| // Syncbase-based implementation of Dispatcher. |
| // |
| // Schema design doc (a bit outdated): |
| // https://docs.google.com/document/d/1GtBk75QmjSorUW6T6BATCoiS_LTqOrGksgqjqJ1Hiow/edit# |
| // |
| // TODO(sadovsky): Currently, list and todo order are not preserved. We should |
| // make the app always order these lexicographically, or better yet, use a |
| // Dewey-Decimal-like scheme (with randomization). |
| // |
| // NOTE: For now, when an item is deleted, any sub-items that were added |
| // concurrently (on some other device) are orphaned. Eventually, we'll GC |
| // orphaned records; for now, we don't bother. This orphaning-based approach |
| // enables us to use simple last-one-wins conflict resolution for all records |
| // stored in Syncbase. |
| // |
| // TODO(sadovsky): Orphaning degrades performance, because scan responses (e.g. |
| // scan to get all lists) include orphaned records. If we switch from scans to |
| // queries, performance should improve since all row filtering will happen |
| // server side. |
| |
| 'use strict'; |
| |
| var _ = require('lodash'); |
| var async = require('async'); |
| var inherits = require('inherits'); |
| var randomBytes = require('randombytes'); |
| var syncbase = require('syncbase'); |
| var nosql = syncbase.nosql; |
| var vanadium = require('vanadium'); |
| var vtrace = vanadium.vtrace; |
| |
| var bm = require('./benchmark'); |
| var Dispatcher = require('./dispatcher'); |
| |
| inherits(SyncbaseDispatcher, Dispatcher); |
| module.exports = SyncbaseDispatcher; |
| |
| function SyncbaseDispatcher(rt, db) { |
| Dispatcher.call(this); |
| this.rt_ = rt; |
| this.ctx_ = rt.getContext(); |
| this.db_ = db; |
| this.tb_ = db.table('tb'); |
| } |
| |
| //////////////////////////////////////// |
| // Helpers |
| |
| function noop() {} |
| |
| var SEP = '.'; // separator for key parts |
| |
| function join() { |
| // TODO(sadovsky): Switch to using naming.join() once Syncbase allows slashes |
| // in row keys. |
| var args = Array.prototype.slice.call(arguments); |
| return args.join(SEP); |
| } |
| |
| function uuid(len) { |
| len = len || 16; |
| return randomBytes(Math.ceil(len / 2)).toString('hex').substr(0, len); |
| } |
| |
| function newListKey() { |
| return uuid(); |
| } |
| |
| function newTodoKey(listId) { |
| return join(listId, 'todos', uuid()); |
| } |
| |
| function tagKey(todoId, tag) { |
| return join(todoId, 'tags', tag); |
| } |
| |
| function marshal(x) { |
| return JSON.stringify(x); |
| } |
| |
| function unmarshal(x) { |
| return JSON.parse(x); |
| } |
| |
| //////////////////////////////////////// |
| // Vanadium helpers |
| |
| // Returns a new Vanadium context object with a timeout. |
| function wt(ctx, timeout) { |
| return ctx.withTimeout(timeout || 5000); |
| } |
| |
| // Returns a new Vanadium context object with the given name. |
| function wn(ctx, name) { |
| return vtrace.withNewSpan(ctx, name); |
| } |
| |
| // Defines a SyncbaseDispatcher method. If the first argument to fn is not a |
| // context, creates a new context with a timeout. |
| function define(name, fn) { |
| SyncbaseDispatcher.prototype[name] = function() { |
| var args = Array.prototype.slice.call(arguments); |
| var ctx = args[0]; |
| if (ctx instanceof vanadium.context.Context) { |
| args.shift(); |
| } else { |
| ctx = wt(this.ctx_); |
| } |
| args = [wn(ctx, name)].concat(args); |
| // The callback argument is optional, and clients don't always pass one. |
