Fix iterator invalidation bug when stopping TCP server (#225)

Author: an-tao

trantor/net/TcpServer.cc

@@ -148,7 +148,15 @@ void TcpServer::stop()
     if (loop_->isInLoopThread())
     {
         acceptorPtr_.reset();
-        for (auto connection : connSet_)
+        // copy the connSet_ to a vector, use the vector to close the
+        // connections to avoid the iterator invalidation.
+        std::vector<TcpConnectionPtr> connPtrs;
+        connPtrs.reserve(connSet_.size());
+        for (auto &conn : connSet_)
+        {
+            connPtrs.push_back(conn);
+        }
+        for (auto connection : connPtrs)
         {
             connection->forceClose();
         }
@@ -159,7 +167,13 @@ void TcpServer::stop()
         auto f = pro.get_future();
         loop_->queueInLoop([this, &pro]() {
             acceptorPtr_.reset();
-            for (auto connection : connSet_)
+            std::vector<TcpConnectionPtr> connPtrs;
+            connPtrs.reserve(connSet_.size());
+            for (auto &conn : connSet_)
+            {
+                connPtrs.push_back(conn);
+            }
+            for (auto connection : connPtrs)
             {
                 connection->forceClose();
             }