| // Copyright 2015 The Vanadium Authors. All rights reserved. |
| // Use of this source code is governed by a BSD-style |
| // license that can be found in the LICENSE file. |
| |
| // Syncbase-based implementation of Dispatcher. |
| // |
| // Schema design doc (a bit outdated): |
| // https://docs.google.com/document/d/1GtBk75QmjSorUW6T6BATCoiS_LTqOrGksgqjqJ1Hiow/edit# |
| // |
| // TODO(sadovsky): Support arbitrary item reordering using a Dewey-Decimal-like |
| // order-tracking scheme, with suffix randomization to prevent conflicts. |
| // |
| // 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. |
| // NOTE: For now, we actually always orphan tags when deleting todo entries. |
| // |
| // TODO(sadovsky): Orphaning degrades performance, because scan responses (e.g. |
| // scan to get all todos for a given list) include orphaned records. |
| |
| 'use strict'; |
| |
| var _ = require('lodash'); |
| var async = require('async'); |
| var inherits = require('inherits'); |
| var syncbase = require('syncbase'); |
| var nosql = syncbase.nosql; |
| var vanadium = require('vanadium'); |
| var verror = vanadium.verror, vtrace = vanadium.vtrace; |
| |
| var Dispatcher = require('./dispatcher'); |
| var util = require('./util'); |
| var wn = util.wn, wt = util.wt; |
| |
| inherits(SyncbaseDispatcher, Dispatcher); |
| module.exports = SyncbaseDispatcher; |
| |
| function SyncbaseDispatcher(rt, db) { |
| var that = this; |
| Dispatcher.call(this); |
| this.rt_ = rt; |
| this.ctx_ = rt.getContext(); |
| this.db_ = db; |
| this.tb_ = db.table('tb'); |
| |
| // Initialize Syncbase watch |
| var errorCb = function(err) { |
| if (err) { |
| this.emit('watchError', err); |
| } |
| } |
| this.db_.getResumeMarker(that.ctx_, function(err, marker) { |
| if (err) { cb(err); } |
| var watchStream = that.db_.watch(that.ctx_, that.tb_.name, '', marker, errorCb); |
| |
| // TODO(aghassemi): Ideally the app would update its in-memory data |
| // structures directly from the watch stream, but since SyncGroup changes |
| // do not yet show up on the watch stream, it can't. |
| watchStream.on('data', function(change) { |
| // TODO(aghassemi): fromSync should be change.fromSync but due to |
| // issue v.io/i/685 we set it to true for now. |
| var fromSync = true; |
| that.emit('change', fromSync); |
| }); |
| |
| watchStream.on('error', errorCb); |
| }); |
| } |
| |
| //////////////////////////////////////// |
| // 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. Also, restrict which chars are allowed in tag names. |
| var args = Array.prototype.slice.call(arguments); |
| return args.join(SEP); |
| } |
| |
| function newListKey() { |
| return util.uid(); |
| } |
| |
| function newTodoKey(listId) { |
| return join(listId, 'todos', util.uid()); |
| } |
| |
| function tagKey(todoId, tag) { |
| return join(todoId, 'tags', tag); |
| } |
| |
| function keyToListId(key) { |
| var parts = key.split(SEP); |
| // Assume key is for list, todo, or tag. |
| if (parts.length === 1 || parts.length === 3 || parts.length === 5) { |
| return parts[0]; |
| } |
| throw new Error('bad key: ' + key); |
| } |
| |
| // TODO(sadovsky): Maybe switch from JSON to VOM/VDL. |
| function marshal(x) { |
| return JSON.stringify(x); |
| } |
| function unmarshal(x) { |
| return JSON.parse(x); |
| } |
| |
| var SILENT = new vanadium.context.ContextKey(); |
| |
| // 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); |
| } |
| if (!ctx.value(SILENT)) { |
| // Build args string for logging the invocation. 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] = util.logFn(name + '(' + argsStr + ')', cb); |
