overleaf/services/clsi/app/coffee/LockManager.coffee

Settings = require('settings-sharelatex')
logger = require "logger-sharelatex"
Lockfile = require('lockfile') # from https://github.com/npm/lockfile
Errors = require "./Errors"
fs = require("fs")
Path = require("path")
module.exports = LockManager =
	LOCK_TEST_INTERVAL: 1000 # 50ms between each test of the lock
	MAX_LOCK_WAIT_TIME: 15000 # 10s maximum time to spend trying to get the lock
	LOCK_STALE: 5*60*1000 # 5 mins time until lock auto expires

	runWithLock: (path, runner = ((releaseLock = (error) ->) ->), callback = ((error) ->)) ->
		lockOpts =
			wait: @MAX_LOCK_WAIT_TIME
			pollPeriod: @LOCK_TEST_INTERVAL
			stale: @LOCK_STALE
		Lockfile.lock path, lockOpts, (error) ->
			if error?.code is 'EEXIST'
				return callback new Errors.AlreadyCompilingError("compile in progress")
			else if error?
				fs.lstat path, (statLockErr, statLock)->
					fs.lstat Path.dirname(path), (statDirErr, statDir)->
						fs.readdir Path.dirname(path), (readdirErr, readdirDir)->
							logger.err error:error, path:path, statLock:statLock, statLockErr:statLockErr, statDir:statDir, statDirErr: statDirErr, readdirErr:readdirErr, readdirDir:readdirDir, "unable to get lock"
							return callback(error)
			else
				runner (error1, args...) ->
					Lockfile.unlock path, (error2) ->
						error = error1 or error2
						return callback(error) if error?
						callback(null, args...)