Make Terminal::Framebuffer::Rows shared and copy-on-write.

* Support both std:: and std::tr1:: shared_ptr. FreeBSD 10 now uses C++11 by default.
* Remove Framebuffer pointers in STMClient

configure.ac

@@ -206,6 +206,9 @@ AC_CHECK_HEADERS([endian.h sys/endian.h])
 AC_CHECK_HEADERS([utmpx.h])
 AC_CHECK_HEADERS([termio.h])
 AC_CHECK_HEADERS([sys/uio.h])
+AC_LANG_PUSH(C++)
+AC_CHECK_HEADERS([tr1/memory])
+AC_LANG_POP(C++)
 
 # Checks for typedefs, structures, and compiler characteristics.
 AC_HEADER_STDBOOL
@@ -371,6 +374,32 @@ public:
   [AC_MSG_RESULT([no])])
 AC_LANG_POP(C++)
 
+AC_MSG_CHECKING([whether std::shared_ptr is available])
+AC_LANG_PUSH(C++)
+AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[#include <memory>
+class T {
+public:
+  std::shared_ptr<int> Fun( void ) { return std::shared_ptr<int>( new int ( 0 ) ); } };]],
+[[T x; return !!x.Fun();]])],
+  [AC_DEFINE([HAVE_STD_SHARED_PTR], [1],
+     [Define if std::shared_ptr is available.])
+   AC_MSG_RESULT([yes])],
+  [AC_MSG_RESULT([no])])
+AC_LANG_POP(C++)
+
+AC_MSG_CHECKING([whether std::tr1::shared_ptr is available])
+AC_LANG_PUSH(C++)
+AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[#include <tr1/memory>
+class T {
+public:
+  std::tr1::shared_ptr<int> Fun( void ) { return std::tr1::shared_ptr<int>( new int ( 0 ) ); } };]],
+[[T x; return !!x.Fun();]])],
+  [AC_DEFINE([HAVE_STD_TR1_SHARED_PTR], [1],
+     [Define if std::tr1::shared_ptr is available.])
+   AC_MSG_RESULT([yes])],
+  [AC_MSG_RESULT([no])])
+AC_LANG_POP(C++)
+
 AC_CHECK_DECLS([__builtin_bswap64, __builtin_ctz])
 
 AC_CHECK_DECL([mach_absolute_time],

src/frontend/stmclient.cc

@@ -237,11 +237,11 @@ void STMClient::main_init( void )
   }  
 
   /* local state */
-  local_framebuffer = new Terminal::Framebuffer( window_size.ws_col, window_size.ws_row );
+  local_framebuffer = Terminal::Framebuffer( window_size.ws_col, window_size.ws_row );
-  new_state = new Terminal::Framebuffer( 1, 1 );
+  new_state = Terminal::Framebuffer( 1, 1 );
 
   /* initialize screen */
-  string init = display.new_frame( false, *local_framebuffer, *local_framebuffer );
+  string init = display.new_frame( false, local_framebuffer, local_framebuffer );
   swrite( STDOUT_FILENO, init.data(), init.size() );
 
   /* open network */
@@ -263,26 +263,23 @@ void STMClient::output_new_frame( void )
   }
 
   /* fetch target state */
-  *new_state = network->get_latest_remote_state().state.get_fb();
+  new_state = network->get_latest_remote_state().state.get_fb();
 
   /* apply local overlays */
-  overlays.apply( *new_state );
+  overlays.apply( new_state );
 
   /* apply any mutations */
-  display.downgrade( *new_state );
+  display.downgrade( new_state );
 
   /* calculate minimal difference from where we are */
   const string diff( display.new_frame( !repaint_requested,
-					*local_framebuffer,
+					local_framebuffer,
-					*new_state ) );
+					new_state ) );
   swrite( STDOUT_FILENO, diff.data(), diff.size() );
 
   repaint_requested = false;
 
