nghttpx: Implement connection blocker for HTTP/1 backend

src/Makefile.am

@@ -113,7 +113,8 @@ NGHTTPX_SRCS = \
 	shrpx_ssl.cc shrpx_ssl.h \
 	shrpx_thread_event_receiver.cc shrpx_thread_event_receiver.h \
 	shrpx_worker.cc shrpx_worker.h \
-	shrpx_worker_config.cc shrpx_worker_config.h
+	shrpx_worker_config.cc shrpx_worker_config.h \
+	shrpx_connect_blocker.cc shrpx_connect_blocker.h
 
 if HAVE_SPDYLAY
 NGHTTPX_SRCS += shrpx_spdy_upstream.cc shrpx_spdy_upstream.h

src/shrpx.cc

@@ -570,6 +570,8 @@ int event_loop()
     listener_handler->create_worker_thread(get_config()->num_worker);
   } else if(get_config()->downstream_proto == PROTO_HTTP2) {
     listener_handler->create_http2_session();
+  } else {
+    listener_handler->create_http1_connect_blocker();
   }
 
 #ifndef NOTHREADS

src/shrpx_client_handler.cc

@@ -526,6 +526,17 @@ Http2Session* ClientHandler::get_http2_session() const
   return http2session_;
 }
 
+void ClientHandler::set_http1_connect_blocker
+(ConnectBlocker *http1_connect_blocker)
+{
+  http1_connect_blocker_ = http1_connect_blocker;
+}
+
+ConnectBlocker* ClientHandler::get_http1_connect_blocker() const
+{
+  return http1_connect_blocker_;
+}
+
 size_t ClientHandler::get_left_connhd_len() const
 {
   return left_connhd_len_;

src/shrpx_client_handler.h

@@ -41,6 +41,7 @@ class Upstream;
 class DownstreamConnection;
 class Http2Session;
 class HttpsUpstream;
+class ConnectBlocker;
 struct WorkerStat;
 
 class ClientHandler {
@@ -71,6 +72,8 @@ public:
   SSL* get_ssl() const;
   void set_http2_session(Http2Session *http2session);
   Http2Session* get_http2_session() const;
+  void set_http1_connect_blocker(ConnectBlocker *http1_connect_blocker);
+  ConnectBlocker* get_http1_connect_blocker() const;
   size_t get_left_connhd_len() const;
   void set_left_connhd_len(size_t left);
   // Call this function when HTTP/2 connection header is received at
@@ -95,6 +98,7 @@ private:
   // Shared HTTP2 session for each thread. NULL if backend is not
   // HTTP2. Not deleted by this object.
   Http2Session *http2session_;
+  ConnectBlocker *http1_connect_blocker_;
   SSL *ssl_;
   event *reneg_shutdown_timerev_;
   WorkerStat *worker_stat_;

src/shrpx_connect_blocker.cc

@@ -0,0 +1,92 @@
+/*
+ * nghttp2 - HTTP/2 C Library
+ *
+ * Copyright (c) 2014 Tatsuhiro Tsujikawa
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining
+ * a copy of this software and associated documentation files (the
+ * "Software"), to deal in the Software without restriction, including
+ * without limitation the rights to use, copy, modify, merge, publish,
+ * distribute, sublicense, and/or sell copies of the Software, and to
+ * permit persons to whom the Software is furnished to do so, subject to
+ * the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
+ * LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
+ * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+ * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+#include "shrpx_connect_blocker.h"
+
+namespace shrpx {
+
+namespace {
+const int INITIAL_SLEEP = 2;
+} // namespace
+
+ConnectBlocker::ConnectBlocker()
+  : timerev_(nullptr),
+    sleep_(INITIAL_SLEEP)
+{}
+
+ConnectBlocker::~ConnectBlocker()
+{
+  if(timerev_) {
+    event_free(timerev_);
+  }
+}
+
+namespace {
+void connect_blocker_cb(evutil_socket_t sig, short events, void *arg)
+{
+  if(LOG_ENABLED(INFO)) {
+    LOG(INFO) << "unblock downstream connection";
+  }
+}
+} // namespace
+
+int ConnectBlocker::init(event_base *evbase)
+{
+  timerev_ = evtimer_new(evbase, connect_blocker_cb, this);
+
+  if(timerev_ == nullptr) {
+    return -1;
+  }
+
+  return 0;
+}
+
+bool ConnectBlocker::blocked() const
+{
+  return evtimer_pending(timerev_, nullptr);
+}
+
+void ConnectBlocker::on_success()
+{
+  sleep_ = INITIAL_SLEEP;
+}
+
+void ConnectBlocker::on_failure()
+{
+  int rv;
+
+  sleep_ = std::min(128, sleep_ * 2);
+
+  LOG(WARNING) << "connect failure, start sleeping " << sleep_;
+
+  timeval t = {sleep_, 0};
+
+  rv = evtimer_add(timerev_, &t);
+
+  if(rv == -1) {
+    LOG(ERROR) << "evtimer_add for ConnectBlocker timerev_ failed";
+  }
+}
+
+} // namespace shrpx

