[Squash] Address feedback

1. Rename to `setEnvironmentData()`/`environmentData`
2. Make `environmentData` a `Map`
3. `setEnvironmentData()` accepts a key and value.
4. Marked experimental

Author: jasnell

doc/api/worker_threads.md

@@ -61,6 +61,35 @@ Worker threads inherit non-process-specific options by default. Refer to
 [`Worker constructor options`][] to know how to customize worker thread options,
 specifically `argv` and `execArgv` options.
 
+## `worker.environmentData`
+<!-- YAML
+added: REPLACEME
+-->
+
+> Stability: 1 - Experimental
+
+Within a worker thread, `worker.environmentData` is a {Map} containing a clone
+of data passed to the spawning thread's `worker.setEnvironmentData()` function.
+The `worker.environmentData` is similar to `worker.workerData` except that
+every new `Worker` receives it's own copy of `worker.environmentData`
+automatically.
+
+```js
+const {
+  Worker,
+  isMainThread,
+  setEnvironmentData,
+  environmentData
+} = require('worker_threads');
+
+if (isMainThread) {
+  setEnvironmentData('Hello', 'World!');
+  const worker = new Worker(__filename);
+} else {
+  console.log(environmentData.get('Hello'));  // Prints 'World!'.
+}
+```
+
 ## `worker.isMainThread`
 <!-- YAML
 added: v10.5.0
@@ -176,32 +205,6 @@ if (isMainThread) {
 }
 ```
 
-## `worker.platformData`
-<!-- YAML
-added: REPLACEME
--->
-
-An arbitrary JavaScript value that contains a clone of the data passed
-to the spawning threads `worker.setPlatformData()` function. The
-`worker.platformData` is similar to `worker.workerData` except that
-every new `Worker` receives it's own copy of `platformData` automatically.
-
-```js
-const {
-  Worker,
-  isMainThread,
-  setPlatformData,
-  platformData
-} = require('worker_threads');
-
-if (isMainThread) {
-  setPlatformData('Hello World!');
-  const worker = new Worker(__filename);
-} else {
-  console.log(platformData);  // Prints 'Hello, world!'.
-}
-```
-
 ## `worker.receiveMessageOnPort(port)`
 <!-- YAML
 added: v12.3.0
@@ -268,19 +271,25 @@ new Worker('process.env.SET_IN_WORKER = "foo"', { eval: true, env: SHARE_ENV })
   });
 ```
 
-## `worker.setPlatformData(value)`
+## `worker.setEnvironmentData(key[, value])`
 <!--YAML
 added: REPLACEME
 -->
 
+> Stability: 1 - Experimental
+
+* `key` {any} Any arbitrary, cloneable JavaScript value that can be used as a
+  {Map} key.
 * `value` {any} Any arbitrary, cloneable JavaScript value that will be cloned
-  and passed automatically to all new `Worker` instances.
+  and passed automatically to all new `Worker` instances. If `value` is passed
+  as `undefined`, any previously set value for the `key` will be deleted.
 
-The `worker.setPlatformData()` API sets the value of the `worker.platformData`
-in all new `Worker` instances spawned from the current context.
+The `worker.setEnvironmentData()` API sets the content of the
+`worker.environmentData` in all new `Worker` instances spawned from the current
+context.
 
-Calling `worker.setPlatformData()` will have no impact on the value of
-`worker.platformData` on existing threads.
+Calling `worker.setEnvironmentData()` will have no impact on the value of
+`worker.environmentData` on existing threads.
 
 ## `worker.threadId`
 <!-- YAML

lib/internal/main/worker_thread.js

@@ -105,7 +105,7 @@ port.on('message', (message) => {
       filename,
       doEval,
       workerData,
-      platformData,
+      environmentData,
       publicPort,
       manifestSrc,
       manifestURL,
@@ -131,7 +131,7 @@ port.on('message', (message) => {
     }
     publicWorker.parentPort = publicPort;
     publicWorker.workerData = workerData;
-    publicWorker.platformData = platformData;
+    publicWorker.environmentData = environmentData;
 
     // The counter is only passed to the workers created by the main thread, not
     // to workers created by other workers.

lib/internal/worker.js

@@ -18,6 +18,7 @@ const {
   ReflectApply,
   RegExpPrototypeTest,
   SafeArrayIterator,
+  SafeMap,
   String,
   Symbol,
   SymbolFor,
@@ -90,7 +91,7 @@ let debug = require('internal/util/debuglog').debuglog('worker', (fn) => {
 
 let cwdCounter;
 
-let platformData;
+const environmentData = new SafeMap();
 
 if (isMainThread) {
   cwdCounter = new Uint32Array(new SharedArrayBuffer(4));
@@ -101,9 +102,13 @@ if (isMainThread) {
   };
 }
 
-function setPlatformData(value) {
-  platformData = value;
+function setEnvironmentData(key, value) {
+  if (value === undefined)
+    environmentData.delete(key);
+  else
+    environmentData.set(key, value);
 }
+
 class Worker extends EventEmitter {
   constructor(filename, options = {}) {
     super();
@@ -233,7 +238,7 @@ class Worker extends EventEmitter {
       doEval,
       cwdCounter: cwdCounter || workerIo.sharedCwdCounter,
       workerData: options.workerData,
-      platformData,
+      environmentData,
       publicPort: port2,
       manifestURL: getOptionValue('--experimental-policy') ?
         require('internal/process/policy').url :
@@ -499,7 +504,7 @@ module.exports = {
   SHARE_ENV,
   resourceLimits:
     !isMainThread ? makeResourceLimits(resourceLimitsRaw) : {},
-  setPlatformData,
+  setEnvironmentData,
   threadId,
   Worker,
 };

lib/worker_threads.js

@@ -4,7 +4,7 @@ const {
   isMainThread,
   SHARE_ENV,
   resourceLimits,
-  setPlatformData,
+  setEnvironmentData,
   threadId,
   Worker
 } = require('internal/worker');
@@ -34,7 +34,7 @@ module.exports = {
   Worker,
   parentPort: null,
   workerData: null,
-  platformData: null,
+  environmentData: null,
   BroadcastChannel,
-  setPlatformData,
+  setEnvironmentData,
 };

test/parallel/test-worker-environmentdata.js

@@ -0,0 +1,28 @@
+'use strict';
+
+require('../common');
+const {
+  Worker,
+  isMainThread,
+  environmentData,
+  setEnvironmentData,
+} = require('worker_threads');
+
+const {
+  deepStrictEqual,
+  strictEqual,
+} = require('assert');
+
+if (isMainThread) {
+  setEnvironmentData('foo', 'bar');
+  setEnvironmentData('hello', { value: 'world' });
+  setEnvironmentData(1, 2);
+  setEnvironmentData(1); // Delete it, key won't show up in the worker.
+  strictEqual(environmentData, null);
+  new Worker(__filename);
+  setEnvironmentData('hello');  // Delete it. Has no impact on the worker.
+} else {
+  strictEqual(environmentData.get('foo'), 'bar');
+  deepStrictEqual(environmentData.get('hello'), { value: 'world' });
+  strictEqual(environmentData.get(1), undefined);
+}