From 8adef5e2163ec805c5f693233b8b209ce937a818 Mon Sep 17 00:00:00 2001
From: Riz Ashraf <reazul.ashraf@inseinc.com>
Date: Tue, 22 Sep 2026 04:50:30 +0100
Subject: [PATCH] perf(nvim-core): eliminate heavy string allocations for
 JSON-RPC msgids in internal request mapping

---
 nvim-core/src/lib.rs | 26 +++++++++++++++-----------
 1 file changed, 15 insertions(+), 11 deletions(-)

diff --git a/nvim-core/src/lib.rs b/nvim-core/src/lib.rs
index 4d3f103..05de299 100644
--- a/nvim-core/src/lib.rs
+++ b/nvim-core/src/lib.rs
@@ -111,7 +111,7 @@ use std::sync::LazyLock;
 use tokio::sync::{mpsc, oneshot};
 
 pub struct NvimRequest {
-    pub msgid_str: String,
+    pub msgid: u64,
     pub req: rmpv::Value,
     pub reply: oneshot::Sender<Result<rmpv::Value, String>>,
 }
@@ -153,7 +153,7 @@ async fn get_nvim_connection() -> Result<mpsc::Sender<NvimRequest>, String> {
     let (mut read_half, mut write_half) = tokio::io::split(stream);
     let (tx, mut rx) = mpsc::channel::<NvimRequest>(32);
     type PendingRequestsMap =
-        Arc<std::sync::Mutex<HashMap<String, oneshot::Sender<Result<rmpv::Value, String>>>>>;
+        Arc<std::sync::Mutex<HashMap<u64, oneshot::Sender<Result<rmpv::Value, String>>>>>;
     let pending_requests: PendingRequestsMap = Arc::new(std::sync::Mutex::new(HashMap::new()));
 
     // Write task
@@ -169,7 +169,7 @@ async fn get_nvim_connection() -> Result<mpsc::Sender<NvimRequest>, String> {
             pending_clone
                 .lock()
                 .unwrap()
-                .insert(req.msgid_str.clone(), req.reply);
+                .insert(req.msgid, req.reply);
 
             if write_half.write_all(&buf).await.is_err() {
                 tracing::error!("Failed to write to Neovim socket");
@@ -193,13 +193,15 @@ async fn get_nvim_connection() -> Result<mpsc::Sender<NvimRequest>, String> {
 
                     if let rmpv::Value::Array(ref arr) = val {
                         if arr.len() >= 4 && arr[0] == rmpv::Value::Integer(1.into()) {
-                            let msgid = &arr[1];
-                            let msgid_str = format!("{msgid:?}");
+                            let msgid = match &arr[1] {
+                                rmpv::Value::Integer(i) => i.as_u64().unwrap_or(0),
+                                _ => 0,
+                            };
 
                             if let Some(reply_sender) = pending_clone2
                                 .lock()
                                 .unwrap_or_else(|e| e.into_inner())
-                                .remove(&msgid_str)
+                                .remove(&msgid)
                             {
                                 let _ = reply_sender.send(Ok(val));
                             }
@@ -279,20 +281,22 @@ async fn get_nvim_connection() -> Result<mpsc::Sender<NvimRequest>, String> {
 async fn call_nvim(req: rmpv::Value) -> Result<rmpv::Value, String> {
     let msgid = if let rmpv::Value::Array(ref arr) = req {
         if arr.len() > 1 {
-            arr[1].clone()
+            match &arr[1] {
+                rmpv::Value::Integer(i) => i.as_u64().unwrap_or(0),
+                _ => 0,
+            }
         } else {
-            rmpv::Value::Nil
+            0
         }
     } else {
-        rmpv::Value::Nil
+        0
     };
 
-    let msgid_str = format!("{msgid:?}");
     let tx = get_nvim_connection().await?;
     let (reply_tx, reply_rx) = oneshot::channel();
 
     tx.send(NvimRequest {
-        msgid_str,
+        msgid,
         req,
         reply: reply_tx,
     })