初始提交: UE5.3项目基础框架

Plugins/CesiumForUnreal/Source/ThirdParty/include/CesiumAsync/ThreadPool.h

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+#pragma once
+
+#include "Impl/ImmediateScheduler.h"
+#include "Impl/cesium-async++.h"
+#include "Library.h"
+
+#include <memory>
+
+namespace CesiumAsync {
+
+/**
+ * @brief A thread pool created by {@link AsyncSystem::createThreadPool}.
+ *
+ * This object has no public methods, but can be used with
+ * {@link AsyncSystem::runInThreadPool} and
+ * {@link Future::thenInThreadPool}.
+ */
+class CESIUMASYNC_API ThreadPool {
+public:
+  /**
+   * @brief Creates a new thread pool with the given number of threads.
+   *
+   * @param numberOfThreads The number of threads to create in this ThreadPool.
+   */
+  ThreadPool(int32_t numberOfThreads);
+
+private:
+  struct Scheduler {
+    Scheduler(int32_t numberOfThreads);
+    void schedule(async::task_run_handle t);
+
+    CesiumImpl::ImmediateScheduler<Scheduler> immediate{this};
+
+    async::threadpool_scheduler scheduler;
+  };
+
+  static auto createPreRun(ThreadPool::Scheduler* pScheduler) {
+    return
+        [pScheduler]() { ThreadPool::_scope = pScheduler->immediate.scope(); };
+  }
+
+  static auto createPostRun() noexcept {
+    return []() noexcept { ThreadPool::_scope.reset(); };
+  }
+
+  static thread_local CesiumImpl::ImmediateScheduler<Scheduler>::SchedulerScope
+      _scope;
+
+  std::shared_ptr<Scheduler> _pScheduler;
+
+  template <typename T> friend class Future;
+  template <typename T> friend class SharedFuture;
+  friend class AsyncSystem;
+};
+
+} // namespace CesiumAsync