use promise pool to handle batch (#19)

package.json

@@ -1,6 +1,6 @@
 {
   "name": "@canva/dependency-tree",
-  "version": "3.1.5",
+  "version": "3.1.6",
   "description": "Calculates a dependency tree for set of files",
   "main": "dist/index.js",
   "author": "Canva Pty Ltd",
@@ -27,6 +27,7 @@
     "test:watch": "jest --watch --notify"
   },
   "dependencies": {
+    "@supercharge/promise-pool": "^2.3.2",
     "acorn": "^8.0.4",
     "builtin-modules": "^3.2.0",
     "cucumber-messages": "3.x",

src/index.ts

@@ -17,6 +17,7 @@ import { TypeScriptFileProcessor } from './processors/typescript';
 import Resolver = require('enhanced-resolve/lib/Resolver');
 import SyncAsyncFileSystemDecorator = require('enhanced-resolve/lib/SyncAsyncFileSystemDecorator');
 import { AbstractInputFileSystem } from 'enhanced-resolve/lib/common-types';
+import { PromisePool } from '@supercharge/promise-pool';
 
 // This is a set of built-in modules, e.g. `path`, `fs`, etc.
 const builtinModules = new Set(bim);
@@ -308,10 +309,9 @@ async function runInBatches(
   tasks: (() => Promise<void>)[],
   batchSize: number,
 ): Promise<void> {
-  for (let i = 0; i < tasks.length; i += batchSize) {
-    const batch = tasks.slice(i, i + batchSize);
-    await Promise.all(batch.map((task) => task()));
-  }
+  await PromisePool.withConcurrency(batchSize)
+    .for(tasks)
+    .process((task) => task());
 }
 
 /**