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index.js
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var async = require('async');
var mongodb = require('./mongodb');
var DB = require('sharedb').DB;
var OpLinkValidator = require('./op-link-validator');
var MiddlewareHandler = require('./src/middleware/middlewareHandler');
module.exports = ShareDbMongo;
function ShareDbMongo(mongo, options) {
// use without new
if (!(this instanceof ShareDbMongo)) {
return new ShareDbMongo(mongo, options);
}
if (typeof mongo === 'object') {
options = mongo;
mongo = options.mongo;
}
if (!options) options = {};
// pollDelay is a dodgy hack to work around race conditions replicating the
// data out to the polling target secondaries. If a separate db is specified
// for polling, it defaults to 300ms
this.pollDelay = (options.pollDelay != null) ? options.pollDelay :
(options.mongoPoll) ? 300 : 0;
// By default, we create indexes on any ops collection that is used
this.disableIndexCreation = options.disableIndexCreation || false;
// The getOps() method depends on a separate operations collection, and that
// collection should have an index on the operations stored there. We could
// ask people to make these indexes themselves, but by default the mongo
// driver will do it automatically. This approach will leak memory relative
// to the number of collections you have. This should be OK, as we are not
// expecting thousands of mongo collections.
// Map from collection name -> true for op collections we've ensureIndex'ed
this.opIndexes = {};
// Allow $while and $mapReduce queries. These queries let you run arbitrary
// JS on the server. If users make these queries from the browser, there's
// security issues.
this.allowJSQueries = options.allowAllQueries || options.allowJSQueries || false;
// Aggregate queries are less dangerous, but you can use them to access any
// data in the mongo database.
this.allowAggregateQueries = options.allowAllQueries || options.allowAggregateQueries || false;
// Setting this flag to true will attempt to infer a canonical op link for
// getOps rather than using the snapshot as the op link. This allows us to
// not fetch all ops to present when asking only for a subset.
// For more details on this, see the README.
this.getOpsWithoutStrictLinking = options.getOpsWithoutStrictLinking || false;
// Track whether the close method has been called
this.closed = false;
if (typeof mongo === 'string' || typeof mongo === 'function') {
// We can only get the mongodb client instance in a callback, so
// buffer up any requests received in the meantime
this.mongo = null;
this._mongoClient = null;
this.mongoPoll = null;
this._mongoPollClient = null;
this.pendingConnect = [];
this._connect(mongo, options);
} else {
throw new Error('deprecated: pass mongo as url string or function with callback');
}
this._middleware = new MiddlewareHandler();
};
ShareDbMongo.prototype = Object.create(DB.prototype);
ShareDbMongo.prototype.projectsSnapshots = true;
ShareDbMongo.prototype.getCollection = function(collectionName, callback) {
// Check the collection name
var err = this.validateCollectionName(collectionName);
if (err) return callback(err);
// Gotcha: calls back sync if connected or async if not
this.getDbs(function(err, mongo) {
if (err) return callback(err);
var collection = mongo.collection(collectionName);
return callback(null, collection);
});
};
ShareDbMongo.prototype._getCollectionPoll = function(collectionName, callback) {
// Check the collection name
var err = this.validateCollectionName(collectionName);
if (err) return callback(err);
// Gotcha: calls back sync if connected or async if not
this.getDbs(function(err, mongo, mongoPoll) {
if (err) return callback(err);
var collection = (mongoPoll || mongo).collection(collectionName);
return callback(null, collection);
});
};
ShareDbMongo.prototype.getCollectionPoll = function(collectionName, callback) {
if (this.pollDelay) {
var self = this;
setTimeout(function() {
self._getCollectionPoll(collectionName, callback);
}, this.pollDelay);
return;
}
this._getCollectionPoll(collectionName, callback);
};
ShareDbMongo.prototype.getDbs = function(callback) {
if (this.closed) {
var err = ShareDbMongo.alreadyClosedError();
return callback(err);
}
// We consider ouself ready to reply if this.mongo is defined and don't check
// this.mongoPoll, since it is optional and is null by default. Thus, it's
