From 366ecf9dfd38d612c0685f3fbf8b3a95b9900697 Mon Sep 17 00:00:00 2001
From: madmaxoft <github@xoft.cz>
Date: Tue, 10 Jun 2014 18:25:53 +0200
Subject: [PATCH] Fixed a race condition when adding a player to a world.

---
 src/ChunkMap.cpp | 24 ++++++++++++++++++++++++
 src/ChunkMap.h   |  4 ++++
 src/World.cpp    |  5 +----
 3 files changed, 29 insertions(+), 4 deletions(-)

diff --git a/src/ChunkMap.cpp b/src/ChunkMap.cpp
index 0a8164b47..dba6f3f41 100644
--- a/src/ChunkMap.cpp
+++ b/src/ChunkMap.cpp
@@ -1665,6 +1665,30 @@ void cChunkMap::AddEntity(cEntity * a_Entity)
 
 
 
+void cChunkMap::AddEntityIfNotPresent(cEntity * a_Entity)
+{
+	cCSLock Lock(m_CSLayers);
+	cChunkPtr Chunk = GetChunkNoGen(a_Entity->GetChunkX(), ZERO_CHUNK_Y, a_Entity->GetChunkZ());
+	if (
+		(Chunk == NULL) ||  // Chunk not present at all
+		(!Chunk->IsValid() && !a_Entity->IsPlayer())  // Chunk present, but no valid data; players need to spawn in such chunks (#953)
+	)
+	{
+		LOGWARNING("Entity at %p (%s, ID %d) spawning in a non-existent chunk, the entity is lost.",
+			a_Entity, a_Entity->GetClass(), a_Entity->GetUniqueID()
+		);
+		return;
+	}
+	if (!Chunk->HasEntity(a_Entity->GetUniqueID()))
+	{
+		Chunk->AddEntity(a_Entity);
+	}
+}
+
+
+
+
+
 bool cChunkMap::HasEntity(int a_UniqueID)
 {
 	cCSLock Lock(m_CSLayers);
diff --git a/src/ChunkMap.h b/src/ChunkMap.h
index 8786d7016..7e85bb6f1 100644
--- a/src/ChunkMap.h
+++ b/src/ChunkMap.h
@@ -199,6 +199,10 @@ public:
 	/** Adds the entity to its appropriate chunk, takes ownership of the entity pointer */
 	void AddEntity(cEntity * a_Entity);
 	
+	/** Adds the entity to its appropriate chunk, if the entity is not already added.
+	Takes ownership of the entity pointer */
+	void AddEntityIfNotPresent(cEntity * a_Entity);
+	
 	/** Returns true if the entity with specified ID is present in the chunks */
 	bool HasEntity(int a_EntityID);
 	
diff --git a/src/World.cpp b/src/World.cpp
index ebe6b53e6..6bcd1391a 100644
--- a/src/World.cpp
+++ b/src/World.cpp
@@ -3148,10 +3148,7 @@ void cWorld::AddQueuedPlayers(void)
 			(*itr)->SetWorld(this);
 
 			// Add to chunkmap, if not already there (Spawn vs MoveToWorld):
-			if (!m_ChunkMap->HasEntity((*itr)->GetUniqueID()))
-			{
-				m_ChunkMap->AddEntity(*itr);
-			}
+			m_ChunkMap->AddEntityIfNotPresent(*itr);
 		}  // for itr - PlayersToAdd[]
 	}  // Lock(m_CSPlayers)