src/shrpx_connect_blocker.h

@@ -0,0 +1,55 @@
+/*
+ * nghttp2 - HTTP/2 C Library
+ *
+ * Copyright (c) 2014 Tatsuhiro Tsujikawa
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining
+ * a copy of this software and associated documentation files (the
+ * "Software"), to deal in the Software without restriction, including
+ * without limitation the rights to use, copy, modify, merge, publish,
+ * distribute, sublicense, and/or sell copies of the Software, and to
+ * permit persons to whom the Software is furnished to do so, subject to
+ * the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
+ * LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
+ * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+ * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+#ifndef SHRPX_CONNECT_BLOCKER_H
+#define SHRPX_CONNECT_BLOCKER_H
+
+#include "shrpx.h"
+
+#include <event2/event.h>
+
+namespace shrpx {
+
+class ConnectBlocker {
+public:
+  ConnectBlocker();
+  ~ConnectBlocker();
+
+  int init(event_base *evbase);
+  // Returns true if making connection is not allowed.
+  bool blocked() const;
+  // Call this function if connect operation succeeded.  This will
+  // reset sleep_ to minimum value.
+  void on_success();
+  // Call this function if connect operation failed.  This will start
+  // timer and blocks connection establishment for sleep_ seconds.
+  void on_failure();
+private:
+  event *timerev_;
+  int sleep_;
+};
+
+} // namespace
+
+#endif // SHRPX_CONNECT_BLOCKER_H

src/shrpx_http_downstream_connection.cc

@@ -31,6 +31,7 @@
 #include "shrpx_error.h"
 #include "shrpx_http.h"
 #include "shrpx_worker_config.h"
+#include "shrpx_connect_blocker.h"
 #include "http2.h"
 #include "util.h"
 
@@ -76,12 +77,20 @@ int HttpDownstreamConnection::attach_downstream(Downstream *downstream)
   }
   auto upstream = downstream->get_upstream();
   if(!bev_) {
+    auto connect_blocker = client_handler_->get_http1_connect_blocker();
+
+    if(connect_blocker->blocked()) {
+      return -1;
+    }
+
     auto evbase = client_handler_->get_evbase();
 
     auto fd = socket(get_config()->downstream_addr.storage.ss_family,
                      SOCK_STREAM | SOCK_CLOEXEC, 0);
 
     if(fd == -1) {
+      connect_blocker->on_failure();
+
       return SHRPX_ERR_NETWORK;
     }
 
@@ -89,6 +98,8 @@ int HttpDownstreamConnection::attach_downstream(Downstream *downstream)
       (evbase, fd,
        BEV_OPT_CLOSE_ON_FREE | BEV_OPT_DEFER_CALLBACKS);
     if(!bev_) {
+      connect_blocker->on_failure();
+
       DCLOG(INFO, this) << "bufferevent_socket_new() failed";
       close(fd);
 
@@ -100,10 +111,15 @@ int HttpDownstreamConnection::attach_downstream(Downstream *downstream)
        const_cast<sockaddr*>(&get_config()->downstream_addr.sa),
        get_config()->downstream_addrlen);
     if(rv != 0) {
+      connect_blocker->on_failure();
+
       bufferevent_free(bev_);
       bev_ = nullptr;
       return SHRPX_ERR_NETWORK;
     }
+
+    connect_blocker->on_success();
+
     if(LOG_ENABLED(INFO)) {
       DCLOG(INFO, this) << "Connecting to downstream server";
     }

src/shrpx_listen_handler.cc

@@ -38,6 +38,7 @@
 #include "shrpx_worker_config.h"
 #include "shrpx_config.h"
 #include "shrpx_http2_session.h"
+#include "shrpx_connect_blocker.h"
 #include "util.h"
 
 using namespace nghttp2;
@@ -220,6 +221,8 @@ int ListenHandler::accept_connection(evutil_socket_t fd,
     }
 
     client->set_http2_session(http2session_.get());
+    client->set_http1_connect_blocker(http1_connect_blocker_.get());
+
     return 0;
   }
   size_t idx = worker_round_robin_cnt_ % workers_.size();
@@ -253,6 +256,20 @@ int ListenHandler::create_http2_session()
   return rv;
 }
 