| if (typeof args[args.length - 1] !== 'function') { |
| args.push(noop); |
| } |
| // Drop ctx and cb, convert to JSON, drop square brackets. |
| var cb = args[args.length - 1]; |
| var argsStr = JSON.stringify(args.slice(1, -1)).slice(1, -1); |
| args[args.length - 1] = bm.logFn(name + '(' + argsStr + ')', cb); |
| return fn.apply(this, args); |
| }; |
| } |
| |
| //////////////////////////////////////// |
| // SyncbaseDispatcher impl |
| |
| // TODO(sadovsky): Switch to storing VDL values (instead of JSON) and use a |
| // query to get all values of a particular type. |
| define('getLists', function(ctx, cb) { |
| var that = this; |
| // NOTE(sadovsky): Storing lists in a separate keyspace from todos and tags |
| // could make this scan faster. But given the size of the data (tiny), it |
| // shouldn't make much difference. |
| async.parallel([ |
| function(cb) { |
| that.getRows_(ctx, null, function(err, rows) { |
| if (err) return cb(err); |
| var lists = []; |
| _.forEach(rows, function(row) { |
| if (row.key.indexOf(SEP) >= 0) { |
| return; |
| } |
| lists.push(_.assign({}, unmarshal(row.value), {_id: row.key})); |
| }); |
| return cb(null, lists); |
| }); |
| }, |
| // Returns a list of SG objects (from getSyncGroup), one per SG. |
| // TODO(sadovsky): Would be nice if Syncbase could provide more info in a |
| // single RPC. |
| function(cb) { |
| bm.logFn('getSyncGroupNames', cb); |
| // FIXME: Remove this hack once db.getSyncGroupNames, sg.getSpec, and |
| // sg.getMembers are implemented. |
| /* jshint -W027 */ |
| return process.nextTick(function() { |
| cb(null, []); |
| }); |
| that.db_.getSyncGroupNames(ctx, function(err, sgNames) { |
| if (err) return cb(err); |
| async.map(sgNames, function(sgName, cb) { |
| that.getSyncGroup(ctx, that.sgNameToListId_(sgName), cb); |
| }, cb); |
| }); |
| } |
| ], function(err, results) { |
| if (err) return cb(err); |
| var lists = results[0], sgs = results[1]; |
| // Left join: add 'sg' field to each list for which there's an SG. |
| _.forEach(lists, function(list) { |
| var listId = list._id; |
| _.forEach(sgs, function(sg) { |
| console.assert(sg.spec.Prefixes.length === 1); |
| if (listId === sg.spec.Prefixes[0]) { |
| list.sg = sg; |
| } |
| }); |
| }); |
| return cb(null, lists); |
| }); |
| }); |
| |
| define('getTodos', function(ctx, listId, cb) { |
| this.getRows_(ctx, listId, function(err, rows) { |
| if (err) return cb(err); |
| var todos = []; |
| var todo = {}; |
| _.forEach(rows, function(row) { |
| var parts = row.key.split(SEP); |
| if (parts.length < 2 || parts[0] !== listId) { |
| return; |
| } else if (parts.length === 3) { // next todo |
| if (todo._id) { |
| todos.push(todo); |
| } |
| todo = _.assign({}, unmarshal(row.value), {_id: row.key}); |
| } else if (parts.length === 5) { // tag for current todo |
| if (!todo.tags) { |
| todo.tags = []; |
| } |
| todo.tags.push(parts[4]); // push tag name |
| } else { |
| throw new Error('bad key: ' + row.key); |
| } |
| }); |
| return cb(null, todos); |
| }); |
| }); |
| |
| define('addList', function(ctx, list, cb) { |
| console.assert(!list._id); |
| var listId = newListKey(); |
| var v = marshal(list); |
| this.tb_.put(ctx, listId, v, this.maybeEmit_(function(err) { |
| if (err) return cb(err); |
| return cb(null, listId); |
| })); |
| }); |
| |
| define('editListName', function(ctx, listId, name, cb) { |
| this.update_(ctx, listId, function(list) { |