-  /* switch pointers */
+  local_framebuffer = new_state;
-  Terminal::Framebuffer *tmp = new_state;
-  new_state = local_framebuffer;
-  local_framebuffer = tmp;
 }
 
 void STMClient::process_network_input( void )
@@ -318,7 +315,7 @@ bool STMClient::process_user_input( int fd )
     for ( int i = 0; i < bytes_read; i++ ) {
       char the_byte = buf[ i ];
 
-      overlays.get_prediction_engine().new_user_byte( the_byte, *local_framebuffer );
+      overlays.get_prediction_engine().new_user_byte( the_byte, local_framebuffer );
 
       if ( quit_sequence_started ) {
 	if ( the_byte == '.' ) { /* Quit sequence is Ctrl-^ . */

src/frontend/stmclient.h

@@ -58,7 +58,7 @@ private:
 
   struct winsize window_size;
 
-  Terminal::Framebuffer *local_framebuffer, *new_state;
+  Terminal::Framebuffer local_framebuffer, new_state;
   Overlay::OverlayManager overlays;
   Network::Transport< Network::UserStream, Terminal::Complete > *network;
   Terminal::Display display;
@@ -89,8 +89,8 @@ public:
     escape_requires_lf( false ), escape_key_help( L"?" ),
       saved_termios(), raw_termios(),
       window_size(),
-      local_framebuffer( NULL ),
+      local_framebuffer( 1, 1 ),
-      new_state( NULL ),
+      new_state( 1, 1 ),
       overlays(),
       network( NULL ),
       display( true ), /* use TERM environment var to initialize display */
@@ -122,14 +122,6 @@ public:
 
   ~STMClient()
   {
-    if ( local_framebuffer != NULL ) {
-      delete local_framebuffer;
-    }
-
-    if ( new_state != NULL ) {
-      delete new_state;
-    }
-
     if ( network != NULL ) {
       delete network;
     }

src/terminal/terminaldisplay.cc

@@ -143,25 +143,20 @@ std::string Display::new_frame( bool initialized, const Framebuffer &last, const
   }
 
   int frame_y = 0;
-  Row blankrow( 0, 0 );
+  Framebuffer::row_pointer blank_row;
-  Framebuffer::rows_p_type rows(frame.last_frame.get_p_rows());
+  Framebuffer::rows_type rows( frame.last_frame.get_rows() );
   /* Extend rows if we've gotten a resize and new is wider than old */
   if ( frame.last_frame.ds.get_width() < f.ds.get_width() ) {
-    for ( Framebuffer::rows_p_type::iterator p = rows.begin(); p != rows.end(); p++ ) {
+    for ( Framebuffer::rows_type::iterator p = rows.begin(); p != rows.end(); p++ ) {
-      Row *bigger_row = new Row( **p );
+      *p = Framebuffer::row_pointer( new Row( **p ) );
-      bigger_row->cells.resize( f.ds.get_width(), Cell( f.ds.get_background_rendition() ) );
+      (*p)->cells.resize( f.ds.get_width(), Cell( f.ds.get_background_rendition() ) );
-      *p = bigger_row;
     }
   }
   /* Add rows if we've gotten a resize and new is taller than old */
   if ( static_cast<int>( rows.size() ) < f.ds.get_height() ) {
-    size_t orig_size = rows.size();
     // get a proper blank row
-    blankrow = Row( f.ds.get_width(), 0 );
+    blank_row = Framebuffer::row_pointer( new Row( f.ds.get_width(), 0 ) );
-    rows.resize( f.ds.get_height() );
+    rows.resize( f.ds.get_height(), blank_row );
-    for ( Framebuffer::rows_p_type::iterator p = rows.begin() + orig_size; p != rows.end(); p++ ) {
-      *p = new Row( blankrow );
-    }
   }
 
