feat: Tree::clear

Author: marvin-j97

src/abstract.rs

@@ -161,9 +161,16 @@ pub trait AbstractTree {
     ///
     /// # Errors
     ///
-    /// Will return `Err` only if an IO error occurs during compaction.
+    /// Will return `Err` only if an IO error occurs.
     fn drop_range<K: AsRef<[u8]>, R: RangeBounds<K>>(&self, range: R) -> crate::Result<()>;
 
+    /// Drops all tables and clears all memtables atomically.
+    ///
+    /// # Errors
+    ///
+    /// Will return `Err` only if an IO error occurs.
+    fn clear(&self) -> crate::Result<()>;
+
     /// Performs major compaction, blocking the caller until it's done.
     ///
     /// # Errors

src/blob_tree/mod.rs

@@ -269,6 +269,10 @@ impl AbstractTree for BlobTree {
         self.index.drop_range(range)
     }
 
+    fn clear(&self) -> crate::Result<()> {
+        self.index.clear()
+    }
+
     fn major_compact(&self, target_size: u64, seqno_threshold: SeqNo) -> crate::Result<()> {
         self.index.major_compact(target_size, seqno_threshold)
     }

src/tree/mod.rs

@@ -208,6 +208,22 @@ impl AbstractTree for Tree {
         self.inner_compact(strategy, 0)
     }
 
+    fn clear(&self) -> crate::Result<()> {
+        let mut versions = self.get_version_history_lock();
+
+        versions.upgrade_version(
+            &self.config.path,
+            |v| {
+                let mut copy = v.clone();
+                copy.active_memtable = Arc::new(Memtable::new(self.memtable_id_counter.next()));
+                copy.sealed_memtables = Arc::default();
+                copy.version = Version::new(v.version.id() + 1, self.tree_type());
+                Ok(copy)
+            },
+            &self.config.seqno,
+        )
+    }
+
     #[doc(hidden)]
     fn major_compact(&self, target_size: u64, seqno_threshold: SeqNo) -> crate::Result<()> {
         let strategy = Arc::new(crate::compaction::major::Strategy::new(target_size));