nqm-minimongo

### Database which caches locally in a localDb but pulls results ultimately from a RemoteDb ### _ = require 'lodash' processFind = require('./utils').processFind module.exports = class HybridDb constructor: (localDb, remoteDb) -> @localDb = localDb @remoteDb = remoteDb @collections = {} addCollection: (name, options, success, error) -> # Shift options over if not present if _.isFunction(options) [options, success, error] = [{}, options, success] collection = new HybridCollection(name, @localDb[name], @remoteDb[name], options) @[name] = collection @collections[name] = collection if success? then success() removeCollection: (name, success, error) -> delete @[name] delete @collections[name] if success? then success() upload: (success, error) -> cols = _.values(@collections) uploadCols = (cols, success, error) -> col = _.first(cols) if col col.upload(-> uploadCols(_.rest(cols), success, error) , (err) -> error(err)) else success() uploadCols(cols, success, error) class HybridCollection # Options includes constructor: (name, localCol, remoteCol, options) -> @name = name @localCol = localCol @remoteCol = remoteCol # Default options options = options or {} _.defaults(options, { caching: true }) # Extract options @caching = options.caching # options.mode defaults to "hybrid" (unless caching=false, in which case "remote") # In "hybrid", it will return local results, then hit remote and return again if different # If remote gives error, it will be ignored # In "remote", it will call remote and not cache, but integrates local upserts/deletes # If remote gives error, then it will return local results # In "local", just returns local results find: (selector, options = {}) -> return fetch: (success, error) => @_findFetch(selector, options, success, error) # options.mode defaults to "hybrid". # In "hybrid", it will return local if present, otherwise fall to remote without returning null # If remote gives error, then it will return null if none locally. If remote and local differ, it # will return twice # In "local", it will return local if present. If not present, only then will it hit remote. # If remote gives error, then it will return null # In "remote", it gets remote and integrates local changes. Much more efficient if _id specified # If remote gives error, falls back to local if caching findOne: (selector, options = {}, success, error) -> if _.isFunction(options) [options, success, error] = [{}, options, success] mode = options.mode || (if @caching then "hybrid" else "remote") if mode == "hybrid" or mode == "local" options.limit = 1 @localCol.findOne selector, options, (localDoc) => # If found, return if localDoc success(localDoc) # No need to hit remote if local if mode == "local" return remoteSuccess = (remoteDoc) => # Cache cacheSuccess = => # Try query again @localCol.findOne selector, options, (localDoc2) -> if not _.isEqual(localDoc, localDoc2) success(localDoc2) else if not localDoc success(null) docs = if remoteDoc then [remoteDoc] else [] @localCol.cache(docs, selector, options, cacheSuccess, error) remoteError = -> # Remote errored out. Return null if local did not return if not localDoc success(null) # Call remote @remoteCol.findOne selector, _.omit(options, 'fields'), remoteSuccess, remoteError , error else if mode == "remote" # If _id specified, use remote findOne if selector._id remoteSuccess2 = (remoteData) => # Check for local upsert @localCol.pendingUpserts (pendingUpserts) => localData = _.findWhere(pendingUpserts, { _id: selector._id }) if localData return success(localData) # Check for local remove @localCol.pendingRemoves (pendingRemoves) -> if selector._id in pendingRemoves # Removed, success null return success(null) success(remoteData) , error # Get remote response @remoteCol.findOne selector, options, remoteSuccess2, error else # Without _id specified, interaction between local and remote changes is complex # For example, if the one result returned by remote is locally deleted, we have no fallback # So instead we do a normal find and then take the first result, which is very inefficient @find(selector, options).fetch (findData) -> if findData.length > 0 success(findData[0]) else success(null) , (err) => # Call local if caching if @caching @localCol.findOne(selector, options, success, error) else # Otherwise bubble up if error error(err) else throw new Error("Unknown mode") _findFetch: (selector, options, success, error) -> mode = options.mode || (if @caching then "hybrid" else "remote") if mode == "hybrid" # Get local results localSuccess = (localData) => # Return data immediately success(localData) # Get remote data remoteSuccess = (remoteData) => # Cache locally cacheSuccess = => # Get local data again localSuccess2 = (localData2) -> # Check if different if not _.isEqual(localData, localData2) # Send again success(localData2) @localCol.find(selector, options).fetch(localSuccess2, error) @localCol.cache(remoteData, selector, options, cacheSuccess, error) @remoteCol.find(selector, _.omit(options, "fields")).fetch(remoteSuccess) @localCol.find(selector, options).fetch(localSuccess, error) else if mode == "local" @localCol.find(selector, options).fetch(success, error) else if mode == "remote" # Get remote results remoteSuccess = (remoteData) => # Remove local remotes data = remoteData @localCol.pendingRemoves (removes) => if removes.length > 0 removesMap = _.object(_.map(removes, (id) -> [id, id])) data = _.filter remoteData, (doc) -> return not _.has(removesMap, doc._id) # Add upserts @localCol.pendingUpserts (upserts) -> if upserts.length > 0 # Remove upserts from data upsertsMap = _.object(_.pluck(upserts, '_id'), _.pluck(upserts, '_id')) data = _.filter data, (doc) -> return not _.has(upsertsMap, doc._id) # Add upserts data = data.concat(upserts) # Refilter/sort/limit data = processFind(data, selector, options) success(data) remoteError = (err) => # Call local if caching if @caching @localCol.find(selector, options).fetch(success, error) else # Otherwise bubble up if error error(err) @remoteCol.find(selector, options).fetch(remoteSuccess, remoteError) else throw new Error("Unknown mode") upsert: (doc, success, error) -> @localCol.upsert(doc, (result) -> success(result) if success? , error) remove: (id, success, error) -> @localCol.remove(id, -> success() if success? , error) upload: (success, error) -> uploadUpserts = (upserts, success, error) => upsert = _.first(upserts) if upsert @remoteCol.upsert upsert, (remoteDoc) => @localCol.resolveUpsert upsert, => # Cache new value if caching if @caching @localCol.cacheOne remoteDoc, -> uploadUpserts(_.rest(upserts), success, error) , error else # Remove document @localCol.remove upsert._id, => # Resolve remove @localCol.resolveRemove upsert._id, -> uploadUpserts(_.rest(upserts), success, error) , error , error , error , (err) => # If 410 error or 403, remove document if err.status == 410 or err.status == 403 @localCol.remove upsert._id, => # Resolve remove @localCol.resolveRemove upsert._id, -> # Continue if was 410 if err.status == 410 uploadUpserts(_.rest(upserts), success, error) else error(err) , error , error else error(err) else success() uploadRemoves = (removes, success, error) => remove = _.first(removes) if remove @remoteCol.remove remove, => @localCol.resolveRemove remove, -> uploadRemoves(_.rest(removes), success, error) , error , (err) => # If 403 or 410, remove document if err.status == 410 or err.status == 403 @localCol.resolveRemove remove, -> # Continue if was 410 if err.status == 410 uploadRemoves(_.rest(removes), success, error) else error(err) , error else error(err) , error else success() # Get pending upserts @localCol.pendingUpserts (upserts) => uploadUpserts upserts, => @localCol.pendingRemoves (removes) -> uploadRemoves(removes, success, error) , error , error , error