Fmt

Author: Dandandan

arrow-select/src/coalesce/byte_view.rs

@@ -250,29 +250,48 @@ impl<B: ByteViewType> InProgressByteViewArray<B> {
             );
         }
 
-        // Copy the views, updating the buffer index and copying the data as needed
-        let new_views = views.iter().map(|v| {
-            let mut b: ByteView = ByteView::from(*v);
+        // Single-pass: rewrite views and copy string data together.
+        // Uses a manual loop with raw pointers so all state lives in
+        // registers (no closure captures that force reloads).
+        let dst_ptr = dst_buffer.as_mut_ptr();
+        let mut dst_len = dst_buffer.len();
+
+        let views_ptr = self.views.as_mut_ptr();
+        let mut views_len = self.views.len();
+        self.views.reserve(views.len());
+
+        for v in views {
+            let mut b = ByteView::from(*v);
             if b.length > MAX_INLINE_VIEW_LEN {
                 let buffer_index = b.buffer_index as usize;
                 let buffer_offset = b.offset as usize;
                 let str_len = b.length as usize;
 
-                // Update view to location in current
-                b.offset = dst_buffer.len() as u32;
+                b.offset = dst_len as u32;
                 b.buffer_index = new_buffer_index;
 
-                // safety: input views are validly constructed
-                let src = unsafe {
-                    buffers
+                // safety: input views are validly constructed and
+                // dst_buffer has sufficient capacity
+                unsafe {
+                    let src_ptr = buffers
                         .get_unchecked(buffer_index)
-                        .get_unchecked(buffer_offset..buffer_offset + str_len)
-                };
-                dst_buffer.extend_from_slice(src);
+                        .as_ptr()
+                        .add(buffer_offset);
+                    std::ptr::copy_nonoverlapping(src_ptr, dst_ptr.add(dst_len), str_len);
+                }
+                dst_len += str_len;
+            }
+            // Safety: we reserved capacity above
+            unsafe {
+                views_ptr.add(views_len).write(b.as_u128());
             }
-            b.as_u128()
-        });
-        self.views.extend(new_views);
+            views_len += 1;
+        }
+
+        unsafe {
+            self.views.set_len(views_len);
+            dst_buffer.set_len(dst_len);
+        }
         self.current = Some(dst_buffer);
     }
 }