Avoid leaking uv_async_t in Dispatcher::Deactivate()

src/callbacks.cc

@@ -48,8 +48,7 @@ v8::Local<v8::Array> TopicPartitionListToV8Array(
   return tp_array;
 }
 
-Dispatcher::Dispatcher() {
-  async = NULL;
+Dispatcher::Dispatcher(): async(nullptr, async_deleter) {
   uv_mutex_init(&async_lock);
 }
 
@@ -66,19 +65,17 @@ Dispatcher::~Dispatcher() {
 // Only run this if we aren't already listening
 void Dispatcher::Activate() {
   if (!async) {
-    async = new uv_async_t;
-    uv_async_init(uv_default_loop(), async, AsyncMessage_);
+    async = std::unique_ptr<uv_async_t, decltype(async_deleter)*>(
+      new uv_async_t(), async_deleter);
+    uv_async_init(uv_default_loop(), async.get(), AsyncMessage_);
 
     async->data = this;
   }
 }
 
 // Should be able to run this regardless of whether it is active or not
 void Dispatcher::Deactivate() {
-  if (async) {
-    uv_close(reinterpret_cast<uv_handle_t*>(async), NULL);
-    async = NULL;
-  }
+  async.reset();
 }
 
 bool Dispatcher::HasCallbacks() {
@@ -87,7 +84,7 @@ bool Dispatcher::HasCallbacks() {
 
 void Dispatcher::Execute() {
   if (async) {
-    uv_async_send(async);
+    uv_async_send(async.get());
   }
 }
 
@@ -119,6 +116,17 @@ void Dispatcher::RemoveCallback(const v8::Local<v8::Function> &cb) {
   }
 }
 
+// Custom deleter for uv_async_t smart pointers
+void Dispatcher::async_deleter(uv_async_t* async) {
+  uv_close(
+    reinterpret_cast<uv_handle_t*>(async),
+    // Release memory after uv_close() has finished.
+    [](uv_handle_t* handle) {
+      delete reinterpret_cast<uv_async_t*>(handle);
+    }
+  );
+}
+
 event_t::event_t(const RdKafka::Event &event) {
   message = "";
   fac = "";

src/callbacks.h

@@ -12,6 +12,7 @@
 #include <uv.h>
 #include <nan.h>
 
+#include <memory>
 #include <vector>
 #include <deque>
 
@@ -49,7 +50,9 @@ class Dispatcher {
      dispatcher->Flush();
   }
 
-  uv_async_t *async;
+  static inline void async_deleter(uv_async_t* async);
+
+  std::unique_ptr<uv_async_t, decltype(async_deleter)*> async;
 };
 
 struct event_t {