   /* shortcut -- has display moved up by a certain number of lines? */
@@ -171,7 +166,7 @@ std::string Display::new_frame( bool initialized, const Framebuffer &last, const
 
     for ( int row = 0; row < f.ds.get_height(); row++ ) {
       const Row *new_row = f.get_row( 0 );
-      const Row *old_row = rows.at( row );
+      const Row *old_row = &*rows.at( row );
       if ( new_row == old_row || *new_row == *old_row ) {
 	/* if row 0, we're looking at ourselves and probably didn't scroll */
 	if ( row == 0 ) {
@@ -201,6 +196,10 @@ std::string Display::new_frame( bool initialized, const Framebuffer &last, const
       frame_y = scroll_height;
 
       if ( lines_scrolled ) {
+	/* Now we need a proper blank row. */
+	if ( blank_row.get() == NULL ) {
+	  blank_row = Framebuffer::row_pointer( new Row( f.ds.get_width(), 0 ) );
+	}
 	frame.update_rendition( initial_rendition(), true );
 
 	int top_margin = 0;
@@ -234,15 +233,12 @@ std::string Display::new_frame( bool initialized, const Framebuffer &last, const
 	  frame.cursor_x = frame.cursor_y = -1;
 	}
 
-	/* Create a full-width blank row to represent newly-scrolled area */
-	blankrow = Row( f.ds.get_width(), 0 );
-
 	/* do the move in our local index */
 	for ( int i = top_margin; i <= bottom_margin; i++ ) {
 	  if ( i + lines_scrolled <= bottom_margin ) {
 	    rows.at( i ) = rows.at( i + lines_scrolled );
 	  } else {
-	    rows.at( i ) = &blankrow;
+	    rows.at( i ) = blank_row;
 	  }
 	}
       }

src/terminal/terminalframebuffer.cc

@@ -84,12 +84,31 @@ DrawState::DrawState( int s_width, int s_height )
 }
 
 Framebuffer::Framebuffer( int s_width, int s_height )
-  : rows( s_height, Row( s_width, 0 ) ), icon_name(), window_title(), bell_count( 0 ), title_initialized( false ), ds( s_width, s_height )
+  : rows( s_height, row_pointer(new Row( s_width, 0 ))), icon_name(), window_title(), bell_count( 0 ), title_initialized( false ), ds( s_width, s_height )
 {
   assert( s_height > 0 );
   assert( s_width > 0 );
 }
 
+Framebuffer::Framebuffer( const Framebuffer &other )
+  : rows( other.rows ), icon_name( other.icon_name ), window_title( other.window_title ),
+    bell_count( other.bell_count ), title_initialized( other.title_initialized ), ds( other.ds )
+{
+}
+
+Framebuffer & Framebuffer::operator=( const Framebuffer &other )
+{
+  if ( this != &other ) {
+    rows = other.rows;
+    icon_name =  other.icon_name;
+    window_title = other.window_title;
+    bell_count = other.bell_count;
+    title_initialized = other.title_initialized;
+    ds = other.ds;
+  }
+  return *this;
+}
+
 void Framebuffer::scroll( int N )
 {
   if ( N >= 0 ) {
@@ -286,14 +305,9 @@ void Framebuffer::insert_line( int before_row, int count )
   // delete old rows
   rows_type::iterator start = rows.begin() + ds.get_scrolling_region_bottom_row() + 1 - count;
   rows.erase( start, start + count );
-  // insert a block of dummy rows
+  // insert new rows
   start = rows.begin() + before_row;
-  rows.insert( start, count, Row( 0, 0 ) );
+  rows.insert( start, count, newrow());
-  // then replace with real new rows
-  start = rows.begin() + before_row;
-  for (rows_type::iterator i = start; i < start + count; i++) {
-    *i = newrow();
-  }
 }
 
 void Framebuffer::delete_line( int row, int count )
@@ -317,12 +331,7 @@ void Framebuffer::delete_line( int row, int count )
   rows.erase( start, start + count );
   // insert a block of dummy rows
   start = rows.begin() + ds.get_scrolling_region_bottom_row() + 1 - count;
-  rows.insert( start, count, Row( 0, 0 ) );
+  rows.insert( start, count, newrow());
-  // then replace with real new rows
-  start = rows.begin() + ds.get_scrolling_region_bottom_row() + 1 - count;
-  for (rows_type::iterator i = start; i < start + count; i++) {
-    *i = newrow();
-  }
 }
 
