init

web/worker.js

@@ -0,0 +1,58 @@
+'use strict';
+
+// Web Worker that hosts the sing-vis WebAssembly engine. It loads the Go runtime
+// shim + singvis.wasm, keeps the Go program alive, and forwards analyze requests
+// to the JS-exported `singvisAnalyze`. Running in a worker keeps the wasm work
+// (DoH resolution, rule-set fetching, matching) off the UI thread.
+//
+// Message protocol:
+//   main → worker:  { id, request }   request = the analyze payload
+//   worker → main:  { id, result }    on success (result = parsed engine.Result)
+//                   { id, error }     on failure (error = message string)
+//                   { type:'ready' }  once the wasm engine is initialized
+//                   { type:'loaderror', error } if the wasm failed to load
+
+importScripts('wasm_exec.js');
+
+// Resolved by the Go program (via the `singvisReady` callback it invokes in main)
+// once `singvisAnalyze` has been registered on the global scope.
+let signalStarted;
+const started = new Promise((resolve) => { signalStarted = resolve; });
+globalThis.singvisReady = () => signalStarted();
+
+const ready = (async () => {
+  const go = new Go();
+  let instance;
+  try {
+    // Preferred path; requires the server to send Content-Type: application/wasm.
+    const res = await WebAssembly.instantiateStreaming(fetch('singvis.wasm'), go.importObject);
+    instance = res.instance;
+  } catch (streamErr) {
+    // Fallback for static servers that don't set the wasm MIME type.
+    const resp = await fetch('singvis.wasm');
+    if (!resp.ok) throw new Error('failed to load singvis.wasm (HTTP ' + resp.status + ')');
+    const bytes = await resp.arrayBuffer();
+    const res = await WebAssembly.instantiate(bytes, go.importObject);
+    instance = res.instance;
+  }
+  // Do NOT await: the Go main blocks forever (select{}) to keep serving calls.
+  go.run(instance);
+  await started;
+})();
+
+ready.then(
+  () => self.postMessage({ type: 'ready' }),
+  (err) => self.postMessage({ type: 'loaderror', error: (err && err.message) || String(err) })
+);
+
+self.onmessage = async (e) => {
+  const data = e.data || {};
+  if (data.id == null) return;
+  try {
+    await ready;
+    const out = await globalThis.singvisAnalyze(JSON.stringify(data.request || {}));
+    self.postMessage({ id: data.id, result: JSON.parse(out) });
+  } catch (err) {
+    self.postMessage({ id: data.id, error: (err && err.message) || String(err) });
+  }
+};