Files
atom/src/buffered-process.coffee
2014-02-24 16:59:58 -08:00

100 lines
3.4 KiB
CoffeeScript

ChildProcess = require 'child_process'
# Public: A wrapper which provides standard error/output line buffering for
# Node's ChildProcess.
#
# ## Requiring in packages
#
# ```coffee
# {BufferedProcess} = require 'atom'
#
# command = 'ps'
# args = ['-ef']
# stdout = (output) -> console.log(output)
# exit = (code) -> console.log("ps -ef exited with #{code}")
# process = new BufferredProcess({command, args, stdout, exit})
# ```
module.exports =
class BufferedProcess
# Public: Runs the given command by spawning a new child process.
#
# options - An {Object} with the following keys:
# :command - The {String} command to execute.
# :args - The {Array} of arguments to pass to the command (optional).
# :options - The options {Object} to pass to Node's `ChildProcess.spawn`
# method (optional).
# :stdout - The callback {Function} that receives a single argument which
# contains the standard output from the command. The callback is
# called as data is received but it's buffered to ensure only
# complete lines are passed until the source stream closes. After
# the source stream has closed all remaining data is sent in a
# final call (optional).
# :stderr - The callback {Function} that receives a single argument which
# contains the standard error output from the command. The
# callback is called as data is received but it's buffered to
# ensure only complete lines are passed until the source stream
# closes. After the source stream has closed all remaining data
# is sent in a final call (optional).
# :exit - The callback {Function} which receives a single argument
# containing the exit status (optional).
constructor: ({command, args, options, stdout, stderr, exit}={}) ->
options ?= {}
@process = ChildProcess.spawn(command, args, options)
@killed = false
stdoutClosed = true
stderrClosed = true
processExited = true
exitCode = 0
triggerExitCallback = ->
return if @killed
if stdoutClosed and stderrClosed and processExited
exit?(exitCode)
if stdout
stdoutClosed = false
@bufferStream @process.stdout, stdout, ->
stdoutClosed = true
triggerExitCallback()
if stderr
stderrClosed = false
@bufferStream @process.stderr, stderr, ->
stderrClosed = true
triggerExitCallback()
if exit
processExited = false
@process.on 'exit', (code) ->
exitCode = code
processExited = true
triggerExitCallback()
# Helper method to pass data line by line.
#
# stream - The Stream to read from.
# onLines - The callback to call with each line of data.
# onDone - The callback to call when the stream has closed.
bufferStream: (stream, onLines, onDone) ->
stream.setEncoding('utf8')
buffered = ''
stream.on 'data', (data) =>
return if @killed
buffered += data
lastNewlineIndex = buffered.lastIndexOf('\n')
if lastNewlineIndex isnt -1
onLines(buffered.substring(0, lastNewlineIndex + 1))
buffered = buffered.substring(lastNewlineIndex + 1)
stream.on 'close', =>
return if @killed
onLines(buffered) if buffered.length > 0
onDone()
# Public: Terminate the process.
kill: ->
@killed = true
@process.kill()
@process = null