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authorWaref Haque <warefhaque@Warefs-MacBook-Pro.local>2016-07-17 20:24:49 +0000
committerWaref Haque <warefhaque@Warefs-MacBook-Pro.local>2016-07-17 20:24:49 +0000
commite58943c3e620f05937656fdde032254ae3373f36 (patch)
tree77072aa55efa1753c8c8ae584669cf3589551268 /node_modules/mongodb-core/lib/cursor.js
parent55098c767afb0b119aaeda330eaedba5c1a87dc3 (diff)
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+"use strict";
+
+var Long = require('bson').Long
+ , Logger = require('./connection/logger')
+ , MongoError = require('./error')
+ , f = require('util').format;
+
+/**
+ * This is a cursor results callback
+ *
+ * @callback resultCallback
+ * @param {error} error An error object. Set to null if no error present
+ * @param {object} document
+ */
+
+/**
+ * @fileOverview The **Cursor** class is an internal class that embodies a cursor on MongoDB
+ * allowing for iteration over the results returned from the underlying query.
+ *
+ * **CURSORS Cannot directly be instantiated**
+ * @example
+ * var Server = require('mongodb-core').Server
+ * , ReadPreference = require('mongodb-core').ReadPreference
+ * , assert = require('assert');
+ *
+ * var server = new Server({host: 'localhost', port: 27017});
+ * // Wait for the connection event
+ * server.on('connect', function(server) {
+ * assert.equal(null, err);
+ *
+ * // Execute the write
+ * var cursor = _server.cursor('integration_tests.inserts_example4', {
+ * find: 'integration_tests.example4'
+ * , query: {a:1}
+ * }, {
+ * readPreference: new ReadPreference('secondary');
+ * });
+ *
+ * // Get the first document
+ * cursor.next(function(err, doc) {
+ * assert.equal(null, err);
+ * server.destroy();
+ * });
+ * });
+ *
+ * // Start connecting
+ * server.connect();
+ */
+
+/**
+ * Creates a new Cursor, not to be used directly
+ * @class
+ * @param {object} bson An instance of the BSON parser
+ * @param {string} ns The MongoDB fully qualified namespace (ex: db1.collection1)
+ * @param {{object}|Long} cmd The selector (can be a command or a cursorId)
+ * @param {object} [options=null] Optional settings.
+ * @param {object} [options.batchSize=1000] Batchsize for the operation
+ * @param {array} [options.documents=[]] Initial documents list for cursor
+ * @param {object} [options.transforms=null] Transform methods for the cursor results
+ * @param {function} [options.transforms.query] Transform the value returned from the initial query
+ * @param {function} [options.transforms.doc] Transform each document returned from Cursor.prototype.next
+ * @param {object} topology The server topology instance.
+ * @param {object} topologyOptions The server topology options.
