overleaf/services/real-time/app/coffee/HealthCheckManager.coffee

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2019-04-15 09:05:26 -04:00
metrics = require "metrics-sharelatex"
os = require "os"
HOST = os.hostname()
PID = process.pid
COUNT = 0
CHANNEL_MANAGER = {} # hash of event checkers by channel name
CHANNEL_ERROR = {} # error status by channel name
module.exports = class HealthCheckManager
# create an instance of this class which checks that an event with a unique
# id is received only once within a timeout
constructor: (@channel, timeout = 1000) ->
# unique event string
@id = "host=#{HOST}:pid=#{PID}:count=#{COUNT++}"
# count of number of times the event is received
@count = 0
# after a timeout check the status of the count
@handler = setTimeout () =>
@setStatus()
, timeout
# use a timer to record the latency of the channel
@timer = new metrics.Timer("event.#{@channel}.latency")
# keep a record of these objects to dispatch on
CHANNEL_MANAGER[@channel] = @
processEvent: (id) ->
# if this is our event record it
if id == @id
@count++
@timer?.done()
@timer = null # only time the latency of the first event
setStatus: () ->
# if we saw the event anything other than a single time that is an error
error = (@count != 1)
CHANNEL_ERROR[@channel] = error
# class methods
@check: (channel, id) ->
# dispatch event to manager for channel
CHANNEL_MANAGER[channel]?.processEvent id
@status: () ->
# return status of all channels for logging
return CHANNEL_ERROR
@isFailing: () ->
# check if any channel status is bad
for channel, error of CHANNEL_ERROR
return true if error is true
return false