nghttpx: Enable kqueue by default

We enabled libev kqueue backend in nghttpx by default.  Since it might
not work on some platforms, we also added --no-kqueue option to
disable it.

gennghttpxfun.py

@@ -129,6 +129,7 @@ OPTIONS = [
     "backend-tls",
     "backend-connections-per-host",
     "error-page",
+    "no-kqueue",
 ]
 
 LOGVARS = [

src/shrpx.cc

@@ -969,7 +969,7 @@ int event_loop() {
     return -1;
   }
 
-  auto loop = EV_DEFAULT;
+  auto loop = ev_default_loop(get_config()->ev_loop_flags);
 
   auto pid = fork_worker_process(&ssv);
 
@@ -1042,6 +1042,10 @@ void fill_default_config() {
   mod_config()->conf_path = "/etc/nghttpx/nghttpx.conf";
   mod_config()->pid = getpid();
 
+  if (ev_supported_backends() & ~ev_recommended_backends() & EVBACKEND_KQUEUE) {
+    mod_config()->ev_loop_flags = ev_recommended_backends() | EVBACKEND_KQUEUE;
+  }
+
   auto &tlsconf = mod_config()->tls;
   {
     auto &ticketconf = tlsconf.ticket;
@@ -1439,6 +1443,10 @@ Performance:
               that have not yet completed the three-way handshake.  If
               value is 0 then fast open is disabled.
               Default: )" << get_config()->conn.listener.fastopen << R"(
+  --no-kqueue Don't use  kqueue.  This  option is only  applicable for
+              the platforms  which have kqueue.  For  other platforms,
+              this option will be simply ignored.
+
 Timeout:
   --frontend-http2-read-timeout=<DURATION>
               Specify  read  timeout  for  HTTP/2  and  SPDY  frontend
@@ -2560,6 +2568,7 @@ int main(int argc, char **argv) {
         {SHRPX_OPT_BACKEND_CONNECTIONS_PER_HOST.c_str(), required_argument,
          &flag, 121},
         {SHRPX_OPT_ERROR_PAGE.c_str(), required_argument, &flag, 122},
+        {SHRPX_OPT_NO_KQUEUE.c_str(), no_argument, &flag, 123},
         {nullptr, 0, nullptr, 0}};
 
     int option_index = 0;
@@ -3135,6 +3144,10 @@ int main(int argc, char **argv) {
         // --error-page
         cmdcfgs.emplace_back(SHRPX_OPT_ERROR_PAGE, StringRef{optarg});
         break;
+      case 123:
+        // --no-kqueue
+        cmdcfgs.emplace_back(SHRPX_OPT_NO_KQUEUE, StringRef::from_lit("yes"));
+        break;
       default:
         break;
       }

src/shrpx_config.cc

@@ -993,6 +993,7 @@ enum {
   SHRPX_OPTID_MRUBY_FILE,
   SHRPX_OPTID_NO_HOST_REWRITE,
   SHRPX_OPTID_NO_HTTP2_CIPHER_BLACK_LIST,
+  SHRPX_OPTID_NO_KQUEUE,
   SHRPX_OPTID_NO_LOCATION_REWRITE,
   SHRPX_OPTID_NO_OCSP,
   SHRPX_OPTID_NO_SERVER_PUSH,
@@ -1161,6 +1162,9 @@ int option_lookup_token(const char *name, size_t namelen) {
   case 9:
     switch (name[8]) {
     case 'e':
+      if (util::strieq_l("no-kqueu", name, 8)) {
+        return SHRPX_OPTID_NO_KQUEUE;
+      }
       if (util::strieq_l("read-rat", name, 8)) {
         return SHRPX_OPTID_READ_RATE;
       }
@@ -2712,6 +2716,15 @@ int parse_config(const StringRef &opt, const StringRef &optarg,
                       opt, optarg);
   case SHRPX_OPTID_ERROR_PAGE:
     return parse_error_page(mod_config()->http.error_pages, opt, optarg);
+  case SHRPX_OPTID_NO_KQUEUE:
+    if ((ev_supported_backends() & EVBACKEND_KQUEUE) == 0) {
+      LOG(WARN) << opt << ": kqueue is not supported on this platform";
+      return 0;
+    }
+
+    mod_config()->ev_loop_flags = ev_recommended_backends() & ~EVBACKEND_KQUEUE;
+
+    return 0;
   case SHRPX_OPTID_CONF:
     LOG(WARN) << "conf: ignored";
 

src/shrpx_config.h

@@ -275,6 +275,7 @@ constexpr auto SHRPX_OPT_BACKEND_TLS = StringRef::from_lit("backend-tls");
 constexpr auto SHRPX_OPT_BACKEND_CONNECTIONS_PER_HOST =
     StringRef::from_lit("backend-connections-per-host");
 constexpr auto SHRPX_OPT_ERROR_PAGE = StringRef::from_lit("error-page");
+constexpr auto SHRPX_OPT_NO_KQUEUE = StringRef::from_lit("no-kqueue");
 
 constexpr size_t SHRPX_OBFUSCATED_NODE_LENGTH = 8;
 
@@ -652,6 +653,8 @@ struct Config {
   bool verbose;
   bool daemon;
   bool http2_proxy;
+  // flags passed to ev_default_loop() and ev_loop_new()
+  int ev_loop_flags;
 };
 
 const Config *get_config();

src/shrpx_connection_handler.cc

@@ -244,7 +244,7 @@ int ConnectionHandler::create_worker_thread(size_t num) {
   auto &memcachedconf = get_config()->tls.session_cache.memcached;
 
   for (size_t i = 0; i < num; ++i) {
-    auto loop = ev_loop_new(0);
+    auto loop = ev_loop_new(get_config()->ev_loop_flags);
 
     SSL_CTX *session_cache_ssl_ctx = nullptr;
     if (memcachedconf.tls) {