[core] Remove mbgl/util/uv.hpp

Now only a few things depend on libuv and they can use it directly.

platform/default/async_task.cpp

@@ -1,35 +1,62 @@
 #include <mbgl/util/async_task.hpp>
 
 #include <mbgl/util/run_loop.hpp>
-#include <mbgl/util/uv.hpp>
 
 #include <atomic>
 #include <functional>
 
+#include <uv.h>
+
+#if UV_VERSION_MAJOR == 0 && UV_VERSION_MINOR <= 10
+#define UV_ASYNC_PARAMS(handle) uv_async_t *handle, int
+#else
+#define UV_ASYNC_PARAMS(handle) uv_async_t *handle
+#endif
+
 namespace mbgl {
 namespace util {
 
 class AsyncTask::Impl {
 public:
     Impl(std::function<void()>&& fn)
-        : async(reinterpret_cast<uv_loop_t*>(RunLoop::getLoopHandle()), [this] { runTask(); })
-        , task(std::move(fn)) {
+        : async(new uv_async_t),
+          task(std::move(fn)) {
+
+        uv_loop_t* 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;
+    }
+
+    ~Impl() {
+        uv_close(handle(), [](uv_handle_t* h) {
+            delete reinterpret_cast<uv_async_t*>(h);
+        });
     }
 
     void maySend() {
-        async.send();
-    }
-
-    void runTask() {
-        task();
+        // uv_async_send will do the call coalescing for us.
+        if (uv_async_send(async) != 0) {
+            throw std::runtime_error("Failed to async send.");
+        }
     }
 
     void unref() {
-        async.unref();
+        uv_unref(handle());
     }
 
 private:
-    uv::async async;
+    static void asyncCallback(UV_ASYNC_PARAMS(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;
 };