Increase MapBlock::actuallyUpdateDayNightDiff() performance by 2-8x. ok @celeron55

Before patch, function consumes up to ~8% of the main server loop. After, ~0% (below level of 2 places of significance)

1 files changed, 12 insertions, 17 deletions

diff --git a/src/mapblock.cpp b/src/mapblock.cpp
index ecd9a016b..a05b7a4da 100644
--- a/src/mapblock.cpp
+++ b/src/mapblock.cpp
@@ -330,47 +330,42 @@ void MapBlock::copyFrom(VoxelManipulator &dst)
 void MapBlock::actuallyUpdateDayNightDiff()
 {
 	INodeDefManager *nodemgr = m_gamedef->ndef();
+
 	// Running this function un-expires m_day_night_differs
 	m_day_night_differs_expired = false;
 
-	if(data == NULL)
-	{
+	if (data == NULL) {
 		m_day_night_differs = false;
 		return;
 	}
 
-	bool differs = false;
+	bool differs;
 
 	/*
 		Check if any lighting value differs
 	*/
-	for(u32 i=0; i<MAP_BLOCKSIZE*MAP_BLOCKSIZE*MAP_BLOCKSIZE; i++)
-	{
+	for (u32 i = 0; i < MAP_BLOCKSIZE*MAP_BLOCKSIZE*MAP_BLOCKSIZE; i++) {
 		MapNode &n = data[i];
-		if(n.getLight(LIGHTBANK_DAY, nodemgr) != n.getLight(LIGHTBANK_NIGHT, nodemgr))
-		{
-			differs = true;
+
+		differs = !n.isLightDayNightEq(nodemgr);
+		if (differs)
 			break;
-		}
 	}
 
 	/*
 		If some lighting values differ, check if the whole thing is
-		just air. If it is, differ = false
+		just air. If it is just air, differs = false
 	*/
-	if(differs)
-	{
+	if (differs) {
 		bool only_air = true;
-		for(u32 i=0; i<MAP_BLOCKSIZE*MAP_BLOCKSIZE*MAP_BLOCKSIZE; i++)
-		{
+		for (u32 i = 0; i < MAP_BLOCKSIZE*MAP_BLOCKSIZE*MAP_BLOCKSIZE; i++) {
 			MapNode &n = data[i];
-			if(n.getContent() != CONTENT_AIR)
-			{
+			if (n.getContent() != CONTENT_AIR) {
 				only_air = false;
 				break;
 			}
 		}
-		if(only_air)
+		if (only_air)
 			differs = false;
 	}