+int ListenHandler::create_http1_connect_blocker()
+{
+  int rv;
+  http1_connect_blocker_ = util::make_unique<ConnectBlocker>();
+
+  rv = http1_connect_blocker_->init(evbase_);
+
+  if(rv != 0) {
+    return -1;
+  }
+
+  return 0;
+}
+
 const WorkerStat* ListenHandler::get_worker_stat() const
 {
   return worker_stat_.get();

src/shrpx_listen_handler.h

@@ -55,6 +55,7 @@ struct WorkerInfo {
 };
 
 class Http2Session;
+class ConnectBlocker;
 struct WorkerStat;
 
 class ListenHandler {
@@ -66,6 +67,7 @@ public:
   void worker_reopen_log_files();
   event_base* get_evbase() const;
   int create_http2_session();
+  int create_http1_connect_blocker();
   const WorkerStat* get_worker_stat() const;
   void set_evlistener4(evconnlistener *evlistener4);
   evconnlistener* get_evlistener4() const;
@@ -86,6 +88,7 @@ private:
   // Shared backend HTTP2 session. NULL if multi-threaded. In
   // multi-threaded case, see shrpx_worker.cc.
   std::unique_ptr<Http2Session> http2session_;
+  std::unique_ptr<ConnectBlocker> http1_connect_blocker_;
   bufferevent_rate_limit_group *rate_limit_group_;
   evconnlistener *evlistener4_;
   evconnlistener *evlistener6_;

src/shrpx_thread_event_receiver.cc

@@ -40,10 +40,12 @@ namespace shrpx {
 
 ThreadEventReceiver::ThreadEventReceiver(event_base *evbase,
                                          SSL_CTX *ssl_ctx,
-                                         Http2Session *http2session)
+                                         Http2Session *http2session,
+                                         ConnectBlocker *http1_connect_blocker)
   : evbase_(evbase),
     ssl_ctx_(ssl_ctx),
     http2session_(http2session),
+    http1_connect_blocker_(http1_connect_blocker),
     rate_limit_group_(bufferevent_rate_limit_group_new
                       (evbase_, get_config()->worker_rate_limit_cfg)),
     worker_stat_(util::make_unique<WorkerStat>())
@@ -124,6 +126,7 @@ void ThreadEventReceiver::on_read(bufferevent *bev)
                                                  worker_stat_.get());
     if(client_handler) {
       client_handler->set_http2_session(http2session_);
+      client_handler->set_http1_connect_blocker(http1_connect_blocker_);
 
       if(LOG_ENABLED(INFO)) {
         TLOG(INFO, this) << "CLIENT_HANDLER:" << client_handler << " created";

src/shrpx_thread_event_receiver.h

@@ -38,6 +38,7 @@
 namespace shrpx {
 
 class Http2Session;
+class ConnectBlocker;
 struct WorkerStat;
 
 enum WorkerEventType {
@@ -60,7 +61,8 @@ struct WorkerEvent {
 class ThreadEventReceiver {
 public:
   ThreadEventReceiver(event_base *evbase, SSL_CTX *ssl_ctx,
-                      Http2Session *http2session);
+                      Http2Session *http2session,
+                      ConnectBlocker *http1_connect_blocker);
   ~ThreadEventReceiver();
   void on_read(bufferevent *bev);
 private:
@@ -69,6 +71,7 @@ private:
   // Shared HTTP2 session for each thread. NULL if not client
   // mode. Not deleted by this object.
   Http2Session *http2session_;
+  ConnectBlocker *http1_connect_blocker_;
   bufferevent_rate_limit_group *rate_limit_group_;
   std::unique_ptr<WorkerStat> worker_stat_;
 };

src/shrpx_worker.cc

@@ -37,6 +37,7 @@
 #include "shrpx_log.h"
 #include "shrpx_http2_session.h"
 #include "shrpx_worker_config.h"
+#include "shrpx_connect_blocker.h"
 #include "util.h"
 
 using namespace nghttp2;
@@ -93,15 +94,25 @@ void Worker::run()
     return;
   }
   std::unique_ptr<Http2Session> http2session;
+  std::unique_ptr<ConnectBlocker> http1_connect_blocker;
   if(get_config()->downstream_proto == PROTO_HTTP2) {
     http2session = util::make_unique<Http2Session>(evbase.get(), cl_ssl_ctx_);
     if(http2session->init_notification() == -1) {
       DIE();
     }
+  } else {
+    http1_connect_blocker = util::make_unique<ConnectBlocker>();
+    if(http1_connect_blocker->init(evbase.get()) == -1) {
+      DIE();
     }
-  auto receiver = util::make_unique<ThreadEventReceiver>(evbase.get(),
+  }
+
+  auto receiver = util::make_unique<ThreadEventReceiver>
+    (evbase.get(),
      sv_ssl_ctx_,
-                                                         http2session.get());
+     http2session.get(),
+     http1_connect_blocker.get());
+
   bufferevent_enable(bev.get(), EV_READ);
   bufferevent_setcb(bev.get(), readcb, nullptr, eventcb, receiver.get());