116 lines
3.7 KiB
JavaScript
116 lines
3.7 KiB
JavaScript
// Copyright IBM Corp. 2015,2016. All Rights Reserved.
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// Node module: loopback-context-cls
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// This file is licensed under the MIT License.
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// License text available at https://opensource.org/licenses/MIT
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'use strict';
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var cls = require('cls-hooked');
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var domain = require('domain');
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var LoopBackContext = module.exports;
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/**
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* Get the current context object. The context is preserved
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* across async calls, it behaves like a thread-local storage.
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*
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* @options {Object} [options]
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* @property {Boolean} bind Bind get/set/bind methods of the context to the
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* context that's current at the time getCurrentContext() is invoked. This
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* can be used to work around 3rd party code breaking CLS context propagation.
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* @returns {Namespace} The context object or null.
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*/
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LoopBackContext.getCurrentContext = function(options) {
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// A placeholder method, see LoopBackContext.createContext() for the real version
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return null;
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};
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/**
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* Run the given function in such way that
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* `LoopBackContext.getCurrentContext` returns the
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* provided context object.
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*
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* **NOTE**
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*
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* The method is supported on the server only, it does not work
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* in the browser at the moment.
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*
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* @param {Function} fn The function to run, it will receive arguments
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* (currentContext, currentDomain).
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* @param {Namespace} context An optional context object.
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* When no value is provided, then the default global context is used.
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*/
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LoopBackContext.runInContext = function(fn, context) {
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var currentDomain = domain.create();
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currentDomain.oldBind = currentDomain.bind;
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currentDomain.bind = function(callback, context) {
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return currentDomain.oldBind(ns.bind(callback, context), context);
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};
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var ns = context || LoopBackContext.createContext('loopback');
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currentDomain.run(function() {
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ns.run(function executeInContext(context) {
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fn(ns, currentDomain);
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});
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});
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};
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/**
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* Create a new LoopBackContext instance that can be used
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* for `LoopBackContext.runInContext`.
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*
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* **NOTES**
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*
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* At the moment, `LoopBackContext.getCurrentContext` supports
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* a single global context instance only. If you call `createContext()`
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* multiple times, `getCurrentContext` will return the last context
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* created.
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*
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* The method is supported on the server only, it does not work
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* in the browser at the moment.
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*
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* @param {String} scopeName An optional scope name.
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* @return {Namespace} The new context object.
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*/
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LoopBackContext.createContext = function(scopeName) {
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// Make the namespace globally visible via the process.context property
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process.context = process.context || {};
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var ns = process.context[scopeName];
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if (!ns) {
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ns = cls.createNamespace(scopeName);
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process.context[scopeName] = ns;
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// Set up LoopBackContext.getCurrentContext()
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LoopBackContext.getCurrentContext = function(options) {
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if (!ns || !ns.active) {
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return null;
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}
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if (!options || !options.bind) {
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return ns;
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}
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/**
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* **NOTE**
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* This only re-binds get, set and bind methods, the most used.
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* If you use other methods of the context, e.g. runInContext(), etc.,
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* you may run into unexpected issues that are fixed only for get & set.
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*/
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var boundContext = Object.create(ns);
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boundContext.get = boundContext.bind(ns.get);
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boundContext.set = boundContext.bind(ns.set);
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// Call to Function.prototype.bind(), not ns.bind()
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boundContext.bind = ns.bind.bind(ns);
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return boundContext;
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};
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}
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return ns;
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};
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/**
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* Create middleware that sets up a new context for each incoming HTTP request.
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*
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* See perRequestContextFactory for more details.
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*/
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LoopBackContext.perRequest = require('./middleware/per-request');
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