Allow omitting name while creating dynamic workers

src/workerd/api/worker-loader-test.js

@@ -510,7 +510,21 @@ export let isolateUniqueness = {
     assert.strictEqual(await anonymousAgain.increment(), 2);
     assert.strictEqual(await anonymousAgain.increment(), 3);
 
-    assert.strictEqual(loadCount, 5);
+    // Test that null/undefined name parameter creates unique isolates each time
+    // Each call should generate a unique name internally.
+    let noName1 = env.loader.get(null, loadCodeCallback).getEntrypoint();
+    let noName2 = env.loader.get(undefined, loadCodeCallback).getEntrypoint();
+    let noName3 = env.loader.get(undefined, loadCodeCallback).getEntrypoint();
+
+    // Each should be a different isolate
+    assert.strictEqual(await noName1.increment(), 0);
+    assert.strictEqual(await noName1.increment(), 1);
+    assert.strictEqual(await noName2.increment(), 0);
+    assert.strictEqual(await noName2.increment(), 1);
+    assert.strictEqual(await noName3.increment(), 0);
+    assert.strictEqual(await noName3.increment(), 1);
+
+    assert.strictEqual(loadCount, 8);
   },
 };
 

src/workerd/api/worker-loader.c++

@@ -59,7 +59,7 @@ jsg::Ref<DurableObjectClass> WorkerStub::getDurableObjectClass(jsg::Lock& js,
 }
 
 jsg::Ref<WorkerStub> WorkerLoader::get(
-    jsg::Lock& js, kj::String name, jsg::Function<jsg::Promise<WorkerCode>()> getCode) {
+    jsg::Lock& js, kj::Maybe<kj::String> name, jsg::Function<jsg::Promise<WorkerCode>()> getCode) {
   auto& ioctx = IoContext::current();
 
   auto reenterAndGetCode = ioctx.makeReentryCallback(

src/workerd/api/worker-loader.h

@@ -125,7 +125,7 @@ class WorkerLoader: public jsg::Object {
   };
 
   jsg::Ref<WorkerStub> get(
-      jsg::Lock& js, kj::String name, jsg::Function<jsg::Promise<WorkerCode>()> getCode);
+      jsg::Lock& js, kj::Maybe<kj::String> name, jsg::Function<jsg::Promise<WorkerCode>()> getCode);
 
   JSG_RESOURCE_TYPE(WorkerLoader) {
     JSG_METHOD(get);

src/workerd/io/io-channels.h

@@ -245,11 +245,9 @@ class IoChannelFactory {
     KJ_UNIMPLEMENTED("Only implemented by single-tenant workerd runtime");
   }
 
-  // Use a dynamic Worker loader binding to obtain an Worker by name. If the named Worker
-  // doesn't already exist, the callback will be called to fetch the source code from which the
-  // Worker should be created.
+  // Use a dynamic Worker loader binding to obtain an Worker by name. If name is null, or if the named Worker doesn't already exist, the callback will be called to fetch the source code from which the Worker should be created.
   virtual kj::Own<WorkerStubChannel> loadIsolate(uint loaderChannel,
-      kj::String name,
+      kj::Maybe<kj::String> name,
       kj::Function<kj::Promise<DynamicWorkerSource>()> fetchSource) {
     JSG_FAIL_REQUIRE(Error, "Dynamic worker loading is not supported by this runtime.");
   }

src/workerd/server/server.c++

@@ -3321,7 +3321,7 @@ class Server::WorkerService final: public Service,
   }
 
   kj::Own<WorkerStubChannel> loadIsolate(uint loaderChannel,
-      kj::String name,
+      kj::Maybe<kj::String> name,
       kj::Function<kj::Promise<DynamicWorkerSource>()> fetchSource) override;
 
