rlc am - use of circular_map container in RLC AM window

The window elements are not being correctly cleaned up when clear() is called
or when overwritten by newer SN. Furthermore, the window count member is not being
correctly updated when the insertion of a newer SN overwrites the previous one.

I used the circular_map container to avoid this sort of bugs

lib/include/srsran/adt/circular_map.h

@@ -170,6 +170,16 @@ public:
     return iterator(this, idx);
   }
 
+  template <typename U>
+  void overwrite(K id, U&& obj)
+  {
+    size_t idx = id % N;
+    if (present[idx]) {
+      erase(buffer[idx].get().first);
+    }
+    insert(id, std::forward<U>(obj));
+  }
+
   bool erase(K id)
   {
     if (not contains(id)) {

lib/include/srsran/upper/rlc_am_lte.h

@@ -15,6 +15,7 @@
 
 #include "srsran/adt/accumulators.h"
 #include "srsran/adt/circular_array.h"
+#include "srsran/adt/circular_map.h"
 #include "srsran/common/buffer_pool.h"
 #include "srsran/common/common.h"
 #include "srsran/common/srsran_assert.h"
@@ -73,53 +74,39 @@ struct pdcp_sdu_info_t {
 
 template <class T>
 struct rlc_ringbuffer_t {
-  rlc_ringbuffer_t() { clear(); }
   T& add_pdu(size_t sn)
   {
     srsran_expect(not has_sn(sn), "The same SN=%zd should not be added twice", sn);
+    window.overwrite(sn, T{});
     window[sn].rlc_sn = sn;
-    active_flag[sn]   = true;
-    count++;
     return window[sn];
   }
   void remove_pdu(size_t sn)
   {
     srsran_expect(has_sn(sn), "The removed SN=%zd is not in the window", sn);
-    window[sn]      = {};
+    window.erase(sn);
-    active_flag[sn] = false;
-    count--;
-  }
-  T& operator[](size_t sn)
-  {
-    srsran_expect(has_sn(sn), "The accessed SN=%zd is not in the window", sn);
-    return window[sn];
-  }
-  size_t size() const { return count; }
-  bool   empty() const { return count == 0; }
-  void   clear()
-  {
-    std::fill(active_flag.begin(), active_flag.end(), false);
-    count = 0;
   }
+  T&     operator[](size_t sn) { return window[sn]; }
+  size_t size() const { return window.size(); }
+  bool   empty() const { return window.empty(); }
+  void   clear() { window.clear(); }
 
-  bool has_sn(uint32_t sn) const { return active_flag[sn] and (window[sn].rlc_sn == sn); }
+  bool has_sn(uint32_t sn) const { return window.contains(sn); }
 
   // Return the sum data bytes of all active PDUs (check PDU is non-null)
   uint32_t get_buffered_bytes()
   {
     uint32_t buff_size = 0;
     for (const auto& pdu : window) {
-      if (pdu.buf != nullptr) {
+      if (pdu.second.buf != nullptr) {
-        buff_size += pdu.buf->N_bytes;
+        buff_size += pdu.second.buf->N_bytes;
       }
     }
     return buff_size;
   }
 
 private:
-  size_t                                           count       = 0;
+  srsran::static_circular_map<uint32_t, T, RLC_AM_WINDOW_SIZE> window;
-  srsran::circular_array<bool, RLC_AM_WINDOW_SIZE> active_flag = {};
-  srsran::circular_array<T, RLC_AM_WINDOW_SIZE>    window;
 };
 
 struct buffered_pdcp_pdu_list {