fixed and simplified multiqueue task api to avoid dangling pointers.

lib/include/srslte/common/multiqueue.h

@@ -230,36 +230,33 @@ private:
  * Specialization for tasks with content that is move-only
  **********************************************************/
 
-template <typename Capture>
-class moveable_task_t
+class move_task_t
 {
 public:
-  moveable_task_t() = default;
+  move_task_t() = default;
   template <typename Func>
-  moveable_task_t(Func&& f) : func(std::forward<Func>(f))
+  move_task_t(Func&& f) : task_ptr(new derived_task<Func>(std::forward<Func>(f)))
   {
   }
-  template <typename Func>
-  moveable_task_t(Func&& f, Capture&& c) : capture(std::forward<Capture>(c))
-  {
-    std::function<void(Capture)> ftmp{std::forward<Func>(f)};
-    func = [this, ftmp]() { ftmp(std::move(capture)); };
-  }
-  void operator()() { func(); }
+  void operator()() { (*task_ptr)(); }
 
 private:
-  std::function<void()> func;
-  Capture               capture;
+  struct base_task {
+    virtual void operator()() = 0;
+  };
+  template <typename Func>
+  struct derived_task : public base_task {
+    derived_task(Func&& f_) : f(std::forward<Func>(f_)) {}
+    void operator()() final { f(); }
+
+  private:
+    Func f;
+  };
+
+  std::unique_ptr<base_task> task_ptr;
 };
 
-template <typename Func, typename Capture>
-moveable_task_t<Capture> bind_task(Func&& f, Capture&& c)
-{
-  return moveable_task_t<Capture>{std::forward<Func>(f), std::forward<Capture>(c)};
-}
-
-template <typename Capture>
-using multiqueue_task_handler = multiqueue_handler<moveable_task_t<Capture> >;
+using multiqueue_task_handler = multiqueue_handler<move_task_t>;
 
 } // namespace srslte
 

srsenb/hdr/stack/enb_stack_lte.h

@@ -146,8 +146,7 @@ private:
   phy_interface_stack_lte* phy = nullptr;
 
   // state
-  bool started = false;
-  using task_t = srslte::moveable_task_t<srslte::unique_byte_buffer_t>;
+  bool                            started = false;
   srslte::multiqueue_task_handler pending_tasks;
   int enb_queue_id = -1, sync_queue_id = -1, mme_queue_id = -1, gtpu_queue_id = -1, mac_queue_id = -1;
 };

srsenb/src/stack/enb_stack_lte.cc

@@ -210,7 +210,7 @@ bool enb_stack_lte::get_metrics(stack_metrics_t* metrics)
 void enb_stack_lte::run_thread()
 {
   while (started) {
-    task_t task{};
+    srslte::move_task_t task{};
     if (pending_tasks.wait_pop(&task) >= 0) {
       task();
     }
@@ -223,11 +223,11 @@ void enb_stack_lte::handle_mme_rx_packet(srslte::unique_byte_buffer_t pdu,
                                          int                          flags)
 {
   // Defer the handling of MME packet to eNB stack main thread
-  auto task_handler = [this, from, sri, flags](srslte::unique_byte_buffer_t t) {
+  auto task_handler = [this, from, sri, flags](srslte::unique_byte_buffer_t& t) {
     s1ap.handle_mme_rx_msg(std::move(t), from, sri, flags);
   };
   // Defer the handling of MME packet to main stack thread
-  pending_tasks.push(mme_queue_id, srslte::bind_task(task_handler, std::move(pdu)));
+  pending_tasks.push(mme_queue_id, std::bind(task_handler, std::move(pdu)));
 }
 
 void enb_stack_lte::add_mme_socket(int fd)

srsue/hdr/stack/ue_stack_lte.h

@@ -159,9 +159,8 @@ private:
   gw_interface_stack*      gw  = nullptr;
 
   // Thread
-  static const int STACK_MAIN_THREAD_PRIO = -1; // Use default high-priority below UHD
-  using task_t                            = srslte::moveable_task_t<srslte::unique_byte_buffer_t>;
-  srslte::multiqueue_task_handler<srslte::unique_byte_buffer_t> pending_tasks;
+  static const int                STACK_MAIN_THREAD_PRIO = -1; // Use default high-priority below UHD
+  srslte::multiqueue_task_handler pending_tasks;
   int sync_queue_id = -1, ue_queue_id = -1, gw_queue_id = -1, mac_queue_id = -1, background_queue_id = -1;
   srslte::task_thread_pool background_tasks; ///< Thread pool used for long, low-priority tasks
 };

srsue/src/stack/ue_stack_lte.cc

@@ -219,7 +219,7 @@ bool ue_stack_lte::get_metrics(stack_metrics_t* metrics)
 void ue_stack_lte::run_thread()
 {
   while (running) {
-    task_t task{};
+    srslte::move_task_t task{};
     if (pending_tasks.wait_pop(&task) >= 0) {
       task();
     }
@@ -242,10 +242,10 @@ void ue_stack_lte::run_thread()
  */
 void ue_stack_lte::write_sdu(uint32_t lcid, srslte::unique_byte_buffer_t sdu, bool blocking)
 {
-  auto task = [this, lcid, blocking](srslte::unique_byte_buffer_t sdu) {
+  auto task = [this, lcid, blocking](srslte::unique_byte_buffer_t& sdu) {
     pdcp.write_sdu(lcid, std::move(sdu), blocking);
   };
-  bool ret = pending_tasks.try_push(gw_queue_id, srslte::bind_task(task, std::move(sdu))).first;
+  bool ret = pending_tasks.try_push(gw_queue_id, std::bind(task, std::move(sdu))).first;
   if (not ret) {
     pdcp_log.warning("GW SDU with lcid=%d was discarded.\n", lcid);
   }