From a0726299786b5a56e8270f77c92fd3136ccfe9ca Mon Sep 17 00:00:00 2001
From: Lars <larsh@apache.org>
Date: Sun, 15 Jun 2025 15:00:01 -0700
Subject: [PATCH] Add single block cache

---
 src/map.cpp | 20 ++++++++++++++++++--
 src/map.h   |  5 +++++
 2 files changed, 23 insertions(+), 2 deletions(-)

diff --git a/src/map.cpp b/src/map.cpp
index 7a12286f3..91873d45f 100644
--- a/src/map.cpp
+++ b/src/map.cpp
@@ -78,12 +78,15 @@ void Map::deleteBlockImmediate(MapBlock *block)
 
 std::unique_ptr<MapBlock> Map::detachBlock(MapBlock *block)
 {
+	v3s16 p = block->getPos();
 	// Remove from container
-	auto it = m_blocks.find(block->getPos());
+	auto it = m_blocks.find(p);
 	assert(it != m_blocks.end());
 	std::unique_ptr<MapBlock> ret = std::move(it->second);
 	assert(ret.get() == block);
 	m_blocks.erase(it);
+	if (m_block_cache_p == p)
+		m_block_cache = nullptr;
 
 	// Mark as removed
 	block->makeOrphan();
@@ -106,8 +109,19 @@ void Map::insertBlock(std::unique_ptr<MapBlock> block)
 
 MapBlock *Map::getBlockNoCreateNoEx(v3s16 p3d)
 {
+	if(m_block_cache && p3d == m_block_cache_p){
+		return m_block_cache;
+	}
+
 	auto it = m_blocks.find(p3d);
-	return it != m_blocks.end() ? it->second.get() : nullptr;
+	if (it == m_blocks.end())
+		return nullptr;
+
+	MapBlock *block = it->second.get();
+	m_block_cache = block;
+	m_block_cache_p = p3d;
+
+	return block;
 }
 
 MapBlock *Map::getBlockNoCreate(v3s16 p3d)
@@ -329,6 +343,8 @@ void Map::timerUpdate(float dtime, float unload_timeout, s32 max_loaded_blocks,
 
 				// Delete directly from container
 				it = m_blocks.erase(it);
+				if (m_block_cache_p == p)
+					m_block_cache = nullptr;
 
 				if (unloaded_blocks)
 					unloaded_blocks->push_back(p);
diff --git a/src/map.h b/src/map.h
index 54e35430b..e3af0bec7 100644
--- a/src/map.h
+++ b/src/map.h
@@ -276,6 +276,11 @@ protected:
 
 	std::unordered_map<v3s16, std::unique_ptr<MapBlock>> m_blocks;
 
+	// Last-used block is cached here for quicker access.
+	// Be sure to set this to nullptr when the cached block is deleted
+	MapBlock *m_block_cache = nullptr;
+	v3s16 m_block_cache_p;
+
 	// This stores the properties of the nodes on the map.
 	const NodeDefManager *m_nodedef;