Run user-supplied regexes in worker threads with a timeout

backend/src/regExpRunners.ts

@@ -0,0 +1,37 @@
+import { RegExpRunner } from "./RegExpRunner";
+
+interface RunnerInfo {
+  users: number;
+  runner: RegExpRunner;
+}
+
+const runners: Map<string, RunnerInfo> = new Map();
+
+export function getRegExpRunner(key: string) {
+  if (!runners.has(key)) {
+    const runner = new RegExpRunner();
+    runners.set(key, {
+      users: 0,
+      runner,
+    });
+  }
+
+  const info = runners.get(key);
+  info.users++;
+
+  return info.runner;
+}
+
+export function discardRegExpRunner(key: string) {
+  if (!runners.has(key)) {
+    throw new Error(`No runners with key ${key}, cannot discard`);
+  }
+
+  const info = runners.get(key);
+  info.users--;
+
+  if (info.users <= 0) {
+    info.runner.dispose();
+    runners.delete(key);
+  }
+}