   // ---------------------------------------------------------------------------
@@ -3865,19 +3865,24 @@ class Server::WorkerLoaderNamespace: public kj::Refcounted {
   }
 
   kj::Own<WorkerStubChannel> loadIsolate(
-      kj::String name, kj::Function<kj::Promise<DynamicWorkerSource>()> fetchSource) {
-    return isolates
-        .findOrCreate(name,
-            [&]() -> decltype(isolates)::Entry {
-      // This name isn't actually used in any maps nor is it ever revealed back to the app, but it
-      // may be used in error logs.
-      auto isolateName = kj::str(namespaceName, ':', name);
-
-      return {.key = kj::mv(name),
-        .value = kj::rc<WorkerStubImpl>(server, kj::mv(isolateName), kj::mv(fetchSource))};
-    })
-        .addRef()
-        .toOwn();
+      kj::Maybe<kj::String> name, kj::Function<kj::Promise<DynamicWorkerSource>()> fetchSource) {
+    KJ_IF_SOME(n, name) {
+      return isolates
+          .findOrCreate(n,
+              [&]() -> decltype(isolates)::Entry {
+        // This name isn't actually used in any maps nor is it ever revealed back to the app, but it
+        // may be used in error logs.
+        auto isolateName = kj::str(namespaceName, ':', n);
+
+        return {.key = kj::mv(n),
+          .value = kj::rc<WorkerStubImpl>(server, kj::mv(isolateName), kj::mv(fetchSource))};
+      })
+          .addRef()
+          .toOwn();
+    } else {
+      auto isolateName = kj::str(namespaceName, ":dynamic:", randomUUID(server.entropySource));
+      return kj::rc<WorkerStubImpl>(server, kj::mv(isolateName), kj::mv(fetchSource)).toOwn();
+    }
   }
 
  private:
@@ -3916,6 +3921,10 @@ class Server::WorkerLoaderNamespace: public kj::Refcounted {
         kj::Function<kj::Promise<DynamicWorkerSource>()> fetchSource)
         : startupTask(start(server, kj::mv(isolateName), kj::mv(fetchSource)).fork()) {}
 
+    ~WorkerStubImpl() {
+      unlink();
+    }
+
     void unlink() {
       KJ_IF_SOME(s, service) {
         s->unlink();
@@ -4147,7 +4156,7 @@ void Server::unlinkWorkerLoaders() {
 }
 
 kj::Own<WorkerStubChannel> Server::WorkerService::loadIsolate(uint loaderChannel,
-    kj::String name,
+    kj::Maybe<kj::String> name,
     kj::Function<kj::Promise<DynamicWorkerSource>()> fetchSource) {
   auto& channels =
       KJ_REQUIRE_NONNULL(ioChannels.tryGet<LinkedIoChannels>(), "link() has not been called");

types/generated-snapshot/experimental/index.d.ts

@@ -4112,7 +4112,7 @@ interface WorkerStubEntrypointOptions {
 }
 interface WorkerLoader {
   get(
-    name: string,
+    name: string | null,
     getCode: () => WorkerLoaderWorkerCode | Promise<WorkerLoaderWorkerCode>,
   ): WorkerStub;
 }

types/generated-snapshot/experimental/index.ts

@@ -4125,7 +4125,7 @@ export interface WorkerStubEntrypointOptions {
 }
 export interface WorkerLoader {
   get(
-    name: string,
+    name: string | null,
     getCode: () => WorkerLoaderWorkerCode | Promise<WorkerLoaderWorkerCode>,
   ): WorkerStub;
 }

types/generated-snapshot/latest/index.d.ts

@@ -3832,7 +3832,7 @@ interface WorkerStubEntrypointOptions {
 }
 interface WorkerLoader {
   get(
-    name: string,
+    name: string | null,
     getCode: () => WorkerLoaderWorkerCode | Promise<WorkerLoaderWorkerCode>,
   ): WorkerStub;
 }

types/generated-snapshot/latest/index.ts

@@ -3843,7 +3843,7 @@ export interface WorkerStubEntrypointOptions {
 }
 export interface WorkerLoader {
   get(
-    name: string,
+    name: string | null,
     getCode: () => WorkerLoaderWorkerCode | Promise<WorkerLoaderWorkerCode>,
   ): WorkerStub;
 }