Make TCP socket options configurable (TCP_NODELAY etc)

[t-cadet]

Hello, is it possible to add a way to configure TCP options on sockets?

My use case is to enable TCP_NODELAY and potentially other options like TCP_QUICKACK etc for performance reasons.

For now I patched the code in http_server.h:

diff --git a/include/crow/http_server.h b/include/crow/http_server.h
index d171632..4b3e06c 100644
--- a/include/crow/http_server.h
+++ b/include/crow/http_server.h
@@ -27,6 +27,19 @@
 #include "crow/logging.h"
 #include "crow/task_timer.h"

+#if defined(__linux__)
+#include <sys/socket.h>
+#include <netinet/tcp.h>
+
+namespace crow
+{
+    inline void set_tcp_option(asio::ip::tcp::socket& sock, int optname) {
+        int flag = 1;
+        ::setsockopt(sock.native_handle(), IPPROTO_TCP, optname, &flag, sizeof(flag));
+    }
+}
+#endif
+

 namespace crow // NOTE: Already documented in "crow/app.h"
 {
@@ -245,6 +258,10 @@ namespace crow // NOTE: Already documented in "crow/app.h"
                   [this, p, &is, service_idx](error_code ec) {
                       if (!ec)
                       {
+                          #if defined(__linux__)
+                            set_tcp_option(p->socket(), TCP_NODELAY);
+                            // set_tcp_option(p->socket(), TCP_QUICKACK);
+                          #endif
                           is.post(
                             [p] {
                                 p->start();