use improved gix-diff API for better buffer handling

Author: Byron

gitoxide-core/src/hours/core.rs

@@ -105,7 +105,7 @@ pub fn spawn_tree_delta_threads<'scope>(
                     for chunk in rx {
                         for (commit_idx, parent_commit, commit) in chunk {
                             if let Some(cache) = cache.as_mut() {
-                                cache.clear_resource_cache();
+                                cache.clear_resource_cache_keep_allocation();
                             }
                             commits.fetch_add(1, Ordering::Relaxed);
                             if gix::interrupt::is_triggered() {

gitoxide-core/src/query/engine/update.rs

@@ -204,8 +204,8 @@ pub fn update(
                                             Some(c) => c,
                                             None => continue,
                                         };
-                                        rewrite_cache.clear_resource_cache();
-                                        diff_cache.clear_resource_cache();
+                                        rewrite_cache.clear_resource_cache_keep_allocation();
+                                        diff_cache.clear_resource_cache_keep_allocation();
                                         from.changes()?
                                             .track_path()
                                             .track_rewrites(Some(rewrites))

gix/src/object/tree/diff/mod.rs

@@ -156,7 +156,7 @@ impl<'a, 'repo> Platform<'a, 'repo> {
                 lines_removed += counts.removals as u64;
             }
 
-            resource_cache.clear_resource_cache();
+            resource_cache.clear_resource_cache_keep_allocation();
             Ok::<_, std::convert::Infallible>(Action::Continue)
         })?;