Add threading primitives.

PiperOrigin-RevId: 562649644
Change-Id: I9c35b270e4b3b50cc7eb5a152f24d71def8e2fcd

src/thread/thread_pool.cc

@@ -0,0 +1,52 @@
+// 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 "thread/thread_pool.h"
+
+#include <cstddef>
+
+#include <mujoco/mjthread.h>
+#include <mujoco/mujoco.h>
+#include "thread/task.h"
+
+static constexpr size_t kMaxThreads = 128;
+
+// create a thread pool
+mjThreadPool* mju_threadPoolCreate(size_t number_of_threads) {
+  mujoco::ThreadPool<kMaxThreads>* thread_pool =
+      new mujoco::ThreadPool<kMaxThreads>(number_of_threads);
+  return static_cast<mjThreadPool*>(static_cast<void*>(thread_pool));
+}
+
+// start a task in the threadpool
+void mju_threadPoolEnqueue(
+    mjThreadPool* thread_pool, mjTask* task, mjStartRoutine start_routine,
+    void* args) {
+  mujoco::ThreadPool<kMaxThreads>* thread_pool_ptr =
+      static_cast<mujoco::ThreadPool<kMaxThreads>*>(
+          static_cast<void*>(thread_pool));
+  thread_pool_ptr->Enqueue(
+      static_cast<mujoco::Task*>(static_cast<void*>(task)), start_routine,
+      args);
+}
+
+// shutdown the threadpool and free the memory
+void mju_threadPoolDestroy(mjThreadPool* thread_pool) {
+  mujoco::ThreadPool<kMaxThreads>* thread_pool_ptr =
+      static_cast<mujoco::ThreadPool<kMaxThreads>*>(
+          static_cast<void*>(thread_pool));
+  thread_pool_ptr->Shutdown();
+  delete thread_pool_ptr;
+}
+