Move Moonraker commands off the UI thread

Pause/resume/stop, g-code sends, temps, and
light ran synchronous HTTP on the UI thread,
freezing the app up to 10s per click on slow
or unreachable printers.

Run them on a single agent-owned FIFO worker
so g-code ordering is preserved, while command
translation stays synchronous so unsupported-
command dialogs still work.

Add a pending-disabled state to the pause,
resume, and abort buttons for Moonraker-family
printers: the icon only flips once the
WebSocket reports the real state, which also
rules out double-click races.

src/slic3r/GUI/StatusPanel.cpp

@@ -12,6 +12,7 @@
 
 #include "MsgDialog.hpp"
 #include "slic3r/Utils/Http.hpp"
+#include "slic3r/Utils/MoonrakerPrinterAgent.hpp"
 #include "libslic3r/Thread.hpp"
 #include "DeviceErrorDialog.hpp"
 
@@ -2714,7 +2715,8 @@ void StatusPanel::on_subtask_partskip(wxCommandEvent &event)
 void StatusPanel::on_subtask_pause_resume(wxCommandEvent &event)
 {
     if (obj) {
-        if (obj->can_resume()) {
+        const bool was_resume = obj->can_resume();
+        if (was_resume) {
             BOOST_LOG_TRIVIAL(info) << "monitor: resume current print task dev_id =" << obj->get_dev_id();
             obj->command_task_resume();
         }
@@ -2722,6 +2724,13 @@ void StatusPanel::on_subtask_pause_resume(wxCommandEvent &event)
             BOOST_LOG_TRIVIAL(info) << "monitor: pause current print task dev_id =" << obj->get_dev_id();
             obj->command_task_pause();
         }
+        if (is_moonraker_agent()) {
+            m_pause_resume_pending = true;
+            m_pause_resume_was_resume = was_resume;
+            m_pause_resume_deadline = std::chrono::steady_clock::now() + std::chrono::seconds(6);
+            m_pause_resume_machine_id = obj->get_dev_id();
+            m_project_task_panel->enable_pause_resume_button(false, was_resume ? "resume_disable" : "pause_disable");
+        }
     }
 }
 
@@ -2733,6 +2742,12 @@ void StatusPanel::on_subtask_abort(wxCommandEvent &event)
             if (obj) {
                 BOOST_LOG_TRIVIAL(info) << "monitor: stop current print task dev_id =" << obj->get_dev_id();
                 obj->command_task_abort();
+                if (is_moonraker_agent()) {
+                    m_abort_pending = true;
+                    m_abort_deadline = std::chrono::steady_clock::now() + std::chrono::seconds(6);
+                    m_abort_machine_id = obj->get_dev_id();
+                    m_project_task_panel->enable_abort_button(false);
+                }
             }
         });
     }
@@ -3706,6 +3721,25 @@ void StatusPanel::update_model_info()
 void StatusPanel::update_subtask(MachineObject *obj)
 {
     if (!obj) return;
+    const auto now = std::chrono::steady_clock::now();
+    if (m_pause_resume_pending) {
+        if (!is_moonraker_agent() || m_pause_resume_machine_id != obj->get_dev_id() ||
+            obj->can_resume() != m_pause_resume_was_resume) {
+            m_pause_resume_pending = false;
+        } else if (now >= m_pause_resume_deadline) {
+            BOOST_LOG_TRIVIAL(warning) << "StatusPanel: Moonraker pause/resume command did not change printer state";
+            m_pause_resume_pending = false;
+        }
+    }
+    if (m_abort_pending) {
+        if (!is_moonraker_agent() || m_abort_machine_id != obj->get_dev_id() || obj->print_status == "FAILED" ||
+            obj->print_status == "FINISH" || obj->print_status == "IDLE") {
+            m_abort_pending = false;
+        } else if (now >= m_abort_deadline) {
+            BOOST_LOG_TRIVIAL(warning) << "StatusPanel: Moonraker abort command did not change printer state";
+            m_abort_pending = false;
+        }
+    }
     if (m_current_print_mode != PRINGINT) {
         if (calib_bitmap == nullptr) {
             m_calib_mode = get_obj_calibration_mode(obj, m_calib_method, cali_stage);
@@ -3813,10 +3847,12 @@ void StatusPanel::update_subtask(MachineObject *obj)
             }
             update_basic_print_data(false);
         } else {
-            if (obj->can_resume()) {
-                m_project_task_panel->enable_pause_resume_button(true, "resume");
-            } else {
-                 m_project_task_panel->enable_pause_resume_button(true, "pause");
+            if (!m_pause_resume_pending) {
+                if (obj->can_resume()) {
+                    m_project_task_panel->enable_pause_resume_button(true, "resume");
+                } else {
+                     m_project_task_panel->enable_pause_resume_button(true, "pause");
+                }
             }
             m_project_task_panel->enable_partskip_button(obj, true);
             // update printing stage
@@ -3873,7 +3909,9 @@ void StatusPanel::update_subtask(MachineObject *obj)
                     m_project_task_panel->market_scoring_hide();
                 }
             } else { // model printing is not finished, hide scoring page
-                m_project_task_panel->enable_abort_button(true);
+                if (!m_abort_pending) {
+                    m_project_task_panel->enable_abort_button(true);
+                }
                 m_project_task_panel->market_scoring_hide();
                 m_project_task_panel->get_request_failed_panel()->Hide();
             }
@@ -4016,6 +4054,8 @@ void StatusPanel::update_sdcard_subtask(MachineObject *obj)
 
