From 93978ec38a345cd0acbc068cde59f7e739ecf1bb Mon Sep 17 00:00:00 2001
From: Kerollmops <clement@meilisearch.com>
Date: Wed, 9 Jun 2021 11:28:38 +0200
Subject: [PATCH] Serializing a RoaringBitmap into a Vec cannot fail

---
 .../roaring_bitmap/cbo_roaring_bitmap_codec.rs           | 9 ++++-----
 milli/src/update/index_documents/merge_function.rs       | 2 +-
 milli/src/update/index_documents/store.rs                | 7 +++----
 3 files changed, 8 insertions(+), 10 deletions(-)

diff --git a/milli/src/heed_codec/roaring_bitmap/cbo_roaring_bitmap_codec.rs b/milli/src/heed_codec/roaring_bitmap/cbo_roaring_bitmap_codec.rs
index 8ccf831e3..325effa73 100644
--- a/milli/src/heed_codec/roaring_bitmap/cbo_roaring_bitmap_codec.rs
+++ b/milli/src/heed_codec/roaring_bitmap/cbo_roaring_bitmap_codec.rs
@@ -23,18 +23,17 @@ impl CboRoaringBitmapCodec {
         }
     }
 
-    pub fn serialize_into(roaring: &RoaringBitmap, vec: &mut Vec<u8>) -> io::Result<()> {
+    pub fn serialize_into(roaring: &RoaringBitmap, vec: &mut Vec<u8>) {
         if roaring.len() <= THRESHOLD as u64 {
             // If the number of items (u32s) to encode is less than or equal to the threshold
             // it means that it would weigh the same or less than the RoaringBitmap
             // header, so we directly encode them using ByteOrder instead.
             for integer in roaring {
-                vec.write_u32::<NativeEndian>(integer)?;
+                vec.write_u32::<NativeEndian>(integer).unwrap();
             }
-            Ok(())
         } else {
             // Otherwise, we use the classic RoaringBitmapCodec that writes a header.
-            roaring.serialize_into(vec)
+            roaring.serialize_into(vec).unwrap();
         }
     }
 
@@ -68,7 +67,7 @@ impl heed::BytesEncode<'_> for CboRoaringBitmapCodec {
 
     fn bytes_encode(item: &Self::EItem) -> Option<Cow<[u8]>> {
         let mut vec = Vec::with_capacity(Self::serialized_size(item));
-        Self::serialize_into(item, &mut vec).ok()?;
+        Self::serialize_into(item, &mut vec);
         Some(Cow::Owned(vec))
     }
 }
diff --git a/milli/src/update/index_documents/merge_function.rs b/milli/src/update/index_documents/merge_function.rs
index 230116e99..6da19bc84 100644
--- a/milli/src/update/index_documents/merge_function.rs
+++ b/milli/src/update/index_documents/merge_function.rs
@@ -112,6 +112,6 @@ fn cbo_roaring_bitmap_merge(values: &[Cow<[u8]>]) -> anyhow::Result<Vec<u8>> {
     }
 
     let mut vec = Vec::new();
-    CboRoaringBitmapCodec::serialize_into(&head, &mut vec)?;
+    CboRoaringBitmapCodec::serialize_into(&head, &mut vec);
     Ok(vec)
 }
diff --git a/milli/src/update/index_documents/store.rs b/milli/src/update/index_documents/store.rs
index 08050092e..69263e5a0 100644
--- a/milli/src/update/index_documents/store.rs
+++ b/milli/src/update/index_documents/store.rs
@@ -407,7 +407,7 @@ impl<'s, A: AsRef<[u8]>> Store<'s, A> {
             // We serialize the document ids into a buffer
             buffer.clear();
             buffer.reserve(CboRoaringBitmapCodec::serialized_size(&docids));
-            CboRoaringBitmapCodec::serialize_into(&docids, &mut buffer)?;
+            CboRoaringBitmapCodec::serialize_into(&docids, &mut buffer);
             // that we write under the generated key into MTBL
             if lmdb_key_valid_size(&key) {
                 sorter.insert(&key, &buffer)?;
@@ -469,8 +469,7 @@ impl<'s, A: AsRef<[u8]>> Store<'s, A> {
                 data_buffer.clear();
                 let positions = RoaringBitmap::from_iter(Some(document_id));
                 // We serialize the positions into a buffer.
-                CboRoaringBitmapCodec::serialize_into(&positions, &mut data_buffer)
-                    .with_context(|| "could not serialize positions")?;
+                CboRoaringBitmapCodec::serialize_into(&positions, &mut data_buffer);
 
                 // that we write under the generated key into MTBL
                 if lmdb_key_valid_size(&key_buffer) {
@@ -706,7 +705,7 @@ impl<'s, A: AsRef<[u8]>> Store<'s, A> {
         let mut docids_buffer = Vec::new();
         for ((fid, count), docids) in self.field_id_word_count_docids {
             docids_buffer.clear();
-            CboRoaringBitmapCodec::serialize_into(&docids, &mut docids_buffer)?;
+            CboRoaringBitmapCodec::serialize_into(&docids, &mut docids_buffer);
             self.field_id_word_count_docids_sorter.insert([fid, count], &docids_buffer)?;
         }