improve internal item counter mechanisms and implement bucket quotas (#326)

- [x] Refactoring of internal counting API
- [x] Repair procedure for counters (it's an offline procedure!!!)
- [x] New counter for objects in buckets
- [x] Add quotas to buckets struct
- [x] Add CLI to manage bucket quotas
- [x] Add admin API to manage bucket quotas
- [x] Apply quotas by adding checks on put operations
- [x] Proof-read

Co-authored-by: Alex Auvolat <alex@adnab.me>
Reviewed-on: https://git.deuxfleurs.fr/Deuxfleurs/garage/pulls/326
Co-authored-by: Alex <alex@adnab.me>
Co-committed-by: Alex <alex@adnab.me>

src/db/lib.rs

@@ -197,6 +197,11 @@ impl Tree {
 	pub fn remove<T: AsRef<[u8]>>(&self, key: T) -> Result<Option<Value>> {
 		self.0.remove(self.1, key.as_ref())
 	}
+	/// Clears all values from the tree
+	#[inline]
+	pub fn clear(&self) -> Result<()> {
+		self.0.clear(self.1)
+	}
 
 	#[inline]
 	pub fn iter(&self) -> Result<ValueIter<'_>> {
@@ -311,6 +316,7 @@ pub(crate) trait IDb: Send + Sync {
 
 	fn insert(&self, tree: usize, key: &[u8], value: &[u8]) -> Result<Option<Value>>;
 	fn remove(&self, tree: usize, key: &[u8]) -> Result<Option<Value>>;
+	fn clear(&self, tree: usize) -> Result<()>;
 
 	fn iter(&self, tree: usize) -> Result<ValueIter<'_>>;
 	fn iter_rev(&self, tree: usize) -> Result<ValueIter<'_>>;

src/db/lmdb_adapter.rs

@@ -139,6 +139,14 @@ impl IDb for LmdbDb {
 		Ok(old_val)
 	}
 
+	fn clear(&self, tree: usize) -> Result<()> {
+		let tree = self.get_tree(tree)?;
+		let mut tx = self.db.write_txn()?;
+		tree.clear(&mut tx)?;
+		tx.commit()?;
+		Ok(())
+	}
+
 	fn iter(&self, tree: usize) -> Result<ValueIter<'_>> {
 		let tree = self.get_tree(tree)?;
 		let tx = self.db.read_txn()?;

src/db/sled_adapter.rs

@@ -113,6 +113,12 @@ impl IDb for SledDb {
 		Ok(old_val.map(|x| x.to_vec()))
 	}
 
+	fn clear(&self, tree: usize) -> Result<()> {
+		let tree = self.get_tree(tree)?;
+		tree.clear()?;
+		Ok(())
+	}
+
 	fn iter(&self, tree: usize) -> Result<ValueIter<'_>> {
 		let tree = self.get_tree(tree)?;
 		Ok(Box::new(tree.iter().map(|v| {

src/db/sqlite_adapter.rs

@@ -182,6 +182,16 @@ impl IDb for SqliteDb {
 		Ok(old_val)
 	}
 
+	fn clear(&self, tree: usize) -> Result<()> {
+		trace!("clear {}: lock db", tree);
+		let this = self.0.lock().unwrap();
+		trace!("clear {}: lock acquired", tree);
+
+		let tree = this.get_tree(tree)?;
+		this.db.execute(&format!("DELETE FROM {}", tree), [])?;
+		Ok(())
+	}
+
 	fn iter(&self, tree: usize) -> Result<ValueIter<'_>> {
 		trace!("iter {}: lock db", tree);
 		let this = self.0.lock().unwrap();