From a149de885cb17b87503ae1c106416590317534f2 Mon Sep 17 00:00:00 2001
From: Alex Zenla <alex@edera.dev>
Date: Sun, 1 Sep 2024 19:41:22 -0400
Subject: [PATCH] Parallelize chunk generation using fan-out pattern.

---
 Sources/Voxelotl/World.swift | 20 ++++++++++++++++++--
 1 file changed, 18 insertions(+), 2 deletions(-)

diff --git a/Sources/Voxelotl/World.swift b/Sources/Voxelotl/World.swift
index 33984d9..11d81b4 100644
--- a/Sources/Voxelotl/World.swift
+++ b/Sources/Voxelotl/World.swift
@@ -62,15 +62,31 @@ public class World {
   func generate(width: Int, height: Int, depth: Int, seed: UInt64) {
     self._generator.reset(seed: seed)
     let orig = SIMD3(width, height, depth) / 2
+
+    var localChunks: [SIMD3<Int>: Chunk] = [:]
+    let localChunksLock = NSLock()
+    let queue = OperationQueue()
+    queue.qualityOfService = .userInitiated
     for z in 0..<depth {
       for y in 0..<height {
         for x in 0..<width {
           let chunkID = SIMD3(x, y, z) &- orig
-          self._chunks[chunkID] = self._generator.makeChunk(id: chunkID)
-          self._chunkDamage.insert(chunkID)
+          queue.addOperation {
+            let chunk = self._generator.makeChunk(id: chunkID)
+            localChunksLock.lock()
+            defer {
+              localChunksLock.unlock()
+            }
+            localChunks[chunkID] = chunk
+          }
         }
       }
     }
+    queue.waitUntilAllOperationsAreFinished()
+    for (chunkID, chunk) in localChunks {
+      self._chunks[chunkID] = chunk
+      self._chunkDamage.insert(chunkID)
+    }
   }
 
   func generate(chunkID: ChunkID) {