overleaf/services/web/app/coffee/infrastructure/LockManager.coffee

54 lines
1.7 KiB
CoffeeScript

metrics = require('metrics-sharelatex')
Settings = require('settings-sharelatex')
RedisWrapper = require("./RedisWrapper")
rclient = RedisWrapper.client("lock")
logger = require "logger-sharelatex"
module.exports = LockManager =
LOCK_TEST_INTERVAL: 50 # 50ms between each test of the lock
MAX_LOCK_WAIT_TIME: 10000 # 10s maximum time to spend trying to get the lock
REDIS_LOCK_EXPIRY: 30 # seconds. Time until lock auto expires in redis.
_blockingKey : (key)-> "lock:web:{#{key}}"
tryLock : (key, callback = (err, isFree)->)->
rclient.set LockManager._blockingKey(key), "locked", "EX", LockManager.REDIS_LOCK_EXPIRY, "NX", (err, gotLock)->
return callback(err) if err?
if gotLock == "OK"
metrics.inc "lock-not-blocking"
callback err, true
else
metrics.inc "lock-blocking"
logger.log key: key, redis_response: gotLock, "lock is locked"
callback err, false
getLock: (key, callback = (error) ->) ->
startTime = Date.now()
do attempt = () ->
if Date.now() - startTime > LockManager.MAX_LOCK_WAIT_TIME
return callback(new Error("Timeout"))
LockManager.tryLock key, (error, gotLock) ->
return callback(error) if error?
if gotLock
callback(null)
else
setTimeout attempt, LockManager.LOCK_TEST_INTERVAL
checkLock: (key, callback = (err, isFree)->)->
multi = rclient.multi()
multi.exists LockManager._blockingKey(key)
multi.exec (err, replys)->
return callback(err) if err?
exists = parseInt replys[0]
if exists == 1
metrics.inc "lock-blocking"
callback err, false
else
metrics.inc "lock-not-blocking"
callback err, true
releaseLock: (key, callback)->
rclient.del LockManager._blockingKey(key), callback