[Network/TcpServer] Made the TCP server run asynchronously

- Starting a server isn't blocking anymore and doesn't require an explicit thread to run asynchronously

Author: Razakhel

examples/networkDemo.cpp

@@ -7,11 +7,7 @@ int main() {
     Raz::Logger::setLoggingLevel(Raz::LoggingLevel::ALL);
 
     Raz::TcpServer server;
-    // The server runs synchronously; starting it in a separate thread to avoid blocking the main one
-    std::thread([&server] () {
-      Raz::Threading::setCurrentThreadName("Server thread");
-      server.start(1234);
-    }).detach();
+    server.start(1234);
 
     Raz::TcpClient client("localhost", 1234);
 

include/RaZ/Network/TcpServer.hpp

@@ -14,7 +14,6 @@ class TcpServer {
   TcpServer(TcpServer&&) noexcept = default;
 
   /// Starts the server and listens for connections.
-  /// \note This operation is blocking; call the function from another thread if needed.
   /// \param port Port to listen for connections on.
   void start(unsigned short port);
   /// Stops the server.

src/RaZ/Network/TcpServer.cpp

@@ -1,5 +1,6 @@
 #include "RaZ/Network/TcpServer.hpp"
 #include "RaZ/Utils/Logger.hpp"
+#include "RaZ/Utils/Threading.hpp"
 
 #include "asio/ip/tcp.hpp"
 #include "asio/write.hpp"
@@ -56,23 +57,32 @@ struct TcpServer::Impl {
 
   asio::io_context context;
   asio::ip::tcp::acceptor acceptor;
+  std::thread contextThread;
 };
 
 TcpServer::TcpServer() : m_impl{ std::make_unique<Impl>() } {}
 
 void TcpServer::start(unsigned short port) {
   Logger::debug("[TcpServer] Starting on port {}...", port);
 
+  stop();
   setup(port);
   accept();
 
-  m_impl->context.run();
+  m_impl->contextThread = std::thread([this] () {
+    Threading::setCurrentThreadName("TCP server");
+    m_impl->context.run();
+  });
 }
 
 void TcpServer::stop() {
   Logger::debug("[TcpServer] Stopping...");
+
   m_impl->acceptor.close();
   m_impl->context.stop();
+  if (m_impl->contextThread.joinable())
+    m_impl->contextThread.join();
+
   Logger::debug("[TcpServer] Stopped");
 }
 

tests/src/RaZ/Network/TcpClient.cpp

@@ -26,7 +26,7 @@ TEST_CASE("TcpClient connection", "[network]") {
 
   CHECK_THROWS(client.connect("localhost", 1234)); // No server to connect to
 
-  std::thread serverThread([&server] () { server.start(1234); });
+  server.start(1234);
 
   CHECK_NOTHROW(client.connect("localhost", 1234));
   CHECK(client.isConnected());
@@ -35,12 +35,11 @@ TEST_CASE("TcpClient connection", "[network]") {
   CHECK_FALSE(client.isConnected());
 
   CHECK_NOTHROW(server.stop());
-  CHECK_NOTHROW(serverThread.join());
 }
 
 TEST_CASE("TcpClient send and receive", "[network]") {
   Raz::TcpServer server;
-  std::thread serverThread([&server] () { server.start(1234); });
+  server.start(1234);
 
   Raz::TcpClient client("localhost", 1234);
   REQUIRE(client.isConnected());
@@ -55,12 +54,11 @@ TEST_CASE("TcpClient send and receive", "[network]") {
 
   client.disconnect();
   server.stop();
-  serverThread.join();
 }
 
 TEST_CASE("TcpClient receive at least", "[network]") {
   Raz::TcpServer server;
-  std::thread serverThread([&server] () { server.start(1234); });
+  server.start(1234);
 
   Raz::TcpClient client("localhost", 1234);
   REQUIRE(client.isConnected());
@@ -74,12 +72,11 @@ TEST_CASE("TcpClient receive at least", "[network]") {
 
   client.disconnect();
   server.stop();
-  serverThread.join();
 }
 
 TEST_CASE("TcpClient receive exactly", "[network]") {
   Raz::TcpServer server;
-  std::thread serverThread([&server] () { server.start(1234); });
+  server.start(1234);
 
   Raz::TcpClient client("localhost", 1234);
   REQUIRE(client.isConnected());
@@ -90,12 +87,11 @@ TEST_CASE("TcpClient receive exactly", "[network]") {
 
   client.disconnect();
   server.stop();
-  serverThread.join();
 }
 
 TEST_CASE("TcpClient receive until delimiter", "[network]") {
   Raz::TcpServer server;
-  std::thread serverThread([&server] () { server.start(1234); });
+  server.start(1234);
 
   Raz::TcpClient client("localhost", 1234);
   REQUIRE(client.isConnected());
@@ -106,5 +102,4 @@ TEST_CASE("TcpClient receive until delimiter", "[network]") {
 
   client.disconnect();
   server.stop();
-  serverThread.join();
 }

tests/src/RaZ/Network/TcpServer.cpp

@@ -9,9 +9,9 @@ TEST_CASE("TcpServer basic", "[network]") {
 
   CHECK_NOTHROW(server.stop()); // Stopping a non-running server isn't an error
 
-  std::thread serverThread([&server] () { server.start(1234); });
-  std::this_thread::sleep_for(std::chrono::milliseconds(100)); // Waiting for the server to start
+  CHECK_NOTHROW(server.start(1234));
+  CHECK_NOTHROW(server.start(1234)); // Starting an already running server restarts it properly
 
-  server.stop();
-  serverThread.join();
+  CHECK_NOTHROW(server.stop());
+  CHECK_NOTHROW(server.stop()); // Stopping an already stopped server does nothing
 }