nghttpx: Add worker-frontend-connections option

src/shrpx.cc

@@ -439,6 +439,7 @@ void fill_default_config()
   mod_config()->http2_no_cookie_crumbling = false;
   mod_config()->upstream_frame_debug = false;
   mod_config()->padding = 0;
+  mod_config()->worker_frontend_connections = 0;
 
   nghttp2_option_new(&mod_config()->http2_option);
 
@@ -539,6 +540,10 @@ Performance:
                      means write burst size is unlimited.
                      Default: )"
       << get_config()->worker_write_burst << R"(
+  --worker-frontend-connections=<NUM>
+                     Set  maximum number  of simultaneous  connections
+                     frontend accepts.  Setting 0 means unlimited.
+                     Default: 0
 
 Timeout:
   --frontend-http2-read-timeout=<SEC>
@@ -844,6 +849,7 @@ int main(int argc, char **argv)
       {"worker-write-burst", required_argument, &flag, 53},
       {"altsvc", required_argument, &flag, 54},
       {"add-response-header", required_argument, &flag, 55},
+      {"worker-frontend-connections", required_argument, &flag, 56},
       {nullptr, 0, nullptr, 0 }
     };
 
@@ -1092,6 +1098,10 @@ int main(int argc, char **argv)
         // --add-response-header
         cmdcfgs.emplace_back(SHRPX_OPT_ADD_RESPONSE_HEADER, optarg);
         break;
+      case 56:
+        // --worker-frontend-connections
+        cmdcfgs.emplace_back(SHRPX_OPT_WORKER_FRONTEND_CONNECTIONS, optarg);
+        break;
       default:
         break;
       }
@@ -1185,6 +1195,11 @@ int main(int argc, char **argv)
     exit(EXIT_FAILURE);
   }
 
+  if(get_config()->worker_frontend_connections == 0) {
+    mod_config()->worker_frontend_connections =
+      std::numeric_limits<size_t>::max();
+  }
+
   if(get_config()->http2_proxy + get_config()->http2_bridge +
      get_config()->client_proxy + get_config()->client > 1) {
     LOG(FATAL) << "--http2-proxy, --http2-bridge, --client-proxy and --client "

src/shrpx_client_handler.cc

@@ -35,6 +35,7 @@
 #include "shrpx_http2_downstream_connection.h"
 #include "shrpx_accesslog.h"
 #include "shrpx_ssl.h"
+#include "shrpx_worker.h"
 #ifdef HAVE_SPDYLAY
 #include "shrpx_spdy_upstream.h"
 #endif // HAVE_SPDYLAY
@@ -219,12 +220,14 @@ void upstream_http1_connhd_readcb(bufferevent *bev, void *arg)
 ClientHandler::ClientHandler(bufferevent *bev,
                              bufferevent_rate_limit_group *rate_limit_group,
                              int fd, SSL *ssl,
-                             const char *ipaddr)
+                             const char *ipaddr,
+                             WorkerStat *worker_stat)
   : ipaddr_(ipaddr),
     bev_(bev),
     http2session_(nullptr),
     ssl_(ssl),
     reneg_shutdown_timerev_(nullptr),
+    worker_stat_(worker_stat),
     left_connhd_len_(NGHTTP2_CLIENT_CONNECTION_PREFACE_LEN),
     fd_(fd),
     should_close_after_write_(false),
@@ -233,6 +236,8 @@ ClientHandler::ClientHandler(bufferevent *bev,
 {
   int rv;
 
+  ++worker_stat->num_connections;
+
   rv = bufferevent_add_to_rate_limit_group(bev_, rate_limit_group);
   if(rv == -1) {
     CLOG(FATAL, this) << "bufferevent_add_to_rate_limit_group() failed";
@@ -260,6 +265,8 @@ ClientHandler::~ClientHandler()
     CLOG(INFO, this) << "Deleting";
   }
 
+  --worker_stat_->num_connections;
+
   if(reneg_shutdown_timerev_) {
     event_free(reneg_shutdown_timerev_);
   }

src/shrpx_client_handler.h

@@ -41,12 +41,14 @@ class Upstream;
 class DownstreamConnection;
 class Http2Session;
 class HttpsUpstream;
+struct WorkerStat;
 
 class ClientHandler {
 public:
   ClientHandler(bufferevent *bev,
                 bufferevent_rate_limit_group *rate_limit_group,
-                int fd, SSL *ssl, const char *ipaddr);
+                int fd, SSL *ssl, const char *ipaddr,
+                WorkerStat *worker_stat);
   ~ClientHandler();
   int on_read();
   int on_event();
@@ -95,6 +97,7 @@ private:
   Http2Session *http2session_;
   SSL *ssl_;
   event *reneg_shutdown_timerev_;
+  WorkerStat *worker_stat_;
   // The number of bytes of HTTP/2 client connection header to read
   size_t left_connhd_len_;
   int fd_;

src/shrpx_config.cc

@@ -118,6 +118,8 @@ const char SHRPX_OPT_FRONTEND_FRAME_DEBUG[] = "frontend-frame-debug";
 const char SHRPX_OPT_PADDING[] = "padding";
 const char SHRPX_OPT_ALTSVC[] = "altsvc";
 const char SHRPX_OPT_ADD_RESPONSE_HEADER[] = "add-response-header";
+const char SHRPX_OPT_WORKER_FRONTEND_CONNECTIONS[] =
+  "worker-frontend-connections";
 
 namespace {
 Config *config = nullptr;
@@ -793,6 +795,21 @@ int parse_config(const char *opt, const char *optarg)
     return 0;
   }
 
