feat(world): add dynamic thread pool resizing

include/Cubed/constants.hpp

@@ -26,7 +26,7 @@ constexpr float DEFAULT_G = 22.5f;
 constexpr int SIZE_X = CHUNK_SIZE;
 constexpr int SIZE_Y = WORLD_SIZE_Y;
 constexpr int SIZE_Z = CHUNK_SIZE;
-
+constexpr int RESERVED_THREADS = 3;
 constexpr ChunkPos CHUNK_DIR[]{{1, 0}, {-1, 0}, {0, 1},  {0, -1},
                                {1, 1}, {-1, 1}, {1, -1}, {-1, -1}};
 

include/Cubed/gameplay/world.hpp

@@ -58,7 +58,7 @@ private:
 
     std::thread m_gen_thread;
     std::thread m_server_thread;
-    std::unique_ptr<ThreadPool> m_gen_thread_pool;
+    std::atomic<std::shared_ptr<ThreadPool>> m_gen_thread_pool;
     std::stop_source m_server_stop_source;
 
     std::atomic<int> m_per_tick_time = DEFAULT_PER_TICK_TIME; // ms
@@ -159,6 +159,8 @@ public:
 
     bool is_tick_running() const;
     void tick_running(bool run);
+
+    void change_pool_threads(int threads);
 };
 
 } // namespace Cubed

include/Cubed/tools/thread_pool.hpp

@@ -43,20 +43,7 @@ public:
             });
         }
     }
-    ~ThreadPool() {
-        m_stopping = true;
-        for (auto& w : m_workers) {
-            w.request_stop();
-        }
-
-        m_cv.notify_all();
-
-        for (auto& w : m_workers) {
-            if (w.joinable()) {
-                w.join();
-            }
-        }
-    }
+    ~ThreadPool() { stop(); }
     template <typename F> auto enqueue(F&& f) {
 
         using R = std::invoke_result_t<F>;
@@ -74,6 +61,20 @@ public:
         m_cv.notify_one();
         return fut;
     }
+    void stop() {
+        m_stopping = true;
+        for (auto& w : m_workers) {
+            w.request_stop();
+        }
+
+        m_cv.notify_all();
+
+        for (auto& w : m_workers) {
+            if (w.joinable()) {
+                w.join();
+            }
+        }
+    }
     size_t thread_sum() const { return m_thread_sum.load(); }
 };