From 1373637da18b3bc58eaddae2ad5614cac94137c1 Mon Sep 17 00:00:00 2001
From: Marin Postma <postma.marin@protonmail.com>
Date: Tue, 27 Apr 2021 14:22:33 +0200
Subject: [PATCH] optimize roaring codec

---
 .../roaring_bitmap/bo_roaring_bitmap_codec.rs         | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/milli/src/heed_codec/roaring_bitmap/bo_roaring_bitmap_codec.rs b/milli/src/heed_codec/roaring_bitmap/bo_roaring_bitmap_codec.rs
index 7ceb69f9a..25c8afe2f 100644
--- a/milli/src/heed_codec/roaring_bitmap/bo_roaring_bitmap_codec.rs
+++ b/milli/src/heed_codec/roaring_bitmap/bo_roaring_bitmap_codec.rs
@@ -1,4 +1,6 @@
 use std::borrow::Cow;
+use std::mem::size_of;
+
 use byteorder::{NativeEndian, ReadBytesExt, WriteBytesExt};
 use roaring::RoaringBitmap;
 
@@ -7,9 +9,14 @@ pub struct BoRoaringBitmapCodec;
 impl heed::BytesDecode<'_> for BoRoaringBitmapCodec {
     type DItem = RoaringBitmap;
 
-    fn bytes_decode(mut bytes: &[u8]) -> Option<Self::DItem> {
+    fn bytes_decode(bytes: &[u8]) -> Option<Self::DItem> {
         let mut bitmap = RoaringBitmap::new();
-        while let Ok(integer) = bytes.read_u32::<NativeEndian>() {
+        let num_u32 = bytes.len() / size_of::<u32>();
+        for i in 0..num_u32 {
+            let start = i * size_of::<u32>();
+            let end = (i + 1) * size_of::<u32>();
+            let mut bytes = bytes.get(start..end)?;
+            let integer = bytes.read_u32::<NativeEndian>().ok()?;
             bitmap.insert(integer);
         }
         Some(bitmap)