Async local storage (#6)

* ready to go just waiting for a v12 backport before I can pull in

* a little less verbose

* Update index.js

Just formatting

* Update README.md

Updating the language to more accurately match what is going on

* Update npmpublish.yml

Adding node versions for expected compatibality

* Update pr.yml

Adding to ensure compatibility across v12 and higher node versions

* Update pr.yml

Correct way to build with multiple version support

* Update npmpublish.yml

Correct way to do multiple versions

* made to be agnostic of node version

* updated tests to ensure that behavior is as expected

* Update npmpublish.yml

Adding v10 to ensure full test coverage given feature clauses in code

* Update pr.yml

Adding v10 to ensure full test coverage given feature clauses in code

* Update pr.yml

not needed

* Update npmpublish.yml

not needed

* needed

* needed

Author: thorough-developer

.github/workflows/npmpublish.yml

@@ -10,15 +10,17 @@ on:
 jobs:
   build:
     runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        node: [ '14', '13', '12', '10']
     steps:
       - uses: actions/checkout@v2
       - uses: actions/setup-node@v1
         with:
-          node-version: 12
+          node-version: ${{ matrix.node }}
       - run: npm ci
       - run: npm test
       - run: npm run benchmark
-
   publish-npm:
     needs: build
     runs-on: ubuntu-latest

.github/workflows/pr.yml

@@ -12,7 +12,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        node: [ '14', '13', '12']
+        node: [ '14', '13', '12', '10' ]
     steps:
       - uses: actions/checkout@v2
       - uses: actions/setup-node@v1

.gitignore

@@ -1,4 +1,3 @@
 node_modules
 .nyc_output
 *.tgz
-package-lock.json

README.md

@@ -4,10 +4,10 @@
 
 > This plugin was inspired by express-http-context, but works more seamlessly within the fastify ecosystem.
  
-The purpose of this fastify plugin is to easily add a true http context, where any variables set within the scope of a single http call won't be overwritten by simultaneous calls to the api
+The purpose of this fastify plugin is to easily add a true thread local http context, where any variables set within the scope of a single http call won't be overwritten by simultaneous calls to the api
 nor will variables remain to be assumed by subsequent calls once a request is completed.
 
-This is ideal when you need, to for instance, set a user in a hook, and then retrieve that user later on to add them as the createdBy or modifiedBy user later in subsequent calls. This plugin
+This is ideal when you need to, for instance, set a user in a hook, and then retrieve that user later on to add them as the createdBy or modifiedBy user later in subsequent calls. This plugin
 will ensure that the user who made the call is the user that is retrieved later on.
 
 ## Getting started
@@ -27,7 +27,7 @@ const fastify = require('fastify');
 fastify.register(fastifyHttpContextPlugin, { defaults: user: { id: 'system' } };
 ``` 
 
-This plugin takes in a single option named `defaults`. These are what the values should be if not set. This is optional and not necessar. There are cases where defaults are not wanted nor
+This plugin takes in a single option named `defaults`. These are what the values should be if not set. This is optional and not necessary. There are cases where defaults are not wanted nor
 necessary.
 
 From there you can set a context in another hook, route, or method that is within scope. For instance:

async-local-storage.js

@@ -0,0 +1,68 @@
+let AsyncLocalStorage = require('async_hooks').AsyncLocalStorage;
+let namespace; // = new AsyncLocalStorage();
+
+if (AsyncLocalStorage == null) {
+  const createNamespace = require('cls-hooked').createNamespace;
+  const hyperid = require('hyperid');
+  const generator = hyperid();
+  const id = generator();
+
+  const namespaceIdentifier = hyperid.decode(id).uuid;
+  
+  namespace = createNamespace(namespaceIdentifier);
+  namespace.getContext = function(key) {
+    if (this.active) {
+      return this.get(key);
+    }
+    return undefined;
+  };  
+
+  namespace.setContext = function(key, value){
+    if (this.active) {
+      this.set(key, value);
+    }
+  }
+  namespace.doRun = ( defaults = {}, callback) => {
+     namespace.run(() => {
+       for (let [key, value] of defaults) {
+        namespace.set(key, value);
+       }
+       callback();
+     });
+   };
+} else {
+ namespace = new class AsyncLocalStorageFacade extends AsyncLocalStorage {
+  constructor() {
+   super();
+  }
+
+  doRun(defaults, callback) {
+    this.run(new Map(), () => {
+      const store = this.getStore();
+      for (let [key, value] of defaults) {
+        store.set(key, value);
+      }
+      callback();
+    });
+  }
+
+  setContext(key, value) {
+    const store = this.getStore();
+
+    if (store != null) {
+     store.set(key, value);
+    }
+  }
+
+  getContext(key) {
+    const store = this.getStore();
+
+    return store != null ? store.get(key) : undefined;
+  }
+ }();
+}
+
+
+module.exports = {
+  namespace: namespace
+}

index.js

@@ -1,41 +1,21 @@
 const fp = require('fastify-plugin');
-const createNamespace = require('cls-hooked').createNamespace;
-const hyperid = require('hyperid');
-const generator = hyperid();
-const id = generator();
 
-const namespaceIdentifier = hyperid.decode(id).uuid;
-
-let namespace;
-
-const getDefaults = (key) => {
-  return namespace.get(namespaceIdentifier) || {};
-}
+const { namespace } = require('./async-local-storage');
 
 const getContext = (key) => {
-  let value;
-  if (namespace && namespace.active) {
-   value = namespace.get(key) || getDefaults()[key];
-  }
-  return value;
+  return namespace.getContext(key);
 };
 
 const setContext = (key, value) => {
-  if (namespace && namespace.active) {
-   namespace.set(key, value);
-  }
+  namespace.setContext(key, value);
 };
 
 function plugin (fastify, opts, next) {
-  namespace = createNamespace(namespaceIdentifier);
-
+  const defaults = new Map(Object.entries(opts.defaults || {}));
   fastify.addHook('onRequest', (req, res, done) => {
-    namespace.run(() => {
-      if (opts && opts.defaults) {
-       setContext(namespaceIdentifier, opts.defaults);   
-      }
+    namespace.doRun(defaults, () => {
       done();
-    });    
+    });
   });
   next();
 }