Graceful shutdown on quit

TODO

@@ -4,7 +4,7 @@
 
 [DONE] Figure out packet double-sending issue [if delay > 1/50 sec?]
 
-Graceful exit / server shutdown
+[DONE] Graceful exit / server shutdown
 
 Make roaming much smoother (with error message placement)
 

networktransport.cpp

@@ -12,7 +12,8 @@ Transport<MyState, RemoteState>::Transport( MyState &initial_state, RemoteState
     sender( &connection, initial_state ),
     received_states( 1, TimestampedState<RemoteState>( timestamp(), 0, initial_remote ) ),
     last_receiver_state( initial_remote ),
-    fragments()
+    fragments(),
+    verbose( false )
 {
   /* server */
 }
@@ -24,7 +25,8 @@ Transport<MyState, RemoteState>::Transport( MyState &initial_state, RemoteState
     sender( &connection, initial_state ),
     received_states( 1, TimestampedState<RemoteState>( timestamp(), 0, initial_remote ) ),
     last_receiver_state( initial_remote ),
-    fragments()
+    fragments(),
+    verbose( false )
 {
   /* client */
 }
@@ -82,11 +84,9 @@ void Transport<MyState, RemoteState>::recv( void )
 	return;
       }
     }
-    /*
     if ( verbose )
       fprintf( stderr, "[%d] Received state %d [ack %d]\n",
-	       (int)timestamp() % 100000, (int)new_state.num, (int)inst.ack_num );
-    */
+	       (int)timestamp() % 100000, (int)new_state.num, (int)inst.ack_num() );
     received_states.push_back( new_state );
     sender.set_ack_num( received_states.back().num );
   }
@@ -128,4 +128,3 @@ string Transport<MyState, RemoteState>::get_remote_diff( void )
 
   return ret;
 }
-

networktransport.hpp

@@ -30,8 +30,8 @@ namespace Network {
     /* simple receiver */
     list< TimestampedState<RemoteState> > received_states;
     RemoteState last_receiver_state; /* the state we were in when user last queried state */
-
     FragmentAssembly fragments;
+    bool verbose;
 
   public:
     Transport( MyState &initial_state, RemoteState &initial_remote );
@@ -47,14 +47,24 @@ namespace Network {
     /* Blocks waiting for a packet. */
     void recv( void );
 
+    /* Find diff between last receiver state and current remote state, then rationalize states. */
+    string get_remote_diff( void );
+
+    /* Shut down other side of connection. */
+    /* Illegal to change current_state after this. */
+    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(); }
+
+    /* Other side has requested shutdown and we have sent one ACK */
+    bool counterparty_shutdown_ack_sent( void ) { return sender.get_counterparty_shutdown_acknowledged(); }
+
     int port( void ) { return connection.port(); }
     string get_key( void ) { return connection.get_key(); }
 
     MyState &get_current_state( void ) { return sender.get_current_state(); }
     void set_current_state( const MyState &x ) { sender.set_current_state( x ); }
 
-    string get_remote_diff( void );
-
     typename list< TimestampedState<RemoteState > >::iterator begin( void ) { return received_states.begin(); }
     typename list< TimestampedState<RemoteState > >::iterator end( void ) { return received_states.end(); }
 
@@ -62,7 +72,7 @@ namespace Network {
 
     int fd( void ) { return connection.fd(); }
 
-    void set_verbose( void ) { sender.set_verbose(); }
+    void set_verbose( void ) { sender.set_verbose(); verbose = true; }
   };
 }
 

stm-server.cpp

@@ -168,7 +168,9 @@ void serve( int host_fd )
 	  }
 
 	  /* update client with new state of terminal */
-	  network.set_current_state( terminal );
+	  if ( !network.shutdown_in_progress() ) {
+	    network.set_current_state( terminal );
+	  }
 	  
 	  /* write any writeback octets back to the host */
 	  if ( swrite( host_fd, terminal_to_host.c_str(), terminal_to_host.length() ) < 0 ) {
@@ -194,7 +196,9 @@ void serve( int host_fd )
 	string terminal_to_host = terminal.act( string( buf, bytes_read ) );
 	
 	/* update client with new state of terminal */
-	network.set_current_state( terminal );
+	if ( !network.shutdown_in_progress() ) {
+	  network.set_current_state( terminal );
+	}
 
 	/* write any writeback octets back to the host */
 	if ( swrite( host_fd, terminal_to_host.c_str(), terminal_to_host.length() ) < 0 ) {
@@ -202,8 +206,25 @@ void serve( int host_fd )
 	}
       }
       
-      if ( (pollfds[ 0 ].revents | pollfds[ 1 ].revents)
+      if ( (pollfds[ 0 ].revents)
 	   & (POLLERR | POLLHUP | POLLNVAL) ) {
+	/* network problem */
+	break;
+      }
+
+      if ( (pollfds[ 1 ].revents)
+	   & (POLLERR | POLLHUP | POLLNVAL) ) {
+	/* host problem */
+	network.start_shutdown();
+      }
+
+      /* quit if our shutdown has been acknowledged */
+      if ( network.shutdown_in_progress() && network.shutdown_acknowledged() ) {
+	break;
+      }
+
+      /* quit if we received and acknowledged a shutdown request */
+      if ( network.counterparty_shutdown_ack_sent() ) {
 	break;
       }
 

stm.cpp

@@ -174,8 +174,10 @@ void client( const char *ip, int port, const char *key )
 	  return;
 	}
 
