Add chunk for oids (#279)

git-pack/src/multi_index/chunk.rs

@@ -144,11 +144,27 @@ pub mod fanout {
 
 /// Information about the oid lookup table.
 pub mod lookup {
+    use crate::multi_index;
     use std::ops::Range;
 
     /// The id uniquely identifying the oid lookup table.
     pub const ID: git_chunk::Id = *b"OIDL";
 
+    /// Return the amount of bytes needed to store the data on disk for the given amount of `entries`
+    pub fn storage_size(entries: usize, object_hash: git_hash::Kind) -> u64 {
+        (entries * object_hash.len_in_bytes()) as u64
+    }
+
+    pub(crate) fn write(
+        sorted_entries: &[multi_index::write::Entry],
+        mut out: impl std::io::Write,
+    ) -> std::io::Result<()> {
+        for entry in sorted_entries {
+            out.write_all(entry.id.as_slice())?;
+        }
+        Ok(())
+    }
+
     /// Return true if the size of the `offset` range seems to match for a `hash` of the given kind and the amount of objects.
     pub fn is_valid(offset: &Range<usize>, hash: git_hash::Kind, num_objects: u32) -> bool {
         (offset.end - offset.start) / hash.len_in_bytes() == num_objects as usize

git-pack/src/multi_index/write.rs

@@ -116,6 +116,10 @@ impl multi_index::File {
             multi_index::chunk::index_names::storage_size(&index_filenames_sorted),
         );
         cf.plan_chunk(multi_index::chunk::fanout::ID, multi_index::chunk::fanout::SIZE as u64);
+        cf.plan_chunk(
+            multi_index::chunk::lookup::ID,
+            multi_index::chunk::lookup::storage_size(entries.len(), object_hash),
+        );
 
         let bytes_written = Self::write_header(
             &mut out,
@@ -130,6 +134,7 @@ impl multi_index::File {
                     multi_index::chunk::index_names::write(&index_filenames_sorted, &mut chunk_write)?
                 }
                 multi_index::chunk::fanout::ID => multi_index::chunk::fanout::write(&entries, &mut chunk_write)?,
+                multi_index::chunk::lookup::ID => multi_index::chunk::lookup::write(&entries, &mut chunk_write)?,
                 unknown => unreachable!("BUG: forgot to implement chunk {:?}", std::str::from_utf8(&unknown)),
             }
         }

git-pack/tests/pack/multi_index.rs

@@ -118,7 +118,6 @@ mod write {
     use std::sync::atomic::AtomicBool;
 
     #[test]
-    #[ignore]
     fn from_paths() {
         let dir = tempfile::TempDir::new().unwrap();
         let input_indices = std::fs::read_dir(fixture_path("objects/pack"))