fix: Telemetry hanging after prefab.close()

.github/workflows/test.yaml

@@ -25,6 +25,12 @@ jobs:
         with:
           node-version: ${{ matrix.node-version }}
 
+      # We use this for a single test that runs Bun for a subprocess
+      - name: Install Bun
+        uses: oven-sh/setup-bun@v1
+        with:
+          bun-version: latest
+
       - run: npm ci
       - run: npm run build --if-present
 

.gitignore

@@ -2,3 +2,4 @@ node_modules
 .eslintcache
 dist
 .envrc
+src/__tests__/temp-test.ts

src/__tests__/prefab.test.ts

@@ -1,5 +1,7 @@
 import * as path from "path";
 import Long from "long";
+import fs from "fs";
+import { spawn } from "child_process";
 
 import basicConfig from "./fixtures/basicConfig";
 import { DEFAULT_SOURCES } from "../sources";
@@ -1158,4 +1160,56 @@ describe("prefab", () => {
       expect(prefab.get(secret.key)).toEqual(clearText);
     });
   });
+
+  describe("closing behavior", () => {
+    // NOTE: for ease of running the subprocess, we use Bun here.
+    // https://bun.sh/docs/installation
+    it("closes the prefab when the resolver is closed", async () => {
+      const testFile = path.join(__dirname, "temp-test.ts");
+      const testCode = `
+import { Prefab } from "../prefab";
+
+(async () => {
+  const prefab = new Prefab({
+    apiKey: "${validApiKey}",
+  });
+  await prefab.init();
+  const value = prefab.get("abc");
+  console.log(\`ABC is \${value}\`);
+  prefab.close();
+})();
+`;
+      fs.writeFileSync(testFile, testCode);
+
+      const startTime = Date.now();
+      const subprocess = spawn("bun", ["run", testFile]);
+
+      let output = "";
+      let errorOutput = "";
+
+      subprocess.stdout.on("data", (data: Buffer) => {
+        output += data.toString();
+      });
+
+      subprocess.stderr.on("data", (data: Buffer) => {
+        errorOutput += data.toString();
+      });
+
+      await new Promise<void>((resolve) => {
+        subprocess.on("close", () => {
+          resolve();
+        });
+      });
+
+      const duration = Date.now() - startTime;
+      fs.unlinkSync(testFile);
+
+      if (errorOutput.length > 0) {
+        console.error("Subprocess stderr:", errorOutput);
+      }
+
+      expect(output.trim()).toEqual("ABC is true");
+      expect(duration).toBeLessThan(3000);
+    });
+  });
 });

src/prefab.ts

@@ -458,6 +458,18 @@ class Prefab implements PrefabInterface {
     if (this.pollTimeout !== undefined && this.pollTimeout !== null) {
       this.pollTimeout.unref();
     }
+
+    // Clear all telemetry timeouts
+    Object.values(this.telemetry).forEach((telemetryComponent) => {
+      // First disable the component
+      telemetryComponent.enabled = false;
+      // Then clear its timeout
+      if (telemetryComponent.timeout !== undefined) {
+        clearTimeout(telemetryComponent.timeout);
+        telemetryComponent.timeout = undefined;
+      }
+    });
+
     this.running = false;
   }
 }

src/telemetry/reporter.ts

@@ -5,9 +5,19 @@ import type { Telemetry } from "./types";
 export const now = (): Long => Long.fromNumber(Date.now());
 
 const syncTelemetry = (telemetry: Telemetry, backoff: Backoff): void => {
+  // Exit early if telemetry is disabled
+  if (!telemetry.enabled) {
+    return;
+  }
+
   const delay = backoff.call();
 
   telemetry.timeout = setTimeout(() => {
+    // Check if telemetry is still enabled before attempting to sync
+    if (!telemetry.enabled) {
+      return;
+    }
+
     telemetry.sync().finally(() => {
       syncTelemetry(telemetry, backoff);
     });