[core] Introduce the AsyncTask

platform/default/async_task.cpp

@@ -0,0 +1,53 @@
+#include <mbgl/util/async_task.hpp>
+
+#include <mbgl/util/run_loop.hpp>
+#include <mbgl/util/uv_detail.hpp>
+
+#include <atomic>
+#include <functional>
+
+namespace mbgl {
+namespace util {
+
+class AsyncTask::Impl {
+public:
+    Impl(std::function<void()>&& fn)
+        : async(RunLoop::getLoop(), [this] { runTask(); })
+        , task(std::move(fn)) {
+    }
+
+    void maySend() {
+        async.send();
+    }
+
+    void runTask() {
+        task();
+    }
+
+    void unref() {
+        async.unref();
+    }
+
+private:
+    uv::async async;
+
+    std::function<void()> task;
+};
+
+AsyncTask::AsyncTask(std::function<void()>&& fn)
+    : impl(std::make_unique<Impl>(std::move(fn))) {
+}
+
+AsyncTask::~AsyncTask() {
+}
+
+void AsyncTask::send() {
+    impl->maySend();
+}
+
+void AsyncTask::unref() {
+    impl->unref();
+}
+
+}
+}