+ * @return {Cursor} A cursor instance
+ * @property {number} cursorBatchSize The current cursorBatchSize for the cursor
+ * @property {number} cursorLimit The current cursorLimit for the cursor
+ * @property {number} cursorSkip The current cursorSkip for the cursor
+ */
+var Cursor = function(bson, ns, cmd, options, topology, topologyOptions) {
+ options = options || {};
+ // Cursor reference
+ var self = this;
+ // Initial query
+ var query = null;
+
+ // Cursor pool
+ this.pool = null;
+ // Cursor server
+ this.server = null;
+
+ // Do we have a not connected handler
+ this.disconnectHandler = options.disconnectHandler;
+
+ // Set local values
+ this.bson = bson;
+ this.ns = ns;
+ this.cmd = cmd;
+ this.options = options;
+ this.topology = topology;
+
+ // All internal state
+ this.cursorState = {
+ cursorId: null
+ , cmd: cmd
+ , documents: options.documents || []
+ , cursorIndex: 0
+ , dead: false
+ , killed: false
+ , init: false
+ , notified: false
+ , limit: options.limit || cmd.limit || 0
+ , skip: options.skip || cmd.skip || 0
+ , batchSize: options.batchSize || cmd.batchSize || 1000
+ , currentLimit: 0
+ // Result field name if not a cursor (contains the array of results)
+ , transforms: options.transforms
+ }
+
+ // Add promoteLong to cursor state
+ if(typeof topologyOptions.promoteLongs == 'boolean') {
+ this.cursorState.promoteLongs = topologyOptions.promoteLongs;
+ }
+
+ // Logger
+ this.logger = Logger('Cursor', topologyOptions);
+
+ //
+ // Did we pass in a cursor id
+ if(typeof cmd == 'number') {
+ this.cursorState.cursorId = Long.fromNumber(cmd);
+ this.cursorState.lastCursorId = this.cursorState.cursorId;
+ } else if(cmd instanceof Long) {
+ this.cursorState.cursorId = cmd;
+ this.cursorState.lastCursorId = cmd;
+ }
+}
+
+Cursor.prototype.setCursorBatchSize = function(value) {
+ this.cursorState.batchSize = value;
+}
+
+Cursor.prototype.cursorBatchSize = function() {
+ return this.cursorState.batchSize;
+}
+
+Cursor.prototype.setCursorLimit = function(value) {
+ this.cursorState.limit = value;
+}
+
+Cursor.prototype.cursorLimit = function() {
+ return this.cursorState.limit;
+}
+
+Cursor.prototype.setCursorSkip = function(value) {
+ this.cursorState.skip = value;
+}
+
+Cursor.prototype.cursorSkip = function() {
+ return this.cursorState.skip;
+}
+
+//
+// Handle callback (including any exceptions thrown)
+var handleCallback = function(callback, err, result) {
+ try {
+ callback(err, result);
+ } catch(err) {
+ process.nextTick(function() {
+ throw err;
+ });
+ }
+}
+
+// Internal methods
+Cursor.prototype._find = function(callback) {
+ var self = this;
+
+ if(self.logger.isDebug()) {
+ self.logger.debug(f("issue initial query [%s] with flags [%s]"
+ , JSON.stringify(self.cmd)
+ , JSON.stringify(self.query)));
+ }
+
+ var queryCallback = function(err, r) {
+ if(err) return callback(err);
+
+ // Get the raw message
+ var result = r.message;
+
+ // Query failure bit set
+ if(result.queryFailure) {
+ return callback(MongoError.create(result.documents[0]), null);
+ }
+
+ // Check if we have a command cursor
+ if(Array.isArray(result.documents) && result.documents.length == 1
+ && (!self.cmd.find || (self.cmd.find && self.cmd.virtual == false))
+ && (result.documents[0].cursor != 'string'
+ || result.documents[0]['$err']
+ || result.documents[0]['errmsg']
+ || Array.isArray(result.documents[0].result))
+ ) {
+
+ // We have a an error document return the error
+ if(result.documents[0]['$err']
+ || result.documents[0]['errmsg']) {
+ return callback(MongoError.create(result.documents[0]), null);
+ }
+
+ // We have a cursor document
+ if(result.documents[0].cursor != null
+ && typeof result.documents[0].cursor != 'string') {
+ var id = result.documents[0].cursor.id;
+ // If we have a namespace change set the new namespace for getmores
