perf(sqlite-native): avoid cloning cached read chunks

Author: NathanFlurry

rivetkit-typescript/packages/sqlite-native/src/vfs.rs

@@ -432,22 +432,15 @@ unsafe extern "C" fn kv_io_read(
 		let end_chunk = (offset + requested_length - 1) / kv::CHUNK_SIZE;
 
 		let mut chunk_keys_to_fetch = Vec::new();
-		let mut buffered_chunks: HashMap<usize, Vec<u8>> = HashMap::new();
 		for chunk_idx in start_chunk..=end_chunk {
-			// Check dirty buffer first (batch mode writes).
 			if state.batch_mode {
-				if let Some(buffered) = state.dirty_buffer.get(&(chunk_idx as u32)) {
-					buffered_chunks.insert(chunk_idx, buffered.clone());
+				if state.dirty_buffer.contains_key(&(chunk_idx as u32)) {
 					continue;
 				}
 			}
-			// Check read cache.
 			let key = kv::get_chunk_key(file.file_tag, chunk_idx as u32);
-			if ctx.read_cache_enabled {
-				if let Some(cached) = state.read_cache.get(key.as_slice()) {
-					buffered_chunks.insert(chunk_idx, cached.clone());
+			if ctx.read_cache_enabled && state.read_cache.contains_key(key.as_slice()) {
 					continue;
-				}
 			}
 			chunk_keys_to_fetch.push(key.to_vec());
 		}
@@ -475,13 +468,26 @@ unsafe extern "C" fn kv_io_read(
 		let value_map = build_value_map(&resp);
 
 		for chunk_idx in start_chunk..=end_chunk {
-			let chunk_data: Option<&[u8]> = buffered_chunks
-				.get(&chunk_idx)
-				.map(|v| v.as_slice())
-				.or_else(|| {
-					let key = kv::get_chunk_key(file.file_tag, chunk_idx as u32);
-					value_map.get(key.as_slice()).copied()
-				});
+			let chunk_key = kv::get_chunk_key(file.file_tag, chunk_idx as u32);
+			let chunk_data = if state.batch_mode {
+				state
+					.dirty_buffer
+					.get(&(chunk_idx as u32))
+					.map(|buffered| buffered.as_slice())
+			} else {
+				None
+			}
+			.or_else(|| {
+				if ctx.read_cache_enabled {
+					state
+						.read_cache
+						.get(chunk_key.as_slice())
+						.map(|cached| cached.as_slice())
+				} else {
+					None
+				}
+			})
+			.or_else(|| value_map.get(chunk_key.as_slice()).copied());
 			let chunk_offset = chunk_idx * kv::CHUNK_SIZE;
 			let read_start = offset.saturating_sub(chunk_offset);
 			let read_end = std::cmp::min(kv::CHUNK_SIZE, offset + requested_length - chunk_offset);