Benchmarks for diff on cloned trees

Author: jenn-le

benchmarks.ts

@@ -313,7 +313,7 @@ console.log("### Measure effect of max node size ###");
 }
 
 console.log();
-console.log("### Delta between B+ trees with various sizes");
+console.log("### Delta between B+ trees");
 {
   console.log();
   const sizes = [100, 1000, 10000, 100000, 1000000];
@@ -334,4 +334,23 @@ console.log("### Delta between B+ trees with various sizes");
       });
     }
   })
+
+  console.log();
+  sizes.forEach((size, i) => {
+    for (let j = i; j < sizes.length; j++) {
+      const otherSize = sizes[j];
+      const keys = makeArray(size + otherSize, true);
+      const tree = new BTree();
+      for (let k of keys.slice(0, size))
+        tree.set(k, k * 10);
+      
+      const otherTree = tree.clone();
+      for (let k of keys.slice(size))
+        tree.set(k, k * 10);
+
+      measure(() => `Delta between B+tree with ${size} nodes and cheap cloned B+tree with ${otherSize} additional nodes`, () => {
+        tree.diffAgainst(otherTree);
+      });
+    }
+  })
 }