// important that these two properties are only set together synchronously
if (this.mongo) return callback(null, this.mongo, this.mongoPoll);
this.pendingConnect.push(callback);
};
ShareDbMongo.prototype._flushPendingConnect = function() {
var pendingConnect = this.pendingConnect;
this.pendingConnect = null;
for (var i = 0; i < pendingConnect.length; i++) {
pendingConnect[i](null, this.mongo, this.mongoPoll);
}
};
function isLegacyMongoClient(client) {
// mongodb 2.0 connect returns a DB object that also implements the
// functionality of client, such as `close()`. mongodb 3.0 connect returns a
// Client without the `collection()` method
return (
typeof client.collection === 'function' &&
typeof client.close === 'function'
);
}
ShareDbMongo.prototype._connect = function(mongo, options) {
// Create the mongo connection client connections if needed
//
// Throw errors in this function if we fail to connect, since we aren't
// implementing a way to retry
var self = this;
var mongoPoll = options.mongoPoll;
if (mongoPoll) {
var tasks = {
mongoClient: connect(mongo, options.mongoOptions),
mongoPollClient: connect(mongoPoll, options.mongoPollOptions)
};
async.parallel(tasks, function(err, results) {
if (err) throw err;
var mongoClient = results.mongoClient;
var mongoPollClient = results.mongoPollClient;
if (isLegacyMongoClient(mongoClient)) {
self.mongo = self._mongoClient = mongoClient;
self.mongoPoll = self._mongoPollClient = mongoPollClient;
} else {
self.mongo = mongoClient.db();
self._mongoClient = mongoClient;
self.mongoPoll = mongoPollClient.db();
self._mongoPollClient = mongoPollClient;
}
self._flushPendingConnect();
});
return;
}
var finish = function(err, client) {
if (err) throw err;
if (isLegacyMongoClient(client)) {
self.mongo = self._mongoClient = client;
} else {
self.mongo = client.db();
self._mongoClient = client;
}
self._flushPendingConnect();
};
if (typeof mongo === 'function') {
mongo(finish);
return;
}
// TODO: Don't pass options directly to mongodb.connect();
// only pass options.mongoOptions
var mongoOptions = options.mongoOptions || options;
connect(mongo, mongoOptions)(finish);
};
function connect(mongo, options) {
if (typeof mongo === 'function') return mongo;
return function(callback) {
options = Object.assign({}, options);
delete options.mongo;
delete options.mongoPoll;
delete options.mongoPollOptions;
delete options.pollDelay;
delete options.disableIndexCreation;
delete options.allowAllQueries;
delete options.allowJSQueries;
delete options.allowAllQueries;
delete options.allowAggregateQueries;
delete options.getOpsWithoutStrictLinking;
if (typeof mongodb.connect === 'function') {
mongodb.connect(mongo, options, callback);
} else {
var client = new mongodb.MongoClient(mongo, options);
client.connect(callback);
}
};
}
ShareDbMongo.prototype.close = function(callback) {
if (!callback) {
callback = function(err) {
if (err) throw err;
};
}
var self = this;
this.getDbs(function(err) {
// Ignore "already closed"
if (err && err.code === 5101) return callback();
if (err) return callback(err);
self.closed = true;
self._mongoClient.close(function(err) {
if (err) return callback(err);
if (!self._mongoPollClient) return callback();
self._mongoPollClient.close(callback);
});
});
};
// **** Commit methods
ShareDbMongo.prototype.commit = function(collectionName, id, op, snapshot, options, callback) {
var self = this;
var request = createRequestForMiddleware(options, collectionName, op);
this._writeOp(collectionName, id, op, snapshot, function(err, result) {
if (err) return callback(err);
var opId = result.insertedId;
self._writeSnapshot(request, id, snapshot, opId, function(err, succeeded) {
if (succeeded) return callback(err, succeeded);
// Cleanup unsuccessful op if snapshot write failed. This is not
// necessary for data correctness, but it gets rid of clutter
self._deleteOp(request.collectionName, opId, function(removeErr) {
callback(err || removeErr, succeeded);
});
});
});
};
function createRequestForMiddleware(options, collectionName, op, fields) {
// Create a new request object which will be passed to helper functions and middleware
var request = {
options: options,
collectionName: collectionName
};
if (op) request.op = op;
// When we're creating a request for submitting an op, let downstream middleware know.
if (fields && fields.$submit === true) {
/**
* TODO What if sharedb populated this? We could use MIDDLEWARE_ACTIONS.
