* Work in progress: multiple tty support
@ 2003-12-27 15:38 Károly Lőrentey
2003-12-27 15:58 ` Károly Lőrentey
0 siblings, 1 reply; 2+ messages in thread
From: Károly Lőrentey @ 2003-12-27 15:38 UTC (permalink / raw)
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As a useful activity during the holidays, I started working on an item
from the Emacs TODO list. I tried to make sure to choose an item that
is not currently worked on by anybody, but I may have missed someone's
similar project -- if so, I'm sorry. The item is:
* Support simultaneous tty and X frames.
I have mostly finished implementing multiple tty device support, and I
have extended emacsclient with a hack to support opening a new frame
on the current terminal. I think this is an important milestone, so I
decided to publish my branch for you to find out if you see something
horribly wrong with my general approach. Note that this is (at the
moment) nothing more than a proof-of-concept implementation. It is
not yet intented to be used in a production environment, so please
don't use this branch for your important work. There are plenty of
known bugs and rough edges (see the attached README file).
Dozens of heavily used global variables were made tty-local, so the
changes are quite extensive, but mostly restricted to the low-level
input/output drivers (cm.c, term.c, frame.c, sysdep.c, keyboard.c).
(Some of these variables were used by other display backends, too, so
these will have to be changed again later, to become
backend-independent, but device-local.)
Check out the emacs--multi-tty branch from my arch archive:
lorentey@elte.hu--2004/emacs--multi-tty--0
The archive location is
http://lorentey.web.elte.hu/arch/2004
If you have arch, you can use the following commands:
tla register-archive http://lorentey.web.elte.hu/arch/2004
tla get lorentey@elte.hu--2004/emacs--multi-tty--0
In case you don't have arch, I attached a patch against patch-137 in
Rob Miles's arch branch, which corresponds to the CVS head from 8th
December. (I intend to frequently synchronize with HEAD once the
regex.c issues are resolved.)
To try it out, compile the multi-tty branch with the following
commands:
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
(from a shell prompt on another terminal) start emacsclient with
lib-src/emacsclient -h /optional/file/names...
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.
X, Mac, Windows and DOS support is broken, probably doesn't even
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.
Comments and suggestions are very much welcome!
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-*- 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!
Retrieving the latest version of the branch:
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.)
STATUS
------
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.
To try it out, compile Emacs with the following commands
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
(from a shell prompt on another terminal) start emacsclient with
lib-src/emacsclient -h
You'll hopefully have two fully working frames on separate terminals.
If you exit emacs, both terminals should be restored to their previous
states. 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.
X, Mac, Windows and DOS support is broken, probably doesn't even
compile -- this will be solved later.
Tested under GNU/Linux only.
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
(`tty-type' parameter) to `make-terminal-frame'. `tty' must be a
terminal device created by the updated emacsclient, or there will
be problems with terminal input and window resizes. (The kernel
notifies processes about pending input or terminal resizes only on
the controlling terminal, so we need emacsclient to sit on the real
terminal device, create SIGIO signals upon terminal input, and
forward SIGWINCH signals to us.)
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.
** Emacsclient has been extended to support opening a new terminal
frame.
CHANGELOG
---------
See arch logs.
DIARY OF CHANGES
----------------
(ex-TODO items with explanations.)
-- 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'.)
-- Implement support for reading from multiple terminals.
(Done, read_avail_input tries to read from each terminal, until one
succeeds. MULTIKBOARD is not used. Secondary terminals don't send
SIGIO!)
-- other-frame should cycle through the frames on the `current'
terminal only.
(Done, by trivially modifiying next_frame and prev_frame.)
-- Support different terminal sizes.
(Done, no problem.)
-- Make sure terminal resizes are handled gracefully. (Could be
problematic.)
(Done. We don't get automatic SIGWINCH for additional ttys,
though.)
-- Extend emacsclient to automatically open a new tty when it connects
to Emacs.
(Done. It's an ugly hack, needs more work.)
-- Redisplay must refresh the topmost frame on *all* terminals, not
just the initial terminal.
(Done, but introduced an ugly redisplay problems. Ugh.)
-- Fix redisplay problems.
(Done; it turned out that the entire Wcm structure must be moved
inside tty_output. Why didn't I catch this earlier?)
-- 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.
(Done, it was quite simple, the input event system already
supported multiple frames.)
-- Fix SIGIO issue with secondary terminals.
(Done, emacsclient signals Emacs after writing to the proxy pseudo
terminal. Note that this means that multi-tty does not work with
raw ttys!)
-- 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.
(Done. It was not fun.)
-- Implement sane error handling after initialization. (Currently
emacs exits if you specify a bad terminal type.) The helpful error
messages must still be provided when Emacs starts.
(Done.)
-- Implement terminal deletion, i.e., deleting local frames, closing
the tty device and restoring its previous state without exiting
Emacs.
(Done, but at the moment only called when an error happens during
initialization. There is a memory corruption error around this
somewhere.)
-- Implement automatic deletion of terminals when the last frame on
that terminal is closed.
(Done.)
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
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?)
The bug does not seem to happen if the error occurs before terminal
initialization or if I comment out all xfree()s in delete_frame.
Update: yes it does, although it is much rarer. Or maybe it's
another bug.
** Change emacsclient/server.el to support the -h argument better,
i.e. automatically close the socket when the frame is closed.
** Export delete_tty to the Lisp environment, for emacsclient.
** Restore tty screen after closing the terminal.
** 'TERM=dumb src/emacs' does not restore the terminal state.
** C-g should work on secondary terminals.
** Make parts of struct tty_output accessible from Lisp. The device
name and the type is sufficient.
** Find out why does Emacs abort when it wants to close its
controlling tty.
** Implement support for starting an interactive Emacs session without
an initial frame. (The user would connect to it and open frames
later, with emacsclient.) Not necessarily a good idea.
** Support raw secondary terminals. (This one is tricky, SIGIO works
only on the controlling terminal. The emacsclient solution works
nicely, so this is not that important anyway.)
** What does interrupt_input do? I tried to disable it for raw
secondary tty support, but it does not seem to do anything useful.
** Move optimalization parameters (costs) from union output_data to
a backend-neutral per-device structure.
** Find out the best way to support suspending Emacs with multiple
ttys.
** Do tty output through term_hooks, like all other display backends.
** Fix X support.
** 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
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--
Károly
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^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: Work in progress: multiple tty support
2003-12-27 15:38 Work in progress: multiple tty support Károly Lőrentey
@ 2003-12-27 15:58 ` Károly Lőrentey
0 siblings, 0 replies; 2+ messages in thread
From: Károly Lőrentey @ 2003-12-27 15:58 UTC (permalink / raw)
Lőrentey Károly <lorentey@elte.hu> writes:
> Rob Miles's arch branch
I meant Miles Bader's, of course. Sorry, Miles. :-)
BTW, thanks for the CVS->Arch gateway service, I would not have
started working on this feature if it was not there. I appreciate
your work.
--
Károly
(But who is Rob, then?)
^ permalink raw reply [flat|nested] 2+ messages in thread
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