| } |
| return fn.apply(this, args); |
| }; |
| } |
| |
| //////////////////////////////////////// |
| // SyncbaseDispatcher impl |
| |
| // Returns list objects without 'sg' fields. |
| define('getListsOnly_', function(ctx, cb) { |
| this.getRowsQuery_(ctx, 'k not like "%' + SEP + '%"', function(err, rows) { |
| if (err) return cb(err); |
| var lists = _.map(rows, function(row) { |
| console.assert(!row.key.includes(SEP)); |
| return _.assign(unmarshal(row.value), {_id: row.key}); |
| }); |
| return cb(null, lists); |
| }); |
| }); |
| |
| // Returns a list of objects describing SyncGroups. |
| // TODO(sadovsky): Would be nice if this could be done with a single RPC. |
| define('getSyncGroups_', function(ctx, cb) { |
| var that = this; |
| this.db_.getSyncGroupNames(ctx, function(err, sgNames) { |
| if (err) return cb(err); |
| async.map(sgNames, function(sgName, cb) { |
| that.getSyncGroup_(ctx, sgName, cb); |
| }, cb); |
| }); |
| }); |
| |
| // Returns list objects with 'sg' fields. |
| define('getLists', function(ctx, cb) { |
| var that = this; |
| async.parallel([ |
| function(cb) { |
| that.getListsOnly_(ctx, cb); |
| }, |
| function(cb) { |
| that.getSyncGroups_(ctx, 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].slice(3)) { // drop 'tb:' prefix |
| list.sg = sg; |
| } |
| }); |
| }); |
| return cb(null, lists); |
| }); |
| }); |
| |
| define('getTodos', function(ctx, listId, cb) { |
| this.getRows_(ctx, join(listId, 'todos'), function(err, rows) { |
| if (err) return cb(err); |
| var todos = []; |
| var todo = {}; |
| _.forEach(rows, function(row) { |
| var parts = row.key.split(SEP); |
| console.assert(parts.length >= 3 && parts[0] === listId); |
| if (parts.length === 3) { // todo entry |
| todo = _.assign(unmarshal(row.value), {_id: row.key, tags: []}); |
| todos.push(todo); |
| } else if (parts.length === 5) { // tag for todo entry |
| var tagName = parts[4]; |
| if (tagKey(todo._id, tagName) !== row.key) { |
| // Orphaned tag (from a deleted todo entry); skip. |
| // TODO(ivanpi): Garbage collect orphaned tags. |
| return; |
| } |
| todo.tags.push(tagName); |
| } 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, 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); |
| }); |
| }, cb); |
| }); |
| |
| define('removeTodo', function(ctx, todoId, cb) { |
| // TODO(ivanpi): Also delete corresponding tags. |
| this.tb_.delete(ctx, todoId, 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, cb); |
| }); |
| |
| define('removeTag', function(ctx, todoId, tag, cb) { |
| this.tb_.delete(ctx, tagKey(todoId, tag), 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) { |
| // TODO(sadovsky): fullName doesn't include the mount table name, i.e. the |
| // part corresponding to namespaceRoots. Our workaround is to specify a |
| // fully-qualified Syncbase name. |
| var prefix = this.tb_.fullName.replace('/todos/db/tb', '/$sync/todos/db/tb'); |
| return prefix + '/' + listId; |
| }; |
| |
| // Returns an object describing the SyncGroup with the given name. |
| // Currently, this object will have two fields: 'name' and 'spec'. |
| define('getSyncGroup_', function(ctx, sgName, cb) { |
| var sg = this.db_.syncGroup(sgName); |
| async.parallel([ |
| function(cb) { |
| sg.getSpec(ctx, function(err, spec, version) { |
| if (err) return cb(err); |
| cb(null, spec); |
| }); |
| }, |
| function(cb) { |
| // TODO(sadovsky): For now, in the UI we just want to show who's on the |
| // ACL for a given list, so we don't bother with getMembers. On top of |
| // that, currently getMembers returns a map of random Syncbase instance |
