Use chunks_exact where possible

GitoxideLabs · Feb 6, 2024 · 2482023 · 2482023
1 parent 8a62fb5
commit 2482023
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Showing 8 changed files with 30 additions and 20 deletions.
diff --git a/gix-commitgraph/src/file/access.rs b/gix-commitgraph/src/file/access.rs
@@ -57,7 +57,7 @@ impl File {
         let start = self.base_graphs_list_offset.unwrap_or(0);
         let base_graphs_list = &self.data[start..][..self.hash_len * usize::from(self.base_graph_count)];
         base_graphs_list
-            .chunks(self.hash_len)
+            .chunks_exact(self.hash_len)
             .map(gix_hash::oid::from_bytes_unchecked)
     }
 

diff --git a/gix-commitgraph/src/file/init.rs b/gix-commitgraph/src/file/init.rs
@@ -259,8 +259,10 @@ impl TryFrom<&Path> for File {
 
 // Copied from gix-odb/pack/index/init.rs
 fn read_fan(d: &[u8]) -> ([u32; FAN_LEN], usize) {
+    assert!(d.len() >= FAN_LEN * 4);
+
     let mut fan = [0; FAN_LEN];
-    for (c, f) in d.chunks(4).zip(fan.iter_mut()) {
+    for (c, f) in d.chunks_exact(4).zip(fan.iter_mut()) {
         *f = u32::from_be_bytes(c.try_into().unwrap());
     }
     (fan, FAN_LEN * 4)

diff --git a/gix-index/src/decode/mod.rs b/gix-index/src/decode/mod.rs
@@ -96,9 +96,10 @@ impl State {
                     let entries_res = match index_offsets_table {
                         Some(entry_offsets) => {
                             let chunk_size = (entry_offsets.len() as f32 / num_threads as f32).ceil() as usize;
-                            let num_chunks = entry_offsets.chunks(chunk_size).count();
+                            let entry_offsets_chunked = entry_offsets.chunks(chunk_size);
+                            let num_chunks = entry_offsets_chunked.len();
                             let mut threads = Vec::with_capacity(num_chunks);
-                            for (id, chunks) in entry_offsets.chunks(chunk_size).enumerate() {
+                            for (id, chunks) in entry_offsets_chunked.enumerate() {
                                 let chunks = chunks.to_vec();
                                 threads.push(
                                     gix_features::parallel::build_thread()

diff --git a/gix-pack/src/index/access.rs b/gix-pack/src/index/access.rs
@@ -31,7 +31,7 @@ impl index::File {
     fn iter_v1(&self) -> impl Iterator<Item = Entry> + '_ {
         match self.version {
             index::Version::V1 => self.data[V1_HEADER_SIZE..]
-                .chunks(N32_SIZE + self.hash_len)
+                .chunks_exact(N32_SIZE + self.hash_len)
                 .take(self.num_objects as usize)
                 .map(|c| {
                     let (ofs, oid) = c.split_at(N32_SIZE);
@@ -47,14 +47,19 @@ impl index::File {
 
