feat(heartbeat): added heartbeat mechanism

Author: sususu5

client/network_manager.cpp

@@ -25,6 +25,7 @@ bool NetworkManager::Connect(const std::string& host, int port) {
     connected_ = true;
     running_ = true;
     listener_thread_ = std::thread(&NetworkManager::ListenerLoop, this);
+    heartbeat_thread_ = std::thread(&NetworkManager::HeartbeatLoop, this);
     return true;
 }
 
@@ -39,6 +40,9 @@ void NetworkManager::Disconnect() {
     if (listener_thread_.joinable()) {
         listener_thread_.join();
     }
+    if (heartbeat_thread_.joinable()) {
+        heartbeat_thread_.join();
+    }
     connected_ = false;
 }
 
@@ -102,12 +106,10 @@ void NetworkManager::ListenerLoop() {
         if (msg_len > 10 * 1024 * 1024) {  // 10MB limit
             if (running_) {
                 if (on_error_callback_) on_error_callback_("Protocol Error: Packet too large");
-                // Do not set running_ = false here immediately to allow error to be reported?
-                // Actually safer to stop.
                 running_ = false;
                 connected_ = false;
             }
-            return;  // Exit thread
+            return;
         }
 
         std::string buffer;
@@ -154,6 +156,19 @@ void NetworkManager::ListenerLoop() {
     }
 }
 
+void NetworkManager::HeartbeatLoop() {
+    while (running_) {
+        std::this_thread::sleep_for(std::chrono::seconds(15));
+        if (!running_) break;
+        if (connected_) {
+            im::Envelope env;
+            env.set_cmd(im::CMD_HEARTBEAT);
+            env.set_timestamp(time(NULL));
+            SendEnvelope(env);
+        }
+    }
+}
+
 bool NetworkManager::Register(const std::string& username, const std::string& password, std::string& error_msg) {
     im::RegisterReq req;
     req.set_username(username);

client/network_manager.h

@@ -53,6 +53,7 @@ class NetworkManager {
     bool SendEnvelope(const im::Envelope& env);
     bool SendRequestAndWait(const im::Envelope& request, im::Envelope& response, im::CommandType expected_cmd);
     void ListenerLoop();
+    void HeartbeatLoop();
     void ClearAuth();
     void Disconnect();
 
@@ -71,6 +72,7 @@ class NetworkManager {
 
     // Async Handling
     std::thread listener_thread_;
+    std::thread heartbeat_thread_;
     std::atomic<bool> running_{false};
 
     std::mutex mutex_;

proto/protocol.proto

@@ -34,6 +34,9 @@ enum CommandType {
     CMD_P2P_MSG_REQ   = 50;
     CMD_P2P_MSG_PUSH  = 51;
     CMD_MSG_ACK       = 52;
+
+    // Heartbeat
+    CMD_HEARTBEAT     = 99;
 }
 
 message Envelope {

server/src/handler/protobuf_handler.cpp

@@ -88,6 +88,9 @@ void ProtobufHandler::Dispatch(const im::Envelope& request, im::Envelope& respon
         case im::CMD_P2P_MSG_REQ:
             HandleP2PMsg(request, response);
             break;
+        case im::CMD_HEARTBEAT:
+            // Heartbeat received, connection timer is already refreshed by OnRead_
+            return;
         default:
             HandleUnknown(request, response);
             break;