*/
request.triggeredBy = 'submitRequest';
}
return request;
}
ShareDbMongo.prototype._writeOp = function(collectionName, id, op, snapshot, callback) {
if (typeof op.v !== 'number') {
var err = ShareDbMongo.invalidOpVersionError(collectionName, id, op.v);
return callback(err);
}
this.getOpCollection(collectionName, function(err, opCollection) {
if (err) return callback(err);
var doc = shallowClone(op);
doc.d = id;
doc.o = snapshot._opLink;
opCollection.insertOne(doc, callback);
});
};
ShareDbMongo.prototype._deleteOp = function(collectionName, opId, callback) {
this.getOpCollection(collectionName, function(err, opCollection) {
if (err) return callback(err);
opCollection.deleteOne({_id: opId}, callback);
});
};
ShareDbMongo.prototype._writeSnapshot = function(request, id, snapshot, opId, callback) {
var self = this;
this.getCollection(request.collectionName, function(err, collection) {
if (err) return callback(err);
request.documentToWrite = castToDoc(id, snapshot, opId);
if (request.documentToWrite._v === 1) {
self._middleware.trigger(MiddlewareHandler.Actions.beforeCreate, request, function(middlewareErr) {
if (middlewareErr) {
return callback(middlewareErr);
}
collection.insertOne(request.documentToWrite, function(err) {
if (err) {
// Return non-success instead of duplicate key error, since this is
// expected to occur during simultaneous creates on the same id
if (err.code === 11000 && /\b_id_\b/.test(err.message)) {
return callback(null, false);
}
return callback(err);
}
callback(null, true);
});
});
} else {
request.query = {_id: id, _v: request.documentToWrite._v - 1};
self._middleware.trigger(MiddlewareHandler.Actions.beforeOverwrite, request, function(middlewareErr) {
if (middlewareErr) {
return callback(middlewareErr);
}
collection.replaceOne(request.query, request.documentToWrite, function(err, result) {
if (err) return callback(err);
var succeeded = !!result.modifiedCount;
callback(null, succeeded);
});
});
}
});
};
// **** Snapshot methods
ShareDbMongo.prototype.getSnapshot = function(collectionName, id, fields, options, callback) {
var self = this;
this.getCollection(collectionName, function(err, collection) {
if (err) return callback(err);
var query = {_id: id};
var projection = getProjection(fields, options);
var request = createRequestForMiddleware(options, collectionName, null, fields);
request.query = query;
self._middleware.trigger(MiddlewareHandler.Actions.beforeSnapshotLookup, request, function(middlewareErr) {
if (middlewareErr) return callback(middlewareErr);
collection.find(request.query, request.findOptions).limit(1).project(projection).next(function(err, doc) {
if (err) return callback(err);
var snapshot = (doc) ? castToSnapshot(doc) : new MongoSnapshot(id, 0, null, undefined);
callback(null, snapshot);
});
});
});
};
ShareDbMongo.prototype.getSnapshotBulk = function(collectionName, ids, fields, options, callback) {
var self = this;
this.getCollection(collectionName, function(err, collection) {
if (err) return callback(err);
var query = {_id: {$in: ids}};
var projection = getProjection(fields, options);
var request = createRequestForMiddleware(options, collectionName, null, fields);
request.query = query;
self._middleware.trigger(MiddlewareHandler.Actions.beforeSnapshotLookup, request, function(middlewareErr) {
if (middlewareErr) return callback(middlewareErr);
collection.find(request.query, request.findOptions).project(projection).toArray(function(err, docs) {
if (err) return callback(err);
var snapshotMap = {};
for (var i = 0; i < docs.length; i++) {
var snapshot = castToSnapshot(docs[i]);
snapshotMap[snapshot.id] = snapshot;
}
for (var i = 0; i < ids.length; i++) {
var id = ids[i];
if (snapshotMap[id]) continue;
snapshotMap[id] = new MongoSnapshot(id, 0, null, undefined);
}
callback(null, snapshotMap);
});
});
});
};
// **** Oplog methods
// Overwrite me if you want to change this behaviour.
