Adds an tcp echo server from libuv.

Makefile.am

@@ -46,8 +46,8 @@ if HAVE_CXX20
 test_high_level_SOURCES = $(top_srcdir)/tests/high_level.cpp
 chat_room_SOURCES = $(top_srcdir)/examples/chat_room.cpp
 echo_server_SOURCES = $(top_srcdir)/examples/echo_server.cpp
-echo_server_direct_SOURCES = $(top_srcdir)/benchmarks/cpp/echo_server_direct.cpp
-echo_server_client_SOURCES = $(top_srcdir)/benchmarks/cpp/echo_server_client.cpp
+echo_server_direct_SOURCES = $(top_srcdir)/benchmarks/cpp/asio/echo_server_direct.cpp
+echo_server_client_SOURCES = $(top_srcdir)/benchmarks/cpp/asio/echo_server_client.cpp
 endif
 
 nobase_include_HEADERS =\

benchmarks/cpp/asio/echo_server_direct.cpp

@@ -29,7 +29,7 @@ awaitable<void> echo(tcp::socket socket)
         co_await async_write(socket, net::buffer(data, n), use_awaitable);
      }
   } catch (std::exception const& e) {
-     std::printf("echo Exception: %s\n", e.what());
+     //std::printf("echo Exception: %s\n", e.what());
   }
 }
 
@@ -49,7 +49,7 @@ int main()
      net::io_context io_context(1);
      co_spawn(io_context, listener(), detached);
      io_context.run();
-  } catch (std::exception& e) {
+  } catch (std::exception const& e) {
      std::printf("Exception: %s\n", e.what());
   }
 }

benchmarks/cpp/libuv/README.md

@@ -0,0 +1,7 @@
+This example was taken from
+
+   https://github.com/libuv/libuv/tree/v1.x/docs/code/tcp-echo-server
+
+To build it run, for example
+
+   $ gcc echo_server_direct.c -luv -O2 -o echo_server_direct

benchmarks/cpp/libuv/echo_server_direct.c

@@ -0,0 +1,87 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <uv.h>
+
+#define DEFAULT_PORT 55555
+#define DEFAULT_BACKLOG 128
+
+uv_loop_t *loop;
+struct sockaddr_in addr;
+
+typedef struct {
+    uv_write_t req;
+    uv_buf_t buf;
+} write_req_t;
+
+void free_write_req(uv_write_t *req) {
+    write_req_t *wr = (write_req_t*) req;
+    free(wr->buf.base);
+    free(wr);
+}
+
+void alloc_buffer(uv_handle_t *handle, size_t suggested_size, uv_buf_t *buf) {
+    buf->base = (char*) malloc(suggested_size);
+    buf->len = suggested_size;
+}
+
+void on_close(uv_handle_t* handle) {
+    free(handle);
+}
+
+void echo_write(uv_write_t *req, int status) {
+    if (status) {
+        fprintf(stderr, "Write error %s\n", uv_strerror(status));
+    }
+    free_write_req(req);
+}
+
+void echo_read(uv_stream_t *client, ssize_t nread, const uv_buf_t *buf) {
+    if (nread > 0) {
+        write_req_t *req = (write_req_t*) malloc(sizeof(write_req_t));
+        req->buf = uv_buf_init(buf->base, nread);
+        uv_write((uv_write_t*) req, client, &req->buf, 1, echo_write);
+        return;
+    }
+    if (nread < 0) {
+        if (nread != UV_EOF)
+            fprintf(stderr, "Read error %s\n", uv_err_name(nread));
+        uv_close((uv_handle_t*) client, on_close);
+    }
+
+    free(buf->base);
+}
+
+void on_new_connection(uv_stream_t *server, int status) {
+    if (status < 0) {
+        fprintf(stderr, "New connection error %s\n", uv_strerror(status));
+        // error!
+        return;
+    }
+
+    uv_tcp_t *client = (uv_tcp_t*) malloc(sizeof(uv_tcp_t));
+    uv_tcp_init(loop, client);
+    if (uv_accept(server, (uv_stream_t*) client) == 0) {
+        uv_read_start((uv_stream_t*) client, alloc_buffer, echo_read);
+    }
+    else {
+        uv_close((uv_handle_t*) client, on_close);
+    }
+}
+
+int main() {
+    loop = uv_default_loop();
+
+    uv_tcp_t server;
+    uv_tcp_init(loop, &server);
+
+    uv_ip4_addr("0.0.0.0", DEFAULT_PORT, &addr);
+
+    uv_tcp_bind(&server, (const struct sockaddr*)&addr, 0);
+    int r = uv_listen((uv_stream_t*) &server, DEFAULT_BACKLOG, on_new_connection);
+    if (r) {
+        fprintf(stderr, "Listen error %s\n", uv_strerror(r));
+        return 1;
+    }
+    return uv_run(loop, UV_RUN_DEFAULT);
+}