Fix the destructor of AresResolver (#162)

Author: an-tao

trantor/net/inner/AresResolver.cc

@@ -73,6 +73,8 @@ AresResolver::AresResolver(EventLoop* loop, size_t timeout)
     {
         loop_ = getLoop();
     }
+    loopValid_ = std::make_shared<bool>(true);
+    loop_->runOnQuit([loopValid = loopValid_]() { *loopValid = false; });
 }
 void AresResolver::init()
 {
@@ -209,7 +211,7 @@ void AresResolver::onSockStateChange(int sockfd, bool read, bool write)
         // update
         // if (write) { } else { }
     }
-    else
+    else if (*loopValid_)
     {
         // remove
         it->second->disableAll();

trantor/net/inner/AresResolver.h

@@ -86,6 +86,7 @@ class AresResolver : public Resolver,
     void resolveInLoop(const std::string& hostname, const Callback& cb);
     void init();
     trantor::EventLoop* loop_;
+    std::shared_ptr<bool> loopValid_;
     ares_channel ctx_{nullptr};
     bool timerActive_{false};
     using ChannelList = std::map<int, std::unique_ptr<trantor::Channel>>;