| return _.assign(list, {name: name}); |
| }, cb); |
| }); |
| |
| define('addTodo', function(ctx, listId, todo, cb) { |
| console.assert(!todo._id); |
| var that = this; |
| var tags = todo.tags; |
| delete todo.tags; |
| var todoId = newTodoKey(listId); |
| var v = marshal(todo); |
| // Write todo and tags in a batch. |
| var opts = new nosql.BatchOptions(); |
| nosql.runInBatch(ctx, this.db_, opts, function(db, cb) { |
| // NOTE: Dealing with tables is awkward given that batches and syncgroups |
| // are database-level. Maybe we should just get rid of tables. Doing so |
| // would solve other problems as well, e.g. the API inconsistency for |
| // creating databases vs. tables. |
| var tb = db.table('tb'); |
| tb.put(wn(ctx, 'put:' + todoId), todoId, v, function(err) { |
| if (err) return cb(err); |
| async.each(tags, function(tag, cb) { |
| that.addTagImpl_(ctx, tb, todoId, tag, cb); |
| }, cb); |
| }); |
| }, this.maybeEmit_(cb)); |
| }); |
| |
| define('removeTodo', function(ctx, todoId, cb) { |
| this.tb_.row(todoId).delete(ctx, this.maybeEmit_(cb)); |
| }); |
| |
| define('editTodoText', function(ctx, todoId, text, cb) { |
| this.update_(ctx, todoId, function(todo) { |
| return _.assign(todo, {text: text}); |
| }, cb); |
| }); |
| |
| define('markTodoDone', function(ctx, todoId, done, cb) { |
| this.update_(ctx, todoId, function(todo) { |
| return _.assign(todo, {done: done}); |
| }, cb); |
| }); |
| |
| define('addTag', function(ctx, todoId, tag, cb) { |
| this.addTagImpl_(ctx, this.tb_, todoId, tag, this.maybeEmit_(cb)); |
| }); |
| |
| define('removeTag', function(ctx, todoId, tag, cb) { |
| // NOTE: Table.delete is awkward (it takes a range), so instead we use |
| // Row.delete. It would be nice for Table.delete to operate on a single row |
| // and have a separate Table.deleteRowRange. |
| this.tb_.row(tagKey(todoId, tag)).delete(ctx, this.maybeEmit_(cb)); |
| }); |
| |
| //////////////////////////////////////// |
| // SyncGroup methods |
| |
| // TODO(sadovsky): It's not clear from the Syncbase API how SG names should be |
| // constructed, and it's also weird that db.SyncGroup(name) expects an absolute |
| // name. We should probably allow clients to specify DB-relative SG names. |
| |
| // Currently, SG names must be of the form <syncbaseName>/$sync/<suffix>. |
| // We use <app>/<db>/<table>/<listId> for the suffix part |
| |
| SyncbaseDispatcher.prototype.sgNameToListId_ = function(sgName) { |
| return sgName.replace(new RegExp('.*/$sync/todos/db/tb/'), ''); |
| }; |
| |
| SyncbaseDispatcher.prototype.listIdToSgName_ = function(listId) { |
| var prefix = this.tb_.fullName.replace('/todos/db/tb/', |
| '/$sync/todos/db/tb/'); |
| return prefix + listId; |
| }; |
| |
| // Returns spec and members for the given list. |
| define('getSyncGroup', function(ctx, listId, cb) { |
| var sg = this.db_.syncGroup(this.listIdToSgName_(listId)); |
| async.parallel([ |
| function(cb) { |
| sg.getSpec(ctx, cb); |
| }, |
| function(cb) { |
| sg.getMembers(ctx, cb); |
| } |
| ], function(err, results) { |
| if (err) return cb(err); |
| // FIXME: Convert 'members' to email addresses. |
| return { |
| spec: results[0], |
| members: _.keys(results[1]) |
| }; |
| }); |
| }); |
| |
| // TODO(sadovsky): Copied from test-syncgroup.js. I have no idea whether this |
| // value is appropriate. |
| var MEMBER_INFO = new nosql.SyncGroupMemberInfo({ |
| syncPriority: 8 |
| }); |
| |