 void StatusPanel::reset_printing_values()
 {
+    m_pause_resume_pending = false;
+    m_abort_pending = false;
     m_project_task_panel->enable_partskip_button(nullptr, false);
     m_project_task_panel->enable_pause_resume_button(false, "pause_disable");
     m_project_task_panel->enable_abort_button(false);
@@ -4041,6 +4081,12 @@ void StatusPanel::reset_printing_values()
     this->Layout();
 }
 
+bool StatusPanel::is_moonraker_agent() const
+{
+    auto* agent = wxGetApp().getAgent();
+    return agent && std::dynamic_pointer_cast<Slic3r::MoonrakerPrinterAgent>(agent->get_printer_agent()) != nullptr;
+}
+
 void StatusPanel::on_axis_ctrl_xy(wxCommandEvent &event)
 {
     if (!obj) return;

src/slic3r/GUI/StatusPanel.hpp

@@ -14,6 +14,7 @@
 #include <wx/sizer.h>
 #include <wx/gbsizer.h>
 #include <wx/webrequest.h>
+#include <chrono>
 #include "wxMediaCtrl2.h"
 #include "MediaPlayCtrl.h"
 #include "AMSSetting.hpp"
@@ -688,6 +689,13 @@ protected:
     CalibrationMethod m_calib_method;
     int cali_stage;
     PrintingTaskType m_current_print_mode = PrintingTaskType::NOT_CLEAR;
+    bool m_pause_resume_pending = false;
+    bool m_pause_resume_was_resume = false;
+    std::chrono::steady_clock::time_point m_pause_resume_deadline;
+    std::string m_pause_resume_machine_id;
+    bool m_abort_pending = false;
+    std::chrono::steady_clock::time_point m_abort_deadline;
+    std::string m_abort_machine_id;
 
     void init_scaled_buttons();
     void create_tasklist_info();
@@ -790,6 +798,7 @@ protected:
     void update_calib_bitmap();
 
     void reset_printing_values();
+    bool is_moonraker_agent() const;
     void on_webrequest_state(wxWebRequestEvent &evt);
     bool is_task_changed(MachineObject* obj);
 

src/slic3r/Utils/MoonrakerPrinterAgent.cpp

@@ -126,6 +126,53 @@ MoonrakerPrinterAgent::~MoonrakerPrinterAgent()
         connect_thread.join();
     }
     stop_status_stream();
+    {
+        std::lock_guard<std::mutex> lock(cmd_mutex);
+        cmd_stop = true;
+        cmd_queue.clear();
+    }
+    cmd_cv.notify_one();
+    if (cmd_thread.joinable()) {
+        cmd_thread.join();
+    }
+}
+
+void MoonrakerPrinterAgent::enqueue_command(std::function<void()> fn)
+{
+    {
+        std::lock_guard<std::mutex> lock(cmd_mutex);
+        if (!cmd_thread.joinable()) {
+            cmd_thread = std::thread(&MoonrakerPrinterAgent::run_command_worker, this);
+        }
+        cmd_queue.emplace_back(std::move(fn));
+    }
+    cmd_cv.notify_one();
+}
+
+void MoonrakerPrinterAgent::run_command_worker()
+{
+    for (;;) {
+        std::function<void()> command;
+        {
+            std::unique_lock<std::mutex> lock(cmd_mutex);
+            cmd_cv.wait(lock, [this] { return cmd_stop || !cmd_queue.empty(); });
+            if (cmd_stop && cmd_queue.empty()) {
+                return;
+            }
+            command = std::move(cmd_queue.front());
+            cmd_queue.pop_front();
+        }
+        // why: an exception escaping a worker thread is std::terminate; the old synchronous
+        // path at least ran under wx's unhandled-exception hook. nlohmann dump() can throw
+        // on invalid UTF-8 smuggled in via custom g-code.
+        try {
+            command();
+        } catch (const std::exception& e) {
+            BOOST_LOG_TRIVIAL(error) << "MoonrakerPrinterAgent: queued command failed: " << e.what();
+        } catch (...) {
+            BOOST_LOG_TRIVIAL(error) << "MoonrakerPrinterAgent: queued command failed: unknown exception";
+        }
+    }
 }
 
