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