add UUID fallback

packages/core/src/Fiber.ts

@@ -1,4 +1,5 @@
 import * as BehaviorSubject from "./BehaviorSubject.js";
+import * as UUID from "./UUID.js";
 
 export { Fiber as t };
 
@@ -35,7 +36,7 @@ export class Fiber {
     /**
      * A unique identifier for this fiber.
      */
-    public readonly id: string = crypto.randomUUID()
+    public readonly id: string = UUID.v4()
   ) {
     table.set(id, this);
   }

packages/core/src/Message.ts

@@ -1,4 +1,5 @@
 import * as JsObject from "./JsObject.js";
+import * as UUID from "./UUID.js";
 
 /**
  * Flattens an intersection type into a single type.
@@ -89,7 +90,7 @@ export type CallFunction<Args> = FlattenIntersection<
 export const CallFunction = <Args>({
   address,
   args,
-  id = crypto.randomUUID(),
+  id = UUID.v4(),
   noReply = false,
   path
 }: {
@@ -122,7 +123,7 @@ export type Error<Error> = FlattenIntersection<
 export const Error = <T>({
   address,
   error,
-  id = crypto.randomUUID()
+  id = UUID.v4()
 }: {
   address: string;
   error: T;
@@ -147,7 +148,7 @@ export type GarbageCollect = FlattenIntersection<
  */
 export const GarbageCollect = ({
   address,
-  id = crypto.randomUUID()
+  id = UUID.v4()
 }: {
   address: string;
   id?: string;
@@ -171,7 +172,7 @@ export type SetValue<Value> = FlattenIntersection<
  */
 export const SetValue = <T>({
   address,
-  id = crypto.randomUUID(),
+  id = UUID.v4(),
   value
 }: {
   address: string;

packages/core/src/PubSub.ts

@@ -39,19 +39,21 @@ export function from<T>(observable: Observable.ObservableLike<T>): PubSub<T> {
       observer: AsyncObserver<T> | ((value: T) => Promise<void>)
     ) => {
       const metadata = Metadata.get(observer);
+      const agent = metadata && Fiber.get(metadata.clientAgentId);
       const subscription = observable.subscribe(observer);
 
-      if (metadata) {
-        Fiber.get(metadata.clientAgentId)?.stateChange.subscribe((state) => {
-          switch (state) {
-            case Fiber.State.Terminated:
-              subscription.unsubscribe();
-          }
-        });
-      }
+      const innerSubscription = agent?.stateChange.subscribe((state) => {
+        switch (state) {
+          case Fiber.State.Terminated:
+            subscription.unsubscribe();
+        }
+      });
 
       return {
-        unsubscribe: async () => subscription.unsubscribe()
+        unsubscribe: async () => {
+          innerSubscription?.unsubscribe();
+          subscription.unsubscribe();
+        }
       };
     }
   };

packages/core/src/Session.ts

@@ -11,6 +11,7 @@ import * as ServerAgent from "./ServerAgent.js";
 import * as Subject from "./Subject.js";
 import * as Subprotocol from "./Subprotocol.js";
 import * as Supervisor from "./Supervisor.js";
+import * as UUID from "./UUID.js";
 
 export { Session as t };
 
@@ -113,7 +114,7 @@ export abstract class Session<
   protected createServer(
     this: Session,
     provide: unknown,
-    address: string = crypto.randomUUID()
+    address: string = UUID.v4()
   ): ServerAgent.t {
     const serverAgent = ServerAgent.init({
       address,

packages/core/src/UUID.test.ts

@@ -0,0 +1,9 @@
+import { expect, test } from "bun:test";
+
+import * as UUID from "./UUID.js";
+
+test("generating a v4 UUID", () => {
+  expect(UUID.v4()).toEqual(
+    expect.stringMatching(/\w{8}-\w{4}-\w{4}-\w{4}-\w{12}/)
+  );
+});

packages/core/src/UUID.ts

@@ -0,0 +1,29 @@
+function hex(bits: number) {
+  if (bits > 53) throw new Error("bits must be less than or equal to 53");
+
+  return Math.floor(Math.random() * (2 ** bits - 1))
+    .toString(16)
+    .padStart(Math.ceil(bits / 4), "0");
+}
+
+/**
+ * Generates a v4 UUID. This implementation generates exactly 122 bits of random
+ * data and concatenates the version and variant.
+ *
+ * @see https://datatracker.ietf.org/doc/html/rfc9562#name-uuid-version-4
+ */
+function v4Fallback(): string {
+  const a = hex(48);
+  const b = hex(12);
+  const c = `${hex(31)}${hex(31)}`;
+
+  return `${a.slice(0, 8)}-${a.slice(8)}-4${b}-a${c.slice(0, 3)}-${c.slice(
+    3,
+    15
+  )}`;
+}
+
+export const v4 =
+  typeof crypto !== "undefined" && typeof crypto.randomUUID !== "undefined"
+    ? crypto.randomUUID.bind(crypto)
+    : v4Fallback;