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129 lines
3.1 KiB
JavaScript
129 lines
3.1 KiB
JavaScript
'use strict';
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const crypto = require('crypto');
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const requireOptional = require('require_optional');
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/**
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* Generate a UUIDv4
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*/
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const uuidV4 = () => {
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const result = crypto.randomBytes(16);
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result[6] = (result[6] & 0x0f) | 0x40;
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result[8] = (result[8] & 0x3f) | 0x80;
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return result;
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};
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/**
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* Returns the duration calculated from two high resolution timers in milliseconds
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*
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* @param {Object} started A high resolution timestamp created from `process.hrtime()`
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* @returns {Number} The duration in milliseconds
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*/
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const calculateDurationInMs = started => {
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const hrtime = process.hrtime(started);
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return (hrtime[0] * 1e9 + hrtime[1]) / 1e6;
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};
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/**
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* Relays events for a given listener and emitter
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*
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* @param {EventEmitter} listener the EventEmitter to listen to the events from
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* @param {EventEmitter} emitter the EventEmitter to relay the events to
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*/
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function relayEvents(listener, emitter, events) {
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events.forEach(eventName => listener.on(eventName, event => emitter.emit(eventName, event)));
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}
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function retrieveKerberos() {
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let kerberos;
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try {
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kerberos = requireOptional('kerberos');
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} catch (err) {
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if (err.code === 'MODULE_NOT_FOUND') {
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throw new Error('The `kerberos` module was not found. Please install it and try again.');
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}
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throw err;
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}
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return kerberos;
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}
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// Throw an error if an attempt to use EJSON is made when it is not installed
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const noEJSONError = function() {
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throw new Error('The `mongodb-extjson` module was not found. Please install it and try again.');
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};
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// Facilitate loading EJSON optionally
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function retrieveEJSON() {
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let EJSON = null;
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try {
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EJSON = requireOptional('mongodb-extjson');
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} catch (error) {} // eslint-disable-line
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if (!EJSON) {
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EJSON = {
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parse: noEJSONError,
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deserialize: noEJSONError,
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serialize: noEJSONError,
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stringify: noEJSONError,
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setBSONModule: noEJSONError,
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BSON: noEJSONError
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};
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}
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return EJSON;
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}
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/**
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* A helper function for determining `maxWireVersion` between legacy and new topology
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* instances
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*
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* @private
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* @param {(Topology|Server)} topologyOrServer
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*/
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function maxWireVersion(topologyOrServer) {
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if (topologyOrServer.ismaster) {
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return topologyOrServer.ismaster.maxWireVersion;
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}
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if (topologyOrServer.description) {
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return topologyOrServer.description.maxWireVersion;
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}
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return null;
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}
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/*
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* Checks that collation is supported by server.
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*
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* @param {Server} [server] to check against
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* @param {object} [cmd] object where collation may be specified
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* @param {function} [callback] callback function
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* @return true if server does not support collation
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*/
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function collationNotSupported(server, cmd) {
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return cmd && cmd.collation && maxWireVersion(server) < 5;
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}
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/**
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* Checks if a given value is a Promise
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*
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* @param {*} maybePromise
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* @return true if the provided value is a Promise
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*/
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function isPromiseLike(maybePromise) {
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return maybePromise && typeof maybePromise.then === 'function';
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}
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module.exports = {
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uuidV4,
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calculateDurationInMs,
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relayEvents,
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collationNotSupported,
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retrieveEJSON,
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retrieveKerberos,
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maxWireVersion,
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isPromiseLike
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};
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