Explicit create() and run()

Signed-off-by: Matteo Collina <[email protected]>

README.md

@@ -14,36 +14,43 @@ npm i asyncforge
 ## Usage
 
 ```js
-import { memo } from 'asyncforge'
+import { create, memo } from 'asyncforge.js'
 
 const a = memo()
 const b = memo()
 
-a.set(42)
-b.set(123)
+const store = create()
 
-// simulate an event loop turn
-setImmediate(() => {
-  console.log('-- first event loop turn --')
-  console.log('a', a())
-  console.log('b', b())
+store.run(() => {
+  a.set(42)
+  b.set(123)
 
-  b.set(456)
+  // simulate an event loop turn
   setImmediate(() => {
-    console.log('-- third event loop turn --')
+    console.log('-- first event loop turn --')
     console.log('a', a())
     console.log('b', b())
   })
 })
 
-a.set(43)
-b.set(321)
+create(() => {
+  a.set(43)
+  b.set(321)
 
-// simulate an event loop turn
-setImmediate(() => {
-  console.log('-- second event loop turn --')
-  console.log('a', a())
-  console.log('b', b())
+  // simulate an event loop turn
+  setImmediate(() => {
+    console.log('-- second event loop turn --')
+    console.log('a', a())
+    console.log('b', b())
+
+    store.run(() => {
+      setImmediate(() => {
+        console.log('-- third event loop turn --')
+        console.log('a', a())
+        console.log('b', b())
+      })
+    })
+  })
 })
 ```
 

asyncforge.d.ts

@@ -1,13 +1,17 @@
 declare namespace asyncforge {
-  export function start(): void;
+  interface Store {
+    run<T>(fn: () => T) : T;
+  }
+
+  export function create () : Store;
+
   export function memo<T extends unknown>(
     name?: string
   ): {
     (): T;
     key: symbol;
     set: (value: T) => void;
   };
-  export function setAll(memos: Record<symbol, unknown>): void;
 }
 
 export = asyncforge

asyncforge.js

@@ -4,9 +4,24 @@ const { AsyncLocalStorage } = require('node:async_hooks')
 
 const asyncLocalStorage = new AsyncLocalStorage()
 
-function start () {
-  const store = Object.create(null)
-  asyncLocalStorage.enterWith(store)
+class Store {
+  #internal
+
+  constructor (internal) {
+    this.#internal = internal
+  }
+
+  run (fn) {
+    return asyncLocalStorage.run(this.#internal, fn)
+  }
+}
+
+function create (fn) {
+  const store = new Store(Object.create(null))
+  if (fn) {
+    store.run(fn)
+  }
+  return store
 }
 
 let memoCounter = 0
@@ -18,16 +33,20 @@ function memo (name) {
   function get () {
     const store = asyncLocalStorage.getStore()
     if (!store) {
-      throw new Error(`asyncforge store is not initialized for ${name}`)
+      throw new Error('asyncforge store has not been created')
     }
     return store[sym]
   }
 
   function set (value) {
-    let store = asyncLocalStorage.getStore()
-    store = Object.create(store || null)
+    const store = asyncLocalStorage.getStore()
+    if (!store) {
+      throw new Error('asyncforge store has not been created')
+    }
+    if (Object.hasOwnProperty.call(store, sym)) {
+      throw new Error(`asyncforge store already initialized for ${name}`)
+    }
     store[sym] = value
-    asyncLocalStorage.enterWith(store)
   }
 
   get.set = set
@@ -36,16 +55,5 @@ function memo (name) {
   return get
 }
 
-function setAll (memos) {
-  let store = asyncLocalStorage.getStore()
-  store = Object.create(store || null)
-  const keys = Object.getOwnPropertySymbols(memos)
-  for (const key of keys) {
-    store[key] = memos[key]
-  }
-  asyncLocalStorage.enterWith(store)
-}
-
+module.exports.create = create
 module.exports.memo = memo
-module.exports.start = start
-module.exports.setAll = setAll

asyncforge.test-d.ts

@@ -1,16 +1,16 @@
 import { expectError, expectType } from "tsd";
-import { start, memo, setAll } from ".";
+import { create, memo } from ".";
+import type { Store } from ".";
 
-expectType<() => void>(start);
+expectType<() => Store>(create);
+
+const store = create();
+
+expectType<number>(store.run(() => 42));
 
 // memo
 const memoNum = memo<number>();
 expectType<symbol>(memoNum.key);
 expectType<void>(memoNum.set(123));
 expectType<number>(memoNum());
 expectError<void>(memoNum.set("wrong"));
-
-// setAll
-const test = memo<string>();
-expectType<void>(setAll({ [test.key]: 42 }));
-expectError<void>(setAll({ wrong: 42 }));

example.mjs

@@ -1,31 +1,38 @@
-import { memo } from './asyncforge.js'
+import { create, memo } from './asyncforge.js'
 
 const a = memo()
 const b = memo()
 
-a.set(42)
-b.set(123)
+const store = create()
 
-// simulate an event loop turn
-setImmediate(() => {
-  console.log('-- first event loop turn --')
-  console.log('a', a())
-  console.log('b', b())
+store.run(() => {
+  a.set(42)
+  b.set(123)
 
-  b.set(456)
+  // simulate an event loop turn
   setImmediate(() => {
-    console.log('-- third event loop turn --')
+    console.log('-- first event loop turn --')
     console.log('a', a())
     console.log('b', b())
   })
 })
 
-a.set(43)
-b.set(321)
+create(() => {
+  a.set(43)
+  b.set(321)
 
-// simulate an event loop turn
-setImmediate(() => {
-  console.log('-- second event loop turn --')
-  console.log('a', a())
-  console.log('b', b())
+  // simulate an event loop turn
+  setImmediate(() => {
+    console.log('-- second event loop turn --')
+    console.log('a', a())
+    console.log('b', b())
+
+    store.run(() => {
+      setImmediate(() => {
+        console.log('-- third event loop turn --')
+        console.log('a', a())
+        console.log('b', b())
+      })
+    })
+  })
 })