Always use struct

src/arena_allocator.hpp

@@ -83,7 +83,7 @@
  * @warning Do not share ArenaAllocator instances between threads. Use separate
  * instances per thread or per logical unit of work.
  */
-class ArenaAllocator {
+struct ArenaAllocator {
 private:
   /**
    * @brief Internal block structure for the intrusive linked list.

src/commit_request.hpp

@@ -60,7 +60,7 @@ struct Operation {
  * memory management and ownership. This class has no knowledge of any
  * specific serialization formats or encoding schemes.
  */
-class CommitRequest {
+struct CommitRequest {
 private:
   ArenaAllocator arena_;
   std::optional<std::string_view> request_id_;

src/commit_request_parser.hpp

@@ -13,7 +13,7 @@
  * and streaming parsing (for incremental data processing). This allows
  * efficient handling of network protocols where data may arrive in chunks.
  */
-class CommitRequestParser {
+struct CommitRequestParser {
 public:
   /**
    * @brief Status returned by streaming parse operations.

src/config.hpp

@@ -83,7 +83,7 @@ struct Config {
  * auto config2 = ConfigParser::parse_toml_string(toml);
  * ```
  */
-class ConfigParser {
+struct ConfigParser {
 public:
   /**
    * @brief Load configuration from a TOML file.

src/connection.cpp

@@ -1,11 +1,13 @@
 #include "connection.hpp"
-#include "server.hpp" // Need this for releaseBackToServer implementation
+
 #include <climits>
 #include <cstdio>
 #include <cstdlib>
 #include <errno.h>
 #include <limits.h>
 
+#include "server.hpp" // Need this for releaseBackToServer implementation
+
 // Static thread-local storage for iovec buffer
 static thread_local std::vector<struct iovec> g_iovec_buffer{IOV_MAX};
 

src/connection.hpp

@@ -1,7 +1,5 @@
 #pragma once
 
-#include "arena_allocator.hpp"
-#include "connection_handler.hpp"
 #include <cassert>
 #include <cstring>
 #include <deque>
@@ -10,6 +8,9 @@
 #include <sys/uio.h>
 #include <unistd.h>
 
+#include "arena_allocator.hpp"
+#include "connection_handler.hpp"
+
 #ifndef __has_feature
 #define __has_feature(x) 0
 #endif
@@ -39,7 +40,7 @@
  * private.
  */
 // Forward declaration
-class Server;
+struct Server;
 
 struct Connection {
   // No public constructor or factory method - only Server can create
@@ -305,7 +306,7 @@ struct Connection {
 
 private:
   // Server is a friend and can access all networking internals
-  friend class Server;
+  friend struct Server;
 
   /**
    * @brief Private constructor - only accessible by Server.

src/connection_handler.hpp

@@ -17,7 +17,7 @@ struct Connection;
  * The networking layer manages connection lifecycle, I/O multiplexing,
  * and efficient data transfer, while handlers focus purely on protocol logic.
  */
-class ConnectionHandler {
+struct ConnectionHandler {
 public:
   virtual ~ConnectionHandler() = default;
 

src/connection_registry.hpp

@@ -16,7 +16,7 @@ struct Connection;
  * allocated on-demand as connections are created.
  *
  */
-class ConnectionRegistry {
+struct ConnectionRegistry {
 public:
   /**
    * Initialize the connection registry.

src/http_handler.hpp

@@ -1,14 +1,16 @@
 #pragma once
 
+#include <memory>
+#include <string_view>
+#include <thread>
+
+#include <llhttp.h>
+
 #include "connection.hpp"
 #include "connection_handler.hpp"
 #include "perfetto_categories.hpp"
 #include "server.hpp"
 #include "thread_pipeline.hpp"
-#include <llhttp.h>
-#include <memory>
-#include <string_view>
-#include <thread>
 
 /**
  * HTTP routes supported by WeaselDB server.
@@ -60,14 +62,7 @@ struct HttpConnectionState {
  * HTTP/1.1 server implementation using llhttp for parsing.
  * Supports the WeaselDB REST API endpoints with enum-based routing.
  */
-class HttpHandler : public ConnectionHandler {
-  static constexpr int kFinalStageThreads = 2;
-  static constexpr int kLogSize = 12;
-  ThreadPipeline<std::unique_ptr<Connection>> pipeline{kLogSize,
-                                                       {kFinalStageThreads}};
-  std::vector<std::thread> finalStageThreads;
-
-public:
+struct HttpHandler : ConnectionHandler {
   HttpHandler() {
     for (int threadId = 0; threadId < kFinalStageThreads; ++threadId) {
       finalStageThreads.emplace_back([this, threadId]() {
@@ -124,6 +119,12 @@ public:
   static int onMessageComplete(llhttp_t *parser);
 
 private:
+  static constexpr int kFinalStageThreads = 2;
+  static constexpr int kLogSize = 12;
+  ThreadPipeline<std::unique_ptr<Connection>> pipeline{kLogSize,
+                                                       {kFinalStageThreads}};
+  std::vector<std::thread> finalStageThreads;
+
   // Route handlers
   void handleGetVersion(Connection &conn, const HttpConnectionState &state);
   void handlePostCommit(Connection &conn, const HttpConnectionState &state);

src/json_commit_request_parser.hpp

@@ -12,7 +12,7 @@
  * This parser uses the weaseljson library to parse JSON-formatted
  * commit requests into CommitRequest objects.
  */
-class JsonCommitRequestParser : public CommitRequestParser {
+struct JsonCommitRequestParser : CommitRequestParser {
 public:
   // Parser state
   enum class ParseState {

src/json_tokens.hpp

@@ -33,7 +33,7 @@ struct JsonToken {
  * }
  * ```
  */
-class PerfectHash {
+struct PerfectHash {
 public:
   /**
    * @brief Look up a JSON token by name using perfect hash.

src/server.cpp

@@ -1,6 +1,5 @@
 #include "server.hpp"
-#include "connection.hpp"
-#include "connection_registry.hpp"
+
 #include <csignal>
 #include <cstdio>
 #include <cstdlib>
@@ -17,6 +16,9 @@
 #include <unistd.h>
 #include <vector>
 
+#include "connection.hpp"
+#include "connection_registry.hpp"
+
 // Static thread-local storage for read buffer (used across different functions)
 static thread_local std::vector<char> g_read_buffer;
 

src/server.hpp

@@ -1,14 +1,15 @@
 #pragma once
 
-#include "config.hpp"
-#include "connection_handler.hpp"
-#include "connection_registry.hpp"
 #include <atomic>
 #include <memory>
 #include <span>
 #include <thread>
 #include <vector>
 
+#include "config.hpp"
+#include "connection_handler.hpp"
+#include "connection_registry.hpp"
+
 /**
  * High-performance multi-threaded server for handling network connections.
  *
@@ -32,8 +33,7 @@
  * - Prevention of accidental stack allocation that would break safety
  * guarantees
  */
-class Server : public std::enable_shared_from_this<Server> {
-public:
+struct Server : std::enable_shared_from_this<Server> {
   /**
    * Factory method to create a Server instance.
    *