ShareDbMongo.prototype.getOplogCollectionName = function(collectionName) {
return 'o_' + collectionName;
};
ShareDbMongo.prototype.validateCollectionName = function(collectionName) {
if (
collectionName === 'system' || (
collectionName[0] === 'o' &&
collectionName[1] === '_'
)
) {
return ShareDbMongo.invalidCollectionError(collectionName);
}
};
// Get and return the op collection from mongo, ensuring it has the op index.
ShareDbMongo.prototype.getOpCollection = function(collectionName, callback) {
var self = this;
this.getDbs(function(err, mongo) {
if (err) return callback(err);
var name = self.getOplogCollectionName(collectionName);
var collection = mongo.collection(name);
// Given the potential problems with creating indexes on the fly, it might
// be preferrable to disable automatic creation
if (self.disableIndexCreation) {
return callback(null, collection);
}
if (self.opIndexes[collectionName]) {
return callback(null, collection);
}
// WARNING: Creating indexes automatically like this is quite dangerous in
// production if we are starting with a lot of data and no indexes
// already. If new indexes were added or definition of these indexes were
// changed, users upgrading this module could unsuspectingly lock up their
// databases. If indexes are created as the first ops are added to a
// collection this won't be a problem, but this is a dangerous mechanism.
// Perhaps we should only warn instead of creating the indexes, especially
// when there is a lot of data in the collection.
collection.createIndex({d: 1, v: 1}, {background: true}, function(err) {
if (err) return callback(err);
collection.createIndex({src: 1, seq: 1, v: 1}, {background: true}, function(err) {
if (err) return callback(err);
self.opIndexes[collectionName] = true;
callback(null, collection);
});
});
});
};
ShareDbMongo.prototype.getOpsToSnapshot = function(collectionName, id, from, snapshot, options, callback) {
if (snapshot._opLink == null) {
var err = ShareDbMongo.missingLastOperationError(collectionName, id);
return callback(err);
}
var options = Object.assign({}, options);
var to = null;
this._getOps(collectionName, id, from, to, options, function(err, ops) {
if (err) return callback(err);
var filtered = getLinkedOps(ops, null, snapshot._opLink);
var err = null;
if (!options.ignoreMissingOps) {
err = checkOpsFrom(collectionName, id, filtered, from);
}
if (err) return callback(err);
callback(null, filtered);
});
};
ShareDbMongo.prototype.getOps = function(collectionName, id, from, to, options, callback) {
var self = this;
var options = Object.assign({}, options);
this._getOpLink(collectionName, id, to, options, function(err, opLink) {
if (err) return callback(err);
// We need to fetch slightly more ops than requested in order to work backwards along
// linked ops to provide only valid ops
var fetchOpsTo = null;
if (opLink) {
if (isCurrentVersion(opLink, from)) {
return callback(null, []);
}
var err = opLink && checkDocHasOp(collectionName, id, opLink);
if (err) return callback(err);
if (self.getOpsWithoutStrictLinking) fetchOpsTo = opLink._v;
}
self._getOps(collectionName, id, from, fetchOpsTo, options, function(err, ops) {
if (err) return callback(err);
var filtered = filterOps(ops, opLink, to);
var err = null;
if (!options.ignoreMissingOps) {
err = checkOpsFrom(collectionName, id, filtered, from);
}
if (err) return callback(err);
callback(null, filtered);
});
});
};
ShareDbMongo.prototype.getOpsBulk = function(collectionName, fromMap, toMap, options, callback) {
var self = this;
var ids = Object.keys(fromMap);
this._getSnapshotOpLinkBulk(collectionName, ids, options, function(err, docs) {
if (err) return callback(err);
var docMap = getDocMap(docs);
// Add empty array for snapshot versions that are up to date and create
// the query conditions for ops that we need to get
var conditions = [];
var opsMap = {};
for (var i = 0; i < ids.length; i++) {
