[wpinet] Move network portions of wpiutil into new wpinet library (#4077)

wpinet/src/main/native/cpp/uv/Async.cpp

@@ -0,0 +1,33 @@
+// Copyright (c) FIRST and other WPILib contributors.
+// Open Source Software; you can modify and/or share it under the terms of
+// the WPILib BSD license file in the root directory of this project.
+
+#include "wpinet/uv/Async.h"
+
+#include "wpinet/uv/Loop.h"
+
+namespace wpi::uv {
+
+Async<>::~Async() noexcept {
+  if (auto loop = m_loop.lock()) {
+    Close();
+  } else {
+    ForceClosed();
+  }
+}
+
+std::shared_ptr<Async<>> Async<>::Create(const std::shared_ptr<Loop>& loop) {
+  auto h = std::make_shared<Async>(loop, private_init{});
+  int err = uv_async_init(loop->GetRaw(), h->GetRaw(), [](uv_async_t* handle) {
+    Async& h = *static_cast<Async*>(handle->data);
+    h.wakeup();
+  });
+  if (err < 0) {
+    loop->ReportError(err);
+    return nullptr;
+  }
+  h->Keep();
+  return h;
+}
+
+}  // namespace wpi::uv