chore: import upstream snapshot with attribution

test/core/ThreadPoolTest.cpp

@@ -0,0 +1,47 @@
+//
+//  ThreadPoolTest.cpp
+//  MNNTests
+//
+//  Created by MNN on 2019/06/30.
+//  Copyright © 2018, Alibaba Group Holding Limited
+//
+
+#ifdef MNN_USE_THREAD_POOL
+#include <MNN/MNNDefine.h>
+#include "MNNTestSuite.h"
+#include "backend/cpu/ThreadPool.hpp"
+
+using namespace MNN;
+
+class ThreadPoolTest : public MNNTestCase {
+public:
+    virtual ~ThreadPoolTest() = default;
+    virtual bool run(int precision) {
+        std::vector<std::thread> threads;
+        for (int i = 0; i < 10; ++i) {
+            threads.emplace_back([i]() {
+                MNN::ThreadPool* threadPool = nullptr;
+                MNN::ThreadPool::init(10 - i, 0, threadPool);
+                // initializer
+                auto workIndex = threadPool->acquireWorkIndex();
+                FUNC_PRINT(workIndex);
+                threadPool->active();
+                ThreadPool::TASK task = std::make_pair([](int index) {
+                    FUNC_PRINT(index);
+                    std::this_thread::yield();
+                }, 10);
+                threadPool->enqueue(&task, workIndex);
+                threadPool->deactive();
+                threadPool->releaseWorkIndex(workIndex);
+            });
+        }
+        for (auto& t : threads) {
+            t.join();
+        }
+        MNN::ThreadPool::destroy();
+        return true;
+    }
+};
+
+MNNTestSuiteRegister(ThreadPoolTest, "core/threadpool");
+#endif