Drop continuation-local-storage, use cls-hooked

Rework the module to use the new cls-hooked module (which uses AsyncWrap
available since Node v4.5) instead of old continuation-local-storage
(based on very unreliable async-listener).

.travis.yml

@@ -1,7 +1,5 @@
 sudo: false
 language: node_js
 node_js:
-  - "0.10"
-  - "0.12"
   - "4"
   - "6"

README.md

@@ -1,7 +1,38 @@
 # loopback-context
 
 Current context for LoopBack applications, based on
-node-continuation-local-storage.
+cls-hooked.
+
+## USAGE WARNING
+
+**Only if you use this package, it's recommended to not run your app using `slc run` or `node .`**
+
+Run using (recommended):
+
+`node -r cls-hooked .`
+
+This uses the `-r` option in order to require `cls-hooked` before your app (see warnings below for more info).
+
+If you wish to use `strong-supervisor`, you would need to pass node options to `slc run`, which currently has issues, according to [strong-supervisor#56](https://github.com/strongloop/strong-supervisor/issues/56).
+
+A less reliable, less recommended way, which instead should be compatible with `strong-supervisor`, would be to add this Javascript line at the first line of your app, and no later than that (**the order of require statements matters**):
+
+`require('cls-hooked')`
+
+Warning: to rely on the order of `require` statements is error-prone.
+
+## INSTALL WARNING
+
+**Only if you use this package, do NOT install your app using `npm install`.**
+
+Install using:
+
+```
+npm config set engine-strict true
+npm install
+```
+
+This keeps you from using Node < v4.5.
 
 ## WARNING
 
@@ -13,8 +44,8 @@ As a result, loopback-context does not work in many situations, as can be
 seen from issues reported in LoopBack's
 [issue tracker](https://github.com/strongloop/loopback/issues?utf8=%E2%9C%93&q=is%3Aissue%20getCurrentcontext).
 
-If you are running on Node v6, you can try the new alternative
-[cls-hooked](https://github.com/Jeff-Lewis/cls-hooked).
+The new alternative
+[cls-hooked](https://github.com/Jeff-Lewis/cls-hooked) is known to possibly inherit these problems if it's not imported before everything else, that's why you are required to follow the advice above if using this.
 
 ## Usage
 

package.json

@@ -1,9 +1,9 @@
 {
   "name": "loopback-context",
   "version": "3.0.0-alpha.1",
-  "description": "Current context for LoopBack applications, based on node-continuation-local-storage",
+  "description": "Current context for LoopBack applications, based on cls-hooked",
   "engines": {
-    "node": ">=4"
+    "node": "^4.5 || ^5.10 || ^6.0"
   },
   "keywords": [
     "StrongLoop",
@@ -23,9 +23,10 @@
   },
   "license": "MIT",
   "dependencies": {
-    "continuation-local-storage": "^3.1.7"
+    "cls-hooked": "^4.0.1"
   },
   "devDependencies": {
+    "async": "1.5.2",
     "chai": "^3.5.0",
     "dirty-chai": "^1.2.2",
     "eslint": "^2.13.1",

server/current-context.js

@@ -5,20 +5,9 @@
 
 'use strict';
 
+var cls = require('cls-hooked');
 var domain = require('domain');
 
-// Require CLS only when using the current context feature.
-// As soon as this require is done, all the instrumentation/patching
-// of async-listener is fired which is not ideal.
-//
-// Some users observed stack overflows due to promise instrumentation
-// and other people have seen similar things:
-//   https://github.com/othiym23/async-listener/issues/57
-// It all goes away when instrumentation is disabled.
-var cls = function() {
-  return require('continuation-local-storage');
-};
-
 var LoopBackContext = module.exports;
 
 /**
@@ -85,7 +74,7 @@ LoopBackContext.createContext = function(scopeName) {
   process.context = process.context || {};
   var ns = process.context[scopeName];
   if (!ns) {
-    ns = cls().createNamespace(scopeName);
+    ns = cls.createNamespace(scopeName);
     process.context[scopeName] = ns;
     // Set up LoopBackContext.getCurrentContext()
     LoopBackContext.getCurrentContext = function() {

test/main.test.js

@@ -5,6 +5,7 @@
 
 'use strict';
 
+var async = require('async');
 var LoopBackContext = require('..');
 var Domain = require('domain');
 var EventEmitter = require('events').EventEmitter;
@@ -98,4 +99,34 @@ describe('LoopBack Context', function() {
       });
     });
   });
+
+  // Credits for the original idea for this test case to @marlonkjoseph
+  // Original source of the POC gist of the idea:
+  // https://gist.github.com/marlonkjoseph/f42f3c71f746896a0d4b7279a34ea753
+  // Heavily edited by others
+  it('keeps context when using waterfall() from async 1.5.2',
+  function(done) {
+    expect(require('async/package.json').version).to.equal('1.5.2');
+    LoopBackContext.runInContext(function() {
+      // Trigger async waterfall callbacks
+      async.waterfall([
+        function pushToContext(next) {
+          var ctx = LoopBackContext.getCurrentContext();
+          expect(ctx).is.an('object');
+          ctx.set('test-key', 'test-value');
+          next();
+        },
+        function pullFromContext(next) {
+          var ctx = LoopBackContext.getCurrentContext();
+          expect(ctx).is.an('object');
+          var testValue = ctx && ctx.get('test-key', 'test-value');
+          next(null, testValue);
+        },
+        function verify(testValue, next) {
+          expect(testValue).to.equal('test-value');
+          next();
+        },
+      ], done);
+    });
+  });
 });

test/mocha.opts

@@ -0,0 +1 @@
+-r cls-hooked