[FEAT] Manger.exists API (#28)

Author: onhate

README.md

@@ -1,6 +1,6 @@
 # node-execution-context
 A straightforward library that provides a persistent process-level context wrapper using node "async_hooks" feature.
-This library will try to use by default [`AsyncLocalStorage`](https://nodejs.org/api/async_hooks.html#async_hooks_class_asynclocalstorage) implementation based if current node version supports it, otherwise it will fallback to raw [`async_hooks`](https://nodejs.org/api/async_hooks.html) implementation for lower versions which mimics this behaviour. 
+This library will try to use by default [`AsyncLocalStorage`](https://nodejs.org/api/async_hooks.html#async_hooks_class_asynclocalstorage) implementation based if current node version supports it, otherwise it will fallback to raw [`async_hooks`](https://nodejs.org/api/async_hooks.html) implementation for lower versions which mimics this behaviour.
 
 ## Installation
 
@@ -10,7 +10,7 @@ npm i node-execution-context
 
 ## Getting started
 
-Let't start with creating the context initialisation point of our app, well take an simples express app for this example
+Let's start with creating the context initialisation point of our app, we will take a simple express app for this example
 
 ```js
 // main.js
@@ -32,7 +32,7 @@ app.listen(port);
 
 ```
 
-This will expose any point of your code form this point that handles that request. 
+This will expose any point of your code form this point that handles that request.
 
 ```js
 // ./controller/user/index.js
@@ -44,12 +44,12 @@ const logger = require('../service/logger');
 export class UserController {
     async create (req) {
         const { user } = req.body;
-        
+
         // This will return the reference number set by out ContextMiddleware (generated by Math.random())
         const { reference } = Context.get();
-        
+
         logger.info('Created user for reference: ', reference);
-        
+
         return await mongo.create('user', user);
     }
 }
@@ -66,7 +66,7 @@ The context will be exposed to all callbacks and promise chains triggered from t
 
 Gets the current asynchronous execution context.
 
-> The `get` result is returned by `reference` meaning if you wish any immutability applied, it will have to be manually applied. 
+> The `get` result is returned by `reference` meaning if you wish any immutability applied, it will have to be manually applied.
 
 > This API may throw CONTEXT_DOES_NOT_EXIST error if accessed without initializing the context properly.
 
@@ -81,7 +81,7 @@ Sets the current asynchronous execution context to given value.
 Creates a given context for the current asynchronous execution.
 It is recommended to use the `run` method. This method should be used in special cases in which the `run` method cannot be used directly.
 
-> Note that if this method will be called not within a AsyncResource context, it will effect current execution context and should be used with caution. 
+> Note that if this method will be called not within a AsyncResource context, it will effect current execution context and should be used with caution.
 
 #### Example
 
@@ -97,7 +97,7 @@ emitter.on('contextual-event', () => {
 
 // service.js
 emitter.on('contextual-event', () => {
-  Context.get(); // Returns { id: random } 
+  Context.get(); // Returns { id: random }
 });
 
 // main.js
@@ -144,26 +144,26 @@ Context.create({
 
 Promise.resolve().then(() => {
     console.log(Context.get()); // outputs: {"value": true}
-    
+
     Context.set({
         value: false
     });
-    
+
     return new Promise((resolve) => {
         setTimeout(() => {
             console.log(Context.get()); // outputs: {"value": false}
-            
+
             Context.set({
                 butter: 'fly'
             });
-            
+
             process.nextTick(() => {
                 console.log(Context.get()); // outputs: {"butter": 'fly'}
                 resolve();
             });
-            
+
         }, 1000);
-        
+
         console.log(Context.get()); // outputs: {"value": false}
     });
 });

src/ExecutionContext/index.js

@@ -40,6 +40,14 @@ class ExecutionContext {
         this.manager.update(context);
     }
 
+    /**
+     * Check if the current asynchronous execution context exists.
+     * @return {boolean}
+     */
+    exists() {
+        return this.manager.exists();
+    }
+
     /**
      * Gets the current asynchronous execution context.
      * @return {*}

src/ExecutionContext/spec.js

@@ -17,6 +17,20 @@ describe('Context', () => {
             });
         });
 
+        describe('Exists', () => {
+            it('Returns false when context is not created', () => {
+                expect(Context.exists()).toBeFalsy();
+            });
+
+            describe('When context is exists', () => {
+                it('Returns true', () => {
+                    Context.create({ val: 'value' });
+
+                    expect(() => Context.exists()).toBeTruthy();
+                });
+            });
+        });
+
         describe('Get', () => {
             it('Throws an error when context is not created', () => {
                 expect(() => Context.get())

src/managers/asyncHooks/index.js

@@ -84,6 +84,12 @@ class AsyncHooksContext {
         });
     }
 
+    exists() {
+        const asyncId = asyncHooks.executionAsyncId();
+
+        return executionContextMap.has(asyncId);
+    }
+
     get() {
         const asyncId = asyncHooks.executionAsyncId();
 

src/managers/asyncLocalStorage/index.js

@@ -31,6 +31,10 @@ class AsyncLocalStorageContext {
         );
     }
 
+    exists() {
+        return validateStore(this.asyncLocaleStorage);
+    }
+
     get() {
         if (!validateStore(this.asyncLocaleStorage)) {
             return handleError(ExecutionContextErrors.CONTEXT_DOES_NOT_EXIST);

src/types.d.ts

@@ -23,6 +23,11 @@ interface ExecutionContextAPI {
      */
     update(context: Record<string, unknown>): void;
 
+    /**
+     * Checks if the current asynchronous execution context exists.
+     */
+    exists(): boolean;
+
     /**
      * Gets the current asynchronous execution context.
      */
@@ -63,4 +68,4 @@ export {
     ExecutionContextAPI
 };
 
-export default context;
+export default context;