overleaf/services/track-changes/app/coffee/RedisManager.coffee
Brian Gough b5b61b98d0 avoid blocking when fetching redis keys
use scan instead of keys method
2017-04-19 15:39:33 +01:00

72 lines
2.8 KiB
CoffeeScript

Settings = require "settings-sharelatex"
redis = require("redis-sharelatex")
rclient = redis.createClient(Settings.redis.web)
rawUpdatesKey = (doc_id) -> "UncompressedHistoryOps:#{doc_id}"
docsWithHistoryOpsKey = (project_id) -> "DocsWithHistoryOps:#{project_id}"
module.exports = RedisManager =
getOldestDocUpdates: (doc_id, batchSize, callback = (error, jsonUpdates) ->) ->
key = rawUpdatesKey(doc_id)
rclient.lrange key, 0, batchSize - 1, callback
expandDocUpdates: (jsonUpdates, callback = (error, rawUpdates) ->) ->
try
rawUpdates = ( JSON.parse(update) for update in jsonUpdates or [] )
catch e
return callback(e)
callback null, rawUpdates
deleteAppliedDocUpdates: (project_id, doc_id, docUpdates, callback = (error) ->) ->
multi = rclient.multi()
# Delete all the updates which have been applied (exact match)
for update in docUpdates or []
multi.lrem rawUpdatesKey(doc_id), 0, update
# It's ok to delete the doc_id from the set here. Even though the list
# of updates may not be empty, we will continue to process it until it is.
multi.srem docsWithHistoryOpsKey(project_id), doc_id
multi.exec (error, results) ->
return callback(error) if error?
callback null
getDocIdsWithHistoryOps: (project_id, callback = (error, doc_ids) ->) ->
rclient.smembers docsWithHistoryOpsKey(project_id), callback
# iterate over keys asynchronously using redis scan (non-blocking)
_getKeys: (pattern, callback) ->
cursor = 0 # redis iterator
keySet = {} # use hash to avoid duplicate results
# scan over all keys looking for pattern
doIteration = (cb) ->
rclient.scan cursor, "MATCH", pattern, "COUNT", 1000, (error, reply) ->
return callback(error) if error?
[cursor, keys] = reply
for key in keys
keySet[key] = true
if cursor == '0' # note redis returns string result not numeric
return callback(null, Object.keys(keySet))
else
doIteration()
doIteration()
# extract ids from keys like DocsWithHistoryOps:57fd0b1f53a8396d22b2c24b
_extractIds: (keyList) ->
ids = (key.split(":")[1] for key in keyList)
return ids
# this will only work on single node redis, not redis cluster
getProjectIdsWithHistoryOps: (callback = (error, project_ids) ->) ->
RedisManager._getKeys docsWithHistoryOpsKey("*"), (error, project_keys) ->
return callback(error) if error?
project_ids = RedisManager._extractIds project_keys
callback(error, project_ids)
# this will only work on single node redis, not redis cluster
getAllDocIdsWithHistoryOps: (callback = (error, doc_ids) ->) ->
# return all the docids, to find dangling history entries after
# everything is flushed.
RedisManager._getKeys rawUpdatesKey("*"), (error, doc_keys) ->
return callback(error) if error?
doc_ids = RedisManager._extractIds doc_keys
callback(error, doc_ids)