added a stack thread to the eNB and move the tti_clock() method to this thread to avoid race conditions

srsenb/hdr/stack/enb_stack_lte.h

@@ -38,11 +38,12 @@
 
 #include "enb_stack_base.h"
 #include "srsenb/hdr/enb.h"
+#include "srslte/common/multiqueue.h"
 #include "srslte/interfaces/enb_interfaces.h"
 
 namespace srsenb {
 
-class enb_stack_lte final : public enb_stack_base, public stack_interface_phy_lte
+class enb_stack_lte final : public enb_stack_base, public stack_interface_phy_lte, public thread
 {
 public:
   enb_stack_lte(srslte::logger* logger_);
@@ -86,16 +87,18 @@ public:
   // Radio-Link status
   void rl_failure(uint16_t rnti) final { mac.rl_failure(rnti); }
   void rl_ok(uint16_t rnti) final { mac.rl_ok(rnti); }
-  void tti_clock() final
-  {
-    timers.step_all();
-    mac.tti_clock();
-  }
+  void tti_clock() override;
 
 private:
+  static const int STACK_MAIN_THREAD_PRIO = -1; // Use default high-priority below UHD
+  // thread loop
+  void run_thread() override;
+  void stop_impl();
+  void tti_clock_impl();
+
+  // args
   stack_args_t args    = {};
   rrc_cfg_t    rrc_cfg = {};
-  bool         started = false;
 
   srsenb::mac      mac;
   srslte::mac_pcap mac_pcap;
@@ -118,6 +121,19 @@ private:
 
   // RAT-specific interfaces
   phy_interface_stack_lte* phy = nullptr;
+
+  // state
+  bool started = false;
+  // NOTE: we use this struct instead of a std::function bc lambdas can't capture by move in C++11
+  struct task_t {
+    std::function<void(task_t*)> func;
+    srslte::unique_byte_buffer_t pdu;
+    task_t() = default;
+    explicit task_t(std::function<void(task_t*)> f_) : func(std::move(f_)) {}
+    void operator()() { func(this); }
+  };
+  srslte::multiqueue_handler<task_t> pending_tasks;
+  int                                enb_queue_id = -1, sync_queue_id = -1;
 };
 
 } // namespace srsenb

srsenb/src/stack/enb_stack_lte.cc

@@ -28,7 +28,9 @@ using namespace srslte;
 
 namespace srsenb {
 
-enb_stack_lte::enb_stack_lte(srslte::logger* logger_) : logger(logger_), pdcp(&pdcp_log), timers(128) {}
+enb_stack_lte::enb_stack_lte(srslte::logger* logger_) : logger(logger_), pdcp(&pdcp_log), timers(128), thread("STACK")
+{
+}
 
 enb_stack_lte::~enb_stack_lte()
 {
@@ -46,6 +48,7 @@ int enb_stack_lte::init(const stack_args_t& args_, const rrc_cfg_t& rrc_cfg_, ph
   if (init(args_, rrc_cfg_)) {
     return SRSLTE_ERROR;
   }
+
   return SRSLTE_SUCCESS;
 }
 
@@ -127,31 +130,56 @@ int enb_stack_lte::init(const stack_args_t& args_, const rrc_cfg_t& rrc_cfg_)
             &gtpu_log,
             args.embms.enable);
 
+  enb_queue_id  = pending_tasks.add_queue();
+  sync_queue_id = pending_tasks.add_queue();
+
   started = true;
+  start(STACK_MAIN_THREAD_PRIO);
 
   return SRSLTE_SUCCESS;
 }
 
+void enb_stack_lte::tti_clock()
+{
+  pending_tasks.push(sync_queue_id, task_t{[this](task_t*) { tti_clock_impl(); }});
+}
+
+void enb_stack_lte::tti_clock_impl()
+{
+  timers.step_all();
+  mac.tti_clock();
+}
+
 void enb_stack_lte::stop()
 {
   if (started) {
-    s1ap.stop();
-    gtpu.stop();
-    mac.stop();
-    usleep(50000);
-
-    rlc.stop();
-    pdcp.stop();
-    rrc.stop();
-
-    usleep(10000);
-    if (args.pcap.enable) {
-      mac_pcap.close();
-    }
-    started = false;
+    pending_tasks.push(enb_queue_id, task_t{[this](task_t*) { stop_impl(); }});
+    wait_thread_finish();
   }
 }
 
+void enb_stack_lte::stop_impl()
+{
+  // stop listening to events
+  pending_tasks.erase_queue(sync_queue_id);
+  pending_tasks.erase_queue(enb_queue_id);
+
+  s1ap.stop();
+  gtpu.stop();
+  mac.stop();
+  usleep(50000);
+
+  rlc.stop();
+  pdcp.stop();
+  rrc.stop();
+
+  usleep(10000);
+  if (args.pcap.enable) {
+    mac_pcap.close();
+  }
+  started = false;
+}
+
 bool enb_stack_lte::get_metrics(stack_metrics_t* metrics)
 {
   mac.get_metrics(metrics->mac);
@@ -160,4 +188,14 @@ bool enb_stack_lte::get_metrics(stack_metrics_t* metrics)
   return true;
 }
 
+void enb_stack_lte::run_thread()
+{
+  while (started) {
+    task_t task{};
+    if (pending_tasks.wait_pop(&task) >= 0) {
+      task();
+    }
+  }
+}
+
 } // namespace srsenb