From d50391fe93a6319c2a554f34d39cce0c946564ec Mon Sep 17 00:00:00 2001
From: xqin <xqin@xqin.net>
Date: Wed, 22 May 2024 18:05:29 +0800
Subject: [PATCH] fix: support nodejs v16.x again (#572)

---
 .github/workflows/nodejs.yml |  4 ++--
 src/common.ts                | 14 ++++++++++++++
 src/index.ts                 |  4 ++--
 test/post-task.ts            |  6 +++---
 4 files changed, 21 insertions(+), 7 deletions(-)

diff --git a/.github/workflows/nodejs.yml b/.github/workflows/nodejs.yml
index 83252ded..1db01426 100644
--- a/.github/workflows/nodejs.yml
+++ b/.github/workflows/nodejs.yml
@@ -34,7 +34,7 @@ jobs:
       fail-fast: false
       matrix:
         os: [ubuntu-latest, macos-latest, windows-latest]
-        node-version: [18.x, 20.x, 22.x]
+        node-version: [16.x, 18.x, 20.x, 22.x]
     runs-on: ${{matrix.os}}
     steps:
       - uses: actions/checkout@v4
@@ -53,7 +53,7 @@ jobs:
           key: ${{ runner.os }}-node-${{ matrix.node-version }}-${{ hashFiles('**/package.json') }}
           restore-keys: |
             ${{ runner.os }}-node-${{ matrix.node-version }}-
-      
+
       - name: Install Dependencies
         run: npm install
       - name: Run Tests
diff --git a/src/common.ts b/src/common.ts
index 51caa22e..9f372b4b 100644
--- a/src/common.ts
+++ b/src/common.ts
@@ -1,5 +1,6 @@
 import type { Histogram } from 'node:perf_hooks';
 import { fileURLToPath, URL } from 'node:url';
+import { availableParallelism, cpus } from 'node:os';
 
 import type { HistogramSummary } from './types';
 import { kMovable, kTransferable, kValue } from './symbols';
@@ -87,3 +88,16 @@ export function maybeFileURLToPath (filename : string) : string {
     ? fileURLToPath(new URL(filename))
     : filename;
 }
+
+// TODO: drop on v5
+export function getAvailableParallelism () : number {
+  if (typeof availableParallelism === 'function') {
+    return availableParallelism();
+  }
+
+  try {
+    return cpus().length;
+  } catch {
+    return 1;
+  }
+}
diff --git a/src/index.ts b/src/index.ts
index 9d985ac4..bfef7224 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -1,7 +1,6 @@
 import { Worker, MessageChannel, MessagePort, receiveMessageOnPort } from 'node:worker_threads';
 import { once, EventEmitterAsyncResource } from 'node:events';
 import { AsyncResource } from 'node:async_hooks';
-import { availableParallelism } from 'node:os';
 import { resolve } from 'node:path';
 import { inspect, types } from 'node:util';
 import { RecordableHistogram, createHistogram, performance } from 'node:perf_hooks';
@@ -49,6 +48,7 @@ import {
   isMovable,
   createHistogramSummary,
   toHistogramIntegerNano,
+  getAvailableParallelism,
   maybeFileURLToPath
 } from './common';
 import FixedQueue from './fixed-queue';
@@ -61,7 +61,7 @@ const { version } = JSON.parse(
     }
   ));
 
-const cpuParallelism : number = availableParallelism();
+const cpuParallelism : number = getAvailableParallelism();
 
 interface Options {
   filename? : string | null,
diff --git a/test/post-task.ts b/test/post-task.ts
index bdcbe3ff..8164756e 100644
--- a/test/post-task.ts
+++ b/test/post-task.ts
@@ -1,5 +1,5 @@
 import { MessageChannel } from 'worker_threads';
-import { availableParallelism } from 'os';
+import { getAvailableParallelism } from '../dist/common';
 import Piscina from '..';
 import { test } from 'tap';
 import { resolve } from 'path';
@@ -168,7 +168,7 @@ test('Piscina.maxThreads should return the max number of threads to be used (def
     filename: resolve(__dirname, 'fixtures/eval.js')
   });
 
-  const maxThreads = (availableParallelism() ?? 1) * 1.5;
+  const maxThreads = getAvailableParallelism() * 1.5;
 
   equal(pool.maxThreads, maxThreads);
 });
@@ -189,7 +189,7 @@ test('Piscina.minThreads should return the max number of threads to be used (def
   const pool = new Piscina({
     filename: resolve(__dirname, 'fixtures/eval.js')
   });
-  const minThreads = Math.max(Math.floor(availableParallelism() / 2), 1);
+  const minThreads = Math.max(Math.floor(getAvailableParallelism() / 2), 1);
 
   plan(1);
   equal(pool.minThreads, minThreads);