From 1f7c3aeeb4d0b56318205b2dc2f09c0c2e0f2586 Mon Sep 17 00:00:00 2001
From: Paul Loyd <pavelko95@gmail.com>
Date: Wed, 10 Apr 2024 10:20:42 +0200
Subject: [PATCH] Fix `DDSketch::length()` to count also the negative store

---
 src/ddsketch.rs | 20 +++++++++++++++++++-
 1 file changed, 19 insertions(+), 1 deletion(-)

diff --git a/src/ddsketch.rs b/src/ddsketch.rs
index 8133aa8..bca9912 100644
--- a/src/ddsketch.rs
+++ b/src/ddsketch.rs
@@ -161,7 +161,7 @@ impl DDSketch {
     /// Returns the length of the underlying `Store`. This is mainly only useful for understanding
     /// how much the sketch has grown given the inserted values.
     pub fn length(&self) -> usize {
-        self.store.length() as usize
+        self.store.length() as usize + self.negative_store.length() as usize
     }
 
     /// Merge the contents of another sketch into this one. The sketch that is merged into this one
@@ -352,4 +352,22 @@ mod tests {
         assert!(dd.quantile(0.5).unwrap().is_some());
         assert!(dd.quantile(0.75).unwrap().is_some());
     }
+
+    #[test]
+    fn test_length() {
+        let mut dd = DDSketch::default();
+        assert_eq!(dd.length(), 0);
+
+        dd.add(1.0);
+        assert_eq!(dd.length(), 128);
+        dd.add(2.0);
+        dd.add(3.0);
+        assert_eq!(dd.length(), 128);
+
+        dd.add(-1.0);
+        assert_eq!(dd.length(), 256);
+        dd.add(-2.0);
+        dd.add(-3.0);
+        assert_eq!(dd.length(), 256);
+    }
 }