 AgentInfo MoonrakerPrinterAgent::get_agent_info_static()
@@ -181,6 +228,10 @@ int MoonrakerPrinterAgent::connect_printer(std::string dev_id, std::string dev_i
 
     // Stop existing status stream and clear state
     stop_status_stream();
+    {
+        std::lock_guard<std::mutex> lock(cmd_mutex);
+        cmd_queue.clear();
+    }
     {
         std::lock_guard<std::recursive_mutex> lock(payload_mutex);
         status_cache = nlohmann::json::object();
@@ -210,6 +261,10 @@ int MoonrakerPrinterAgent::disconnect_printer()
     }
 
     stop_status_stream();
+    {
+        std::lock_guard<std::mutex> lock(cmd_mutex);
+        cmd_queue.clear();
+    }
     return BAMBU_NETWORK_SUCCESS;
 }
 
@@ -1016,6 +1071,10 @@ bool MoonrakerPrinterAgent::fetch_hh_filament_info(std::vector<AmsTrayData>& tra
 
 int MoonrakerPrinterAgent::handle_request(const std::string& dev_id, const std::string& json_str)
 {
+    auto connection_snapshot = [this]() {
+        std::lock_guard<std::recursive_mutex> lock(connect_mutex);
+        return std::make_pair(device_info.base_url, device_info.api_key);
+    };
     auto json = nlohmann::json::parse(json_str, nullptr, false);
     if (json.is_discarded()) {
         BOOST_LOG_TRIVIAL(error) << "MoonrakerPrinterAgent: Invalid JSON request";
@@ -1092,13 +1151,14 @@ int MoonrakerPrinterAgent::handle_request(const std::string& dev_id, const std::
                 BOOST_LOG_TRIVIAL(warning) << "MoonrakerPrinterAgent: ledctrl - no light object found, dropping";
                 return ORCA_NETWORK_ERR_CAP_NOT_AVAILABLE;
             }
-            if (!send_gcode(dev_id, gcode)) {
-                return BAMBU_NETWORK_ERR_CONNECTION_TO_PRINTER_FAILED;
-            }
-            {
-                std::lock_guard<std::recursive_mutex> lock(payload_mutex);
-                assumed_light_on = requested_light_on;
-            }
+            auto [base_url, api_key] = connection_snapshot();
+            enqueue_command([this, dev_id, gcode = std::move(gcode), base_url = std::move(base_url),
+                             api_key = std::move(api_key), requested_light_on]() {
+                if (send_gcode(dev_id, gcode, base_url, api_key)) {
+                    std::lock_guard<std::recursive_mutex> lock(payload_mutex);
+                    assumed_light_on = requested_light_on;
+                }
+            });
             return BAMBU_NETWORK_SUCCESS;
         }
     }
@@ -1143,25 +1203,38 @@ int MoonrakerPrinterAgent::handle_request(const std::string& dev_id, const std::
             }
             response["print"]["param"] = gcode;
 
-            if (send_gcode(dev_id, gcode)) {
-                response["print"]["result"] = "success";
+            auto [base_url, api_key] = connection_snapshot();
+            enqueue_command([this, dev_id, response = std::move(response), base_url = std::move(base_url),
+                             api_key = std::move(api_key)]() mutable {
+                response["print"]["result"] = send_gcode(dev_id, response["print"]["param"].get<std::string>(), base_url, api_key)
+                    ? "success"
+                    : "failed";
                 dispatch_message(dev_id, response.dump());
-                return BAMBU_NETWORK_SUCCESS;
-            }
-            response["print"]["result"] = "failed";
-            dispatch_message(dev_id, response.dump());
-            return BAMBU_NETWORK_ERR_CONNECTION_TO_PRINTER_FAILED;
+            });
+            return BAMBU_NETWORK_SUCCESS;
         }
 