+  if(util::strieq(opt, SHRPX_OPT_WORKER_FRONTEND_CONNECTIONS)) {
+    errno = 0;
+    auto n = strtoul(optarg, nullptr, 10);
+
+    if(errno != 0) {
+      LOG(ERROR) << "worker-frontend-connections: invalid argument: "
+                 << optarg;
+      return -1;
+    }
+
+    mod_config()->worker_frontend_connections = n;
+
+    return 0;
+  }
+
   if(util::strieq(opt, "conf")) {
     LOG(WARNING) << "conf is ignored";
 

src/shrpx_config.h

@@ -108,6 +108,7 @@ extern const char SHRPX_OPT_FRONTEND_FRAME_DEBUG[];
 extern const char SHRPX_OPT_PADDING[];
 extern const char SHRPX_OPT_ALTSVC[];
 extern const char SHRPX_OPT_ADD_RESPONSE_HEADER[];
+extern const char SHRPX_OPT_WORKER_FRONTEND_CONNECTIONS[];
 
 union sockaddr_union {
   sockaddr sa;
@@ -212,6 +213,7 @@ struct Config {
   size_t worker_write_rate;
   size_t worker_write_burst;
   size_t padding;
+  size_t worker_frontend_connections;
   // Bit mask to disable SSL/TLS protocol versions.  This will be
   // passed to SSL_CTX_set_options().
   long int tls_proto_mask;

src/shrpx_listen_handler.cc

@@ -38,6 +38,9 @@
 #include "shrpx_worker.h"
 #include "shrpx_config.h"
 #include "shrpx_http2_session.h"
+#include "util.h"
+
+using namespace nghttp2;
 
 namespace shrpx {
 
@@ -50,6 +53,7 @@ ListenHandler::ListenHandler(event_base *evbase, SSL_CTX *sv_ssl_ctx,
     http2session_(nullptr),
     rate_limit_group_(bufferevent_rate_limit_group_new
                       (evbase, get_config()->worker_rate_limit_cfg)),
+    worker_stat_(util::make_unique<WorkerStat>()),
     num_worker_(0),
     worker_round_robin_cnt_(0)
 {}
@@ -110,12 +114,29 @@ int ListenHandler::accept_connection(evutil_socket_t fd,
     LLOG(INFO, this) << "Accepted connection. fd=" << fd;
   }
   if(num_worker_ == 0) {
+
+    if(worker_stat_->num_connections >=
+       get_config()->worker_frontend_connections) {
+
+      if(LOG_ENABLED(INFO)) {
+        TLOG(INFO, this) << "Too many connections >="
+                         << get_config()->worker_frontend_connections;
+      }
+
+      close(fd);
+      return -1;
+    }
+
     auto client = ssl::accept_connection(evbase_, rate_limit_group_,
-                                         sv_ssl_ctx_, fd, addr, addrlen);
+                                         sv_ssl_ctx_, fd, addr, addrlen,
+                                         worker_stat_.get());
     if(!client) {
       LLOG(ERROR, this) << "ClientHandler creation failed";
-      return 0;
+
+      close(fd);
+      return -1;
     }
+
     client->set_http2_session(http2session_);
     return 0;
   }
@@ -129,8 +150,10 @@ int ListenHandler::accept_connection(evutil_socket_t fd,
   auto output = bufferevent_get_output(workers_[idx].bev);
   if(evbuffer_add(output, &wev, sizeof(wev)) != 0) {
     LLOG(FATAL, this) << "evbuffer_add() failed";
+    close(fd);
     return -1;
   }
+
   return 0;
 }
 

src/shrpx_listen_handler.h

@@ -30,6 +30,8 @@
 #include <sys/types.h>
 #include <sys/socket.h>
 
+#include <memory>
+
 #include <openssl/ssl.h>
 
 #include <event.h>
@@ -45,6 +47,7 @@ struct WorkerInfo {
 };
 
 class Http2Session;
+struct WorkerStat;
 
 class ListenHandler {
 public:
@@ -65,6 +68,7 @@ private:
   // multi-threaded case, see shrpx_worker.cc.
   Http2Session *http2session_;
   bufferevent_rate_limit_group *rate_limit_group_;
+  std::unique_ptr<WorkerStat> worker_stat_;
   size_t num_worker_;
   unsigned int worker_round_robin_cnt_;
 };

