Proper queueing for delayed inserts, now backed to disk

src/table/data.rs

@@ -31,6 +31,10 @@ pub struct TableData<F: TableSchema, R: TableReplication> {
 	pub(crate) merkle_tree: db::Tree,
 	pub(crate) merkle_todo: db::Tree,
 	pub(crate) merkle_todo_notify: Notify,
+
+	pub(crate) insert_queue: db::Tree,
+	pub(crate) insert_queue_notify: Notify,
+
 	pub(crate) gc_todo: CountedTree,
 
 	pub(crate) metrics: TableMetrics,
@@ -53,9 +57,13 @@ where
 			.open_tree(&format!("{}:merkle_todo", F::TABLE_NAME))
 			.expect("Unable to open DB Merkle TODO tree");
 
+		let insert_queue = db
+			.open_tree(&format!("{}:insert_queue", F::TABLE_NAME))
+			.expect("Unable to open insert queue DB tree");
+
 		let gc_todo = db
 			.open_tree(&format!("{}:gc_todo_v2", F::TABLE_NAME))
-			.expect("Unable to open DB tree");
+			.expect("Unable to open GC DB tree");
 		let gc_todo = CountedTree::new(gc_todo).expect("Cannot count gc_todo_v2");
 
 		let metrics = TableMetrics::new(
@@ -74,6 +82,8 @@ where
 			merkle_tree,
 			merkle_todo,
 			merkle_todo_notify: Notify::new(),
+			insert_queue,
+			insert_queue_notify: Notify::new(),
 			gc_todo,
 			metrics,
 		})
@@ -306,6 +316,32 @@ where
 		Ok(removed)
 	}
 
+	// ---- Insert queue functions ----
+
+	pub(crate) fn queue_insert(
+		&self,
+		tx: &mut db::Transaction,
+		ins: &F::E,
+	) -> db::TxResult<(), Error> {
+		let tree_key = self.tree_key(ins.partition_key(), ins.sort_key());
+
+		let new_entry = match tx.get(&self.insert_queue, &tree_key)? {
+			Some(old_v) => {
+				let mut entry = self.decode_entry(&old_v).map_err(db::TxError::Abort)?;
+				entry.merge(ins);
+				rmp_to_vec_all_named(&entry)
+					.map_err(Error::RmpEncode)
+					.map_err(db::TxError::Abort)?
+			}
+			None => rmp_to_vec_all_named(ins)
+				.map_err(Error::RmpEncode)
+				.map_err(db::TxError::Abort)?,
+		};
+		tx.insert(&self.insert_queue, &tree_key, new_entry)?;
+
+		Ok(())
+	}
+
 	// ---- Utility functions ----
 
 	pub fn tree_key(&self, p: &F::P, s: &F::S) -> Vec<u8> {