Support graceful shutdown on both HTTP/1.1 and HTTP/2

For HTTP/1.1, add Connection: close header
For HTTP/2, send GOAWAY frames

Author: maskit

iocore/net/I_NetProcessor.h

@@ -152,6 +152,7 @@ class NetProcessor : public Processor
 
   */
   virtual Action *main_accept(Continuation *cont, SOCKET listen_socket_in, AcceptOptions const &opt = DEFAULT_ACCEPT_OPTIONS);
+  virtual void stop_accept();
 
   /**
     Open a NetVConnection for connection oriented I/O. Connects

iocore/net/P_NetAccept.h

@@ -98,6 +98,7 @@ struct NetAccept : public Continuation {
   void init_accept_loop(const char *);
   virtual void init_accept(EThread *t = nullptr);
   virtual void init_accept_per_thread();
+  virtual void stop_accept();
   virtual NetAccept *clone() const;
 
   // 0 == success

iocore/net/UnixNetAccept.cc

@@ -197,6 +197,15 @@ NetAccept::init_accept_per_thread()
   }
 }
 
+void
+NetAccept::stop_accept()
+{
+  if (!action_->cancelled) {
+    action_->cancel();
+  }
+  server.close();
+}
+
 int
 NetAccept::do_listen(bool non_blocking)
 {

iocore/net/UnixNetProcessor.cc

@@ -196,6 +196,14 @@ UnixNetProcessor::accept_internal(Continuation *cont, int fd, AcceptOptions cons
   return na->action_.get();
 }
 
+void
+NetProcessor::stop_accept()
+{
+  for (auto na = naVec.begin(); na != naVec.end(); ++na) {
+    (*na)->stop_accept();
+  }
+}
+
 Action *
 UnixNetProcessor::connect_re_internal(Continuation *cont, sockaddr const *target, NetVCOptions *opt)
 {

proxy/Main.cc

@@ -75,6 +75,7 @@ extern "C" int plock(int);
 #include "ProxyConfig.h"
 #include "HttpProxyServerMain.h"
 #include "HttpBodyFactory.h"
+#include "ProxyClientSession.h"
 #include "logging/Log.h"
 #include "CacheControl.h"
 #include "IPAllow.h"
@@ -276,7 +277,8 @@ class SignalContinuation : public Continuation
       REC_ReadConfigInteger(timeout, "proxy.config.stop.shutdown_timeout");
 
       if (timeout) {
-        http2_drain = true;
+        http_client_session_draining = true;
+        stop_HttpProxyServer();
       }
 
       Debug("server", "received SIGTERM, shutting down in %" PRId64 "secs", timeout);

proxy/ProxyClientSession.cc

@@ -25,6 +25,8 @@
 #include "HttpDebugNames.h"
 #include "ProxyClientSession.h"
 
+volatile bool http_client_session_draining = false;
+
 static int64_t next_cs_id = 0;
 
 ProxyClientSession::ProxyClientSession() : VConnection(nullptr)

proxy/ProxyClientSession.h

@@ -30,6 +30,8 @@
 #include "InkAPIInternal.h"
 #include "http/HttpServerSession.h"
 
+extern volatile bool http_client_session_draining;
+
 // Emit a debug message conditional on whether this particular client session
 // has debugging enabled. This should only be called from within a client session
 // member function.
@@ -119,6 +121,12 @@ class ProxyClientSession : public VConnection
     return m_active;
   }
 
+  bool
+  is_draining() const
+  {
+    return http_client_session_draining;
+  }
+
   // Initiate an API hook invocation.
   void do_api_callout(TSHttpHookID id);
 

proxy/http/HttpProxyServerMain.cc

@@ -321,3 +321,10 @@ start_HttpProxyServerBackDoor(int port, int accept_threads)
   // The backdoor only binds the loopback interface
   netProcessor.main_accept(new HttpSessionAccept(ha_opt), NO_FD, opt);
 }
+
+void
+stop_HttpProxyServer()
+{
+  sslNetProcessor.stop_accept();
+  netProcessor.stop_accept();
+}

proxy/http/HttpProxyServerMain.h

@@ -32,6 +32,8 @@ void init_HttpProxyServer(int n_accept_threads = 0);
 */
 void start_HttpProxyServer();
 
+void stop_HttpProxyServer();
+
 void start_HttpProxyServerBackDoor(int port, int accept_threads = 0);
 
 NetProcessor::AcceptOptions make_net_accept_options(const HttpProxyPort *port, unsigned nthreads);

proxy/http/HttpTransact.cc

@@ -7822,6 +7822,10 @@ HttpTransact::build_response(State *s, HTTPHdr *base_response, HTTPHdr *outgoing
 
   HttpTransactHeaders::add_server_header_to_response(s->txn_conf, outgoing_response);
 
+  if (s->state_machine->ua_session && s->state_machine->ua_session->get_parent()->is_draining()) {
+    HttpTransactHeaders::add_connection_close(outgoing_response);
+  }
+
   // auth-response update
   // if (!s->state_machine->authAdapter.disabled()) {
   //  s->state_machine->authAdapter.UpdateResponseHeaders(outgoing_response);