process: split worker IO into internal/worker/io.js

- Move `setupProcessStdio` which contains write access to
  the process object into `bootstrap/node.js`
- Move `MessagePort`, `MessageChannel`, `ReadableWorkerStdio`,
  and `WritableWorkerStdio` into `internal/worker/io.js`
- Move more worker-specific bootstrap code into
  `internal/process/worker_thread_only` from `setupChild`
  in `internal/worker.js`, and move the `process._fatalException`
  overwrite into `bootstrap/node.js` for clarity.

PR-URL: https://github.com/nodejs/node/pull/25199
Reviewed-By: James M Snell <jasnell@gmail.com>

1 files changed, 41 insertions, 10 deletions

diff --git a/lib/internal/process/worker_thread_only.js b/lib/internal/process/worker_thread_only.js
index 834ba6078f..a9332fb427 100644
--- a/lib/internal/process/worker_thread_only.js
+++ b/lib/internal/process/worker_thread_only.js
@@ -2,23 +2,54 @@
 
 // This file contains process bootstrappers that can only be
 // run in the worker thread.
+const {
+  getEnvMessagePort,
+  threadId
+} = internalBinding('worker');
+
+const debug = require('util').debuglog('worker');
 
 const {
-  setupProcessStdio
-} = require('internal/process/stdio');
+  kWaitingStreams,
+  ReadableWorkerStdio,
+  WritableWorkerStdio
+} = require('internal/worker/io');
 
 const {
-  workerStdio
+  createMessageHandler,
+  createWorkerFatalExeception
 } = require('internal/worker');
 
-function setupStdio() {
-  setupProcessStdio({
-    getStdout: () => workerStdio.stdout,
-    getStderr: () => workerStdio.stderr,
-    getStdin: () => workerStdio.stdin
-  });
+const workerStdio = {};
+
+function initializeWorkerStdio() {
+  const port = getEnvMessagePort();
+  port[kWaitingStreams] = 0;
+  workerStdio.stdin = new ReadableWorkerStdio(port, 'stdin');
+  workerStdio.stdout = new WritableWorkerStdio(port, 'stdout');
+  workerStdio.stderr = new WritableWorkerStdio(port, 'stderr');
+
+  return {
+    getStdout() { return workerStdio.stdout; },
+    getStderr() { return workerStdio.stderr; },
+    getStdin() { return workerStdio.stdin; }
+  };
+}
+
+function setup() {
+  debug(`[${threadId}] is setting up worker child environment`);
+
+  const port = getEnvMessagePort();
+  const publicWorker = require('worker_threads');
+  port.on('message', createMessageHandler(publicWorker, port, workerStdio));
+  port.start();
+
+  return {
+    workerFatalExeception: createWorkerFatalExeception(port)
+  };
 }
 
 module.exports = {
-  setupStdio
+  initializeWorkerStdio,
+  setup
 };