+ if(result.documents[0].cursor.ns) {
+ self.ns = result.documents[0].cursor.ns;
+ }
+ // Promote id to long if needed
+ self.cursorState.cursorId = typeof id == 'number' ? Long.fromNumber(id) : id;
+ self.cursorState.lastCursorId = self.cursorState.cursorId;
+ // If we have a firstBatch set it
+ if(Array.isArray(result.documents[0].cursor.firstBatch)) {
+ self.cursorState.documents = result.documents[0].cursor.firstBatch;//.reverse();
+ }
+
+ // Return after processing command cursor
+ return callback(null, null);
+ }
+
+ if(Array.isArray(result.documents[0].result)) {
+ self.cursorState.documents = result.documents[0].result;
+ self.cursorState.cursorId = Long.ZERO;
+ return callback(null, null);
+ }
+ }
+
+ // Otherwise fall back to regular find path
+ self.cursorState.cursorId = result.cursorId;
+ self.cursorState.documents = result.documents;
+ self.cursorState.lastCursorId = result.cursorId;
+
+ // Transform the results with passed in transformation method if provided
+ if(self.cursorState.transforms && typeof self.cursorState.transforms.query == 'function') {
+ self.cursorState.documents = self.cursorState.transforms.query(result);
+ }
+
+ // Return callback
+ callback(null, null);
+ }
+
+ // Options passed to the pool
+ var queryOptions = {};
+
+ // If we have a raw query decorate the function
+ if(self.options.raw || self.cmd.raw) {
+ // queryCallback.raw = self.options.raw || self.cmd.raw;
+ queryOptions.raw = self.options.raw || self.cmd.raw;
+ }
+
+ // Do we have documentsReturnedIn set on the query
+ if(typeof self.query.documentsReturnedIn == 'string') {
+ // queryCallback.documentsReturnedIn = self.query.documentsReturnedIn;
+ queryOptions.documentsReturnedIn = self.query.documentsReturnedIn;
+ }
+
+ // Add promote Long value if defined
+ if(typeof self.cursorState.promoteLongs == 'boolean') {
+ // queryCallback.promoteLongs = self.cursorState.promoteLongs;
+ queryOptions.promoteLongs = self.cursorState.promoteLongs;
+ }
+
+ // Write the initial command out
+ self.server.s.pool.write(self.query.toBin(), queryOptions, queryCallback);
+}
+
+Cursor.prototype._getmore = function(callback) {
+ if(this.logger.isDebug()) this.logger.debug(f("schedule getMore call for query [%s]", JSON.stringify(this.query)))
+ // Determine if it's a raw query
+ var raw = this.options.raw || this.cmd.raw;
+
+ // Set the current batchSize
+ var batchSize = this.cursorState.batchSize;
+ if(this.cursorState.limit > 0
+ && ((this.cursorState.currentLimit + batchSize) > this.cursorState.limit)) {
+ batchSize = this.cursorState.limit - this.cursorState.currentLimit;
+ }
+
+ // Default pool
+ var pool = this.server.s.pool;
+
+ // We have a wire protocol handler
+ this.server.wireProtocolHandler.getMore(this.bson, this.ns, this.cursorState, batchSize, raw, pool, this.options, callback);
+}
+
+Cursor.prototype._killcursor = function(callback) {
+ // Set cursor to dead
+ this.cursorState.dead = true;
+ this.cursorState.killed = true;
+ // Remove documents
+ this.cursorState.documents = [];
+
+ // If no cursor id just return
+ if(this.cursorState.cursorId == null || this.cursorState.cursorId.isZero() || this.cursorState.init == false) {
+ if(callback) callback(null, null);
+ return;
+ }
+
+ // // Default pool
+ // var pool = this.pool;
+ // // If we have a connection get the corresponding pool
+ // if(this.connection && this.connection.isConnected()) {
+ // // Get the server
+ // var server = this.topology.getServerFrom(this.connection);
+ // // Get the pool
+ // if(server && server.s.pool) {
+ // pool = server.s.pool;
+ // }
+ // }
+
+ // Default pool
+ var pool = this.server.s.pool;
+ // // Set cursorId to ZERO
+ // this.cursorState.cursorId = Long.fromNumber(0);
+ // Execute command
