Fixed minimap memory leak

src/client.cpp

@@ -540,20 +540,19 @@ void Client::step(float dtime)
 				}
 
 				if (r.mesh) {
-					minimap_mapblock = r.mesh->getMinimapMapblock();
-					do_mapper_update = (minimap_mapblock != NULL);
+					minimap_mapblock = r.mesh->moveMinimapMapblock();
+					if (minimap_mapblock == NULL)
+						do_mapper_update = false;
 				}
 
 				if (r.mesh && r.mesh->getMesh()->getMeshBufferCount() == 0) {
 					delete r.mesh;
-					block->mesh = NULL;
 				} else {
 					// Replace with the new mesh
 					block->mesh = r.mesh;
 				}
 			} else {
 				delete r.mesh;
-				minimap_mapblock = NULL;
 			}
 
 			if (do_mapper_update)

src/mapblock_mesh.cpp

@@ -1278,6 +1278,7 @@ MapBlockMesh::~MapBlockMesh()
 {
 	m_mesh->drop();
 	m_mesh = NULL;
+	delete m_minimap_mapblock;
 }
 
 bool MapBlockMesh::animate(bool faraway, float time, int crack, u32 daynight_ratio)

src/mapblock_mesh.h

@@ -104,14 +104,16 @@ class MapBlockMesh
 	// Returns true if anything has been changed.
 	bool animate(bool faraway, float time, int crack, u32 daynight_ratio);
 
-	scene::SMesh* getMesh()
+	scene::SMesh *getMesh()
 	{
 		return m_mesh;
 	}
 
-	MinimapMapblock* getMinimapMapblock()
+	MinimapMapblock *moveMinimapMapblock()
 	{
-		return m_minimap_mapblock;
+		MinimapMapblock *p = m_minimap_mapblock;
+		m_minimap_mapblock = NULL;
+		return p;
 	}
 
 	bool isAnimationForced() const

src/minimap.cpp

@@ -102,7 +102,13 @@ void MinimapUpdateThread::doUpdate()
 
 	while (popBlockUpdate(&update)) {
 		if (update.data) {
-			m_blocks_cache[update.pos] = update.data;
+			// Swap two values in the map using single lookup
+			std::pair<std::map<v3s16, MinimapMapblock*>::iterator, bool>
+			    result = m_blocks_cache.insert(std::make_pair(update.pos, update.data));
+			if (result.second == false) {
+				delete result.first->second;
+				result.first->second = update.data;
+			}
 		} else {
 			std::map<v3s16, MinimapMapblock *>::iterator it;
 			it = m_blocks_cache.find(update.pos);