 logger = require "logger-sharelatex"
 os = require "os"
 crypto = require "crypto"
+
+Profiler = require "./Profiler"
 
 HOST = os.hostname()
 PID = process.pid

	tryLock : (doc_id, callback = (err, isFree)->)->
		lockValue = LockManager.randomLock()
		key = keys.blockingKey(doc_id:doc_id)
		logger.log {doc_id: doc_id, key: key}, "tryLock"
		rclient.set key, lockValue, "EX", @LOCK_TTL, "NX", (err, gotLock)->
			return callback(err) if err?
			if gotLock == "OK"
				metrics.inc "doc-not-blocking"
				logger.log {doc_id: doc_id, key: key, lockValue: lockValue}, "got lock"
				callback err, true, lockValue
			else
				metrics.inc "doc-blocking"
				logger.log {doc_id: doc_id, key: key}, "doc is locked"
				callback err, false

	getLock: (doc_id, callback = (error, lockValue) ->) ->
		startTime = Date.now()
		testInterval = LockManager.LOCK_TEST_INTERVAL
		do attempt = () ->
			if Date.now() - startTime > LockManager.MAX_LOCK_WAIT_TIME
				e = new Error("Timeout")
				e.doc_id = doc_id
				return callback(e)

			LockManager.tryLock doc_id, (error, gotLock, lockValue) ->
				return callback(error) if error?
				if gotLock
					callback(null, lockValue)
				else
					logger.log {doc_id: doc_id, delay: testInterval}, "will retry lock"
					setTimeout attempt, testInterval
					# back off when the lock is taken to avoid overloading
					testInterval = Math.min(testInterval * 2, LockManager.MAX_TEST_INTERVAL)


	releaseLock: (doc_id, lockValue, callback)->
		key = keys.blockingKey(doc_id:doc_id)
		profile = new Profiler("releaseLock", {doc_id, key, lockValue})
		rclient.eval LockManager.unlockScript, 1, key, lockValue, (err, result) ->
			if err?
				return callback(err)
			else if result? and result isnt 1 # successful unlock should release exactly one key
				profile.log("unlockScript:expired-lock").end()
				logger.error {doc_id:doc_id, key:key, lockValue:lockValue, redis_err:err, redis_result:result}, "unlocking error"
				return callback(new Error("tried to release timed out lock"))
			else
				profile.log("unlockScript:ok").end()
				callback(err,result)
