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*job_control.txt* Nvim
NVIM REFERENCE MANUAL by Thiago de Arruda
Nvim job control *job* *job-control*
Job control is a way to perform multitasking in Nvim, so scripts can spawn and
control multiple processes without blocking the current Nvim instance.
Type |gO| to see the table of contents.
==============================================================================
Concepts
Job Id *job-id*
Each job is identified by an integer id, unique for the life of the current
Nvim session. Each job-id is a valid |channel-id|: they share the same "key
space". Functions like |jobstart()| return job ids; functions like
|jobstop()|, |chansend()|, |rpcnotify()|, and |rpcrequest()| take job ids.
Job stdio streams form a |channel| which can send and receive raw bytes or
|msgpack-rpc| messages.
==============================================================================
Usage *job-control-usage*
To control jobs, use the "job…" family of functions: |jobstart()|,
|jobstop()|, etc.
Example: >vim
function! s:OnEvent(job_id, data, event) dict
if a:event == 'stdout'
let str = self.shell.' stdout: '.join(a:data)
elseif a:event == 'stderr'
let str = self.shell.' stderr: '.join(a:data)
else
let str = self.shell.' exited'
endif
call append(line('$'), str)
endfunction
let s:callbacks = {
\ 'on_stdout': function('s:OnEvent'),
\ 'on_stderr': function('s:OnEvent'),
\ 'on_exit': function('s:OnEvent')
\ }
let job1 = jobstart(['bash'], extend({'shell': 'shell 1'}, s:callbacks))
let job2 = jobstart(['bash', '-c', 'for i in {1..10}; do echo hello $i!; sleep 1; done'], extend({'shell': 'shell 2'}, s:callbacks))
To test the above script, copy it to a file ~/foo.vim and run it: >bash
nvim -u ~/foo.vim
<
Description of what happens:
- Two bash shells are spawned by |jobstart()| with their stdin/stdout/stderr
streams connected to nvim.
- The first shell is idle, waiting to read commands from its stdin.
- The second shell is started with -c which executes the command (a for-loop
printing 0 through 9) and then exits.
- `OnEvent()` callback is passed to |jobstart()| to handle various job
events. It displays stdout/stderr data received from the shells.
For |on_stdout| and |on_stderr| see |channel-callback|.
*on_exit*
Arguments passed to on_exit callback:
0: |job-id|
1: Exit-code of the process, or 128+SIGNUM if by signal (e.g. 143 on SIGTERM).
2: Event type: "exit"
Note: Buffered stdout/stderr data which has not been flushed by the sender
will not trigger the on_stdout/on_stderr callback (but if the process
ends, the on_exit callback will be invoked).
For example, "ruby -e" buffers output, so small strings will be
buffered unless "auto-flushing" ($stdout.sync=true) is enabled. >vim
function! Receive(job_id, data, event)
echom printf('%s: %s',a:event,string(a:data))
endfunction
call jobstart(['ruby', '-e',
\ '$stdout.sync = true; 5.times do sleep 1 and puts "Hello Ruby!" end'],
\ {'on_stdout': 'Receive'})
< https://github.com/neovim/neovim/issues/1592
Note 2:
Job event handlers may receive partial (incomplete) lines. For a given
invocation of on_stdout/on_stderr, `a:data` is not guaranteed to end
with a newline.
- `abcdefg` may arrive as `['abc']`, `['defg']`.
- `abc\nefg` may arrive as `['abc', '']`, `['efg']` or `['abc']`,
`['','efg']`, or even `['ab']`, `['c','efg']`.
Easy way to deal with this: initialize a list as `['']`, then append
to it as follows: >vim
let s:chunks = ['']
func! s:on_stdout(job_id, data, event) dict
let s:chunks[-1] .= a:data[0]
call extend(s:chunks, a:data[1:])
endf
<
The |jobstart-options| dictionary is passed as |self| to the callback.
The above example could be written in this "object-oriented" style: >vim
let Shell = {}
function Shell.on_stdout(_job_id, data, event)
call append(line('$'),
\ printf('[%s] %s: %s', a:event, self.name, join(a:data[:-2])))
endfunction
let Shell.on_stderr = function(Shell.on_stdout)
function Shell.on_exit(job_id, _data, event)
let msg = printf('job %d ("%s") finished', a:job_id, self.name)
call append(line('$'), printf('[%s] BOOM!', a:event))
call append(line('$'), printf('[%s] %s!', a:event, msg))
endfunction
function Shell.new(name, cmd)
let object = extend(copy(g:Shell), {'name': a:name})
let object.cmd = ['sh', '-c', a:cmd]
let object.id = jobstart(object.cmd, object)
$
return object
endfunction
let instance = Shell.new('bomb',
\ 'for i in $(seq 9 -1 1); do echo $i 1>&$((i % 2 + 1)); sleep 1; done')
<
To send data to the job's stdin, use |chansend()|: >vim
:call chansend(job1, "ls\n")
:call chansend(job1, "invalid-command\n")
:call chansend(job1, "exit\n")
<
A job may be killed at any time with the |jobstop()| function:
>vim
:call jobstop(job1)
<
Individual streams can be closed without killing the job, see |chanclose()|.
==============================================================================
vim:tw=78:ts=8:noet:ft=help:norl:
|