src/shrpx_ssl.cc

@@ -49,6 +49,7 @@
 #include "shrpx_client_handler.h"
 #include "shrpx_config.h"
 #include "shrpx_accesslog.h"
+#include "shrpx_worker.h"
 #include "util.h"
 
 using namespace nghttp2;
@@ -467,13 +468,19 @@ ClientHandler* accept_connection
  bufferevent_rate_limit_group *rate_limit_group,
  SSL_CTX *ssl_ctx,
  evutil_socket_t fd,
- sockaddr *addr, int addrlen)
+ sockaddr *addr, int addrlen,
+ WorkerStat *worker_stat)
 {
   char host[NI_MAXHOST];
   int rv;
   rv = getnameinfo(addr, addrlen, host, sizeof(host), nullptr, 0,
                    NI_NUMERICHOST);
-  if(rv == 0) {
+  if(rv != 0) {
+    LOG(ERROR) << "getnameinfo() failed: " << gai_strerror(rv);
+
+    return nullptr;
+  }
+
   if(get_config()->accesslog) {
     upstream_connect(host);
   }
@@ -515,11 +522,8 @@ ClientHandler* accept_connection
     }
     return nullptr;
   }
-    return new ClientHandler(bev, rate_limit_group, fd, ssl, host);
-  } else {
-    LOG(ERROR) << "getnameinfo() failed: " << gai_strerror(rv);
-    return nullptr;
-  }
+
+  return new ClientHandler(bev, rate_limit_group, fd, ssl, host, worker_stat);
 }
 
 namespace {

src/shrpx_ssl.h

@@ -37,6 +37,7 @@
 namespace shrpx {
 
 class ClientHandler;
+struct WorkerStat;
 
 namespace ssl {
 
@@ -50,7 +51,8 @@ ClientHandler* accept_connection
  bufferevent_rate_limit_group *rate_limit_group,
  SSL_CTX *ssl_ctx,
  evutil_socket_t fd,
- sockaddr *addr, int addrlen);
+ sockaddr *addr, int addrlen,
+ WorkerStat *worker_stat);
 
 int check_cert(SSL *ssl);
 

src/shrpx_thread_event_receiver.cc

@@ -30,6 +30,10 @@
 #include "shrpx_log.h"
 #include "shrpx_client_handler.h"
 #include "shrpx_http2_session.h"
+#include "shrpx_worker.h"
+#include "util.h"
+
+using namespace nghttp2;
 
 namespace shrpx {
 
@@ -40,7 +44,8 @@ ThreadEventReceiver::ThreadEventReceiver(event_base *evbase,
     ssl_ctx_(ssl_ctx),
     http2session_(http2session),
     rate_limit_group_(bufferevent_rate_limit_group_new
-                      (evbase_, get_config()->worker_rate_limit_cfg))
+                      (evbase_, get_config()->worker_rate_limit_cfg)),
+    worker_stat_(util::make_unique<WorkerStat>())
 {}
 
 ThreadEventReceiver::~ThreadEventReceiver()
@@ -67,12 +72,27 @@ void ThreadEventReceiver::on_read(bufferevent *bev)
       TLOG(INFO, this) << "WorkerEvent: client_fd=" << wev.client_fd
                        << ", addrlen=" << wev.client_addrlen;
     }
+
+    if(worker_stat_->num_connections >=
+       get_config()->worker_frontend_connections) {
+
+      if(LOG_ENABLED(INFO)) {
+        TLOG(INFO, this) << "Too many connections >= "
+                         << get_config()->worker_frontend_connections;
+      }
+
+      close(wev.client_fd);
+
+      continue;
+    }
+
     auto evbase = bufferevent_get_base(bev);
     auto client_handler = ssl::accept_connection(evbase, rate_limit_group_,
                                                  ssl_ctx_,
                                                  wev.client_fd,
                                                  &wev.client_addr.sa,
-                                                 wev.client_addrlen);
+                                                 wev.client_addrlen,
+                                                 worker_stat_.get());
     if(client_handler) {
       client_handler->set_http2_session(http2session_);
 

src/shrpx_thread_event_receiver.h

@@ -27,6 +27,8 @@
 
 #include "shrpx.h"
 
+#include <memory>
+
 #include <openssl/ssl.h>
 
 #include <event2/bufferevent.h>
@@ -36,6 +38,7 @@
 namespace shrpx {
 
 class Http2Session;
+struct WorkerStat;
 
 struct WorkerEvent {
   sockaddr_union client_addr;
@@ -56,6 +59,7 @@ private:
   // mode. Not deleted by this object.
   Http2Session *http2session_;
   bufferevent_rate_limit_group *rate_limit_group_;
+  std::unique_ptr<WorkerStat> worker_stat_;
 };
 
 } // namespace shrpx

src/shrpx_worker.h

@@ -34,6 +34,12 @@
 
 namespace shrpx {
 
+struct WorkerStat {
+  WorkerStat() : num_connections(0) {}
+
+  size_t num_connections;
+};
+
 class Worker {
 public:
   Worker(WorkerInfo *info);