var id = ids[i];
var doc = docMap[id];
var from = fromMap[id];
if (doc) {
if (isCurrentVersion(doc, from)) {
opsMap[id] = [];
continue;
}
var err = checkDocHasOp(collectionName, id, doc);
if (err) return callback(err);
}
var condition = getOpsQuery(id, from);
conditions.push(condition);
}
// Return right away if none of the snapshot versions are newer than the
// requested versions
if (!conditions.length) return callback(null, opsMap);
// Otherwise, get all of the ops that are newer
self._getOpsBulk(collectionName, conditions, options, function(err, opsBulk) {
if (err) return callback(err);
for (var i = 0; i < conditions.length; i++) {
var id = conditions[i].d;
var ops = opsBulk[id];
var doc = docMap[id];
var from = fromMap[id];
var to = toMap && toMap[id];
var filtered = filterOps(ops, doc, to);
var err = checkOpsFrom(collectionName, id, filtered, from);
if (err) return callback(err);
opsMap[id] = filtered;
}
callback(null, opsMap);
});
});
};
ShareDbMongo.prototype.getCommittedOpVersion = function(collectionName, id, snapshot, op, options, callback) {
var self = this;
this.getOpCollection(collectionName, function(err, opCollection) {
if (err) return callback(err);
var query = {
src: op.src,
seq: op.seq
};
var projection = {v: 1, _id: 0};
var sort = {v: 1};
// Find the earliest version at which the op may have been committed.
// Since ops are optimistically written prior to writing the snapshot, the
// op could end up being written multiple times or have been written but
// not count as committed if not backreferenced from the snapshot
opCollection.find(query).project(projection).sort(sort).limit(1).next(function(err, doc) {
if (err) return callback(err);
// If we find no op with the same src and seq, we definitely don't have
// any match. This should prevent us from accidentally querying a huge
// history of ops
if (!doc) return callback();
// If we do find an op with the same src and seq, we still have to get
// the ops from the snapshot to figure out if the op was actually
// committed already, and at what version in case of multiple matches
var from = doc.v;
self.getOpsToSnapshot(collectionName, id, from, snapshot, options, function(err, ops) {
if (err) return callback(err);
for (var i = ops.length; i--;) {
var item = ops[i];
if (op.src === item.src && op.seq === item.seq) {
return callback(null, item.v);
}
}
callback();
});
});
});
};
function checkOpsFrom(collectionName, id, ops, from) {
if (ops.length === 0) return;
if (ops[0] && ops[0].v === from) return;
if (from == null) return;
return ShareDbMongo.missingOpsError(collectionName, id, from);
};
function checkDocHasOp(collectionName, id, doc) {
if (doc._o) return;
return ShareDbMongo.missingLastOperationError(collectionName, id);
}
function isCurrentVersion(doc, version) {
return doc._v === version;
}
function getDocMap(docs) {
var docMap = {};
for (var i = 0; i < docs.length; i++) {
var doc = docs[i];
docMap[doc._id] = doc;
}
return docMap;
}
function filterOps(ops, doc, to) {
// Always return in the case of no ops found whether or not consistent with
// the snapshot
if (!ops) return [];
if (!ops.length) return ops;
if (!doc) {
// There is no snapshot currently. We already returned if there are no
// ops, so this could happen if:
// 1. The doc was deleted
// 2. The doc create op is written but not the doc snapshot
// 3. Same as 3 for a recreate
// 4. We are in an inconsistent state because of an error
//
// We treat the snapshot as the canonical version, so if the snapshot
// doesn't exist, the doc should be considered deleted. Thus, a delete op
// should be in the last version if no commits are inflight or second to
// last version if commit(s) are inflight. Rather than trying to detect
// ops inconsistent with a deleted state, we are simply returning ops from
// the last delete. Inconsistent states will ultimately cause write
// failures on attempt to commit.