+ this.server.wireProtocolHandler.killCursor(this.bson, this.ns, this.cursorState.cursorId, pool, callback);
+}
+
+/**
+ * Clone the cursor
+ * @method
+ * @return {Cursor}
+ */
+Cursor.prototype.clone = function() {
+ return this.topology.cursor(this.ns, this.cmd, this.options);
+}
+
+/**
+ * Checks if the cursor is dead
+ * @method
+ * @return {boolean} A boolean signifying if the cursor is dead or not
+ */
+Cursor.prototype.isDead = function() {
+ return this.cursorState.dead == true;
+}
+
+/**
+ * Checks if the cursor was killed by the application
+ * @method
+ * @return {boolean} A boolean signifying if the cursor was killed by the application
+ */
+Cursor.prototype.isKilled = function() {
+ return this.cursorState.killed == true;
+}
+
+/**
+ * Checks if the cursor notified it's caller about it's death
+ * @method
+ * @return {boolean} A boolean signifying if the cursor notified the callback
+ */
+Cursor.prototype.isNotified = function() {
+ return this.cursorState.notified == true;
+}
+
+/**
+ * Returns current buffered documents length
+ * @method
+ * @return {number} The number of items in the buffered documents
+ */
+Cursor.prototype.bufferedCount = function() {
+ return this.cursorState.documents.length - this.cursorState.cursorIndex;
+}
+
+/**
+ * Returns current buffered documents
+ * @method
+ * @return {Array} An array of buffered documents
+ */
+Cursor.prototype.readBufferedDocuments = function(number) {
+ var unreadDocumentsLength = this.cursorState.documents.length - this.cursorState.cursorIndex;
+ var length = number < unreadDocumentsLength ? number : unreadDocumentsLength;
+ var elements = this.cursorState.documents.slice(this.cursorState.cursorIndex, this.cursorState.cursorIndex + length);
+
+ // Transform the doc with passed in transformation method if provided
+ if(this.cursorState.transforms && typeof this.cursorState.transforms.doc == 'function') {
+ // Transform all the elements
+ for(var i = 0; i < elements.length; i++) {
+ elements[i] = this.cursorState.transforms.doc(elements[i]);
+ }
+ }
+
+ // Ensure we do not return any more documents than the limit imposed
+ // Just return the number of elements up to the limit
+ if(this.cursorState.limit > 0 && (this.cursorState.currentLimit + elements.length) > this.cursorState.limit) {
+ elements = elements.slice(0, (this.cursorState.limit - this.cursorState.currentLimit));
+ this.kill();
+ }
+
+ // Adjust current limit
+ this.cursorState.currentLimit = this.cursorState.currentLimit + elements.length;
+ this.cursorState.cursorIndex = this.cursorState.cursorIndex + elements.length;
+
+ // Return elements
+ return elements;
+}
+
+/**
+ * Kill the cursor
+ * @method
+ * @param {resultCallback} callback A callback function
+ */
+Cursor.prototype.kill = function(callback) {
+ this._killcursor(callback);
+}
+
+/**
+ * Resets the cursor
+ * @method
+ * @return {null}
+ */
+Cursor.prototype.rewind = function() {
+ if(this.cursorState.init) {
+ if(!this.cursorState.dead) {
+ this.kill();
+ }
+
+ this.cursorState.currentLimit = 0;
+ this.cursorState.init = false;
+ this.cursorState.dead = false;
+ this.cursorState.killed = false;
+ this.cursorState.notified = false;
+ this.cursorState.documents = [];
+ this.cursorState.cursorId = null;
+ this.cursorState.cursorIndex = 0;
+ }
+}
+
+/**
+ * Validate if the pool is dead and return error
+ */
+var isConnectionDead = function(self, callback) {
+ if(self.pool
+ && self.pool.isDestroyed()) {
+ self.cursorState.notified = true;
+ self.cursorState.killed = true;
+ self.cursorState.documents = [];
+ self.cursorState.cursorIndex = 0;
+ callback(MongoError.create(f('connection to host %s:%s was destroyed', self.pool.host, self.pool.port)))
+ return true;
+ }
+
+ return false;
+}
+
+/**
+ * Validate if the cursor is dead but was not explicitly killed by user