         // Print control commands
         if (cmd == "pause") {
-            return pause_print(dev_id);
+            auto [base_url, api_key] = connection_snapshot();
+            enqueue_command([this, base_url = std::move(base_url), api_key = std::move(api_key)] {
+                post_print_action("pause", base_url, api_key);
+            });
+            return BAMBU_NETWORK_SUCCESS;
         }
         if (cmd == "resume") {
-            return resume_print(dev_id);
+            auto [base_url, api_key] = connection_snapshot();
+            enqueue_command([this, base_url = std::move(base_url), api_key = std::move(api_key)] {
+                post_print_action("resume", base_url, api_key);
+            });
+            return BAMBU_NETWORK_SUCCESS;
         }
         if (cmd == "stop") {
-            return cancel_print(dev_id);
+            auto [base_url, api_key] = connection_snapshot();
+            enqueue_command([this, base_url = std::move(base_url), api_key = std::move(api_key)] {
+                post_print_action("cancel", base_url, api_key);
+            });
+            return BAMBU_NETWORK_SUCCESS;
         }
 
         // Bed temperature - UI sends "temp" field
@@ -1169,7 +1242,11 @@ int MoonrakerPrinterAgent::handle_request(const std::string& dev_id, const std::
             if (json["print"].contains("temp") && json["print"]["temp"].is_number()) {
                 int         temp  = json["print"]["temp"].get<int>();
                 std::string gcode = "SET_HEATER_TEMPERATURE HEATER=heater_bed TARGET=" + std::to_string(temp);
-                send_gcode(dev_id, gcode);
+                auto [base_url, api_key] = connection_snapshot();
+                enqueue_command([this, dev_id, gcode = std::move(gcode), base_url = std::move(base_url),
+                                 api_key = std::move(api_key)] {
+                    send_gcode(dev_id, gcode, base_url, api_key);
+                });
                 return BAMBU_NETWORK_SUCCESS;
             }
         }
@@ -1184,7 +1261,11 @@ int MoonrakerPrinterAgent::handle_request(const std::string& dev_id, const std::
                 }
                 std::string heater = (extruder_idx == 0) ? "extruder" : "extruder" + std::to_string(extruder_idx);
                 std::string gcode  = "SET_HEATER_TEMPERATURE HEATER=" + heater + " TARGET=" + std::to_string(temp);
-                send_gcode(dev_id, gcode);
+                auto [base_url, api_key] = connection_snapshot();
+                enqueue_command([this, dev_id, gcode = std::move(gcode), base_url = std::move(base_url),
+                                 api_key = std::move(api_key)] {
+                    send_gcode(dev_id, gcode, base_url, api_key);
+                });
                 return BAMBU_NETWORK_SUCCESS;
             }
         }
@@ -1192,7 +1273,11 @@ int MoonrakerPrinterAgent::handle_request(const std::string& dev_id, const std::
         // why: no current OrcaSlicer sender emits the "home" discriminator;
         // GUI homing uses gcode_line with G28 instead.
         if (cmd == "home") {
-            return send_gcode(dev_id, "G28") ? BAMBU_NETWORK_SUCCESS : BAMBU_NETWORK_ERR_SEND_MSG_FAILED;
+            auto [base_url, api_key] = connection_snapshot();
+            enqueue_command([this, dev_id, base_url = std::move(base_url), api_key = std::move(api_key)] {
+                send_gcode(dev_id, "G28", base_url, api_key);
+            });
+            return BAMBU_NETWORK_SUCCESS;
         }
     }
 
