1 files changed, 89 insertions, 0 deletions
diff --git a/ext/node/polyfills/diagnostics_channel.ts b/ext/node/polyfills/diagnostics_channel.ts
new file mode 100644
index 000000000..c0918e4e2
--- /dev/null
+++ b/ext/node/polyfills/diagnostics_channel.ts
@@ -0,0 +1,89 @@
+// Copyright 2018-2023 the Deno authors. All rights reserved. MIT license.
+import { ERR_INVALID_ARG_TYPE } from "internal:deno_node/polyfills/internal/errors.ts";
+import { validateFunction } from "internal:deno_node/polyfills/internal/validators.mjs";
+import { nextTick } from "internal:deno_node/polyfills/process.ts";
+
+type Subscriber = (message: unknown, name?: string) => void;
+
+export class Channel {
+  _subscribers: Subscriber[];
+  name: string;
+  constructor(name: string) {
+    this._subscribers = [];
+    this.name = name;
+  }
+
+  publish(message: unknown) {
+    for (const subscriber of this._subscribers) {
+      try {
+        subscriber(message, this.name);
+      } catch (err) {
+        nextTick(() => {
+          throw err;
+        });
+      }
+    }
+  }
+
+  subscribe(subscription: Subscriber) {
+    validateFunction(subscription, "subscription");
+
+    this._subscribers.push(subscription);
+  }
+
+  unsubscribe(subscription: Subscriber) {
+    if (!this._subscribers.includes(subscription)) {
+      return false;
+    }
+
+    this._subscribers.splice(this._subscribers.indexOf(subscription), 1);
+
+    return true;
+  }
+
+  get hasSubscribers() {
+    return this._subscribers.length > 0;
+  }
+}
+
+const channels: Record<string, Channel> = {};
+
+export function channel(name: string) {
+  if (typeof name !== "string" && typeof name !== "symbol") {
+    throw new ERR_INVALID_ARG_TYPE("channel", ["string", "symbol"], name);
+  }
+
+  if (!Object.hasOwn(channels, name)) {
+    channels[name] = new Channel(name);
+  }
+
+  return channels[name];
+}
+
+export function hasSubscribers(name: string) {
+  if (!Object.hasOwn(channels, name)) {
+    return false;
+  }
+
+  return channels[name].hasSubscribers;
+}
+
+export function subscribe(name: string, subscription: Subscriber) {
+  const c = channel(name);
+
+  return c.subscribe(subscription);
+}
+
+export function unsubscribe(name: string, subscription: Subscriber) {
+  const c = channel(name);
+
+  return c.unsubscribe(subscription);
+}
+
+export default {
+  channel,
+  hasSubscribers,
+  subscribe,
+  unsubscribe,
+  Channel,
+};