 Row::Row( size_t s_width, color_type background_color )
@@ -355,12 +364,12 @@ void Row::delete_cell( int col, color_type background_color )
 
 void Framebuffer::insert_cell( int row, int col )
 {
-  rows.at( row ).insert_cell( col, ds.get_background_rendition() );
+  get_mutable_row( row )->insert_cell( col, ds.get_background_rendition() );
 }
 
 void Framebuffer::delete_cell( int row, int col )
 {
-  rows.at( row ).delete_cell( col, ds.get_background_rendition() );
+  get_mutable_row( row )->delete_cell( col, ds.get_background_rendition() );
 }
 
 void Framebuffer::reset( void )
@@ -388,8 +397,8 @@ void Framebuffer::posterize( void )
   for ( rows_type::iterator i = rows.begin();
         i != rows.end();
         i++ ) {
-    for ( Row::cells_type::iterator j = i->cells.begin();
+    for ( Row::cells_type::iterator j = (*i)->cells.begin();
-          j != i->cells.end();
+          j != (*i)->cells.end();
           j++ ) {
       j->renditions.posterize();
     }
@@ -401,15 +410,23 @@ void Framebuffer::resize( int s_width, int s_height )
   assert( s_width > 0 );
   assert( s_height > 0 );
 
+  int oldheight = ds.get_height();
+  int oldwidth = ds.get_width();
   ds.resize( s_width, s_height );
 
-  rows.resize( s_height, newrow() );
+  row_pointer blankrow( newrow());
-
+  if ( oldheight != s_height ) {
+    rows.resize( s_height, blankrow );
+  }
+  if (oldwidth == s_width) {
+    return;
+  }
   for ( rows_type::iterator i = rows.begin();
-	i != rows.end();
+	i != rows.end() && *i != blankrow;
 	i++ ) {
-    i->set_wrap( false );
+    *i = Framebuffer::row_pointer( new Row( **i ) );
-    i->cells.resize( s_width, Cell( ds.get_background_rendition() ) );
+    (*i)->set_wrap( false );
+    (*i)->cells.resize( s_width, Cell( ds.get_background_rendition() ) );
   }
 }
 

src/terminal/terminalframebuffer.h

@@ -42,9 +42,12 @@
 #include <string>
 #include <list>
 
+#include "shared.h"
+
 /* Terminal framebuffer */
 
 namespace Terminal {
+  using shared::shared_ptr;
   typedef uint16_t color_type;
 
   class Renditions {
@@ -288,41 +291,48 @@ namespace Terminal {
   };
 
   class Framebuffer {
+    // To minimize copying of rows and cells, we use shared_ptr to
+    // share unchanged rows between multiple Framebuffers.  If we
+    // write to a row in a Framebuffer and it is shared with other
+    // owners, we copy it first.  The shared_ptr naturally manages the
+    // usage of the actual rows themselves.
+    //
+    // We gain a couple of free extras by doing this:
+    //
+    // * A quick check for equality between rows in different
+    // Framebuffers is to simply compare the pointer values.  If they
+    // are equal, then the rows are obviously identical.
+    // * If no row is shared, the frame has not been modified.
   public:
     typedef std::vector<wchar_t> title_type;
-    typedef std::vector<const Row *> rows_p_type;
+    typedef shared_ptr<Row> row_pointer;
+    typedef std::vector<row_pointer> rows_type; /* can be either std::vector or std::deque */
 
   private:
-    typedef std::vector<Row> rows_type;
     rows_type rows;
     title_type icon_name;
     title_type window_title;
     unsigned int bell_count;
     bool title_initialized; /* true if the window title has been set via an OSC */
 
-    Row newrow( void ) { return Row( ds.get_width(), ds.get_background_rendition() ); }
+    row_pointer newrow( void ) { return row_pointer( new Row( ds.get_width(), ds.get_background_rendition())); }
 
   public:
     Framebuffer( int s_width, int s_height );
+    Framebuffer( const Framebuffer &other );
+    Framebuffer &operator=( const Framebuffer &other );
     DrawState ds;
 
