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add createMonitoredSubscriptionClient method

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James Allen 2014-11-19 14:05:16 +00:00
parent 42cbaecbe0
commit 1ee287ed98
1 changed files with 31 additions and 0 deletions
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31
libraries/redis-wrapper/index.coffee
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@ -20,6 +20,7 @@ module.exports = RedisSharelatex =
client = require("redis").createClient opts.port, opts.host, standardOpts
return client
# DO NOT USE. Not robust at all (ends up getting subscribed twice, etc)!
createRobustSubscriptionClient: (opts, heartbeatOpts = {}) ->
sub = RedisSharelatex.createClient(opts)
pub = RedisSharelatex.createClient(opts)
@ -64,6 +65,36 @@ module.exports = RedisSharelatex =
, heartbeatInterval
return sub
# Attaches an isAlive() method to the subsciption client which returns true
# so long as we have had a heartbeat recently.
createMonitoredSubscriptionClient: (opts, heartbeatOpts = {}) ->
sub = RedisSharelatex.createClient(opts)
pub = RedisSharelatex.createClient(opts)
heartbeatInterval = heartbeatOpts.heartbeat_interval or 2000 #ms
isAliveTimeout = heartbeatOpts.is_alive_timeout or 10000 #ms
id = require("crypto").pseudoRandomBytes(16).toString("hex")
heartbeatChannel = "heartbeat-#{id}"
lastHeartbeat = Date.now()
sub.subscribe heartbeatChannel, (error) ->
if error?
console.error "ERROR: failed to subscribe to #{heartbeatChannel} channel", error
sub.on "message", (channel, message) ->
if channel == heartbeatChannel
lastHeartbeat = Date.now()
sub.isAlive = () ->
timeSinceLastHeartbeat = Date.now() - lastHeartbeat
return (timeSinceLastHeartbeat < isAliveTimeout)
setInterval () ->
pub.publish heartbeatChannel, "PING"
, heartbeatInterval
return sub