lib,rlc_am_nr: make sure that tx_buffer_queue size is configurable

lib/include/srsran/rlc/rlc_am_nr.h

@@ -101,6 +101,7 @@ public:
 
   int  write_sdu(unique_byte_buffer_t sdu);
   void empty_queue() final;
+  void empty_queue_no_lock();
 
   // Data PDU helpers
   uint32_t build_new_pdu(uint8_t* payload, uint32_t nof_bytes);

lib/src/rlc/rlc_am_base.cc

@@ -79,17 +79,18 @@ bool rlc_am::configure(const rlc_config_t& cfg_)
 
   if (cfg.rat == srsran_rat_t::lte) {
     RlcInfo("AM LTE configured - t_poll_retx=%d, poll_pdu=%d, poll_byte=%d, max_retx_thresh=%d, "
-            "t_reordering=%d, t_status_prohibit=%d",
+            "t_reordering=%d, t_status_prohibit=%d, tx_queue_length=%d",
             cfg.am.t_poll_retx,
             cfg.am.poll_pdu,
             cfg.am.poll_byte,
             cfg.am.max_retx_thresh,
             cfg.am.t_reordering,
-            cfg.am.t_status_prohibit);
+            cfg.am.t_status_prohibit,
+            cfg.tx_queue_length);
   } else if (cfg.rat == srsran_rat_t::nr) {
     RlcInfo("AM NR configured - tx_sn_field_length=%d, rx_sn_field_length=%d, "
             "t_poll_retx=%d, poll_pdu=%d, poll_byte=%d, "
-            "max_retx_thresh=%d, t_reassembly=%d, t_status_prohibit=%d",
+            "max_retx_thresh=%d, t_reassembly=%d, t_status_prohibit=%di, tx_queue_length=%d",
             to_number(cfg.am_nr.tx_sn_field_length),
             to_number(cfg.am_nr.rx_sn_field_length),
             cfg.am_nr.t_poll_retx,
@@ -97,7 +98,8 @@ bool rlc_am::configure(const rlc_config_t& cfg_)
             cfg.am_nr.poll_byte,
             cfg.am_nr.max_retx_thresh,
             cfg.am_nr.t_reassembly,
-            cfg.am_nr.t_status_prohibit);
+            cfg.am_nr.t_status_prohibit,
+            cfg.tx_queue_length);
   } else {
     RlcError("Invalid RAT at entity configuration");
   }

lib/src/rlc/rlc_am_nr.cc

@@ -69,6 +69,10 @@ bool rlc_am_nr_tx::configure(const rlc_config_t& cfg_)
 
   max_hdr_size = min_hdr_size + so_size;
 
+  // make sure Tx queue is empty before attempting to resize
+  empty_queue_no_lock();
+  tx_sdu_queue.resize(cfg_.tx_queue_length);
+
   tx_enabled = true;
 
   RlcDebug("RLC AM NR configured tx entity.");
@@ -1063,8 +1067,19 @@ bool rlc_am_nr_tx::sdu_queue_is_full()
   return false;
 }
 
-void rlc_am_nr_tx::empty_queue() {}
+void rlc_am_nr_tx::empty_queue()
+{
+  std::lock_guard<std::mutex> lock(mutex);
+  empty_queue_no_lock();
+}
 
+void rlc_am_nr_tx::empty_queue_no_lock()
+{
+  // deallocate all SDUs in transmit queue
+  while (tx_sdu_queue.size() > 0) {
+    unique_byte_buffer_t buf = tx_sdu_queue.read();
+  }
+}
 void rlc_am_nr_tx::stop() {}
 
 /*