[core] Abstract main loop inside RunLoop class

platform/default/run_loop.cpp

@@ -0,0 +1,83 @@
+#include <mbgl/util/run_loop.hpp>
+
+#include <uv.h>
+
+namespace mbgl {
+namespace util {
+
+uv::tls<RunLoop> RunLoop::current;
+
+class RunLoop::Impl {
+public:
+    Impl() = default;
+
+    uv_loop_t *loop;
+    RunLoop::Type type;
+};
+
+RunLoop::RunLoop(Type type) : impl(std::make_unique<Impl>()) {
+    switch (type) {
+    case Type::New:
+#if UV_VERSION_MAJOR == 0 && UV_VERSION_MINOR <= 10
+        impl->loop = uv_loop_new();
+        if (impl->loop == nullptr) {
+#else
+        impl->loop = new uv_loop_t;
+        if (uv_loop_init(impl->loop) != 0) {
+#endif
+            throw std::runtime_error("Failed to initialize loop.");
+        }
+        break;
+    case Type::Default:
+        impl->loop = uv_default_loop();
+        break;
+    }
+
+    impl->type = type;
+
+    current.set(this);
+    async = std::make_unique<AsyncTask>(std::bind(&RunLoop::process, this));
+}
+
+RunLoop::~RunLoop() {
+    current.set(nullptr);
+
+    if (impl->type == Type::Default) {
+        return;
+    }
+
+    // Run the loop again to ensure that async
+    // close callbacks have been called. Not needed
+    // for the default main loop because it is only
+    // closed when the application exits.
+    async.reset();
+    runOnce();
+
+#if UV_VERSION_MAJOR == 0 && UV_VERSION_MINOR <= 10
+    uv_loop_delete(impl->loop);
+#else
+    if (uv_loop_close(impl->loop) == UV_EBUSY) {
+        throw std::runtime_error("Failed to close loop.");
+    }
+    delete impl->loop;
+#endif
+}
+
+LOOP_HANDLE RunLoop::getLoopHandle() {
+    return current.get()->impl->loop;
+}
+
+void RunLoop::run() {
+    uv_run(impl->loop, UV_RUN_DEFAULT);
+}
+
+void RunLoop::runOnce() {
+    uv_run(impl->loop, UV_RUN_ONCE);
+}
+
+void RunLoop::stop() {
+    invoke([&] { async->unref(); });
+}
+
+}
+}