//
// Different delete ops must be identical and must link back to the same
// prior version in order to be inserted, so if there are multiple delete
// ops at the same version, we can grab any of them for this method.
// However, the _id of the delete op might not ultimately match the delete
// op that gets maintained if two are written as a result of two
// simultanous delete commits. Thus, the _id of the op should *not* be
// assumed to be consistent in the future.
var deleteOp = getLatestDeleteOp(ops);
// Don't return any ops if we don't find a delete operation, which is the
// correct thing to do if the doc was just created and the op has been
// written but not the snapshot. Note that this will simply return no ops
// if there are ops but the snapshot doesn't exist.
if (!deleteOp) return [];
return getLinkedOps(ops, to, deleteOp._id);
}
return getLinkedOps(ops, to, doc._o);
}
function getLatestDeleteOp(ops) {
for (var i = ops.length; i--;) {
var op = ops[i];
if (op.del) return op;
}
}
function getLinkedOps(ops, to, link) {
var linkedOps = [];
for (var i = ops.length; i-- && link;) {
var op = ops[i];
if (link.equals ? !link.equals(op._id) : link !== op._id) continue;
link = op.o;
if (to == null || op.v < to) {
delete op._id;
delete op.o;
linkedOps.push(op);
}
}
return linkedOps.reverse();
}
function getOpsQuery(id, from, to) {
from = from == null ? 0 : from;
var query = {
d: id,
v: {$gte: from}
};
if (to != null) {
query.v.$lt = to;
}
return query;
}
ShareDbMongo.prototype._getOps = function(collectionName, id, from, to, options, callback) {
this.getOpCollection(collectionName, function(err, opCollection) {
if (err) return callback(err);
var query = getOpsQuery(id, from, to);
// Exclude the `d` field, which is only for use internal to livedb-mongo.
// Also exclude the `m` field, which can be used to store metadata on ops
// for tracking purposes
var projection = (options && options.metadata) ? {d: 0} : {d: 0, m: 0};
var sort = {v: 1};
opCollection.find(query).project(projection).sort(sort).toArray(callback);
});
};
ShareDbMongo.prototype._getOpsBulk = function(collectionName, conditions, options, callback) {
this.getOpCollection(collectionName, function(err, opCollection) {
if (err) return callback(err);
var query = {$or: conditions};
// Exclude the `m` field, which can be used to store metadata on ops for
// tracking purposes
var projection = (options && options.metadata) ? null : {m: 0};
var stream = opCollection.find(query).project(projection).stream();
readOpsBulk(stream, callback);
});
};
function readOpsBulk(stream, callback) {
var opsMap = {};
var errored;
stream.on('error', function(err) {
errored = true;
return callback(err);
});
stream.on('end', function() {
if (errored) return;
// Sort ops for each doc in ascending order by version
for (var id in opsMap) {
opsMap[id].sort(function(a, b) {
return a.v - b.v;
});
}
callback(null, opsMap);
});
// Read each op and push onto a list for the appropriate doc
stream.on('data', function(op) {
var id = op.d;
if (opsMap[id]) {
opsMap[id].push(op);
} else {
opsMap[id] = [op];
}
delete op.d;
});
}
ShareDbMongo.prototype._getOpLink = function(collectionName, id, to, options, callback) {
if (!this.getOpsWithoutStrictLinking) return this._getSnapshotOpLink(collectionName, id, options, callback);
var db = this;
this.getOpCollection(collectionName, function(error, collection) {
if (error) return callback(error);
// If to is null, we want the most recent version, so just return the
// snapshot link, which is more efficient than cursoring
if (to == null) {
return db._getSnapshotOpLink(collectionName, id, options, callback);
}
var query = {
d: id,
v: {$gte: to}
};
var projection = {
_id: 0,
v: 1,
o: 1
};
var cursor = collection.find(query).sort({v: 1}).project(projection);
getFirstOpWithUniqueVersion(cursor, null, function(error, op) {
if (error) return callback(error);
if (op) return callback(null, {_o: op.o, _v: op.v});
// If we couldn't find an op to link back from, then fall back to using the current
// snapshot, which is guaranteed to have a link to a valid op.
db._getSnapshotOpLink(collectionName, id, options, callback);
});
});
};
// When getting ops, we need to consider the case where an op is committed to the database,
// but its application to the snapshot is subsequently rejected. This can leave multiple ops
// with the same values for 'd' and 'v', and means that we may return multiple ops for a single
// version if we just perform a naive 'find' operation.
