Add threading primitives.

PiperOrigin-RevId: 562649644
Change-Id: I9c35b270e4b3b50cc7eb5a152f24d71def8e2fcd

test/thread/thread_pool_test.cc

@@ -0,0 +1,134 @@
+// Copyright 2023 DeepMind Technologies Limited
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include "src/thread/thread_pool.h"
+
+#include <atomic>
+#include <condition_variable>
+#include <memory>
+#include <mutex>
+#include <thread>
+
+#include <gtest/gtest.h>
+#include "src/thread/task.h"
+
+namespace mujoco {
+namespace {
+
+struct TestFunctionArgs {
+  int input;
+  // make this atomic to avoid red-herring tsan failures.
+  std::atomic<int> output;
+};
+
+void* test_function(void* args) {
+  TestFunctionArgs* test_function_args = static_cast<TestFunctionArgs*>(args);
+  test_function_args->output = test_function_args->input;
+  return nullptr;
+}
+
+TEST(TestMjThreadPool, TestMjThreadPool10Threads) {
+  ThreadPool<10> thread_pool(10);
+
+  constexpr int kTasks = 1000;
+  TestFunctionArgs test_function_args[kTasks];
+  Task tasks[kTasks];
+  for (int i = 0; i < kTasks; ++i) {
+    test_function_args[i].input = i;
+    thread_pool.Enqueue(
+        &tasks[i], test_function, static_cast<void*>(&test_function_args[i]));
+  }
+
+  for (int i = 0; i < kTasks; ++i) {
+    tasks[i].Join();
+  }
+
+  for (int i = 0; i < kTasks; ++i) {
+    EXPECT_EQ(test_function_args[i].input, test_function_args[i].output);
+  }
+
+  thread_pool.Shutdown();
+}
+
+TEST(TestMjThreadPool, TestMjThreadPool100Threads) {
+  ThreadPool<100> thread_pool(100);
+
+  constexpr int kTasks = 1000;
+  TestFunctionArgs test_function_args[kTasks];
+  Task tasks[kTasks];
+  for (int i = 0; i < kTasks; ++i) {
+    test_function_args[i].input = i;
+    thread_pool.Enqueue(
+        &tasks[i], test_function, static_cast<void*>(&test_function_args[i]));
+  }
+
+  for (int i = 0; i < kTasks; ++i) {
+    tasks[i].Join();
+  }
+
+  for (int i = 0; i < kTasks; ++i) {
+    EXPECT_EQ(test_function_args[i].input, test_function_args[i].output);
+  }
+
+  thread_pool.Shutdown();
+}
+
+TEST(TestMjThreadPool, TestMjThreadPoolManyWriters) {
+  ThreadPool<10> thread_pool(10);
+
+  constexpr int kTasks = 20;
+  TestFunctionArgs test_function_args[kTasks];
+  Task tasks[kTasks];
+  std::unique_ptr<std::thread> enqueue_threads[kTasks];
+
+  // add tasks to the thread pool from many threads
+  std::condition_variable start_cv;
+  std::mutex start_mutex;
+  bool start = false;
+  for (int i = 0; i < kTasks; ++i) {
+    test_function_args[i].input = i;
+    enqueue_threads[i] = std::make_unique<std::thread>([&, i] {
+      // synchronize all threads adding to the thread_pool at the same time
+      {
+        std::unique_lock<std::mutex> lock(start_mutex);
+        start_cv.wait(lock, [&] { return start; });
+      }
+      // enqueue outside the lock, to get some concurrency
+      thread_pool.Enqueue(
+          &tasks[i], test_function, static_cast<void*>(&test_function_args[i]));
+    });
+  }
+  {
+    std::unique_lock<std::mutex> lock(start_mutex);
+    start = true;
+  }
+  start_cv.notify_all();
+
+  for (int i = 0; i < kTasks; ++i) {
+    enqueue_threads[i]->join();
+  }
+
+  for (int i = 0; i < kTasks; ++i) {
+    tasks[i].Join();
+  }
+
+  for (int i = 0; i < kTasks; ++i) {
+    EXPECT_EQ(test_function_args[i].input, test_function_args[i].output);
+  }
+
+  thread_pool.Shutdown();
+}
+
+}  // namespace
+}  // namespace mujoco