task_scheduler: use block_queue for internal tasks

TSAN detected wrong use of the old deque-based internal queue. To avoid
unwanted/undetected mis-use the patch uses the thread-safe block_queue
data structure instead.

lib/include/srsran/common/task_scheduler.h

@@ -13,6 +13,7 @@
 #ifndef SRSRAN_TASK_SCHEDULER_H
 #define SRSRAN_TASK_SCHEDULER_H
 
+#include "block_queue.h"
 #include "interfaces_common.h"
 #include "multiqueue.h"
 #include "thread_pool.h"
@@ -24,7 +25,7 @@ class task_scheduler
 {
 public:
   explicit task_scheduler(uint32_t default_extern_tasks_size = 512, uint32_t nof_timers_prealloc = 100) :
-    external_tasks{default_extern_tasks_size}, timers{nof_timers_prealloc}
+    external_tasks{default_extern_tasks_size}, timers{nof_timers_prealloc}, internal_tasks(512)
   {
     background_queue = external_tasks.add_queue();
   }
@@ -49,7 +50,12 @@ public:
   }
 
   //! Enqueues internal task to be run in next tic
-  void defer_task(srsran::move_task_t func) { internal_tasks.push_back(std::move(func)); }
+  void defer_task(srsran::move_task_t func)
+  {
+    if (not internal_tasks.try_push(std::move(func))) {
+      srslog::fetch_basic_logger("COMN", false).warning("Couldn't add new internal task");
+    }
+  }
 
   //! Defer the handling of the result of a background task to next tic
   void notify_background_task_result(srsran::move_task_t task)
@@ -90,21 +96,20 @@ public:
   srsran::timer_handler* get_timer_handler() { return &timers; }
 
 private:
+  // Perform pending stack deferred tasks
   void run_all_internal_tasks()
   {
-    // Perform pending stack deferred tasks
-    // Note: Using a deque because tasks can enqueue new tasks, which would lead to
-    // reference invalidation in case of vector
-    while (not internal_tasks.empty()) {
-      internal_tasks.front()();
-      internal_tasks.pop_front();
+    srsran::move_task_t task{};
+    while (internal_tasks.try_pop(task)) {
+      task();
     }
   }
 
-  srsran::task_multiqueue         external_tasks;
-  srsran::task_queue_handle       background_queue; ///< Queue for handling the outcomes of tasks run in the background
-  srsran::timer_handler           timers;
-  std::deque<srsran::move_task_t> internal_tasks; ///< enqueues stack tasks from within main thread. Avoids locking
+  srsran::task_multiqueue   external_tasks;
+  srsran::task_queue_handle background_queue; ///< Queue for handling the outcomes of tasks run in the background
+  srsran::timer_handler     timers;
+  srsran::dyn_blocking_queue<srsran::move_task_t>
+      internal_tasks; ///< enqueues stack tasks from within main thread. Avoids locking
 };
 
 //! Task scheduler handle given to classes/functions running within the main control thread