| define('createSyncGroup', function(ctx, listId, cb) { |
| var sg = this.db_.syncGroup(this.listIdToSgName_(listId)); |
| var spec = new nosql.SyncGroupSpec({ |
| // TODO(sadovsky): Make perms more restrictive. |
| perms: new Map([ |
| ['Admin', {'In': ['...']}], |
| ['Read', {'In': ['...']}], |
| ['Write', {'In': ['...']}], |
| ['Resolve', {'In': ['...']}], |
| ['Debug', {'In': ['...']}] |
| ]), |
| // TODO(sadovsky): Update this once we switch to {table, prefix} tuples. |
| prefixes: ['tb:' + listId] |
| }); |
| sg.create(ctx, spec, MEMBER_INFO, this.maybeEmit_(cb)); |
| }); |
| |
| define('joinSyncGroup', function(ctx, listId, cb) { |
| var sg = this.db_.syncGroup(this.listIdToSgName_(listId)); |
| sg.join(ctx, MEMBER_INFO, this.maybeEmit_(cb)); |
| }); |
| |
| //////////////////////////////////////// |
| // vtrace methods |
| |
| // DO NOT USE THIS. vtrace RPCs are extremely slow in JavaScript because VOM |
| // decoding is slow for trace records, which are deeply nested. E.g. 100 puts |
| // can take 20+ seconds with vtrace vs. 2 seconds without. |
| SyncbaseDispatcher.prototype.resetTraceRecords = function() { |
| this.ctx_ = vtrace.withNewStore(this.rt_.getContext()); |
| vtrace.getStore(this.ctx_).setCollectRegexp('.*'); |
| }; |
| |
| SyncbaseDispatcher.prototype.getTraceRecords = function() { |
| return vtrace.getStore(this.ctx_).traceRecords(); |
| }; |
| |
| SyncbaseDispatcher.prototype.logTraceRecords = function() { |
| console.log(vtrace.formatTraces(this.getTraceRecords())); |
| }; |
| |
| //////////////////////////////////////// |
| // Internal helpers |
| |
| // TODO(sadovsky): Watch for changes on Syncbase itself so that we can detect |
| // when data arrives via sync, and drop this method. |
| SyncbaseDispatcher.prototype.maybeEmit_ = function(cb) { |
| var that = this; |
| cb = cb || noop; |
| return function(err) { |
| cb.apply(null, arguments); |
| if (!err) that.emit('change'); |
| }; |
| }; |
| |
| // Writes the given tag into the given table. |
| define('addTagImpl_', function(ctx, tb, todoId, tag, cb) { |
| // TODO(sadovsky): Syncbase currently disallows whitespace in keys, so as a |
| // quick hack we drop all whitespace before storing tags. |
| tag = tag.replace(/\s+/g, ''); |
| tb.put(ctx, tagKey(todoId, tag), null, cb); |
| }); |
| |
| // Returns all rows in the table. |
| define('getRows_', function(ctx, listId, cb) { |
| var rows = [], streamErr = null; |
| var range = nosql.rowrange.prefix(listId || ''); |
| this.tb_.scan(ctx, range, function(err) { |
| if (err) return cb(err); |
| if (streamErr) return cb(streamErr); |
| cb(null, rows); |
| }).on('data', function(row) { |
| rows.push(row); |
| }).on('error', function(err) { |
| streamErr = streamErr || err.error; |
| }); |
| }); |
| |
| // Performs a read-modify-write on key, applying updateFn to the value. |
| // Takes care of value marshalling and unmarshalling. |
| // TODO(sadovsky): Atomic read-modify-write requires 4 RPCs. MongoDB-style API |
| // would bring it down to 1. |
| define('update_', function(ctx, key, updateFn, cb) { |
| var opts = new nosql.BatchOptions(); |
| nosql.runInBatch(ctx, this.db_, opts, function(db, cb) { |
| var tb = db.table('tb'); |
| tb.get(wn(ctx, 'get:' + key), key, function(err, value) { |
| if (err) return cb(err); |
| var newValue = marshal(updateFn(unmarshal(value))); |
| tb.put(wn(ctx, 'put:' + key), key, newValue, cb); |
| }); |
| }, this.maybeEmit_(cb)); |
| }); |