+    const rows_type &get_rows() const { return rows; }
+
     void scroll( int N );
     void move_rows_autoscroll( int rows );
 
-    rows_p_type get_p_rows() const
+    inline const Row *get_row( int row ) const
-    {
-      rows_p_type retval;
-      for ( size_t i = 0; i < rows.size(); i++ ) {
-	retval.push_back( &rows.at(i) );
-      }
-      return retval;
-    }
-
-    const Row *get_row( int row ) const
     {
       if ( row == -1 ) row = ds.get_cursor_row();
 
-      return &rows.at( row );
+      return rows.at( row ).get();
     }
 
     inline const Cell *get_cell( int row = -1, int col = -1 ) const
@@ -330,17 +340,26 @@ namespace Terminal {
       if ( row == -1 ) row = ds.get_cursor_row();
       if ( col == -1 ) col = ds.get_cursor_col();
 
-      return &rows.at( row ).cells.at( col );
+      return &rows.at( row )->cells.at( col );
     }
 
     Row *get_mutable_row( int row )
     {
-      return const_cast<Row *>(get_row( row ));
+      if ( row == -1 ) row = ds.get_cursor_row();
+      row_pointer &mutable_row = rows.at( row );
+      // If the row is shared, copy it.
+      if (!mutable_row.unique()) {
+	mutable_row = row_pointer( new Row( *mutable_row ));
+      }
+      return mutable_row.get();
     }
 
-    inline Cell *get_mutable_cell( int row = -1, int col = -1 )
+    Cell *get_mutable_cell( int row = -1, int col = -1 )
     {
-      return const_cast<Cell *>(get_cell( row, col ));
+      if ( row == -1 ) row = ds.get_cursor_row();
+      if ( col == -1 ) col = ds.get_cursor_col();
+
+      return &get_mutable_row( row )->cells.at( col );
     }
 
     Cell *get_combining_cell( void );

src/util/Makefile.am

@@ -2,4 +2,4 @@ AM_CXXFLAGS = $(WARNING_CXXFLAGS) $(PICKY_CXXFLAGS) $(HARDEN_CFLAGS) $(MISC_CXXF
 
 noinst_LIBRARIES = libmoshutil.a
 
-libmoshutil_a_SOURCES = locale_utils.cc locale_utils.h swrite.cc swrite.h dos_assert.h fatal_assert.h select.h select.cc timestamp.h timestamp.cc pty_compat.cc pty_compat.h
+libmoshutil_a_SOURCES = locale_utils.cc locale_utils.h swrite.cc swrite.h dos_assert.h fatal_assert.h select.h select.cc timestamp.h timestamp.cc pty_compat.cc pty_compat.h shared.h

src/util/shared.h

@@ -0,0 +1,53 @@
+/*
+    Mosh: the mobile shell
+    Copyright 2012 Keith Winstein
+
+    This program is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+    In addition, as a special exception, the copyright holders give
+    permission to link the code of portions of this program with the
+    OpenSSL library under certain conditions as described in each
+    individual source file, and distribute linked combinations including
+    the two.
+
+    You must obey the GNU General Public License in all respects for all
+    of the code used other than OpenSSL. If you modify file(s) with this
+    exception, you may extend this exception to your version of the
+    file(s), but you are not obligated to do so. If you do not wish to do
+    so, delete this exception statement from your version. If you delete
+    this exception statement from all source files in the program, then
+    also delete it here.
+*/
+
+#ifndef SHARED_HPP
+#define SHARED_HPP
+
+#include "config.h"
+
+#ifdef HAVE_TR1_MEMORY
+#include <tr1/memory>
+#endif
+
+namespace shared {
+#ifdef HAVE_STD_SHARED_PTR
+  using std::shared_ptr;
+#else
+#ifdef HAVE_STD_TR1_SHARED_PTR
+  using std::tr1::shared_ptr;
+#else
+#error Need a shared_ptr class.  Try Boost::TR1.
+#endif
+#endif
+}
+#endif