// To avoid this, we try to fetch the first op from 'to' which has a unique 'v', and then we
// work backwards from that op using the linked op 'o' field to get a valid chain of ops.
// See the README for more details.
function getFirstOpWithUniqueVersion(cursor, opLinkValidator, callback) {
opLinkValidator = opLinkValidator || new OpLinkValidator();
var opWithUniqueVersion = opLinkValidator.opWithUniqueVersion();
if (opWithUniqueVersion || opLinkValidator.isAtEndOfList()) {
var error = null;
return closeCursor(cursor, callback, error, opWithUniqueVersion);
}
cursor.next(function(error, op) {
if (error) {
return closeCursor(cursor, callback, error);
}
opLinkValidator.push(op);
getFirstOpWithUniqueVersion(cursor, opLinkValidator, callback);
});
}
function closeCursor(cursor, callback, error, returnValue) {
cursor.close(function(closeError) {
error = error || closeError;
callback(error, returnValue);
});
}
ShareDbMongo.prototype._getSnapshotOpLink = function(collectionName, id, options, callback) {
var self = this;
this.getCollection(collectionName, function(err, collection) {
if (err) return callback(err);
var query = {_id: id};
var projection = {_id: 0, _o: 1, _v: 1};
var request = createRequestForMiddleware(options, collectionName);
request.query = query;
self._middleware.trigger(MiddlewareHandler.Actions.beforeSnapshotLookup, request, function(middlewareErr) {
if (middlewareErr) return callback(middlewareErr);
collection.find(query, request.findOptions).limit(1).project(projection).next(callback);
});
});
};
ShareDbMongo.prototype._getSnapshotOpLinkBulk = function(collectionName, ids, options, callback) {
var self = this;
this.getCollection(collectionName, function(err, collection) {
if (err) return callback(err);
var query = {_id: {$in: ids}};
var projection = {_o: 1, _v: 1};
var request = createRequestForMiddleware(options, collectionName);
request.query = query;
self._middleware.trigger(MiddlewareHandler.Actions.beforeSnapshotLookup, request, function(middlewareErr) {
if (middlewareErr) return callback(middlewareErr);
collection.find(query, request.findOptions).project(projection).toArray(callback);
});
});
};
// **** Query methods
ShareDbMongo.prototype._query = function(collection, inputQuery, projection, callback) {
var parsed = this._getSafeParsedQuery(inputQuery, callback);
if (!parsed) return;
// Collection operations such as $aggregate run on the whole
// collection. Only one operation is run. The result goes in the
// "extra" argument in the callback.
if (parsed.collectionOperationKey) {
collectionOperationsMap[parsed.collectionOperationKey](
collection,
parsed.query,
parsed.collectionOperationValue,
function(err, extra) {
if (err) return callback(err);
callback(null, [], extra);
}
);
return;
}
// No collection operations were used. Create an initial cursor for
// the query, that can be transformed later.
var cursor = collection.find(parsed.query).project(projection);
// Cursor transforms such as $skip transform the cursor into a new
// one. If multiple transforms are specified on inputQuery, they all
// run.
for (var key in parsed.cursorTransforms) {
var transform = cursorTransformsMap[key];
cursor = transform(cursor, parsed.cursorTransforms[key]);
if (!cursor) {
var err = ShareDbMongo.malformedQueryOperatorError(key);
return callback(err);
}
}
// Cursor operations such as $count run on the cursor, after all
// transforms. Only one operation is run. The result goes in the
// "extra" argument in the callback.