+ */
+var isCursorDeadButNotkilled = function(self, callback) {
+ // Cursor is dead but not marked killed, return null
+ if(self.cursorState.dead && !self.cursorState.killed) {
+ self.cursorState.notified = true;
+ self.cursorState.killed = true;
+ self.cursorState.documents = [];
+ self.cursorState.cursorIndex = 0;
+ handleCallback(callback, null, null);
+ return true;
+ }
+
+ return false;
+}
+
+/**
+ * Validate if the cursor is dead and was killed by user
+ */
+var isCursorDeadAndKilled = function(self, callback) {
+ if(self.cursorState.dead && self.cursorState.killed) {
+ handleCallback(callback, MongoError.create("cursor is dead"));
+ return true;
+ }
+
+ return false;
+}
+
+/**
+ * Validate if the cursor was killed by the user
+ */
+var isCursorKilled = function(self, callback) {
+ if(self.cursorState.killed) {
+ self.cursorState.notified = true;
+ self.cursorState.documents = [];
+ self.cursorState.cursorIndex = 0;
+ handleCallback(callback, null, null);
+ return true;
+ }
+
+ return false;
+}
+
+/**
+ * Mark cursor as being dead and notified
+ */
+var setCursorDeadAndNotified = function(self, callback) {
+ self.cursorState.dead = true;
+ self.cursorState.notified = true;
+ self.cursorState.documents = [];
+ self.cursorState.cursorIndex = 0;
+ handleCallback(callback, null, null);
+}
+
+/**
+ * Mark cursor as being notified
+ */
+var setCursorNotified = function(self, callback) {
+ self.cursorState.notified = true;
+ self.cursorState.documents = [];
+ self.cursorState.cursorIndex = 0;
+ handleCallback(callback, null, null);
+}
+
+var push = Array.prototype.push;
+
+var nextFunction = function(self, callback) {
+ // We have notified about it
+ if(self.cursorState.notified) {
+ return callback(new Error('cursor is exhausted'));
+ }
+
+ // Cursor is killed return null
+ if(isCursorKilled(self, callback)) return;
+
+ // Cursor is dead but not marked killed, return null
+ if(isCursorDeadButNotkilled(self, callback)) return;
+
+ // We have a dead and killed cursor, attempting to call next should error
+ if(isCursorDeadAndKilled(self, callback)) return;
+
+ // We have just started the cursor
+ if(!self.cursorState.init) {
+ // Topology is not connected, save the call in the provided store to be
+ // Executed at some point when the handler deems it's reconnected
+ if(!self.topology.isConnected(self.options) && self.disconnectHandler != null) {
+ return self.disconnectHandler.addObjectAndMethod('cursor', self, 'next', [callback], callback);
+ }
+
+ try {
+ self.server = self.topology.getServer(self.options);
+ } catch(err) {
+ // Handle the error and add object to next method call
+ if(self.disconnectHandler != null) {
+ return self.disconnectHandler.addObjectAndMethod('cursor', self, 'next', [callback], callback);
+ }
+
+ // Otherwise return the error
+ return callback(err);
+ }
+
+ // Set as init
+ self.cursorState.init = true;
+
+ try {
+ self.query = self.server.wireProtocolHandler.command(self.bson, self.ns, self.cmd, self.cursorState, self.topology, self.options);
+ } catch(err) {
+ return callback(err);
+ }
+ }
+
+ // If we don't have a cursorId execute the first query
+ if(self.cursorState.cursorId == null) {
+ // Check if pool is dead and return if not possible to
+ // execute the query against the db
+ if(isConnectionDead(self, callback)) return;
+
+ // Check if topology is destroyed
+ if(self.topology.isDestroyed()) return callback(new MongoError(f('connection destroyed, not possible to instantiate cursor')));
+
+ // query, cmd, options, cursorState, callback
+ self._find(function(err, r) {
+ if(err) return handleCallback(callback, err, null);
+
+ if(self.cursorState.documents.length == 0
+ && self.cursorState.cursorId && self.cursorState.cursorId.isZero()
