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(); }
 };
 

src/gameplay/world.cpp

@@ -22,7 +22,11 @@ World::~World() {
     stop_gen_thread();
     stop_server_thread();
     wait_all_chunk_tasks();
-    m_gen_thread_pool.reset();
+    auto pool_ptr = m_gen_thread_pool.load();
+    if (pool_ptr) {
+        pool_ptr->stop();
+    }
+    m_gen_thread_pool.store(nullptr);
 
     m_chunks.clear();
     {
@@ -86,10 +90,7 @@ void World::init_world() {
     m_river_worm.init(ChunkGenerator::seed());
     m_chunks.reserve(MAX_DISTANCE * MAX_DISTANCE * 4);
     int max_thread = std::thread::hardware_concurrency();
-    int used_thread = std::max(max_thread - 3, 1);
-    Logger::info("Max Support Thread is {}, use {} threads to gen", max_thread,
-                 used_thread);
-    m_gen_thread_pool = std::make_unique<ThreadPool>(used_thread);
+    change_pool_threads(max_thread - RESERVED_THREADS);
 
     auto t1 = std::chrono::system_clock::now();
 
@@ -170,8 +171,12 @@ void World::gen_chunks_internal() {
     {
         std::scoped_lock lock{m_cave_carcer.path_mutex(),
                               m_river_worm.paths_mutex()};
-        parallel_do(*m_gen_thread_pool, temp_neighbor.begin(),
-                    temp_neighbor.end(), m_gen_thread_pool->thread_sum(),
+        auto pool_ptr = m_gen_thread_pool.load();
+        if (!pool_ptr) {
+            return;
+        }
+        parallel_do(*pool_ptr, temp_neighbor.begin(), temp_neighbor.end(),
+                    pool_ptr->thread_sum(),
                     [this](std::pair<ChunkPos, Chunk>& new_chunk) {
                         auto& [pos, chunk] = new_chunk;
                         chunk.gen_phase_one();
@@ -251,10 +256,14 @@ void World::sync_and_collect_missing_chunks(
 
 void World::submit_new_chunks() {
     std::lock_guard lock(m_new_chunk_mutex);
+    auto pool_ptr = m_gen_thread_pool.load();
+    if (!pool_ptr) {
+        return;
+    }
     for (auto& [pos, task] : new_chunks) {
         if (!task.future.valid()) {
-            task.future = m_gen_thread_pool->enqueue(
-                [&task]() { task.chunk.gen_chunk(); });
+            task.future =
+                pool_ptr->enqueue([&task]() { task.chunk.gen_chunk(); });
         }
     }
 }
@@ -648,4 +657,13 @@ void World::per_tick_time(int ms) { m_per_tick_time = ms; }
 
 bool World::is_tick_running() const { return m_tick_running.load(); }
 void World::tick_running(bool run) { m_tick_running = run; }
+void World::change_pool_threads(int threads) {
+    int max_thread = std::thread::hardware_concurrency();
+    if (max_thread < 1) {
+        max_thread = 4;
+    }
+    int used_thread = std::clamp(threads, 1, max_thread);
+    Logger::info("Create New Thread Pool Use {} Threads", used_thread);
+    m_gen_thread_pool.store(std::make_shared<ThreadPool>(used_thread));
+}
 } // namespace Cubed