1 files changed, 114 insertions, 0 deletions
diff --git a/docs/code/multi-echo-server/main.c b/docs/code/multi-echo-server/main.c
new file mode 100644
index 00000000..25f49612
--- /dev/null
+++ b/docs/code/multi-echo-server/main.c
@@ -0,0 +1,114 @@
+#include <inttypes.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <uv.h>
+
+uv_loop_t *loop;
+
+struct child_worker {
+    uv_process_t req;
+    uv_process_options_t options;
+    uv_pipe_t pipe;
+} *workers;
+
+int round_robin_counter;
+int child_worker_count;
+
+uv_buf_t dummy_buf;
+char worker_path[500];
+
+void close_process_handle(uv_process_t *req, int64_t exit_status, int term_signal) {
+    fprintf(stderr, "Process exited with status %" PRId64 ", signal %d\n", exit_status, term_signal);
+    uv_close((uv_handle_t*) req, NULL);
+}
+
+void alloc_buffer(uv_handle_t *handle, size_t suggested_size, uv_buf_t *buf) {
+  buf->base = malloc(suggested_size);
+  buf->len = suggested_size;
+}
+
+void on_new_connection(uv_stream_t *server, int status) {
+    if (status == -1) {
+        // 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_write_t *write_req = (uv_write_t*) malloc(sizeof(uv_write_t));
+        dummy_buf = uv_buf_init("a", 1);
+        struct child_worker *worker = &workers[round_robin_counter];
+        uv_write2(write_req, (uv_stream_t*) &worker->pipe, &dummy_buf, 1, (uv_stream_t*) client, NULL);
+        round_robin_counter = (round_robin_counter + 1) % child_worker_count;
+    }
+    else {
+        uv_close((uv_handle_t*) client, NULL);
+    }
+}
+
+void setup_workers() {
+    size_t path_size = 500;
+    uv_exepath(worker_path, &path_size);
+    strcpy(worker_path + (strlen(worker_path) - strlen("multi-echo-server")), "worker");
+    fprintf(stderr, "Worker path: %s\n", worker_path);
+
+    char* args[2];
+    args[0] = worker_path;
+    args[1] = NULL;
+
+    round_robin_counter = 0;
+
+    // ...
+
+    // launch same number of workers as number of CPUs
+    uv_cpu_info_t *info;
+    int cpu_count;
+    uv_cpu_info(&info, &cpu_count);
+    uv_free_cpu_info(info, cpu_count);
+
+    child_worker_count = cpu_count;
+
+    workers = calloc(sizeof(struct child_worker), cpu_count);
+    while (cpu_count--) {
+        struct child_worker *worker = &workers[cpu_count];
+        uv_pipe_init(loop, &worker->pipe, 1);
+
+        uv_stdio_container_t child_stdio[3];
+        child_stdio[0].flags = UV_CREATE_PIPE | UV_READABLE_PIPE;
+        child_stdio[0].data.stream = (uv_stream_t*) &worker->pipe;
+        child_stdio[1].flags = UV_IGNORE;
+        child_stdio[2].flags = UV_INHERIT_FD;
+        child_stdio[2].data.fd = 2;
+
+        worker->options.stdio = child_stdio;
+        worker->options.stdio_count = 3;
+
+        worker->options.exit_cb = close_process_handle;
+        worker->options.file = args[0];
+        worker->options.args = args;
+
+        uv_spawn(loop, &worker->req, &worker->options); 
+        fprintf(stderr, "Started worker %d\n", worker->req.pid);
+    }
+}
+
+int main() {
+    loop = uv_default_loop();
+
+    setup_workers();
+
+    uv_tcp_t server;
+    uv_tcp_init(loop, &server);
+
+    struct sockaddr_in bind_addr;
+    uv_ip4_addr("0.0.0.0", 7000, &bind_addr);
+    uv_tcp_bind(&server, (const struct sockaddr *)&bind_addr, 0);
+    int r;
+    if ((r = uv_listen((uv_stream_t*) &server, 128, on_new_connection))) {
+        fprintf(stderr, "Listen error %s\n", uv_err_name(r));
+        return 2;
+    }
+    return uv_run(loop, UV_RUN_DEFAULT);
+}