fix: Chunks are now goroutine safe

- added Chunk.ForEachEntity()
- refactored SendPacketExclude() to use it
- Chunk.Entities is now Chunk.entities, which is private.
- Chunk.AddEntity() && RemoveEntity() now lock the chunk mutex

internal/entity/chunk.go

@@ -7,23 +7,29 @@ import (
 
 type Chunk struct {
 	Position ChunkPosition
-	Entities map[Entity]struct{}
+	entities map[Entity]struct{}
 	lock     sync.Mutex
 }
 
 func NewChunk(position ChunkPosition) *Chunk {
 	return &Chunk{
 		Position: position,
-		Entities: make(map[Entity]struct{}),
+		entities: make(map[Entity]struct{}),
 	}
 }
 
 func (c *Chunk) AddEntity(entity Entity) {
-	c.Entities[entity] = struct{}{}
+	c.lock.Lock()
+	defer c.lock.Unlock()
+
+	c.entities[entity] = struct{}{}
 }
 
 func (c *Chunk) RemoveEntity(entity Entity) {
-	delete(c.Entities, entity)
+	c.lock.Lock()
+	defer c.lock.Unlock()
+
+	delete(c.entities, entity)
 }
 
 // send packet to all peers in this chunk and kill each peer if error
@@ -31,14 +37,23 @@ func (c *Chunk) SendPacket(typeID uint32, pkt ...interface{}) {
 	c.SendPacketExclude(nil, typeID, pkt...)
 }
 
-func (c *Chunk) SendPacketExclude(exclude Entity, typeID uint32, pkt ...interface{}) {
+// calls f for each entity in this chunk, if f returns true, stop iterating
+func (c *Chunk) ForEachEntity(f func(entity Entity) bool) {
 	c.lock.Lock()
 	defer c.lock.Unlock()
 
-	for entity := range c.Entities {
+	for entity := range c.entities {
+		if f(entity) {
+			break
+		}
+	}
+}
+
+func (c *Chunk) SendPacketExclude(exclude Entity, typeID uint32, pkt ...interface{}) {
+	c.ForEachEntity(func(entity Entity) bool {
 		// only send to players, and exclude the player that sent the packet
 		if entity.GetKind() != ENTITY_KIND_PLAYER || entity == exclude {
-			continue
+			return false
 		}
 
 		plr, ok := entity.(*Player)
@@ -51,7 +66,9 @@ func (c *Chunk) SendPacketExclude(exclude Entity, typeID uint32, pkt ...interfac
 			log.Printf("Error sending packet to peer %p: %v", peer, err)
 			peer.Kill()
 		}
-	}
+
+		return false
+	})
 }
 
 func (c *Chunk) GetAdjacentPositions() []ChunkPosition {

internal/entity/entity.go

@@ -12,11 +12,11 @@ const (
 type Entity interface {
 	GetKind() EntityKind
 
-	GetChunk() ChunkPosition
+	GetChunkPos() ChunkPosition
 	GetPosition() (x int, y int, z int)
 	GetAngle() int
 
-	SetChunk(chunk ChunkPosition)
+	SetChunkPos(chunk ChunkPosition)
 	SetPosition(x, y, z int)
 	SetAngle(angle int)
 

internal/entity/npc.go

@@ -36,7 +36,7 @@ func (npc *NPC) GetKind() EntityKind {
 	return ENTITY_KIND_NPC
 }
 
-func (npc *NPC) GetChunk() ChunkPosition {
+func (npc *NPC) GetChunkPos() ChunkPosition {
 	return npc.Chunk
 }
 
@@ -48,7 +48,7 @@ func (npc *NPC) GetAngle() int {
 	return npc.Angle
 }
 
-func (npc *NPC) SetChunk(chunk ChunkPosition) {
+func (npc *NPC) SetChunkPos(chunk ChunkPosition) {
 	npc.Chunk = chunk
 }
 

internal/entity/player.go

@@ -44,7 +44,7 @@ func (plr *Player) GetKind() EntityKind {
 	return ENTITY_KIND_PLAYER
 }
 
-func (plr *Player) GetChunk() ChunkPosition {
+func (plr *Player) GetChunkPos() ChunkPosition {
 	return plr.Chunk
 }
 