+ && !self.cmd.tailable && !self.cmd.awaitData) {
+ return setCursorNotified(self, callback);
+ }
+
+ nextFunction(self, callback);
+ });
+ } else if(self.cursorState.limit > 0 && self.cursorState.currentLimit >= self.cursorState.limit) {
+ // Ensure we kill the cursor on the server
+ self.kill();
+ // Set cursor in dead and notified state
+ return setCursorDeadAndNotified(self, callback);
+ } else if(self.cursorState.cursorIndex == self.cursorState.documents.length
+ && !Long.ZERO.equals(self.cursorState.cursorId)) {
+ // Ensure an empty cursor state
+ self.cursorState.documents = [];
+ self.cursorState.cursorIndex = 0;
+
+ // Check if topology is destroyed
+ if(self.topology.isDestroyed()) return callback(new MongoError(f('connection destroyed, not possible to instantiate cursor')));
+
+ // Check if connection is dead and return if not possible to
+ // execute a getmore on this connection
+ if(isConnectionDead(self, callback)) return;
+
+ // Execute the next get more
+ self._getmore(function(err, doc, connection) {
+ if(err) return handleCallback(callback, err);
+
+ // Save the returned connection to ensure all getMore's fire over the same connection
+ self.connection = connection;
+
+ // Tailable cursor getMore result, notify owner about it
+ // No attempt is made here to retry, this is left to the user of the
+ // core module to handle to keep core simple
+ if(self.cursorState.documents.length == 0
+ && self.cmd.tailable && Long.ZERO.equals(self.cursorState.cursorId)) {
+ // No more documents in the tailed cursor
+ return handleCallback(callback, MongoError.create({
+ message: "No more documents in tailed cursor"
+ , tailable: self.cmd.tailable
+ , awaitData: self.cmd.awaitData
+ }));
+ } else if(self.cursorState.documents.length == 0
+ && self.cmd.tailable && !Long.ZERO.equals(self.cursorState.cursorId)) {
+ return nextFunction(self, callback);
+ }
+
+ if(self.cursorState.limit > 0 && self.cursorState.currentLimit >= self.cursorState.limit) {
+ return setCursorDeadAndNotified(self, callback);
+ }
+
+ nextFunction(self, callback);
+ });
+ } else if(self.cursorState.documents.length == self.cursorState.cursorIndex
+ && self.cmd.tailable && Long.ZERO.equals(self.cursorState.cursorId)) {
+ return handleCallback(callback, MongoError.create({
+ message: "No more documents in tailed cursor"
+ , tailable: self.cmd.tailable
+ , awaitData: self.cmd.awaitData
+ }));
+ } else if(self.cursorState.documents.length == self.cursorState.cursorIndex
+ && Long.ZERO.equals(self.cursorState.cursorId)) {
+ setCursorDeadAndNotified(self, callback);
+ } else {
+ if(self.cursorState.limit > 0 && self.cursorState.currentLimit >= self.cursorState.limit) {
+ // Ensure we kill the cursor on the server
+ self.kill();
+ // Set cursor in dead and notified state
+ return setCursorDeadAndNotified(self, callback);
+ }
+
+ // Increment the current cursor limit
+ self.cursorState.currentLimit += 1;
+
+ // Get the document
+ var doc = self.cursorState.documents[self.cursorState.cursorIndex++];
+
+ // Doc overflow
+ if(doc.$err) {
+ // Ensure we kill the cursor on the server
+ self.kill();
+ // Set cursor in dead and notified state
+ return setCursorDeadAndNotified(self, function() {
+ handleCallback(callback, new MongoError(doc.$err));
+ });
+ }
+
+ // Transform the doc with passed in transformation method if provided
+ if(self.cursorState.transforms && typeof self.cursorState.transforms.doc == 'function') {
+ doc = self.cursorState.transforms.doc(doc);
+ }
+
+ // Return the document
+ handleCallback(callback, null, doc);
+ }
+}
+
+/**
+ * Retrieve the next document from the cursor
+ * @method
+ * @param {resultCallback} callback A callback function
+ */
+Cursor.prototype.next = function(callback) {
+ nextFunction(this, callback);
+}
+
+module.exports = Cursor;