core: rename mbgl directories to mln (#4511)

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>

platform/default/src/mln/util/async_task.cpp

@@ -0,0 +1,59 @@
+#include <mln/util/async_task.hpp>
+
+#include <mln/util/run_loop.hpp>
+
+#include <atomic>
+#include <functional>
+#include <stdexcept>
+
+#include <uv.h>
+
+namespace mln {
+namespace util {
+
+class AsyncTask::Impl {
+public:
+    explicit Impl(std::function<void()> fn)
+        : async(new uv_async_t),
+          task(std::move(fn)) {
+        auto* loop = reinterpret_cast<uv_loop_t*>(RunLoop::getLoopHandle());
+        if (uv_async_init(loop, async, asyncCallback) != 0) {
+            throw std::runtime_error("Failed to initialize async.");
+        }
+
+        handle()->data = this;
+        uv_unref(handle());
+    }
+
+    ~Impl() {
+        uv_close(handle(), [](uv_handle_t* h) { delete reinterpret_cast<uv_async_t*>(h); });
+    }
+
+    void maySend() {
+        // uv_async_send will do the call coalescing for us.
+        if (uv_async_send(async) != 0) {
+            throw std::runtime_error("Failed to async send.");
+        }
+    }
+
+private:
+    static void asyncCallback(uv_async_t* handle) { reinterpret_cast<Impl*>(handle->data)->task(); }
+
+    uv_handle_t* handle() { return reinterpret_cast<uv_handle_t*>(async); }
+
+    uv_async_t* async;
+
+    std::function<void()> task;
+};
+
+AsyncTask::AsyncTask(std::function<void()>&& fn)
+    : impl(std::make_unique<Impl>(std::move(fn))) {}
+
+AsyncTask::~AsyncTask() = default;
+
+void AsyncTask::send() {
+    impl->maySend();
+}
+
+} // namespace util
+} // namespace mln