Improve client shutdown robustness

networktransport.hpp

@@ -55,6 +55,7 @@ namespace Network {
     void start_shutdown( void ) { sender.start_shutdown(); }
     bool shutdown_in_progress( void ) { return sender.get_shutdown_in_progress(); }
     bool shutdown_acknowledged( void ) { return sender.get_shutdown_acknowledged(); }
+    bool shutdown_ack_timed_out( void ) { return sender.shutdown_ack_timed_out(); }
     bool attached( void ) { return connection.get_attached(); }
 
     /* Other side has requested shutdown and we have sent one ACK */

stmclient.cpp

@@ -227,7 +227,16 @@ void STMClient::main( void )
 
       if ( pollfds[ 3 ].revents & POLLIN ) {
 	/* shutdown signal */
-	if ( network->attached() ) {
+	struct signalfd_siginfo the_siginfo;
+	ssize_t bytes_read = read( pollfds[ 3 ].fd, &the_siginfo, sizeof( the_siginfo ) );
+	if ( bytes_read == 0 ) {
+	  break;
+	} else if ( bytes_read < 0 ) {
+	  perror( "read" );
+	  break;
+	}
+
+	if ( network->attached() && (!network->shutdown_in_progress()) ) {
 	  network->start_shutdown();
 	} else {
 	  break;
@@ -243,7 +252,11 @@ void STMClient::main( void )
       if ( (pollfds[ 1 ].revents)
 	   & (POLLERR | POLLHUP | POLLNVAL) ) {
 	/* user problem */
+	if ( network->attached() && (!network->shutdown_in_progress()) ) {
 	  network->start_shutdown();
+	} else {
+	  break;
+	}
       }
 
       /* quit if our shutdown has been acknowledged */
@@ -251,6 +264,11 @@ void STMClient::main( void )
 	break;
       }
 
+      /* quit after shutdown acknowledgement timeout */
+      if ( network->shutdown_in_progress() && network->shutdown_ack_timed_out() ) {
+	break;
+      }
+
       /* quit if we received and acknowledged a shutdown request */
       if ( network->counterparty_shutdown_ack_sent() ) {
 	break;

transportsender.cpp

@@ -14,6 +14,7 @@ TransportSender<MyState>::TransportSender( Connection *s_connection, MyState &in
     next_send_time( timestamp() ),
     verbose( false ),
     shutdown_in_progress( false ),
+    shutdown_timestamp( -1 ),
     ack_num( 0 ),
     pending_data_ack( false )
 {
@@ -279,3 +280,17 @@ void TransportSender<MyState>::process_acknowledgment_through( uint64_t ack_num
   assert( !sent_states.empty() );
 }
 
+/* give up on getting acknowledgement for shutdown after 5 RTTs */
+template <class MyState>
+bool TransportSender<MyState>::shutdown_ack_timed_out( void )
+{
+  if ( !shutdown_in_progress ) {
+    return false;
+  }
+
+  if ( timestamp() - shutdown_timestamp > 5 * connection->get_SRTT() ) {
+    return true;
+  }
+
+  return false;
+}

transportsender.hpp

@@ -55,6 +55,7 @@ namespace Network {
 
     bool verbose;
     bool shutdown_in_progress;
+    uint64_t shutdown_timestamp;
 
     /* information about receiver state */
     uint64_t ack_num;
@@ -80,7 +81,7 @@ namespace Network {
     void set_data_ack( void ) { pending_data_ack = true; }
 
     /* Starts shutdown sequence */
-    void start_shutdown( void ) { shutdown_in_progress = true; }
+    void start_shutdown( void ) { shutdown_in_progress = true; shutdown_timestamp = timestamp(); }
 
     /* Misc. getters and setters */
     /* Cannot modify current_state while shutdown in progress */
@@ -91,6 +92,7 @@ namespace Network {
     bool get_shutdown_in_progress( void ) { return shutdown_in_progress; }
     bool get_shutdown_acknowledged( void ) { return sent_states.front().num == uint64_t(-1); }
     bool get_counterparty_shutdown_acknowledged( void ) { return fragmenter.last_ack_sent() == uint64_t(-1); }
+    bool shutdown_ack_timed_out( void );
 
     /* nonexistent methods to satisfy -Weffc++ */
     TransportSender( const TransportSender &x );