README.multi-tty 8.51 KB
Newer Older
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
			-*- coding: utf-8; -*-
GOAL
----

The ultimate goal of this branch is to implement support for opening
multiple, different tty devices and simultaneous X and tty frames from
a single Emacs session.

WHO IS DOING IT
---------------

I'm Károly Lőrentey.  My address: lorentey@elte.hu.

Patches or suggestions are welcome!

16
Retrieving the latest version of the branch:
17 18 19 20 21 22

	tla register-archive lorentey@elte.hu--2004 http://lorentey.web.elte.hu/arch/2004/
	tla get lorentey@elte.hu--2004/emacs--multi-tty--0 <directory>

(I use tla 1.1.)

23 24 25 26

STATUS
------

27 28 29
Basic multi-tty support is there; there are some rough edges, but it
already seems to be usable.  Emacsclient has been extended to support
opening a new terminal frame.
30

Karoly Lorentey's avatar
Karoly Lorentey committed
31 32
To try it out, compile the multi-tty branch with the following
commands:
33 34 35 36 37 38 39

   	mkdir +build
	cd +build
	../configure --with-x-toolkit=no --without-x
	make bootstrap

then start up the emacs server (src/emacs, M-x server-start), and then
40
(from a shell prompt on another terminal) start emacsclient with
41

Karoly Lorentey's avatar
Karoly Lorentey committed
42
	lib-src/emacsclient -h  /optional/file/names...
43

Karoly Lorentey's avatar
Karoly Lorentey committed
44 45 46 47 48 49 50 51 52
You'll hopefully have two fully working, independent frames on
separate terminals.  (This seems to be very useful, emacsclient starts
up even faster than vi!) :-) You can close the newly opened frame and
return to the shell without exiting Emacs by pressing C-x 5 0, i.e.,
delete-frame.  (Note that this does not seem to work yet on the
original terminal.)  Creating new frames on the same tty with C-x 5 2
works exactly as before.  Suspending Emacs is disabled at the moment.
If you exit emacs, all terminals should be restored to their previous
states.
53 54

X, Mac, Windows and DOS support is broken, probably doesn't even
Karoly Lorentey's avatar
Karoly Lorentey committed
55 56 57 58
compile -- this will be solved later.  Please see the attached README
for other issues, implementation notes and sub-TODO items.

Only tested on my GNU/Linux box.
59

60 61 62 63 64 65 66 67

NEWS
----

For the NEWS file:

** Support for multiple terminal devices has been added.  You can
   specify a terminal device (`tty' parameter) and a terminal type
68
   (`tty-type' parameter) to `make-terminal-frame'. `tty' must be a
69
   terminal device created by the updated emacsclient, or there will
Karoly Lorentey's avatar
Karoly Lorentey committed
70
   be problems with terminal input and window resizes.  
71 72 73 74 75 76

   You can test for the presence of multiple terminal support by
   testing for the `multi-tty' feature.

** A make-frame-on-tty function has been added to make it easier to
   create frames on new terminals.
77

78 79
** Emacsclient has been extended to support opening a new terminal
   frame.
80 81 82 83 84 85 86

CHANGELOG
---------

See arch logs.


87 88 89 90
DIARY OF CHANGES
----------------

(ex-TODO items with explanations.)
91 92 93 94 95 96 97 98 99 100 101 102 103 104

-- Introduce a new abstraction for terminal devices.  

   (Done, see struct tty_output.  The abstraction is not yet
   complete.)

-- Change the bootstrap procedure to initialize tty_list.

   (Done, but needs review.)

-- Change make-terminal-frame to support specifying another tty.

   (Done, new frame parameters: `tty' and `tty-type'.)

105 106 107
-- Implement support for reading from multiple terminals.

   (Done, read_avail_input tries to read from each terminal, until one
108 109
   succeeds.  MULTIKBOARD is not used.  Secondary terminals don't send
   SIGIO!)
110 111

-- other-frame should cycle through the frames on the `current'
112
   terminal only.  
113

114
   (Done, by trivially modifiying next_frame and prev_frame.)
115 116 117 118 119 120 121 122

-- Support different terminal sizes.
   
   (Done, no problem.)

-- Make sure terminal resizes are handled gracefully.  (Could be
   problematic.)

123 124
   (Done.  We don't get automatic SIGWINCH for additional ttys,
   though.)
125 126 127 128 129 130

-- Extend emacsclient to automatically open a new tty when it connects
   to Emacs.
   
   (Done.  It's an ugly hack, needs more work.)

131 132
-- Redisplay must refresh the topmost frame on *all* terminals, not
   just the initial terminal.
133
   
134
   (Done, but introduced an ugly redisplay problems.  Ugh.)
135

136 137
-- Fix redisplay problems.

138 139
   (Done; it turned out that the entire Wcm structure must be moved
   inside tty_output.  Why didn't I catch this earlier?)
140 141 142 143 144 145 146 147 148 149

-- Provide a way for emacsclient to tell Emacs that the tty has been
   resized.

   (Done, simply forward the SIGWINCH signal.)

-- Each keypress should automatically select the frame corresponding
   to the terminal that it was coming from.  This means that Emacs
   must know from which terminal the last keyboard event came from.

