From 6218702ec69bd00416c6246f6c4212b9ff96f420 Mon Sep 17 00:00:00 2001
From: Mathias Kraus <elboberido@m-hias.de>
Date: Mon, 23 Oct 2023 20:12:02 +0200
Subject: [PATCH] iox-#2044 Optimize 'size' method

---
 .../iox/detail/fixed_position_container.inl   | 19 +++++--------------
 .../include/iox/fixed_position_container.hpp  |  1 +
 2 files changed, 6 insertions(+), 14 deletions(-)

diff --git a/iceoryx_dust/container/include/iox/detail/fixed_position_container.inl b/iceoryx_dust/container/include/iox/detail/fixed_position_container.inl
index 1959638c75d..925ca96d775 100644
--- a/iceoryx_dust/container/include/iox/detail/fixed_position_container.inl
+++ b/iceoryx_dust/container/include/iox/detail/fixed_position_container.inl
@@ -69,6 +69,7 @@ inline void FixedPositionContainer<T, CAPACITY>::clear() noexcept
     }
     m_slots[Index::LAST].next = Index::INVALID;
 
+    m_size = 0;
     m_begin_free = Index::FIRST;
     m_begin_used = Index::INVALID;
 }
@@ -146,6 +147,7 @@ FixedPositionContainer<T, CAPACITY>::emplace(Targs&&... args) noexcept
 
     new (&m_data[index]) T(std::forward<Targs>(args)...);
     m_slots[index].status = SlotStatus::USED;
+    ++m_size;
 
     if (index < m_begin_used)
     {
@@ -256,6 +258,7 @@ FixedPositionContainer<T, CAPACITY>::erase(const IndexType index) noexcept
 
     m_data[index].~T();
     m_slots[index].status = SlotStatus::FREE;
+    --m_size;
 
     auto next_used = m_slots[index].next;
     bool is_removed_from_used_list{false};
@@ -347,7 +350,7 @@ FixedPositionContainer<T, CAPACITY>::erase(ConstIterator it) noexcept
 template <typename T, uint64_t CAPACITY>
 inline bool FixedPositionContainer<T, CAPACITY>::empty() const noexcept
 {
-    return m_begin_used >= Index::INVALID;
+    return m_size == 0;
 }
 
 template <typename T, uint64_t CAPACITY>
@@ -359,19 +362,7 @@ inline bool FixedPositionContainer<T, CAPACITY>::full() const noexcept
 template <typename T, uint64_t CAPACITY>
 inline uint64_t FixedPositionContainer<T, CAPACITY>::size() const noexcept
 {
-    uint64_t count{0};
-    IndexType pos = m_begin_used;
-    // use a for loop to abort at CAPACITY iterations in case the container is corrupted
-    for (IndexType i = 0; i < CAPACITY; ++i)
-    {
-        if (pos > Index::LAST)
-        {
-            break;
-        }
-        ++count;
-        pos = m_slots[pos].next;
-    }
-    return count;
+    return m_size;
 }
 
 template <typename T, uint64_t CAPACITY>
diff --git a/iceoryx_dust/container/include/iox/fixed_position_container.hpp b/iceoryx_dust/container/include/iox/fixed_position_container.hpp
index 7c755f4b17c..b8ff9dc55a3 100644
--- a/iceoryx_dust/container/include/iox/fixed_position_container.hpp
+++ b/iceoryx_dust/container/include/iox/fixed_position_container.hpp
@@ -327,6 +327,7 @@ class FixedPositionContainer final
   private:
     UninitializedArray<T, CAPACITY> m_data;
     UninitializedArray<Slot, CAPACITY> m_slots;
+    IndexType m_size{0};
     IndexType m_begin_free{Index::FIRST};
     IndexType m_begin_used{Index::INVALID};
 };