| // ids to SyncGroupMemberInfo structs, neither of which tell us anything |
| // useful. |
| if (true) { |
| process.nextTick(cb); |
| } else { |
| sg.getMembers(ctx, cb); |
| } |
| } |
| ], function(err, results) { |
| if (err) return cb(err); |
| cb(null, { |
| name: sgName, |
| spec: results[0] |
| }); |
| }); |
| }); |
| |
| // 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, sgName, blessings, mtName, cb) { |
| var sg = this.db_.syncGroup(sgName); |
| var spec = new nosql.SyncGroupSpec({ |
| // TODO(sadovsky): Maybe make perms more restrictive. |
| perms: new Map([ |
| ['Admin', {'in': blessings}], |
| ['Read', {'in': blessings}], |
| ['Write', {'in': blessings}], |
| ['Resolve', {'in': blessings}], |
| ['Debug', {'in': blessings}] |
| ]), |
| // TODO(sadovsky): Update this once we switch to {table, prefix} tuples. |
| prefixes: ['tb:' + this.sgNameToListId(sgName)], |
| mountTables: [vanadium.naming.join(mtName, 'rendezvous')] |
| }); |
| sg.create(ctx, spec, MEMBER_INFO, this.maybeEmit_(cb)); |
| }); |
| |
| define('joinSyncGroup', function(ctx, sgName, cb) { |
| var sg = this.db_.syncGroup(sgName); |
| 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. |
| // EDIT: It might not be quite that bad - the "20+ seconds" cited above might |
| // also include the latency added by having the Chrome dev console open. |
| 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(aghassemi): Remove this once changes to SyncGroups are included |
| // in the watch stream. |
| SyncbaseDispatcher.prototype.maybeEmit_ = function(cb) { |
| var that = this; |
| cb = cb || noop; |
| return function(err) { |
| cb.apply(null, arguments); |
| if (err) return; |
| that.emit('change'); |
| }; |
| }; |
| |
| // Writes the given tag into the given table. |
| define('addTagImpl_', function(ctx, tb, todoId, tag, cb) { |
| // TODO(sadovsky): Syncbase currently disallows most characters in keys, so |
| // as a quick hack we drop all unsavory characters before storing tags. |
| tag = tag.replace(/[^a-zA-Z0-9_.-]/g, ''); // taken from Syncbase key check |
| tag = tag.split(SEP).join(''); // also eliminate separator |
| if (tag === '') { |
| return process.nextTick(cb); |
| } |
| tb.put(ctx, tagKey(todoId, tag), null, cb); |
| }); |
| |
| // Returns all rows in the table with the given key prefix. |
| define('getRows_', function(ctx, prefix, cb) { |
| var rows = [], streamErr = null; |
| var range = nosql.rowrange.prefix(prefix || ''); |
| 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; |
| }); |
| }); |
| |
| // Returns all rows in the table matching the where clause. |
| define('getRowsQuery_', function(ctx, where, cb) { |
| var rows = [], streamErr = null; |
| var q = 'select k, v from ' + this.tb_.name + ' where ' + where; |
| this.db_.exec(ctx, q, function(err) { |
| if (err) return cb(err); |
| if (streamErr) return cb(streamErr); |
| rows = rows.slice(1); // remove header |
| cb(null, rows); |
| }).on('data', function(row) { |
| rows.push({key: row[0], value: row[1]}); |
| }).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) { |
| if (err instanceof verror.NoExistError) { |
| // Concurrent delete, likely from a remote peer. Pretend this update |
| // never happened. |
| // TODO(sadovsky): Maybe make it so client transactions take priority |
| // over sync transactions, so that app developers don't have to worry |
| // about this concurrency scenario. |
| return cb(); |
| } |
| return cb(err); |
| } |
| var newValue = marshal(updateFn(unmarshal(value))); |
| tb.put(wn(ctx, 'put:' + key), key, newValue, cb); |
| }); |
| }, cb); |
| }); |