if (parsed.cursorOperationKey) {
cursorOperationsMap[parsed.cursorOperationKey](
cursor,
parsed.cursorOperationValue,
function(err, extra) {
if (err) return callback(err);
callback(null, [], extra);
}
);
return;
}
// If no collection operation or cursor operations were used, return
// an array of snapshots that are passed in the "results" argument
// in the callback
cursor.toArray(callback);
};
ShareDbMongo.prototype.query = function(collectionName, inputQuery, fields, options, callback) {
var self = this;
this.getCollection(collectionName, function(err, collection) {
if (err) return callback(err);
var projection = getProjection(fields, options);
self._query(collection, inputQuery, projection, function(err, results, extra) {
if (err) return callback(err);
var snapshots = [];
for (var i = 0; i < results.length; i++) {
var snapshot = castToSnapshot(results[i]);
snapshots.push(snapshot);
}
callback(null, snapshots, extra);
});
});
};
ShareDbMongo.prototype.queryPoll = function(collectionName, inputQuery, options, callback) {
var self = this;
this.getCollectionPoll(collectionName, function(err, collection) {
if (err) return callback(err);
var projection = {_id: 1};
self._query(collection, inputQuery, projection, function(err, results, extra) {
if (err) return callback(err);
var ids = [];
for (var i = 0; i < results.length; i++) {
ids.push(results[i]._id);
}
callback(null, ids, extra);
});
});
};
ShareDbMongo.prototype.queryPollDoc = function(collectionName, id, inputQuery, options, callback) {
var self = this;
self.getCollectionPoll(collectionName, function(err, collection) {
if (err) return callback(err);
var parsed = self._getSafeParsedQuery(inputQuery, callback);
if (!parsed) return;
// Run the query against a particular mongo document by adding an _id filter
var queryId = parsed.query._id;
if (queryId && typeof queryId === 'object') {
// Check if the query contains the id directly in the common pattern of
// a query for a specific list of ids, such as {_id: {$in: [1, 2, 3]}}
if (Array.isArray(queryId.$in) && Object.keys(queryId).length === 1) {
if (queryId.$in.indexOf(id) === -1) {
// If the id isn't in the list of ids, then there is no way this
// can be a match
return callback(null, false);
} else {
// If the id is in the list, then it is equivalent to restrict to our
// particular id and override the current value
parsed.query._id = id;
}
} else {
delete parsed.query._id;
parsed.query.$and = (parsed.query.$and) ?
parsed.query.$and.concat({_id: id}, {_id: queryId}) :
[{_id: id}, {_id: queryId}];
}
} else if (queryId && queryId !== id) {
// If queryId is a primative value such as a string or number and it
// isn't equal to the id, then there is no way this can be a match
return callback(null, false);
} else {
// Restrict the query to this particular document
parsed.query._id = id;
}
collection.find(parsed.query).limit(1).project({_id: 1}).next(function(err, doc) {
callback(err, !!doc);
});
});
};
// **** Polling optimization
// Can we poll by checking the query limited to the particular doc only?
ShareDbMongo.prototype.canPollDoc = function(collectionName, query) {
for (var operation in collectionOperationsMap) {
if (query.hasOwnProperty(operation)) return false;
}
for (var operation in cursorOperationsMap) {
if (query.hasOwnProperty(operation)) return false;
}
if (
query.hasOwnProperty('$sort') ||
query.hasOwnProperty('$orderby') ||
query.hasOwnProperty('$limit') ||
query.hasOwnProperty('$skip') ||
query.hasOwnProperty('$max') ||
query.hasOwnProperty('$min') ||
query.hasOwnProperty('$returnKey')
) {
return false;
}
return true;
};
// Return true to avoid polling if there is no possibility that an op could
// affect a query's results
ShareDbMongo.prototype.skipPoll = function(collectionName, id, op, query) {
// ShareDB is in charge of doing the validation of ops, so at this point we
// should be able to assume that the op is structured validly
if (op.create || op.del) return false;
if (!op.op) return true;
// Right now, always re-poll if using a collection operation such as
// $distinct or a cursor operation such as $count. This could be