Call epoll_ctl in release stage

src/pipeline_entry.hpp

@@ -1,5 +1,6 @@
 #pragma once
 
+#include "arena.hpp"
 #include "connection.hpp"
 #include <variant>
 
@@ -19,14 +20,21 @@ struct CommitEntry {
   // Copied HTTP state (pipeline threads cannot access connection user_data)
   int64_t http_request_id = 0;
   bool connection_close = false;
-  const CommitRequest *commit_request =
-      nullptr; // Points to connection's arena data
+  const CommitRequest *commit_request = nullptr; // Points to request_arena data
+
+  // Request arena contains parsed request data and formatted response
+  Arena request_arena;
+
+  // Response data (set by persist stage, consumed by release stage)
+  // Points to response formatted in request_arena
+  std::span<std::string_view> response_message;
 
   CommitEntry() = default; // Default constructor for variant
   explicit CommitEntry(WeakRef<MessageSender> conn, int64_t req_id,
-                       bool close_conn, const CommitRequest *req)
+                       bool close_conn, const CommitRequest *req, Arena arena)
       : connection(std::move(conn)), http_request_id(req_id),
-        connection_close(close_conn), commit_request(req) {}
+        connection_close(close_conn), commit_request(req),
+        request_arena(std::move(arena)) {}
 };
 
 /**
@@ -40,13 +48,18 @@ struct StatusEntry {
   // Copied HTTP state
   int64_t http_request_id = 0;
   bool connection_close = false;
-  std::string_view status_request_id; // Points to connection's arena data
+  std::string_view status_request_id; // Points to request_arena data
+
+  // Request arena for HTTP request data
+  Arena request_arena;
 
   StatusEntry() = default; // Default constructor for variant
   explicit StatusEntry(WeakRef<MessageSender> conn, int64_t req_id,
-                       bool close_conn, std::string_view request_id)
+                       bool close_conn, std::string_view request_id,
+                       Arena arena)
       : connection(std::move(conn)), http_request_id(req_id),
-        connection_close(close_conn), status_request_id(request_id) {}
+        connection_close(close_conn), status_request_id(request_id),
+        request_arena(std::move(arena)) {}
 };
 
 /**
@@ -61,11 +74,18 @@ struct HealthCheckEntry {
   int64_t http_request_id = 0;
   bool connection_close = false;
 
+  // Request arena for formatting response
+  Arena request_arena;
+
+  // Response data (set by persist stage, consumed by release stage)
+  // Points to response formatted in request_arena
+  std::span<std::string_view> response_message;
+
   HealthCheckEntry() = default; // Default constructor for variant
   explicit HealthCheckEntry(WeakRef<MessageSender> conn, int64_t req_id,
-                            bool close_conn)
+                            bool close_conn, Arena arena)
       : connection(std::move(conn)), http_request_id(req_id),
-        connection_close(close_conn) {}
+        connection_close(close_conn), request_arena(std::move(arena)) {}
 };
 
 /**