rs

@@ -22,11 +22,9 @@ pub struct Transaction<'a>(pub(crate) &'a dyn ITx<'a>);
 pub struct Tree(pub(crate) Arc<dyn IDb>, pub(crate) usize);
 
 pub type Value<'a> = Cow<'a, [u8]>;
-pub type ValueIter<'a> =
+pub type ValueIter<'a> = Box<dyn std::iter::Iterator<Item = Result<(Value<'a>, Value<'a>)>> + 'a>;
-	Box<dyn std::iter::Iterator<Item = Result<(Value<'a>, Value<'a>)>> + Send + 'a>;
 
-pub type Exporter<'a> =
+pub type Exporter<'a> = Box<dyn std::iter::Iterator<Item = Result<(String, ValueIter<'a>)>> + 'a>;
-	Box<dyn std::iter::Iterator<Item = Result<(String, ValueIter<'a>)>> + 'a>;
 
 // ----
 

src/db/sqlite_adapter.rs

@@ -1,11 +1,12 @@
 use core::ops::Bound;
 
 use std::cell::Cell;
-use std::sync::{Arc, Mutex, RwLock, MutexGuard};
+use std::marker::PhantomPinned;
+use std::pin::Pin;
+use std::ptr::NonNull;
+use std::sync::{Arc, Mutex, MutexGuard, RwLock};
 
-use ouroboros::self_referencing;
+use rusqlite::{params, Connection, Rows, Statement, Transaction};
-
-use rusqlite::{params, Connection, Transaction};
 
 use crate::{
 	Db, Error, Exporter, IDb, ITx, ITxFn, Result, TxError, TxFnResult, TxResult, Value, ValueIter,
@@ -114,16 +115,14 @@ impl IDb for SqliteDb {
 
 	fn iter<'a>(&'a self, tree: usize) -> Result<ValueIter<'a>> {
 		let tree = self.get_tree(tree)?;
-		let db = self.db.lock().unwrap();
 		let sql = format!("SELECT k, v FROM {} ORDER BY k ASC", tree);
-		let mut stmt = db.prepare(&sql)?; 
+		DbValueIterator::new(self.db.lock().unwrap(), &sql, [])
-		let res = stmt.query([])?;
-		unimplemented!();
 	}
 
 	fn iter_rev<'a>(&'a self, tree: usize) -> Result<ValueIter<'a>> {
 		let tree = self.get_tree(tree)?;
-		unimplemented!();
+		let sql = format!("SELECT k, v FROM {} ORDER BY k DESC", tree);
+		DbValueIterator::new(self.db.lock().unwrap(), &sql, [])
 	}
 
 	fn range<'a, 'r>(
@@ -263,3 +262,80 @@ impl<'a> ITx<'a> for SqliteTx<'a> {
 	}
 }
 
+// ----
+
+struct DbValueIterator<'a> {
+	db: Option<MutexGuard<'a, Connection>>,
+	stmt: Option<Statement<'a>>,
+	iter: Option<Rows<'a>>,
+	_pin: PhantomPinned,
+}
+
+impl<'a> DbValueIterator<'a> {
+	fn new<P: rusqlite::Params>(
+		db: MutexGuard<'a, Connection>,
+		sql: &str,
+		args: P,
+	) -> Result<ValueIter<'a>> {
+		let res = DbValueIterator {
+			db: Some(db),
+			stmt: None,
+			iter: None,
+			_pin: PhantomPinned,
+		};
+		let mut boxed = Box::pin(res);
+
+		unsafe {
+			let db = NonNull::from(&boxed.db);
+			let stmt = db.as_ref().as_ref().unwrap().prepare(&sql)?;
+
+			let mut_ref: Pin<&mut DbValueIterator<'a>> = Pin::as_mut(&mut boxed);
+			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)?;
+
+			let mut_ref: Pin<&mut DbValueIterator<'a>> = Pin::as_mut(&mut boxed);
+			Pin::get_unchecked_mut(mut_ref).iter = Some(iter);
+		}
+
+		Ok(Box::new(DbValueIteratorPin(boxed)))
+	}
+}
+
+struct DbValueIteratorPin<'a>(Pin<Box<DbValueIterator<'a>>>);
+
+impl<'a> Iterator for DbValueIteratorPin<'a> {
+	type Item = Result<(Value<'a>, Value<'a>)>;
+
+	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) => {
+				// finished, drop everything
+				unsafe {
+					let mut_ref: Pin<&mut DbValueIterator<'a>> = Pin::as_mut(&mut self.0);
+					let t = Pin::get_unchecked_mut(mut_ref);
+					drop(t.iter.take());
+					drop(t.stmt.take());
+					drop(t.db.take());
+				}
+				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.into(), v.into())))
+	}
+}

src/garage/repair.rs

@@ -66,18 +66,10 @@ impl Repair {
 	async fn repair_versions(&self, must_exit: &watch::Receiver<bool>) -> Result<(), Error> {
 		let mut pos = vec![];
 