     fn iter_v2(&self) -> impl Iterator<Item = Entry> + '_ {
         let pack64_offset = self.offset_pack_offset64_v2();
+        let oids = self.data[V2_HEADER_SIZE..]
+            .chunks_exact(self.hash_len)
+            .take(self.num_objects as usize);
+        let crcs = self.data[self.offset_crc32_v2()..]
+            .chunks_exact(N32_SIZE)
+            .take(self.num_objects as usize);
+        let offsets = self.data[self.offset_pack_offset_v2()..]
+            .chunks_exact(N32_SIZE)
+            .take(self.num_objects as usize);
+        assert_eq!(oids.len(), crcs.len());
+        assert_eq!(crcs.len(), offsets.len());
         match self.version {
-            index::Version::V2 => izip!(
-                self.data[V2_HEADER_SIZE..].chunks(self.hash_len),
-                self.data[self.offset_crc32_v2()..].chunks(N32_SIZE),
-                self.data[self.offset_pack_offset_v2()..].chunks(N32_SIZE)
-            )
-            .take(self.num_objects as usize)
-            .map(move |(oid, crc32, ofs32)| Entry {
+            index::Version::V2 => izip!(oids, crcs, offsets).map(move |(oid, crc32, ofs32)| Entry {
                 oid: gix_hash::ObjectId::from_bytes_or_panic(oid),
                 pack_offset: self.pack_offset_from_offset_v2(ofs32, pack64_offset),
                 crc32: Some(crate::read_u32(crc32)),
@@ -162,10 +167,10 @@ impl index::File {
             index::Version::V1 => self.iter().map(|e| e.pack_offset).collect(),
             index::Version::V2 => {
                 let offset32_start = &self.data[self.offset_pack_offset_v2()..];
+                let offsets32 = offset32_start.chunks_exact(N32_SIZE).take(self.num_objects as usize);
+                assert_eq!(self.num_objects as usize, offsets32.len());
                 let pack_offset_64_start = self.offset_pack_offset64_v2();
-                offset32_start
-                    .chunks(N32_SIZE)
-                    .take(self.num_objects as usize)
+                offsets32
                     .map(|offset| self.pack_offset_from_offset_v2(offset, pack_offset_64_start))
                     .collect()
             }

diff --git a/gix-pack/src/index/init.rs b/gix-pack/src/index/init.rs
@@ -83,8 +83,10 @@ impl index::File {
 }
 
 fn read_fan(d: &[u8]) -> ([u32; FAN_LEN], usize) {
+    assert!(d.len() >= FAN_LEN * N32_SIZE);
+
     let mut fan = [0; FAN_LEN];
-    for (c, f) in d.chunks(N32_SIZE).zip(fan.iter_mut()) {
+    for (c, f) in d.chunks_exact(N32_SIZE).zip(fan.iter_mut()) {
         *f = crate::read_u32(c);
     }
     (fan, FAN_LEN * N32_SIZE)

diff --git a/gix-pack/src/index/traverse/with_lookup.rs b/gix-pack/src/index/traverse/with_lookup.rs
@@ -121,7 +121,7 @@ impl index::File {
                 let (chunk_size, thread_limit, available_cores) =
                     parallel::optimize_chunk_size_and_thread_limit(1000, Some(index_entries.len()), thread_limit, None);
                 let there_are_enough_entries_to_process = || index_entries.len() > chunk_size * available_cores;
-                let input_chunks = index_entries.chunks(chunk_size.max(chunk_size));
+                let input_chunks = index_entries.chunks(chunk_size);
                 let reduce_progress = OwnShared::new(Mutable::new({
                     let mut p = progress.add_child_with_id("Traversing".into(), ProgressId::DecodedObjects.into());
                     p.init(Some(self.num_objects() as usize), progress::count("objects"));

diff --git a/gix-pack/src/multi_index/chunk.rs b/gix-pack/src/multi_index/chunk.rs
@@ -121,7 +121,7 @@ pub mod fanout {
             return None;
         }
         let mut out = [0; 256];
-        for (c, f) in chunk.chunks(4).zip(out.iter_mut()) {
+        for (c, f) in chunk.chunks_exact(4).zip(out.iter_mut()) {
             *f = u32::from_be_bytes(c.try_into().unwrap());
         }
         out.into()

diff --git a/src/plumbing/main.rs b/src/plumbing/main.rs
@@ -226,8 +226,8 @@ pub fn main() -> Result<()> {
                         add_paths: add_path,
                         prefix,
                         files: add_virtual_file
-                            .chunks(2)
-                            .map(|c| (c[0].to_owned(), c[1].clone()))
+                            .chunks_exact(2)
+                            .map(|c| (c[0].clone(), c[1].clone()))
                             .collect(),
                         format: format.map(|f| match f {
                             crate::plumbing::options::archive::Format::Internal => {