150 151
   (Done, it was quite simple, the input event system already
   supported multiple frames.)
152 153 154 155

-- Fix SIGIO issue with secondary terminals.

   (Done, emacsclient signals Emacs after writing to the proxy pseudo
156 157
   terminal.  Note that this means that multi-tty does not work with
   raw ttys!)
158

Karoly Lorentey's avatar
Karoly Lorentey committed
159 160 161
   (Update: This is bullshit.  There is a read_input_waiting function,
   extend that somehow.)

162 163 164 165 166 167 168 169 170 171
-- Make make-terminal-frame look up the `tty' and `tty-type' frame
   parameters from the currently selected terminal before the global
   default.

   (Done.)

-- Put all cached terminal escape sequences into struct tty_output.
   Currently, they are still stored in global variables, so we don't
   really support multiple terminal types.

172
   (Done.  It was not fun.)
173 174

-- Implement sane error handling after initialization.  (Currently
175 176 177
   emacs exits if you specify a bad terminal type.)  The helpful error
   messages must still be provided when Emacs starts.

178 179 180 181 182
   (Done.)

-- Implement terminal deletion, i.e., deleting local frames, closing
   the tty device and restoring its previous state without exiting
   Emacs.
183

184 185 186 187
   (Done, but at the moment only called when an error happens during
   initialization.  There is a memory corruption error around this
   somewhere.)

188 189 190 191 192
-- Implement automatic deletion of terminals when the last frame on
   that terminal is closed.

   (Done.)

Karoly Lorentey's avatar
Karoly Lorentey committed
193 194 195 196 197 198 199
-- Restore tty screen after closing the terminal.

   (Done, we do the same as Emacs 21.2 for all terminals.)

-- 'TERM=dumb src/emacs' does not restore the terminal state.
   
   (Done.)
200

201 202 203 204 205 206 207 208 209 210 211 212 213 214 215
-- C-g should work on secondary terminals.

   (Done, but the binding is not configurable.)

-- Deal with SIGHUP in Emacs and in emacsclient.  (After this, the
   server-frames may be removed from server.el.)

   (Done, nothing to do.  It seems that Emacs does not receive SIGHUP
   from secondary ttys.)

-- Change emacsclient/server.el to support the -h argument better,
   i.e. automatically close the socket when the frame is closed.

   (Seems to be working OK.)

216 217 218 219 220 221 222 223 224 225
THINGS TO DO
------------

** Fix mysterious memory corruption error with tty deletion.  To
   trigger it, try the following shell command:

	while true; do TERM=no-such-terminal-definition emacsclient -h; done

   Emacs usually dumps core after a few dozen iterations.  (The bug
   seems to be related to the xfree()ing or bzero()ing of
226 227 228
   tty_output.Wcm or some other tty_output part.  Maybe there are
   outside references to struct Wcm?  Why were these vars collected
   into a struct before multi-tty support?)
229

230
   The bug does not seem to happen if the error occurs before terminal
231
   initialization or if I comment out all xfree()s in delete_frame.
232 233
   Update: yes it does, although it is much rarer.  Or maybe it's
   another bug.
234

235 236
** Make parts of struct tty_output accessible from Lisp.  The device
   name and the type is sufficient.
237

238 239
** Export delete_tty to the Lisp environment, for emacsclient.

240 241
** Make sure C-g goes to the right frame.  This is hard, as SIGINT
   doesn't have a tty parameter. :-(
242

Karoly Lorentey's avatar
Karoly Lorentey committed
243
** Find out why does Emacs abort when it wants to close its
Karoly Lorentey's avatar
Karoly Lorentey committed
244 245
   controlling tty.  Hint: chan_process[] array.  Hey, maybe
   noninterrupt-IO would work, too?
Karoly Lorentey's avatar
Karoly Lorentey committed
246

247 248
** Implement support for starting an interactive Emacs session without
   an initial frame.  (The user would connect to it and open frames
249
   later, with emacsclient.)  Not necessarily a good idea.
250

Karoly Lorentey's avatar
Karoly Lorentey committed
251 252 253
** Support raw secondary terminals.  (Note that SIGIO works only on
   the controlling terminal.) Hint: extend read_input_waiting() for
   multiple ttys and hopefully this will be fixed.
254 255

** What does interrupt_input do?  I tried to disable it for raw
256
   secondary tty support, but it does not seem to do anything useful.
257

Karoly Lorentey's avatar
Karoly Lorentey committed
258 259 260
** Issue with SIGIO: it needs to be disabled during redisplay.  See if
   fcntl() kernel behaviour could be emulated by emacsclient.

261 262
** Move optimalization parameters (costs) from union output_data to
   a backend-neutral per-device structure.
263

Karoly Lorentey's avatar
Karoly Lorentey committed
264 265 266 267
** Find out the best way to support suspending Emacs with multiple
   ttys.

** Do tty output through term_hooks, like all other display backends.
268

269 270
** Fix X support.

271 272 273 274 275 276 277 278 279 280 281
** Allow simultaneous X and tty frames.

** Fix Mac support (I can't do this myself).

** Fix W32 support (I can't do this myself).

** Fix DOS support (I can't do this myself).



;;; arch-tag: 8da1619e-2e79-41a8-9ac9-a0485daad17d