-		while let Some(item) = self
+		while let Some((item_key, item_bytes)) = self.get_next_version_after(&pos)? {
-			.garage
+			pos = item_key;
-			.version_table
-			.data
-			.store
-			.range((Bound::Excluded(pos), Bound::Unbounded))?
-			.next()
-		{
-			let (item_key, item_bytes) = item?;
-			pos = item_key.to_vec();
 
-			let version = rmp_serde::decode::from_read_ref::<_, Version>(item_bytes.as_ref())?;
+			let version = rmp_serde::decode::from_read_ref::<_, Version>(&item_bytes)?;
 			if version.deleted.get() {
 				continue;
 			}
@@ -113,22 +105,30 @@ impl Repair {
 		Ok(())
 	}
 
+	fn get_next_version_after(&self, pos: &[u8]) -> Result<Option<(Vec<u8>, Vec<u8>)>, Error> {
+		match self
+			.garage
+			.version_table
+			.data
+			.store
+			.range::<&[u8], _>((Bound::Excluded(pos), Bound::Unbounded))?
+			.next()
+		{
+			None => Ok(None),
+			Some(item) => {
+				let (item_key, item_bytes) = item?;
+				Ok(Some((item_key.into_owned(), item_bytes.into_owned())))
+			}
+		}
+	}
+
 	async fn repair_block_ref(&self, must_exit: &watch::Receiver<bool>) -> Result<(), Error> {
 		let mut pos = vec![];
 
-		while let Some(item) = self
+		while let Some((item_key, item_bytes)) = self.get_next_block_ref_after(&pos)? {
-			.garage
+			pos = item_key;
-			.block_ref_table
-			.data
-			.store
-			.range((Bound::Excluded(pos), Bound::Unbounded))?
-			.next()
-		{
-			let (item_key, item_bytes) = item?;
 
-			pos = item_key.to_vec();
+			let block_ref = rmp_serde::decode::from_read_ref::<_, BlockRef>(&item_bytes)?;
-
-			let block_ref = rmp_serde::decode::from_read_ref::<_, BlockRef>(item_bytes.as_ref())?;
 			if block_ref.deleted.get() {
 				continue;
 			}
@@ -160,4 +160,21 @@ impl Repair {
 		}
 		Ok(())
 	}
+
+	fn get_next_block_ref_after(&self, pos: &[u8]) -> Result<Option<(Vec<u8>, Vec<u8>)>, Error> {
+		match self
+			.garage
+			.block_ref_table
+			.data
+			.store
+			.range::<&[u8], _>((Bound::Excluded(pos), Bound::Unbounded))?
+			.next()
+		{
+			None => Ok(None),
+			Some(item) => {
+				let (item_key, item_bytes) = item?;
+				Ok(Some((item_key.into_owned(), item_bytes.into_owned())))
+			}
+		}
+	}
 }

src/model/migrate.rs

@@ -25,11 +25,15 @@ impl Migrate {
 			.open_tree("bucket:table")
 			.map_err(GarageError::from)?;
 
+		let mut old_buckets = vec![];
 		for res in tree.iter().map_err(GarageError::from)? {
 			let (_k, v) = res.map_err(GarageError::from)?;
 			let bucket = rmp_serde::decode::from_read_ref::<_, old_bucket::Bucket>(&v[..])
 				.map_err(GarageError::from)?;
+			old_buckets.push(bucket);
+		}
 
+		for bucket in old_buckets {
 			if let old_bucket::BucketState::Present(p) = bucket.state.get() {
 				self.migrate_buckets050_do_bucket(&bucket, p).await?;
 			}

src/table/merkle.rs

@@ -89,33 +89,33 @@ where
 
 	async fn updater_loop(self: Arc<Self>, mut must_exit: watch::Receiver<bool>) {
 		while !*must_exit.borrow() {
-			if let Some(x) = self.data.merkle_todo.iter().unwrap().next() {
+			match self.updater_loop_iter() {
-				// TODO unwrap to remove
+				Ok(true) => (),
-				match x {
+				Ok(false) => {
-					Ok((key, valhash)) => {
+					select! {
-						if let Err(e) = self.update_item(&key[..], &valhash[..]) {
+						_ = self.data.merkle_todo_notify.notified().fuse() => {},
-							warn!(
+						_ = must_exit.changed().fuse() => {},
-								"({}) Error while updating Merkle tree item: {}",
-								F::TABLE_NAME,
-								e
-							);
 					}
 				}
 				Err(e) => {
 					warn!(
-							"({}) Error while iterating on Merkle todo tree: {}",
+						"({}) Error while updating Merkle tree item: {}",
 						F::TABLE_NAME,
 						e
 					);
 					tokio::time::sleep(Duration::from_secs(10)).await;
 				}
 			}
+		}
+	}
+
+	fn updater_loop_iter(&self) -> Result<bool, Error> {
+		if let Some(x) = self.data.merkle_todo.iter()?.next() {
+			let (key, valhash) = x?;
+			self.update_item(&key[..], &valhash[..])?;
+			Ok(true)
 		} else {
-				select! {
+			Ok(false)
-					_ = self.data.merkle_todo_notify.notified().fuse() => {},
-					_ = must_exit.changed().fuse() => {},
-				}
-			}
 		}
 	}