105 lines
3.1 KiB
JavaScript
Executable File
105 lines
3.1 KiB
JavaScript
Executable File
/**
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* create-logger.js: Logger factory for winston logger instances.
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*
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* (C) 2010 Charlie Robbins
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* MIT LICENCE
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*/
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'use strict';
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const { LEVEL } = require('triple-beam');
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const config = require('./config');
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const Logger = require('./logger');
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const debug = require('@dabh/diagnostics')('winston:create-logger');
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function isLevelEnabledFunctionName(level) {
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return 'is' + level.charAt(0).toUpperCase() + level.slice(1) + 'Enabled';
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}
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/**
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* Create a new instance of a winston Logger. Creates a new
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* prototype for each instance.
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* @param {!Object} opts - Options for the created logger.
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* @returns {Logger} - A newly created logger instance.
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*/
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module.exports = function (opts = {}) {
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//
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// Default levels: npm
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//
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opts.levels = opts.levels || config.npm.levels;
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/**
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* DerivedLogger to attach the logs level methods.
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* @type {DerivedLogger}
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* @extends {Logger}
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*/
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class DerivedLogger extends Logger {
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/**
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* Create a new class derived logger for which the levels can be attached to
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* the prototype of. This is a V8 optimization that is well know to increase
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* performance of prototype functions.
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* @param {!Object} options - Options for the created logger.
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*/
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constructor(options) {
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super(options);
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}
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}
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const logger = new DerivedLogger(opts);
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//
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// Create the log level methods for the derived logger.
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//
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Object.keys(opts.levels).forEach(function (level) {
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debug('Define prototype method for "%s"', level);
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if (level === 'log') {
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// eslint-disable-next-line no-console
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console.warn('Level "log" not defined: conflicts with the method "log". Use a different level name.');
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return;
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}
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//
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// Define prototype methods for each log level e.g.:
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// logger.log('info', msg) implies these methods are defined:
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// - logger.info(msg)
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// - logger.isInfoEnabled()
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//
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// Remark: to support logger.child this **MUST** be a function
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// so it'll always be called on the instance instead of a fixed
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// place in the prototype chain.
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//
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DerivedLogger.prototype[level] = function (...args) {
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// Prefer any instance scope, but default to "root" logger
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const self = this || logger;
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// Optimize the hot-path which is the single object.
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if (args.length === 1) {
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const [msg] = args;
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const info = msg && msg.message && msg || { message: msg };
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info.level = info[LEVEL] = level;
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self._addDefaultMeta(info);
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self.write(info);
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return (this || logger);
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}
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// When provided nothing assume the empty string
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if (args.length === 0) {
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self.log(level, '');
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return self;
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}
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// Otherwise build argument list which could potentially conform to
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// either:
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// . v3 API: log(obj)
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// 2. v1/v2 API: log(level, msg, ... [string interpolate], [{metadata}], [callback])
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return self.log(level, ...args);
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};
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DerivedLogger.prototype[isLevelEnabledFunctionName(level)] = function () {
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return (this || logger).isLevelEnabled(level);
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};
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});
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return logger;
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};
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