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#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(cpu_count, sizeof(struct child_worker));
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);
}
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