From 05850e2fc0226cb7b647ac349cf1b66938405792 Mon Sep 17 00:00:00 2001
From: Daniel Agar <daniel@agar.ca>
Date: Sat, 23 Apr 2022 15:44:30 -0400
Subject: [PATCH] mavlink: eliminate timestamped_list dynamic allocation

---
 src/modules/mavlink/mavlink_command_sender.h |  2 +-
 src/modules/mavlink/timestamped_list.h       | 36 +++++++-------------
 2 files changed, 13 insertions(+), 25 deletions(-)

diff --git a/src/modules/mavlink/mavlink_command_sender.h b/src/modules/mavlink/mavlink_command_sender.h
index 9d5eb82bee..478648f507 100644
--- a/src/modules/mavlink/mavlink_command_sender.h
+++ b/src/modules/mavlink/mavlink_command_sender.h
@@ -115,7 +115,7 @@ private:
 #endif
 	};
 
-	TimestampedList<command_item_s> _commands{3};
+	TimestampedList<command_item_s, 3> _commands{};
 
 	bool _debug_enabled = false;
 	static constexpr uint8_t RETRIES = 3;
diff --git a/src/modules/mavlink/timestamped_list.h b/src/modules/mavlink/timestamped_list.h
index 67f1df2a5d..1bdb38acad 100644
--- a/src/modules/mavlink/timestamped_list.h
+++ b/src/modules/mavlink/timestamped_list.h
@@ -49,20 +49,12 @@
 /**
  * @class TimestampedList
  */
-template <class T>
+template <class T, int NUM_ITEMS>
 class TimestampedList
 {
 public:
-	TimestampedList(int num_items)
-	{
-		_list = new item_s[num_items];
-		_list_len = num_items;
-	}
-
-	~TimestampedList()
-	{
-		delete[] _list;
-	}
+	TimestampedList() = default;
+	~TimestampedList() = default;
 
 	/**
 	 * Insert a value into the list, overwrite the oldest entry if full.
@@ -72,7 +64,7 @@ public:
 		hrt_abstime now = hrt_absolute_time();
 
 		// Insert it wherever there is a free space.
-		for (int i = 0; i < _list_len; ++i) {
+		for (int i = 0; i < NUM_ITEMS; ++i) {
 			if (_list[i].timestamp_us == 0) {
 				_list[i].timestamp_us = now;
 				_list[i].value = new_value;
@@ -83,7 +75,7 @@ public:
 		// Find oldest entry.
 		int oldest_i = 0;
 
-		for (int i = 1; i < _list_len; ++i) {
+		for (int i = 1; i < NUM_ITEMS; ++i) {
 			if (_list[i].timestamp_us < _list[oldest_i].timestamp_us) {
 				oldest_i = i;
 			}
@@ -113,7 +105,7 @@ public:
 		// Increment first, then leave it until called again.
 		++_current_i;
 
-		for (int i = _current_i; i < _list_len; ++i) {
+		for (int i = _current_i; i < NUM_ITEMS; ++i) {
 			if (_list[i].timestamp_us != 0) {
 				_current_i = i;
 				return &_list[i].value;
@@ -128,7 +120,7 @@ public:
 	 */
 	void drop_current()
 	{
-		if (_current_i < _list_len) {
+		if (_current_i < NUM_ITEMS) {
 			_list[_current_i].timestamp_us = 0;
 		}
 	}
@@ -138,22 +130,18 @@ public:
 	 */
 	void update_current()
 	{
-		if (_current_i < _list_len) {
+		if (_current_i < NUM_ITEMS) {
 			_list[_current_i].timestamp = hrt_absolute_time();
 		}
 	}
 
-	/* do not allow copying or assigning this class */
-	TimestampedList(const TimestampedList &) = delete;
-	TimestampedList operator=(const TimestampedList &) = delete;
-
 private:
 	struct item_s {
 		hrt_abstime timestamp_us = 0; // 0 signals inactive.
-		T value;
+		T value{};
 	};
 
-	item_s *_list = nullptr;
-	int _list_len = 0;
-	int _current_i = -1;
+	item_s _list[NUM_ITEMS] {};
+
+	int _current_i{-1};
 };