@@ -56,7 +56,7 @@ func (plr *Player) GetAngle() int {
 	return plr.Angle
 }
 
-func (plr *Player) SetChunk(chunk ChunkPosition) {
+func (plr *Player) SetChunkPos(chunk ChunkPosition) {
 	plr.Chunk = chunk
 }
 

shard/entitymanager.go

@@ -5,15 +5,15 @@ import (
 )
 
 func (server *ShardServer) addEntity(e entity.Entity) {
-	pos := e.GetChunk()
+	pos := e.GetChunkPos()
-	server.addEntityToChunks(server.getViewableChunks(pos), e)
+	server.addEntityToChunks(e, server.getViewableChunks(pos))
 	server.getChunk(pos).AddEntity(e)
 }
 
 func (server *ShardServer) removeEntity(e entity.Entity) {
 	// TODO: chunk cleanup
-	pos := e.GetChunk()
+	pos := e.GetChunkPos()
-	server.removeEntityFromChunks(server.getViewableChunks(pos), e)
+	server.removeEntityFromChunks(e, server.getViewableChunks(pos))
 	server.getChunk(pos).RemoveEntity(e)
 }
 
@@ -56,11 +56,11 @@ func (server *ShardServer) sendAllPacket(plr *entity.Player, typeID uint32, pkt
 	return nil
 }
 
-func (server *ShardServer) removeEntityFromChunks(chunks []*entity.Chunk, this entity.Entity) {
+func (server *ShardServer) removeEntityFromChunks(this entity.Entity, chunks []*entity.Chunk) {
 	for _, chunk := range chunks {
-		for e := range chunk.Entities {
+		chunk.ForEachEntity(func(e entity.Entity) bool {
 			if e == this {
-				continue
+				return false
 			}
 
 			// notify other players we're leaving
@@ -74,15 +74,17 @@ func (server *ShardServer) removeEntityFromChunks(chunks []*entity.Chunk, this e
 				thisPlr := this.(*entity.Player)
 				e.DisappearFromViewOf(thisPlr.Peer)
 			}
-		}
+
+			return false
+		})
 	}
 }
 
-func (server *ShardServer) addEntityToChunks(chunks []*entity.Chunk, this entity.Entity) {
+func (server *ShardServer) addEntityToChunks(this entity.Entity, chunks []*entity.Chunk) {
 	for _, chunk := range chunks {
-		for e := range chunk.Entities {
+		chunk.ForEachEntity(func(e entity.Entity) bool {
 			if e == this {
-				continue
+				return false
 			}
 
 			// notify other players we're entering
@@ -96,7 +98,9 @@ func (server *ShardServer) addEntityToChunks(chunks []*entity.Chunk, this entity
 				thisPlr := this.(*entity.Player)
 				e.EnterIntoViewOf(thisPlr.Peer)
 			}
-		}
+
+			return false
+		})
 	}
 }
 
@@ -114,9 +118,9 @@ func (server *ShardServer) updateEntityChunk(e entity.Entity, from entity.ChunkP
 	toEnter := entity.ChunkSliceDifference(newViewables, oldViewables)
 
 	// update chunks
-	server.removeEntityFromChunks(toExit, e)
+	server.removeEntityFromChunks(e, toExit)
-	server.addEntityToChunks(toEnter, e)
+	server.addEntityToChunks(e, toEnter)
 	server.getChunk(from).RemoveEntity(e)
 	server.getChunk(to).AddEntity(e)
-	e.SetChunk(to)
+	e.SetChunkPos(to)
 }

shard/movement.go

@@ -10,7 +10,7 @@ func (server *ShardServer) updatePlayerPosition(plr *entity.Player, X, Y, Z, Ang
 	plr.Y = Y
 	plr.Z = Z
 	plr.Angle = Angle
-	server.updateEntityChunk(plr, plr.GetChunk(), entity.MakeChunkPosition(X, Y))
+	server.updateEntityChunk(plr, plr.GetChunkPos(), entity.MakeChunkPosition(X, Y))
 }
 
 func (server *ShardServer) playerMove(peer *protocol.CNPeer, pkt protocol.Packet) error {