Fix multi-device task list using a deleted network agent after plug-in reload

src/slic3r/GUI/GUI_App.cpp

@@ -4020,6 +4020,11 @@ bool GUI_App::on_init_network(bool try_backup)
     else
         m_user_manager->set_agent(m_agent);
 
+    // A hot reload deletes the agent the task manager was built with. It lives until restart, so repoint it
+    // even if multi-device has since been turned off.
+    if (m_task_manager)
+        m_task_manager->set_agent(m_agent);
+
     if (this->is_enable_multi_machine()) {
         if (!m_task_manager) {
             m_task_manager = new Slic3r::TaskManager(m_agent);

src/slic3r/GUI/TaskManager.cpp

@@ -171,6 +171,11 @@ TaskManager::TaskManager(NetworkAgent* agent)
     ;
 }
 
+void TaskManager::set_agent(NetworkAgent* agent)
+{
+    m_agent = agent;
+}
+
 
 int TaskManager::start_print(const std::vector<PrintParams>& params, TaskSettings* settings)
 {
@@ -240,17 +245,18 @@ int TaskManager::schedule(TaskStateInfo* task)
             fire_lifecycle_event(LifecycleEvent::PrintJobStarted, start_ctx);
 
             int result = -1;
-            if (!m_agent) {
+            NetworkAgent* agent = m_agent;
+            if (!agent) {
                 BOOST_LOG_TRIVIAL(trace) << "task_manager: NetworkAgent is nullptr";
             }
             else {
-                assert(m_agent);
+                assert(agent);
                 try {
 // DEBUG FOR TEST
 #if 0
                     result = start_print_test(task->get_params(), task->update_status_fn, task->cancel_fn, task->wait_fn);
 #else
-                    result = m_agent->start_print(task->get_params(), task->update_status_fn, task->cancel_fn, task->wait_fn);
+                    result = agent->start_print(task->get_params(), task->update_status_fn, task->cancel_fn, task->wait_fn);
 #endif
                 } catch (const std::exception& ex) {
                     BOOST_LOG_TRIVIAL(error) << "task_manager: start_print threw: " << ex.what();
@@ -363,12 +369,13 @@ std::map<int, TaskStateInfo*> TaskManager::get_local_task_list()
 std::map<std::string, TaskStateInfo> TaskManager::get_task_list(int curr_page, int page_count, int& total)
 {
     std::map<std::string, TaskStateInfo> out;
-    if (m_agent) {
+    NetworkAgent* agent = m_agent;
+    if (agent) {
         TaskQueryParams task_query_params;
         task_query_params.limit = page_count;
         task_query_params.offset = curr_page * page_count;
         std::string task_info;
-        int result = m_agent->get_user_tasks(task_query_params, &task_info);
+        int result = agent->get_user_tasks(task_query_params, &task_info);
         BOOST_LOG_TRIVIAL(trace) << "task_manager: get_task_list task_info=" << task_info;
         if (result == 0) {
             try {

src/slic3r/GUI/TaskManager.hpp

@@ -16,6 +16,7 @@
 #include <vector>
 #include <map>
 #include <mutex>
+#include <atomic>
 #include <wx/event.h>
 
 
@@ -158,6 +159,8 @@ public:
     static int SendingInterval;
     TaskManager(NetworkAgent* agent);
 
+    void set_agent(NetworkAgent* agent);
+
     int start_print(const std::vector<PrintParams>& params, TaskSettings* settings = nullptr);
 
     static void set_max_send_at_same_time(int count);
@@ -184,7 +187,8 @@ private:
     std::vector<boost::thread*>   m_sending_thread_list;
     std::mutex                    m_scedule_mutex;
     bool                        m_started { false };
-    NetworkAgent*               m_agent { nullptr };
+    // Replaced on the main thread whenever networking is re-initialised, read by the sending threads.
+    std::atomic<NetworkAgent*>  m_agent { nullptr };
 
     std::chrono::system_clock::time_point last_sent_timestamp;
 };