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71 lines
2.7 KiB
CoffeeScript
71 lines
2.7 KiB
CoffeeScript
metrics = require('metrics-sharelatex')
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Settings = require('settings-sharelatex')
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RedisWrapper = require("./RedisWrapper")
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rclient = RedisWrapper.client("lock")
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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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SLOW_EXECUTION_THRESHOLD: 5000 # 5s, if execution takes longer than this then log
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runWithLock: (namespace, id, runner = ( (releaseLock = (error) ->) -> ), callback = ( (error) -> )) ->
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# This error is defined here so we get a useful stacktrace
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slowExecutionError = new Error "slow execution during lock"
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timer = new metrics.Timer("lock.#{namespace}")
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key = "lock:web:#{namespace}:#{id}"
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LockManager._getLock key, namespace, (error) ->
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return callback(error) if error?
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# The lock can expire in redis but the process carry on. This setTimout call
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# is designed to log if this happens.
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countIfExceededLockTimeout = () ->
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metrics.inc "lock.#{namespace}.exceeded_lock_timeout"
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logger.log "exceeded lock timeout", { namespace, id, slowExecutionError }
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exceededLockTimeout = setTimeout countIfExceededLockTimeout, LockManager.REDIS_LOCK_EXPIRY * 1000
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runner (error1, values...) ->
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LockManager._releaseLock key, (error2) ->
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clearTimeout exceededLockTimeout
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timeTaken = new Date - timer.start
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if timeTaken > LockManager.SLOW_EXECUTION_THRESHOLD
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logger.log "slow execution during lock", { namespace, id, timeTaken, slowExecutionError }
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timer.done()
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error = error1 or error2
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return callback(error) if error?
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callback null, values...
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_tryLock : (key, namespace, callback = (err, isFree)->)->
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rclient.set 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 "lock.#{namespace}.try.success"
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callback err, true
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else
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metrics.inc "lock.#{namespace}.try.failed"
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logger.log key: key, redis_response: gotLock, "lock is locked"
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callback err, false
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_getLock: (key, namespace, callback = (error) ->) ->
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startTime = Date.now()
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attempts = 0
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do attempt = () ->
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if Date.now() - startTime > LockManager.MAX_LOCK_WAIT_TIME
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metrics.inc "lock.#{namespace}.get.failed"
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return callback(new Error("Timeout"))
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attempts += 1
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LockManager._tryLock key, namespace, (error, gotLock) ->
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return callback(error) if error?
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if gotLock
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metrics.gauge "lock.#{namespace}.get.success.tries", attempts
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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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_releaseLock: (key, callback)->
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rclient.del key, callback
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