perf(draft): optimize memory layout by removing double indirection & implemented optimistic locking via Arc::ptr_eq for with_data_modify (#5942)

* perf(draft): optimize memory layout by removing double indirection

- Replace `Arc<Box<T>>` with `Arc<T>` to reduce pointer chasing and memory overhead.
- Leverage `Arc::from(Box<T>)` in async modify path for efficient ownership transfer.
- Fix race conditions in `edit_draft` by ensuring atomicity under write lock.
- Performance improved by ~16-24% across all operations (based on Criterion bench).

Benchmarks:
- latest_arc:     41.1ns (-24.2%)
- edit_draft:     92.2ns (-17.6%)
- apply:          89.8ns (-17.7%)
- async_modify:   66.0ns (-16.6%)

* perf(draft): implemented optimistic locking via Arc::ptr_eq for with_data_modify

Benchmarks confirm only a negligible ~2% (1.3ns) overhead for async operations, ensuring total data integrity during concurrent updates.

crates/clash-verge-draft/src/lib.rs

@@ -1,8 +1,8 @@
 use parking_lot::RwLock;
 use std::sync::Arc;
 
-pub type SharedBox<T> = Arc<Box<T>>;
-type DraftInner<T> = (SharedBox<T>, Option<SharedBox<T>>);
+pub type SharedDraft<T> = Arc<T>;
+type DraftInner<T> = (SharedDraft<T>, Option<SharedDraft<T>>);
 
 /// Draft 管理：committed 与 optional draft 都以 Arc<Box<T>> 存储，
 // (committed_snapshot, optional_draft_snapshot)
@@ -15,12 +15,12 @@ impl<T: Clone> Draft<T> {
     #[inline]
     pub fn new(data: T) -> Self {
         Self {
-            inner: Arc::new(RwLock::new((Arc::new(Box::new(data)), None))),
+            inner: Arc::new(RwLock::new((Arc::new(data), None))),
         }
     }
     /// 以 Arc<Box<T>> 的形式获取当前“已提交（正式）”数据的快照（零拷贝，仅 clone Arc）
     #[inline]
-    pub fn data_arc(&self) -> SharedBox<T> {
+    pub fn data_arc(&self) -> SharedDraft<T> {
         let guard = self.inner.read();
         Arc::clone(&guard.0)
     }
@@ -28,7 +28,7 @@ impl<T: Clone> Draft<T> {
     /// 获取当前（草稿若存在则返回草稿，否则返回已提交）的快照
     /// 这也是零拷贝：只 clone Arc，不 clone T
     #[inline]
-    pub fn latest_arc(&self) -> SharedBox<T> {
+    pub fn latest_arc(&self) -> SharedDraft<T> {
         let guard = self.inner.read();
         guard.1.clone().unwrap_or_else(|| Arc::clone(&guard.0))
     }
@@ -41,21 +41,11 @@ impl<T: Clone> Draft<T> {
     where
         F: FnOnce(&mut T) -> R,
     {
-        // 先获得写锁以创建或取出草稿 Arc 的可变引用位置
         let mut guard = self.inner.write();
-        let mut draft_arc = if guard.1.is_none() {
-            Arc::clone(&guard.0)
-        } else {
-            #[allow(clippy::unwrap_used)]
-            guard.1.take().unwrap()
-        };
-        drop(guard);
-        // Arc::make_mut: 如果只有一个引用则返回可变引用；否则会克隆底层 Box<T>（要求 T: Clone）
-        let boxed = Arc::make_mut(&mut draft_arc); // &mut Box<T>
-        // 对 Box<T> 解引用得到 &mut T
-        let result = f(&mut **boxed);
-        // 恢复修改后的草稿 Arc
-        self.inner.write().1 = Some(draft_arc);
+        let mut draft_arc = guard.1.take().unwrap_or_else(|| Arc::clone(&guard.0));
+        let data_mut = Arc::make_mut(&mut draft_arc);
+        let result = f(data_mut);
+        guard.1 = Some(draft_arc);
         result
     }
 