-	for ( int i = 0; i < bytes_read; i++ ) {
-	  network.get_current_state().push_back( Parser::UserByte( buf[ i ] ) );
+	if ( !network.shutdown_in_progress() ) {
+	  for ( int i = 0; i < bytes_read; i++ ) {
+	    network.get_current_state().push_back( Parser::UserByte( buf[ i ] ) );
+	  }
 	}
       }
 
@@ -194,7 +196,9 @@ void client( const char *ip, int port, const char *key )
 	/* tell remote emulator */
 	Parser::Resize res( window_size.ws_col, window_size.ws_row );
 
-	network.get_current_state().push_back( res );
+	if ( !network.shutdown_in_progress() ) {
+	  network.get_current_state().push_back( res );
+	}
 
 	/* tell local emulator -- there is probably a safer way to do this */
 	for ( list< Network::TimestampedState<Terminal::Complete> >::iterator i = network.begin();
@@ -204,8 +208,25 @@ void client( const char *ip, int port, const char *key )
 	}
       }
 
-      if ( (pollfds[ 0 ].revents | pollfds[ 1 ].revents)
+      if ( (pollfds[ 0 ].revents)
 	   & (POLLERR | POLLHUP | POLLNVAL) ) {
+	/* network problem */
+	break;
+      }
+
+      if ( (pollfds[ 1 ].revents)
+	   & (POLLERR | POLLHUP | POLLNVAL) ) {
+	/* user problem */
+	network.start_shutdown();
+      }
+
+      /* quit if our shutdown has been acknowledged */
+      if ( network.shutdown_in_progress() && network.shutdown_acknowledged() ) {
+	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_ack_time( timestamp() ),
     next_send_time( timestamp() ),
     verbose( false ),
+    shutdown_in_progress( false ),
     ack_num( 0 )
 {
 }
@@ -50,10 +51,15 @@ int TransportSender<MyState>::wait_time( void )
     if ( next_send_time < sent_states.back().timestamp + send_interval() ) {
       next_send_time = sent_states.back().timestamp + send_interval();
     }
+  }
 
-    if ( next_send_time < next_wakeup ) {
-      next_wakeup = next_send_time;
-    }
+  /* speed up shutdown sequence */
+  if ( shutdown_in_progress || (ack_num == uint64_t(-1)) ) {
+    next_ack_time = sent_states.back().timestamp + send_interval();
+  }
+
+  if ( next_send_time < next_wakeup ) {
+    next_wakeup = next_send_time;
   }
 
   if ( !connection->get_attached() ) {
@@ -110,6 +116,11 @@ void TransportSender<MyState>::send_empty_ack( void )
 
   uint64_t new_num = sent_states.back().num + 1;
 
+  /* special case for shutdown sequence */
+  if ( shutdown_in_progress ) {
+    new_num = uint64_t( -1 );
+  }
+
   send_in_fragments( "", new_num, false );
   sent_states.push_back( TimestampedState<MyState>( sent_states.back().timestamp, new_num, current_state ) );
   next_ack_time = timestamp() + ACK_INTERVAL;
@@ -125,6 +136,11 @@ void TransportSender<MyState>::send_to_receiver( string diff )
     new_num = sent_states.back().num + 1;
   }
 
+  /* special case for shutdown sequence */
+  if ( shutdown_in_progress ) {
+    new_num = uint64_t( -1 );
+  }
+
   bool done = false;
   int MTU_tries = 0;
   while ( !done ) {
@@ -157,7 +173,7 @@ void TransportSender<MyState>::send_to_receiver( string diff )
   assumed_receiver_state = sent_states.end();
   assumed_receiver_state--;
   next_ack_time = timestamp() + ACK_INTERVAL;
-  next_send_time = -1;
+  next_send_time = uint64_t(-1);
 }
 
 template <class MyState>

transportsender.hpp

@@ -53,6 +53,7 @@ namespace Network {
     uint64_t next_send_time;
 
     bool verbose;
+    bool shutdown_in_progress;
 
     /* information about receiver state */
     uint64_t ack_num;
@@ -67,15 +68,24 @@ namespace Network {
     /* Returns the number of ms to wait until next possible event. */
     int wait_time( void );
 
-    /* executed upon receipt of ack */
+    /* Executed upon receipt of ack */
     void process_acknowledgment_through( uint64_t ack_num );
 
-    /* getters and setters */
-    MyState &get_current_state( void ) { return current_state; }
-    void set_current_state( const MyState &x ) { current_state = x; }
-    void set_verbose( void ) { verbose = true; }
+    /* Executed upon entry to new receiver state */
     void set_ack_num( uint64_t s_ack_num ) { ack_num = s_ack_num; }
 
+    /* Starts shutdown sequence */
+    void start_shutdown( void ) { shutdown_in_progress = true; }
+    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 last_instruction_sent.ack_num() == uint64_t(-1); }
+
+    /* Misc. getters and setters */
+    /* Cannot modify current_state while shutdown in progress */
+    MyState &get_current_state( void ) { assert( !shutdown_in_progress ); return current_state; }
+    void set_current_state( const MyState &x ) { assert( !shutdown_in_progress ); current_state = x; }
+    void set_verbose( void ) { verbose = true; }
+
     /* nonexistent methods to satisfy -Weffc++ */
     TransportSender( const TransportSender &x );
     TransportSender & operator=( const TransportSender &x );