From cbc5dc04ef7d200e93475a110aca472384a2ccb2 Mon Sep 17 00:00:00 2001
From: Antonio Scandurra <me@as-cii.com>
Date: Thu, 27 Jul 2023 12:28:26 +0200
Subject: [PATCH] Avoid pushing empty leaves into the tree

---
 crates/crdb/src/btree.rs | 52 +++++++++++++++++++++++++++-------------
 1 file changed, 35 insertions(+), 17 deletions(-)

diff --git a/crates/crdb/src/btree.rs b/crates/crdb/src/btree.rs
index c20d7f9aa56..20173254f4c 100644
--- a/crates/crdb/src/btree.rs
+++ b/crates/crdb/src/btree.rs
@@ -425,26 +425,44 @@ impl<T: Item> Sequence<T> {
             }
             ChildTree::Unloaded { saved_id } => {
                 if self.0.is_leaf() {
-                    let mut summary = self.0.summary().clone();
-                    Summary::add_summary(&mut summary, &other_summary, cx);
+                    if self.0.items().is_empty() {
+                        let mut child_summaries = ArrayVec::new();
+                        child_summaries.push(other_summary.clone());
 
-                    let mut child_summaries = ArrayVec::new();
-                    child_summaries.push(self.0.summary().clone());
-                    child_summaries.push(other_summary);
+                        let mut child_trees = ArrayVec::new();
+                        child_trees.push(ChildTree::Unloaded {
+                            saved_id: saved_id.clone(),
+                        });
 
-                    let mut child_trees = ArrayVec::new();
-                    child_trees.push(ChildTree::Loaded { tree: self.clone() });
-                    child_trees.push(ChildTree::Unloaded {
-                        saved_id: saved_id.clone(),
-                    });
+                        *self = Self(Arc::new(Node::Internal {
+                            saved_id: Default::default(),
+                            height: 1,
+                            summary: other_summary,
+                            child_summaries,
+                            child_trees,
+                        }));
+                    } else {
+                        let mut summary = self.0.summary().clone();
+                        Summary::add_summary(&mut summary, &other_summary, cx);
 
-                    *self = Self(Arc::new(Node::Internal {
-                        saved_id: Default::default(),
-                        height: self.0.height() + 1,
-                        summary,
-                        child_summaries,
-                        child_trees,
-                    }));
+                        let mut child_summaries = ArrayVec::new();
+                        child_summaries.push(self.0.summary().clone());
+                        child_summaries.push(other_summary);
+
+                        let mut child_trees = ArrayVec::new();
+                        child_trees.push(ChildTree::Loaded { tree: self.clone() });
+                        child_trees.push(ChildTree::Unloaded {
+                            saved_id: saved_id.clone(),
+                        });
+
+                        *self = Self(Arc::new(Node::Internal {
+                            saved_id: Default::default(),
+                            height: 1,
+                            summary,
+                            child_summaries,
+                            child_trees,
+                        }));
+                    }
                 } else if let Some(split_tree) =
                     self.push_tree_recursive(other_child, other_summary, cx)
                 {