@@ -84,19 +74,19 @@ impl<T: Clone> Draft<T> {
         F: FnOnce(Box<T>) -> Fut + Send,
         Fut: std::future::Future<Output = Result<(Box<T>, R), anyhow::Error>> + Send,
     {
-        // 读取已提交快照（cheap Arc clone, 然后得到 Box<T> 所有权 via clone）
-        // 注意：为了让闭包接收 Box<T> 所有权，我们需要 clone 底层 T（不可避免）
-        let local: Box<T> = {
+        let (local, original_arc) = {
             let guard = self.inner.read();
-            // 将 Arc<Box<T>> 的 Box<T> clone 出来（会调用 T: Clone）
-            (*guard.0).clone()
+            let arc = Arc::clone(&guard.0);
+            (Box::new((*arc).clone()), arc)
         };
-
         let (new_local, res) = f(local).await?;
-
-        // 将新的 Box<T> 放到已提交位置（包进 Arc）
-        self.inner.write().0 = Arc::new(new_local);
-
+        let mut guard = self.inner.write();
+        if !Arc::ptr_eq(&guard.0, &original_arc) {
+            return Err(anyhow::anyhow!(
+                "Optimistic lock failed: Committed data has changed during async operation"
+            ));
+        }
+        guard.0 = Arc::from(new_local);
         Ok(res)
     }
 }

src-tauri/src/cmd/profile.rs

@@ -16,7 +16,7 @@ use crate::{
     ret_err,
     utils::{dirs, help},
 };
-use clash_verge_draft::SharedBox;
+use clash_verge_draft::SharedDraft;
 use clash_verge_logging::{Type, logging};
 use scopeguard::defer;
 use smartstring::alias::String;
@@ -26,7 +26,7 @@ use std::time::Duration;
 static CURRENT_SWITCHING_PROFILE: AtomicBool = AtomicBool::new(false);
 
 #[tauri::command]
-pub async fn get_profiles() -> CmdResult<SharedBox<IProfiles>> {
+pub async fn get_profiles() -> CmdResult<SharedDraft<IProfiles>> {
     logging!(debug, Type::Cmd, "获取配置文件列表");
     let draft = Config::profiles().await;
     let data = draft.data_arc();

src-tauri/src/cmd/verge.rs

@@ -1,10 +1,10 @@
 use super::CmdResult;
 use crate::{cmd::StringifyErr as _, config::IVerge, feat};
-use clash_verge_draft::SharedBox;
+use clash_verge_draft::SharedDraft;
 
 /// 获取Verge配置
 #[tauri::command]
-pub async fn get_verge_config() -> CmdResult<SharedBox<IVerge>> {
+pub async fn get_verge_config() -> CmdResult<SharedDraft<IVerge>> {
     feat::fetch_verge_config().await.stringify_err()
 }
 

src-tauri/src/enhance/mod.rs

@@ -106,7 +106,7 @@ async fn get_config_values() -> ConfigValues {
         ref verge_http_enabled,
         ref enable_dns_settings,
         ..
-    } = **verge_arc;
+    } = *verge_arc;
 
     let (clash_core, enable_tun, enable_builtin, socks_enabled, http_enabled, enable_dns_settings) = (
         Some(verge_arc.get_valid_clash_core()),

src-tauri/src/feat/config.rs

@@ -4,7 +4,7 @@ use crate::{
     module::{auto_backup::AutoBackupManager, lightweight},
 };
 use anyhow::Result;
-use clash_verge_draft::SharedBox;
+use clash_verge_draft::SharedDraft;
 use clash_verge_logging::{Type, logging, logging_error};
 use serde_yaml_ng::Mapping;
 
@@ -269,7 +269,7 @@ pub async fn patch_verge(patch: &IVerge, not_save_file: bool) -> Result<()> {
     Ok(())
 }
 
-pub async fn fetch_verge_config() -> Result<SharedBox<IVerge>> {
+pub async fn fetch_verge_config() -> Result<SharedDraft<IVerge>> {
     let draft = Config::verge().await;
     let data = draft.data_arc();
     Ok(data)