@@ -1456,6 +1541,21 @@ bool MoonrakerPrinterAgent::fetch_webcam_info(const std::string& base_url, const
 }
 
 bool MoonrakerPrinterAgent::post_print_action(const std::string& action) const
+{
+    // why: snapshot then release - holding connect_mutex across the blocking HTTP call
+    // would stall any UI-thread handle_request waiting to take its own snapshot.
+    std::string base_url, api_key;
+    {
+        std::lock_guard<std::recursive_mutex> lock(connect_mutex);
+        base_url = device_info.base_url;
+        api_key  = device_info.api_key;
+    }
+    return post_print_action(action, base_url, api_key);
+}
+
+bool MoonrakerPrinterAgent::post_print_action(const std::string& action,
+                                              const std::string& base_url,
+                                              const std::string& api_key) const
 {
     // why: /printer/print/{pause,resume,cancel} map to Klipper's pause_resume
     // webhook (a direct interrupt). A raw PAUSE/RESUME/CANCEL_PRINT queued through
@@ -1463,13 +1563,13 @@ bool MoonrakerPrinterAgent::post_print_action(const std::string& action) const
     // printer is busy (long move, heating, inside a macro).
     // note: empty JSON body avoids a body-less POST (curl would treat it as a
     // streamed upload) - same reason start_print_file sends a body.
-    const std::string full_url = join_url(device_info.base_url, "/printer/print/" + action);
+    const std::string full_url = join_url(base_url, "/printer/print/" + action);
     bool              success  = false;
     std::string       http_error;
 
     auto http = Http::post(full_url);
-    if (!device_info.api_key.empty()) {
-        http.header("X-Api-Key", device_info.api_key);
+    if (!api_key.empty()) {
+        http.header("X-Api-Key", api_key);
     }
     http.header("Content-Type", "application/json")
         .set_post_body(std::string("{}"))
@@ -1501,6 +1601,19 @@ bool MoonrakerPrinterAgent::post_print_action(const std::string& action) const
 }
 
 bool MoonrakerPrinterAgent::send_gcode(const std::string& dev_id, const std::string& gcode) const
+{
+    // why: snapshot then release - see post_print_action.
+    std::string base_url, api_key;
+    {
+        std::lock_guard<std::recursive_mutex> lock(connect_mutex);
+        base_url = device_info.base_url;
+        api_key  = device_info.api_key;
+    }
+    return send_gcode(dev_id, gcode, base_url, api_key);
+}
+
+bool MoonrakerPrinterAgent::send_gcode(const std::string& dev_id, const std::string& gcode,
+                                       const std::string& base_url, const std::string& api_key) const
 {
     nlohmann::json payload;
     payload["script"]       = gcode;
@@ -1510,10 +1623,10 @@ bool MoonrakerPrinterAgent::send_gcode(const std::string& dev_id, const std::str
     bool        success = false;
     std::string http_error;
 
-    auto full_url = join_url(device_info.base_url, "/printer/gcode/script");
+    auto full_url = join_url(base_url, "/printer/gcode/script");
     auto http = Http::post(full_url);
-    if (!device_info.api_key.empty()) {
-        http.header("X-Api-Key", device_info.api_key);
+    if (!api_key.empty()) {
+        http.header("X-Api-Key", api_key);
     }
     http.header("Content-Type", "application/json")
         .set_post_body(payload_str)

src/slic3r/Utils/MoonrakerPrinterAgent.hpp

@@ -9,6 +9,9 @@
 #include <set>
 #include <string>
 #include <thread>
+#include <condition_variable>
+#include <deque>
+#include <functional>
 
 #include <nlohmann/json.hpp>
 
@@ -125,7 +128,11 @@ protected:
 
     // Send a G-code script via Moonraker (/printer/gcode/script)
     bool send_gcode(const std::string& dev_id, const std::string& gcode) const;
+    bool send_gcode(const std::string& dev_id, const std::string& gcode,
+                    const std::string& base_url, const std::string& api_key) const;
     bool post_print_action(const std::string& action) const;
+    bool post_print_action(const std::string& action,
+                           const std::string& base_url, const std::string& api_key) const;
 
 private:
     int handle_request(const std::string& dev_id, const std::string& json_str);
@@ -221,7 +228,15 @@ private:
     // Connection thread management
     std::atomic<uint64_t>  connect_generation{0};
     std::thread            connect_thread;
-    std::recursive_mutex   connect_mutex;
+    mutable std::recursive_mutex connect_mutex;
+
+    void enqueue_command(std::function<void()> fn);
+    void run_command_worker();
+    std::thread cmd_thread;
+    std::deque<std::function<void()>> cmd_queue;
+    std::mutex cmd_mutex;
+    std::condition_variable cmd_cv;
+    bool cmd_stop = false;
 };
 
 } // namespace Slic3r