feat: allow running JavaScript workers with async methods

vmware-labs · May 29, 2023 · ec2fc6f · ec2fc6f
1 parent a948002
commit ec2fc6f
Show file tree

Hide file tree

Showing 5 changed files with 88 additions and 9 deletions.
diff --git a/examples/js-async/index.js b/examples/js-async/index.js
@@ -0,0 +1,52 @@
+// Using an async function to reply!
+async function handle(request) {
+  if (request.method != "GET") {
+    // Don't allow other methods.
+    // Here you can see how to return a custom status
+    return new Response("Method not allowed", {
+      status: 405
+    });
+  }
+
+  // Body response
+  const body = `<!DOCTYPE html>
+<head>
+  <title>Wasm Workers Server</title>
+  <meta name="viewport" content="width=device-width,initial-scale=1">
+  <meta charset="UTF-8">
+  <link rel="stylesheet" href="https://cdn.jsdelivr.net/npm/water.css@2/out/water.css">
+  <style>
+    body { max-width: 1000px; }
+    main { margin: 5rem 0; }
+    h1, p { text-align: center; }
+    h1 { margin-bottom: 2rem; }
+    pre { font-size: .9rem; }
+    pre > code { padding: 2rem; }
+    p { margin-top: 2rem; }
+  </style>
+</head>
+<body>
+  <main>
+    <h1>Hello from Wasm Workers Server 👋</h1>
+    <pre><code>Replying to ${request.url}
+Method: ${request.method}
+User Agent: ${request.headers.get("user-agent")}
+Payload: ${request.body || "-"}</code></pre>
+    <p>
+      This page was generated by a JavaScript (async worker) file running in WebAssembly.
+    </p>
+  </main>
+</body>`;
+
+  // Build a new response
+  let response = new Response(body);
+
+  // Add a new header
+  response.headers.set("x-generated-by", "wasm-workers-server");
+
+  return response;
+}
+
+addEventListener('fetch', event => {
+  event.respondWith(handle(event.request));
+});
diff --git a/kits/javascript/src/glue.js b/kits/javascript/src/glue.js
@@ -128,13 +128,25 @@ const requestToHandler = input => {
 
   handlerFunction(event);
 
-  return {
-    data: event.response.body,
-    headers: event.response.headers.headers,
-    status: event.response.status,
-    kv: Cache.state
-  };
+  // Always convert event.response to a Promise
+  Promise.resolve(
+    event.response
+  ).then(res => {
+    // Set the result in the global value
+    result = {
+      data: res.body,
+      headers: res.headers.headers,
+      status: res.status,
+      kv: Cache.state
+    };
+  })
+  .catch((err) => {
+    throw new Error(`Error getting the response in the worker: ${err}`);
+  });
 };
 
 // This is the entrypoint for the project.
-entrypoint = requestToHandler;
+entrypoint = requestToHandler;
+
+// Set the result
+result = {};
diff --git a/kits/javascript/src/main.rs b/kits/javascript/src/main.rs
@@ -37,11 +37,20 @@ fn main() {
     let input_value = json::transcode_input(context, input_bytes).unwrap();
 
     // Run the handler to get the output
-    let output_value = match entrypoint.call(&global, &[input_value]) {
-        Ok(result) => result,
+    match entrypoint.call(&global, &[input_value]) {
+        Ok(_) => {}
         Err(err) => panic!("{}", err.to_string()),
     };
 
+    if context.is_pending() {
+        if let Err(err) = context.execute_pending() {
+            panic!("{}", err.to_string());
+        }
+    }
+
+    let global = context.global_object().unwrap();
+    let output_value = global.get_property("result").unwrap();
+
     let output = json::transcode_output(output_value).unwrap();
 
     stdout()

diff --git a/kits/javascript/wasm-workers-quick-js-engine.wasm b/kits/javascript/wasm-workers-quick-js-engine.wasm
diff --git a/tests/e2e.rs b/tests/e2e.rs
@@ -124,6 +124,12 @@ mod test {
                 "http://localhost:8080",
                 "This page was generated by a JavaScript file",
             ),
+            (
+                "js-async",
+                global_timeout.unwrap_or(5),
+                "http://localhost:8080",
+                "This page was generated by a JavaScript (async worker) file",
+            ),
             (
                 "js-json",
                 global_timeout.unwrap_or(5),